Papers for Wednesday, Sep 03 2025

Extracting cosmological information from microwave sky observations requires accurate estimation of the underlying Cosmic Microwave Background (CMB) by removing foreground contamination, instrumental noise, and the effects of beam convolution. In this work, we develop a machine learning-based approach for CMB reconstruction using a generative adversarial network (GAN) architecture, where the generator is modeled as a U-Net-based convolutional neural network. To train the network, we generate realistic microwave sky maps by simulating Planck-like observations: scanning HEALPix-simulated skies with real Planck beam profile, actual scan patterns, and anisotropic noise consistent with Planck data. Our method achieves high-fidelity reconstruction, with the difference between the input and recovered maps being less than $2\mu\mathrm{K}$ (approximately $1\%$) outside the Galactic region. Even within the Galactic plane, the reconstruction error remains below $2-3\%$ in most areas, except for a few isolated pixels. Most importantly, we demonstrate for the first time that a GAN-based method can effectively correct for both foreground contamination and the systematic effects of non-circular beams and the asymmetric Planck scan pattern. Our results demonstrate the effectiveness of our method for robust and accurate recovery of the CMB signal, even in the presence of strong astrophysical foregrounds and instrumental systematics.

We present an accelerated calibration framework for semi-analytic galaxy formation models, demonstrated with Galacticus. Rather than fitting directly to properties such as the low-redshift stellar mass function (SMF) - which requires evolving thousands of halos per likelihood evaluation - we construct a fast likelihood from the stellar-to-halo mass relation (SHMR; mean and scatter) evaluated at a small set of target halo masses, reducing each evaluation to simulating only tens of galaxies. We sample the posterior over Galacticus parameters with Markov Chain Monte Carlo and show that the resulting calibration reproduces the low-redshift SMF. We then extend the method to additional datasets, using a higher-redshift SHMR and the low-redshift stellar mass-size relation as examples, and assess performance for large scale structure survey-relevant properties: stellar masses, sizes, and emission-line strengths. The SMF matches data well at low redshift, but toward higher redshift the model yields too few massive galaxies and too many low-mass galaxies. Size evolution with redshift is approximately correct, but the mass-size relation is too flat, producing massive galaxies that are too small. The H$\alpha$ luminosity function is well reproduced at z~2, but by z~0.4 the model overproduces highly star-forming, H$\alpha$-bright systems. These discrepancies suggest the model lacks sufficient flexibility (e.g. in gas cooling/recycling or feedback) to reconcile all datasets simultaneously. Our strategy complements emulator-based methods for calibrating semi-analytic models by enabling rapid, low-cost scans of model choices and parameterisations - a capability we envision leveraging to supply calibrated starting points for more detailed follow-up inference.

In this paper, we analyze James Webb Space Telescope Near Infrared Imager and Slitless Spectrograph time-series spectroscopy data to characterize the atmosphere of the planetary-mass brown dwarf SIMP J01365662+093347. Principal component analysis reveals that 81\% of spectral variations can be described by two components, implying that variability within a single rotational phase is induced by at least three distinct spectral regions. By comparing our data to a grid of Sonora Diamondback atmospheric models, we confirm that the time-averaged spectrum cannot be explained by a single model but require a linear combination of at least three regions. Projecting these models onto the principal component plane shows that the overall variability is highly correlated with changes in temperature, cloud coverage, and possibly effective metallicity. We also extract brightness maps from the lightcurve and establish North-South asymmetry in the atmosphere. A combined multidimensional analysis of spectro-photometric variability links the three spectral regions to three atmospheric layers. Forsterite cloud and water abundance at each level form unique harmonics of atmospheric variability observed in different spectral bands. Atmospheric retrievals on the time-averaged spectrum are consistent with an optically thick iron cloud deck beneath a patchy forsterite cloud layer and with the overall adiabatic curve. We also demonstrate two new analysis methods: a regionally-resolved spectra retrieval that relies on multi-wavelength spherical harmonics maps, and a method to constrain brightness maps using Doppler information present in the spectra. Future observations of variable brown dwarfs of higher spectral resolution or spanning multiple rotations should help break mapping degeneracy.

We present ProMage, a feed-forward neural network that emulates the computation of observer- and rest-frame magnitudes from the generative galaxy SED package ProSpect. The network predicts magnitudes conditioned on input galaxy physical properties, including redshift, star formation history, gas and dust parameters. ProMage accelerates magnitude computation by a factor of $10^4$ compared to ProSpect, while achieving per-mille relative accuracy for $99\%$ of sources in the test set across the $g,r,i,z,y$ Hyper Suprime-Cam bands. This acceleration is key to enabling fast inference of galaxy physical properties in next-generation Stage IV surveys and to generating large catalogue realisations in forward-modelling frameworks such as GalSBI-SPS.

Ultra-hot Jupiters like WASP-121b provide unique laboratories for studying atmospheric chemistry and dynamics under extreme irradiation. Constraining their composition and circulation is key to tracing planet formation pathways. We present a comprehensive characterisation of WASP-121b using high-resolution transit spectroscopy from HARPS, NIRPS, and CRIRES+ across nine transits, complemented by five TESS sectors, two EulerCam light curves simultaneous with HARPS/NIRPS, and an extensive RV dataset refining orbital parameters. Cross-correlation detects Fe, CO, and V with SNRs of 5.8, 5.0, and 4.7, respectively. Retrieval analysis constrains H$_2$O to $-6.52^{+0.49}_{-0.68}$ dex, though its signal might be muted by the H$^-$ continuum. We measure volatile/refractory ratios, key to uncover planetary chemistry, evolution, and formation. Retrieved values align with solar composition in chemical equilibrium, suggesting minimal disequilibrium chemistry at the probed pressures (around $10^{-4}$-$10^{-3}$ bar). We update WASP-121b's orbital parameters analysing its largest RV dataset to date. Comparing orbital velocities from RVs and atmospheric retrieval reveals a non-zero circulation offset, $\mathrm{\Delta K}_{\mathrm{p}} = -15 \pm 3 \ \mathrm{km}\mathrm{s}^{-1}$ (assuming $\mathrm{M}_{\star} = 1.38 \pm 0.02 \ \mathrm{M}_{\odot}$), consistent with drag-free or weak-drag 3D GCM predictions, though sensitive to stellar mass. These results provide new constraints on WASP-121b's thermal structure, dynamics, and chemistry, underscoring the power of multi-instrument and multi-wavelength high-resolution spectroscopy to probe exoplanet atmospheres.

High-energy gamma rays can trigger electromagnetic cascades via pair production on ambient photons, reprocessing their energy to lower frequencies. A classic example is the cascade from the gamma rays produced by ultra-high-energy cosmic rays in extragalactic photon fields, whose universal spectral shape was first described by Berezinsky in the 1970s. Recently, internal cascades, developing within the gamma-ray sources themselves, have gained a prominent role, as the IceCube data suggest that most detected neutrinos originate in gamma-ray-opaque environments. We analyze under what conditions these internal cascades can approach a universal spectrum. Since the Berezinsky treatment breaks down if synchrotron losses dominate, we present a generalized theory incorporating synchrotron-dominated cascades. We show the emergence of universal cascade spectrum among various examples of high-energy sources containing non-thermal cosmic rays, and discuss the conditions for its appearance.

We present observational evidence that intense ionizing radiation from a luminous quasar suppresses nebular emission in nearby galaxies on intergalactic scales at $z=6.3$. Using JWST/NIRCam grism spectroscopy from the SAPPHIRES and EIGER programs, we identify a pronounced decline in [O III] $\lambda5008$ luminosity relative to the UV continuum ($L_{5008}/L_{1500}$) among galaxies within $\sim$10 comoving Mpc (cMpc) of the quasar J0100$+$2802, the most UV-luminous quasar known at this epoch ($M_{1450}=-29.26$). While $L_{1500}$ remains roughly constant with transverse distance, $L_{5008}$ increases significantly, suggesting suppression of very recent star formation toward the quasar. The effect persists after controlling for completeness, local density, and UV luminosity, and correlates with the projected photoionization-rate profile $\Gamma_{\mathrm{qso}}$. A weaker but directionally consistent suppression in $L_{5008}/L_{1500}$ is also observed along the line of sight. The transverse suppression radius ($\sim$8-10 cMpc) implies a recent radiative episode with a cumulative duration $\sim$4.5 Myr, shorter than required for thermal photoheating to dominate and thus more naturally explained by rapid H$_2$ photodissociation and related radiative processes. Environmental effects alone appear insufficient to explain the signal. Our results provide direct, geometry-based constraints on large-scale quasar radiative feedback and recent quasar lifetimes.

Among the over 200 gravitational wave detections reported so far, GW231123 is a remarkable event that not only holds the record for the most massive black hole merger, but also exhibits extreme spins. Its origin is actively debated. Proposed scenarios include dynamical formation involving a sequence of mergers, Population III stars, accretion in an AGN disk and also more exotic explanations including primordial black holes and cosmic strings, each facing different challenges. Recent work showed that the incoming black holes of GW231123 can be formed out of massive rapidly rotating collapsing helium stars. Here, we address the question how such very massive rapidly rotating helium stars can be formed in very close binary systems. For this we explore chemically homogeneous evolution (CHE) involving progenitors with masses above the pair-instability mass gap. We compute a grid of detailed massive binary models with the stellar evolution code MESA to follow the early evolution of binary progenitors and show that: (i) very massive ($M_i > 140\, M_\odot$) CHE binaries at low metallicity ($Z=10^{-5}$) naturally produce rapidly rotating progenitors with high masses and high spins matching the properties of the black holes in GW231123 and (ii) the maximum spin of the progenitors is bound by their critical rotation rate leading to a tight correlation between the dimensionless spin and mass, $a \propto M^{-0.9}$, in models that have no hydrogen left. We conclude that the CHE channel appears to be a viable and natural scenario to produce progenitors. We compare and discuss the differences with earlier studies and comment on the large uncertainties in the final fate and collapse.

The most pressing problems in modern astrophysics have often required the largest telescopes. With the cost scaling of mirror diameters, the field as a whole is faced with a challenge -- how to replicate or improve on the collecting area and sensitivity of the current generation of ELTs, which already boast 30 m class apertures and are multi-billion dollar facilities. One such approach is being pursued by the Large Fiber Array Spectroscopic Telescope (LFAST) -- a scalable array telescope. Each element of the array will consist of multiple mirrors each feeding to an individual fiber; with those fiber feeds feeding optical and infrared spectrometers. Coupling fiber bundle to spectrometer slit input must be optimized to take full advantage of the photon collecting ability of the telescope array, requiring precise alignment of microlenses to each fiber. Advances in two photon polymerization processes (2PP) now allow for optical quality microlenses with wavefront aberrations as small as $\lambda/20 to be created, opening up the design parameter of bespoke optical design and custom fabricated lenses. We present our approach to tackling these coupling problems with rapid prototyping and detailed quantification of the tolerances of the lenses. Our approach leverages our access to the Nanoscribe GT2 system at Penn State, enabling tests of new optically transparent resins like IPX-Clear to explore multiple design approaches. Our goal is to share our results and enable wider use of these techniques for astronomical applications.

Aims. The analysis of variability of astronomical sources is of extraordinary interest, as it allows the study of astrophysical phenomena in real time. This paper presents the Javalambre Variability Survey (J-VAR) which leverages the narrow band filters available at the Javalambre Auxiliary Survey Telescope (JAST80) at the Observatorio Astrofísico de Javalambre (OAJ). Methods. The JAST80 equipped with T80Cam, providing a field of view of 2\,square degrees and a pixel scale of 0.55\,arcsec/pixel has been designed for wide-field studies. The main characteristic is the availability of a variety of narrow band filters strategically located on stellar spectral features (the $J0395$ in correspondence of the Ca H+K doublet, the $J0515$ of the Mg $b$ triplet, the $J0660$ of the H$\alpha$ line, and the $J0861$ of the Ca~triplet). This project combines, for the first time, the wide-field with a variety of narrow band filters for a unique variability survey, observing each field 11~times with a standardised observing sequence. The median limiting magnitude for individual exposures are 19.1 mag in $J0395$ and $J0515$, $19.6$ mag in $J0660$ and $J0861$, $19.8$ mag in $i$, and $20.2$ in $g$ and $r$. The typical FWHM of the $r$-band images is $1.5$ arcsec. Results. This article introduces the first data release of J-VAR including more than 6000 individual asteroids, 10\,detected optical transients (4\,discovered supernovae), and 1.3 million light curves of point-sources. On average, J-VAR delivers an unprecedented $\sim$5000 light curves per square degree of 11\,epochs in 7\,bands, opening research opportunities for theoretical studies and new discoveries alike.

Galaxy groups and clusters assembled through dynamical interactions of smaller systems, resulting in the formation of a diffuse stellar halo known as the intragroup or intracluster light (IGL/ICL). By preserving the records of these interactions, the IGL/ICL provides valuable insight into the growth history of galaxy groups and clusters. Groups are especially interesting because they represent the link between galactic haloes and massive clusters. However, the low surface brightness of this diffuse light makes it extremely challenging to detect individually. Recent deep wide-field imaging surveys allow us to push such measurements to lower brightness limits by stacking data for large ensembles of groups. In this work, we present a special-purpose pipeline to reprocess individual $r-$band Kilo-Degree Survey (KiDS) exposures to optimise the IGL detection. Using an initial sample of 2385 groups with at least five spectroscopically-confirmed member galaxies from the Galaxy and Mass Assembly (GAMA) survey and reprocessed deep images from the KiDS, we present the first robust measurement of IGL from a large group sample (~ 750) down to 31-32 mag/arcsec$^2$ (varying in different stacked bins). We also compare our stacked IGL measurements to predictions from matched mock observations from the Hydrangea cosmological hydrodynamic simulations. Systematics in the imaging data can affect IGL measurements, even with our special-purpose pipeline. However, with a large sample and optimised analysis, we can place well-constrained upper and lower limits on the IGL fraction (3 - 21 per cent) for our group ensemble across $0.09\leq z\leq 0.27$ and $12.5\leq \log_{10}[M_{200}/\mathrm{M}_\odot] \leq 14.0$. This work explores the potential performance of stacked statistical analysis of diffuse light in large samples of systems from next-generation observational programs, such as $Euclid$ and LSST.

We consider possible observable signals from explosive events in the very early universe, ``bursts". These could be expected in connection with massive black hole or ``baby universe'' formation. We anticipate that such major disruptions of spacetime would be associated with neutrino and perhaps other pulses. While these seem to be not detectable directly, we discuss how they could lead to potentially observable signals. We analyze how the pulses from very early times may ``escape'', that is propagate to the last scattering epoch at the time $t_{cmb}$ and later, or alternatively be absorbed earlier, ``contained''. The possibly detectable signals include effects on small regions of the CMB, a soft x-ray resulting from positron production, or a nonthermal addition to the relic neutrino background.

We describe the scientific objectives and instrument design of the ASPIICS coronagraph launched aboard the Proba-3 mission of the European Space Agency (ESA) on 5 December 2024. Proba-3 consists of two spacecraft in a highly elliptical orbit around the Earth. One spacecraft carries the telescope, and the external occulter is mounted on the second spacecraft. The two spacecraft fly in a precise formation during 6 hours out of 19.63 hour orbit, together forming a giant solar coronagraph called ASPIICS (Association of Spacecraft for Polarimetric and Imaging Investigation of the Corona of the Sun). Very long distance between the external occulter and the telescope (around 144 m) represents an increase of two orders of magnitude compared to classical externally occulted solar coronagraphs. This allows us to observe the inner corona in eclipse-like conditions, i.e. close to the solar limb (down to 1.099 Rs) and with very low straylight. ASPIICS will provide a new perspective on the inner solar corona that will help solve several outstanding problems in solar physics, such as the origin of the slow solar wind and physical mechanism of coronal mass ejections.

Dynamical tides of neutron stars in the late stages of binary inspirals provide a viable probe into dense matter through gravitational waves, and potentially trigger electromagnetic precursors. We model the tidal response as a set of driven harmonic oscillators, where the natural frequencies are given by the quasinormal modes of a nonrotating neutron star. These modes are calculated in general relativity by applying linear perturbation theory to stellar models that include a solid crust and compositional stratification. For the mode spectrum, we find that the canonical interface mode associated with the crust-core boundary vanishes in stratified neutron stars and is replaced by compositional gravity modes with mixed gravity-interfacial character, driven primarily by strong buoyancy in the outer core. We also find that fluid modes such as the core gravity mode and the fundamental mode can penetrate the crust, and we establish a criterion for such penetration. Regarding the tidal interaction, we find that transfer of binding energy to oscillations is dominated by the fundamental mode despite its frequency being too high to resonate with the tidal forcing. In general, we find that lower-frequency modes induce gravitational-wave phase shifts smaller than $\sim 10^{-3},\rm rad$ for the equation of state we consider. We discover that nonresonant fundamental and crustal shear modes can trigger crust breaking already near the first gravity-mode resonance, while gravity-mode resonance concentrates strain at the base of the crust and may marginally crack it. These results suggest that both resonant and nonresonant excitations can overstress the crust and may channel energy into the magnetosphere prior to merger, potentially powering electromagnetic precursors. Our work represents an important step toward realistic modeling of dynamical tides of neutron stars in multimessenger observations.

We present PUCHEROS +, a new spectrograph developed as an enhanced version of PUCHEROS (Pontificia Universidad Catolica High Echelle Resolution Optical Spectrograph), which was the first high-resolution spectrograph built at the Pontificia Universidad Catolica de Chile (UC). With respect to its predecessor, PUCHEROS + includes a substantial number of improvements, mainly: a new scientific detector, improved objective optics, calibration system, guiding, active thermal control, and remote observing mode. These upgrades convert our early prototype into a much more powerful instrument for science. With a spectral resolution of R = 18000, a spectral range between 400 and 730 nm and an instrument efficiency of about 30 per cent, PUCHEROS + was tested at the ESO (European Southern Observatory) 1.52-m telescope where it has reached a limiting magnitude of about 12 in V band and radial velocity precision of about 30 m/s. The instrument was conceived as a pathfinder for the high-resolution echelle spectrograph PLATOSpec and at the same time, it demonstrates that a compact, relatively low-cost spectrograph can be efficiently employed for long-term monitoring campaigns and as support facility for space missions, in particular if operated remotely at relatively small- or medium-sized telescopes.

The radioactive $\beta$-decay of nuclei synthesized in the rapid neutron capture process ($r$-process) releases a variety of particles, including electrons, $\gamma$-rays, neutrinos, and neutrons. These particles provide a rich set of multi-messenger signals that carry information about the astrophysical environments where neutron-rich nucleosynthesis occurs. In this work, we calculate from first principles the emission spectra resulting from the $\beta$-decay of $r$-process nuclei. Our approach incorporates detailed nuclear structure and decay data to model the energy distributions of each particle species. We couple the spectra with a nuclear reaction network simulation to obtain the temporal evolution of these distributions. We find that the emission distributions vary significantly in time and are non-thermal, with substantial average energies. We investigate these nuclear signals as a direct probe of heavy element formation and show that they are complementary observables to kilonova.

The next generation of large telescopes for direct imaging of exoplanets will require segmented primary mirrors. Over both long and short timescales, these telescopes experience segment misalignments which degrade the final science image. Adaptive optics (AO) systems can be used to correct these aberrations in real time. AO systems require wavefront sensors (WFSs) that measure the phase of the incoming light in order to reconstruct optical aberrations. However, most WFSs used for sensing atmospheric turbulence cannot correctly detect aberrations induced by misalignments in segmented telescopes, as they show poor sensitivity to phase discontinuities. We investigate the potential of photonic lanterns (PLs), which are waveguides that allow for the low-loss transmission from multi-mode to multiple single-mode optical signals, for sensing segment misalignments at the focal plane. We assess the ability of PLs to measure piston offsets in segmented mirrors through both simulations and laboratory experiments. We simulate the photonic lantern and demonstrate linear reconstruction on segment pistons. Further, we train a neural network to reconstruct aberrations outside of the linear regime. We experimentally validate reconstruction of segment piston offsets on the Miniature Infrared SEAL (muirSEAL) testbed, which includes a segmented deformable mirror, a PSF imaging branch, and a PL. This work demonstrates the potential of the PL as a compact WFS for future space- and ground-based segmented-mirror telescopes.

Widening cracks are appearing in the $\Lambda$CDM model and it is becoming increasingly clear that the standard cosmological model struggles to describe the full expansion history of the Universe as revealed by the Cosmic Microwave Background, Baryon Acoustic Oscillation measurements, and locally calibrated Type Ia supernovae. Taken at face value, recent results suggest a dark sector that may be more complex than commonly assumed. We must prepare for the possibility of moving beyond the $\Lambda$CDM era, where merely testing $w=-1$ is no longer sufficient, and embrace the challenge of unraveling the physics of dark matter, dark energy and gravity on cosmic scales. Guided by increasingly robust data - secured through considerable investment - we should pursue deeper understanding while being open to complexity in the dark sector, rather than settling for the simplest phenomenology. New data from new facilities and a new dark energy task force could help illuminate the path forward while changes to our scientific practices will be essential to navigate the potentially rocky road ahead.

Magnetic reconnection driving two-sided-loop jet is typically associated with interactions between an emerging bipole and the overlying horizontal magnetic field, or between filaments from separate magnetic systems. Leveraging high temporal and spatial resolution observations from ground-based and space-borne instruments, we have identified a two-sided-loop jet originating from magnetic reconnection between threads within a single filament. Our observations show that as two initially crossing filamentary threads within the filament converge, reconnection takes place at their intersection. In the Doppler images, distinct redshift and blueshift signals are observed at the locations where the filament threads intersected. This process generates a two-sided-loop jet with outflow speeds of \speed{22.2} and \speed{62.5}. Following reconnection, the original crossing threads transform into two parallel threads that subsequently separate at speeds of \speed{2.8} and \speed{8.3}. This observation offers a new perspective on the mechanisms responsible for jet formation.

Binding energy (BE) is a critical parameter in astrochemical modeling, governing the retention of species on interstellar dust grains and their subsequent chemical evolution. However, conventional models often rely on single-valued BEs, overlooking the intrinsic distribution arising from diverse adsorption sites. In this study, we present BEs for monohydric alcohols, thiols, and their plausible precursors, including aldehydes and thioaldehydes. We incorporate a distribution of BEs to capture the realistic variation in adsorption strengths. The quantum chemical calculations provide a range of BE values rather than a single estimate, ensuring a more precise description of molecular diffusion and surface chemistry. The BE trend of analogous species provides qualitative insight into the dominant reaction pathways and key precursors that drive the formation of larger molecules under interstellar conditions. Oxygen-bearing species generally exhibit higher BEs than their sulfur analogues, primarily due to stronger interactions, further influencing molecular adsorption and reactivity. We implemented BE distributions in astrochemical models, revealing significant effects on predicted abundances and establishing a more accurate framework for future astrochemical modeling.

Probable past and future close encounters of open clusters with known characteristics over 64 million years have been calculated by integrating the orbits of cluster centers in the Galactic potential using the _galpy_ package. It has been shown that in the Galactic neighborhood of the Sun, pairwise cluster encounters at distances comparable to or smaller than their sizes occur at a characteristic rate of 35 to 40 events per 1 Myr. Close encounters between open clusters with a significant age difference occur at a rate of 15 events per Myr. It can be expected that in the Galaxy as a whole, such events occur an order of magnitude more frequently per unit time. Thus, dynamical interactions between stellar ensembles of different ages may not be too rare and could influence the properties of stellar populations. A pair of clusters with similar ages: HSC 1428 and Gulliver 22 was identified as a likely physically bound binary cluster system. A forecast of expected close encounters over the next 32 Myr has been provided for 490 pairs of clusters. Currently, 29 pairs of clusters are at their closest approach.

This Note proposes the concept and theory of energy transition domain (ETD) defined by the mechanical energy of spacecraft in the Earth-Moon planar circular restricted three-body problem (PCR3BP) inspired by the pioneering work from Ano{è} et al. (2024) on the ETD defined by the two-body energy with respect to the secordary body in the PCR3BP. An effective construction method of gravity-assist escape trajectories is then proposed. Firstly, the concept of the ETD defined by the mechanical energy is presented, and its dependency on the Jacobi energy is analyzed. This dependency may provide prior knowledge about selecting the range of the Jacobi energy in the construction of escape trajectories. Then, gravity-assist escape trajectories departing from the 167 km low Earth orbit and 36000 km geosynchronous Earth orbit are constructed based on the ETD. The initial states are selected in the sphere of influence of the Moon, and the trajectories are searched from the forward and backward integration. Finally, the obtained solutions are presented and analyzed.

The extreme solar storm of May 10, 2024, during the 25th solar cycle, which recorded a symmetric H component index (Sym-H) reaching -500 nT, was the strongest since the 2003 Halloween storm. This event offered a unique opportunity for unprecedented multipoint observation of the complex interaction of Interplanetary Coronal Mass Ejections (ICME) from different vantage points. Utilizing NASA's Wind, ACE, DSCOVR, THEMIS-C, STEREO-A, MMS, and ISRO's recently launched Aditya-L1 spacecraft, we comprehensively investigated the spatio-temporal variations in interplanetary plasma and magnetic field parameters. Our study reveals large-scale quasi-steady magnetic reconnection within the interior of the ICME flux rope, possibly triggered by interactions between multiple ICMEs. A current sheet (CS) forms within the flux rope, enabling internal magnetic reconnection between concentric magnetic surfaces, which leads to a sharp reversal of the IMF By component, as observed at the L1 point. Concurrently, reconnection exhaust and enhanced electron and ion fluxes were detected with the CS, extending over 200 RE (1.3 million km) along the GSE-y direction. This finding sheds new light on the role of internal reconnection in ICME evolution, highlighting its pivotal role in modifying the morphology of the ICME magnetic structure and exerting severe space weather effects on Earth.

During the second half of Cycle 1 of the James Webb Space Telescope (JWST), we conducted the Parallel Application of Slitless Spectroscopy to Analyze Galaxy Evolution (PASSAGE) program. PASSAGE received the largest allocation of JWST observing time in Cycle 1, 591 hours of NIRISS observations to obtain direct near-IR imaging and slitless spectroscopy. About two thirds of these were ultimately executed, to observe 63 high-latitude fields in Pure Parallel mode. These have provided more than ten thousand near-infrared grism spectrograms of faint galaxies. PASSAGE brings unique advantages in studying galaxy evolution: A) Unbiased spectroscopic search, without prior photometric pre-selection. By including the most numerous galaxies, with low masses and strong emission lines, slitless spectroscopy is the indispensable complement to any pre-targeted spectroscopy; B) The combination of several dozen independent fields to overcome cosmic variance; C) Near-infrared spectral coverage, often spanning the full range from 1.0--2.3 $\mu$m, with minimal wavelength gaps, to measure multiple diagnostic rest-frame optical lines, minimizing sensitivity to dust reddening; D) JWST's unprecedented spatial resolution, in some cases using two orthogonal grism orientations, to overcome contamination due to blending of overlapping spectra; E) Discovery of rare bright objects especially for detailed JWST followup. PASSAGE data are public immediately, and our team plans to deliver fully-processed high-level data products. In this PASSAGE overview, we describe the survey and data quality, and present examples of these accomplishments in several areas of current interest in the evolution of emission-line galaxy properties, particularly at low masses.

Galaxy evolution and extragalactic astronomy research depend on an understanding of the interactions between active galactic nuclei (AGN) and their host galaxies. We investigate the relationships between X-ray luminosity (Lx), star formation rate (SFR), and stellar mass (M) in distinct samples of radio-loud (RL) and radio-quiet (RQ) AGN. Using data from 4XMM-DR11, SDSS-DR16, and the DESI AGN Host Galaxies VAC, we examine how these key properties correlate within each AGN population. Our analysis reveals different behaviors: RL-AGN show a strong, statistically significant Lx-SFR correlation but no significant link with M, suggesting that accretion and star formation are coupled, possibly independent of host mass. In contrast, RQ-AGN display moderate, significant positive correlations across all parameters, consistent with joint growth driven by a shared cold gas this http URL results suggest that radio-loud AGN might slow down star formation in their galaxies, while radio-quiet AGN seem to grow together with it.

In this Letter, we study the structure of the strange stars admixed with bosonic dark matter, and find that these stars can well explain the mass and radius observations of XTE J1814-338. We also find that for the strong interaction coupling constant $\alpha_{S}=0.6$ and $B^{1/4}=135$ MeV ($B$ is the bag constant), the observations of XTE J1814-338 constrain the mass of the bosonic dark matter to $m_{\chi}\leq 307 (\lambda /\pi)^{1/4}$ MeV ($\lambda$ is the dimensionless coupling constant of the bosonic dark matter).

We have developed a wide-gap CdTe double-sided strip detector (CdTe-DSD) for the fourth and fifth flights of the Focusing Optics X-ray Solar Imager sounding rocket experiment (FOXSI-4/FOXSI-5). This detector features a 30 um strip width and a variable gap width from 30 um to 70 um, enabling position resolution finer than the strip pitch by inducing charge sharing across adjacent strip electrodes and utilizing this shared energy information for position reconstruction. However, this wide-gap configuration introduces complex detector responses, such as charge loss in the gap regions and electric field distortion near the electrodes, requiring a more advanced modeling approach for interpreting observation results in FOXSI-4/FOXSI-5 and for further optimization of future detector design. To address these complexities, we have constructed a first-principles simulation framework to model the detector response. The simulation integrates Geant4-based Monte Carlo simulations of energy deposition, finite element calculations of electric and weighting fields using COMSOL Multiphysics, charge transport modeling incorporating trapping and diffusion, and calculation of the induced charge on the electrodes based on the Shockley-Ramo theorem. By introducing a surface conductive layer, which causes electric field distortion, the model successfully reproduces the experimentally observed charge loss on the cathode side. In addition, the model reproduces the distinct charge sharing behavior on the cathode and anode sides. These results validate the effectiveness of the model in characterizing the wide-gap CdTe-DSD.

We investigate the evolution and formation of double-layered vacuum bubbles during cosmological phase transitions with mltiple vacua. Using a semiclassical approach with initial velocity fluctuations, we demonstrate that under certain conditions, quantum effects do not lead to the formation of double-layered vacuum bubbles, while flyover transitions allow for their stable formation by overcoming successive potential barriers. The evolution of these bubbles, including wall acceleration, collisions, and the formation of trapped regions, is explored through numerical simulations. Our results show that the dynamics of double-layered bubbles differ significantly from standard single-wall bubbles, with implications for cosmological observables such as gravitational wave production and baryogenesis. These findings indicate that flyover transitions represent a complementary decay mechanism to the conventional quantum tunneling process.

We aim to refine the fundamental parameters of the TOI-2141 planetary system, which includes a transiting sub-Neptune orbiting a Sun-like star in a relatively long orbit of 18.26 days, by combining new photometric and spectroscopic observations. We analyze new space-based photometry from TESS and CHEOPS as well as 61 radial velocity measurements from HARPS-N. We perform individual and joint photometric and RV analyses using several modeling tools within a Bayesian model comparison framework. We refine the radius and mass of the transiting planet TOI-2141 b to 3.15 $\pm$ 0.04 $R_\oplus$ and 20.1 $\pm$ 1.6 $M_\oplus$, respectively, five and two times more precise than the previously reported values. Our radial velocity analysis reveals two additional non-transiting companions with orbital periods of 5.46 and 60.45 days. Despite the innermost planet's high geometric transit probability, we find no evidence for transits in the photometric data. The bulk properties of TOI-2141 b suggest a significant volatile envelope atop an Earth-like core, with modeling indicating a hydrogen-rich atmosphere that may have experienced mild photoevaporation over the system's history. Planets b and c must exhibit a modest mutual inclination of at least 2.4 degrees.

Being ionized nebulae where star formation events take place, H ii regions are not only natural laboratories for studying physical processes of star formation and photoionization but also signatures reflecting evolution of their internal stellar populations and hosting galaxies. In this paper, we present a comprehensive analysis of spectral emission-line data for H ii regions in the nearby spiral galaxy NGC 2403, aimed at gaining deep insight into underlying properties and evolution for the H ii regions and the galaxy. The spectroscopic data are obtained through observations with the 2.16 m telescope at National Astronomical Observatories of China and a collection of published data in the literature. Photoionization modeling is combined in the analysis for diagnosing the spectral features and interpreting the observational data with certain physical mechanisms. Results of this work not only involve estimates of a set of parameters such as metallicity, the ionization parameter, etc., and evolution stages for the H ii regions in NGC 2403 but also reveal distinct characteristics of different spectral features and their sensitivities to specific parameters, which provides an instructive implication for proper usages of emission-line diagnostics for H ii regions or galaxies nearby and far away.

[Abridged] $Context.$ Pre-stellar cores are centrally concentrated starless cores on the verge of star formation and they represent the initial conditions for star and planet formation. Pre-stellar cores host an active organic chemistry and isotopic fractionation, kept stored into thick icy mantles, which can be inherited by the future protoplanetary disks and planetesimals. So far, only a few have been studied in detail, with special attention being paid to L1544 in the Taurus Molecular Cloud. $Aims.$ The aim is to identify nearby ($<$200 pc) pre-stellar cores in an unbiased way, to build a sample that can then be studied in detail. $Methods.$ We first used the Herschel Gould Belt Survey archival data, selecting all those starless cores with central H$_2$ number densities higher than or equal to 3$\times$10$^5$ cm$^{-3}$, the density of L1544 within the Herschel beam. The selected 40 (out of 1746) cores have then been observed in N$_2$H$^+$(3-2) and N$_2$D$^+$(4-3) using the APEX antenna. $Results.$ A total of 17 bona-fide (i.e., with a deuterium fraction larger than 10%) pre-stellar cores have been identified. Other 16 objects can also be considered pre-stellar, as they are dynamically evolved starless cores, but their deuterium fraction is relatively low ($<$10%). The remaining 7 objects have been found associated with very young stellar objects. $Conclusions.$ Dust continuum emission, together with spectroscopic observations of N$_2$H$^+$(3-2) and N$_2$D$^+$(4-3), is a powerful tool to identify pre-stellar cores in molecular clouds. Detailed modeling of the physical structure of the objects is now required for reconstructing the chemical composition as a function of radius. This work has provided a statistically significant sample of 33 pre-stellar cores, a crucial step in the understanding of the process of star and planet formation.

Observed galactic globular clusters reveal power-law structural profiles in the inner halos around the core-collapse stage. However, the origin of the power-law has not been explained in an acceptable manner. The present paper applies the Buckingham's Pi theorem to the orbit-averaged Fokker-Plank (OAFP) model of equal masses to study the inner-halo structure of a core-collapsing isotropic star cluster. We first prove that an infinite OAFP model evolves self-similarly because of the principle of covariance. We then show that the inner halo must form a power-law profile in a finite OAFP model that has complete similarity so that the principle of covariance and conservation laws hold. The conventional assumption that inner halos are self-similar and stationary is unnecessary to explain the power-law profiles.

We present an extensive photometric and spectroscopic ultraviolet-optical-infrared campaign on the luminous fast blue optical transient (LFBOT) AT 2024wpp over the first ~100 d. AT 2024wpp is the most luminous LFBOT discovered to date, with $L_{\rm{pk}}\approx(2-4)\times10^{45}$ erg s$^{-1}$ (5-10 times that of the prototypical AT 2018cow). This extreme luminosity enabled the acquisition of the most detailed LFBOT UV light curve thus far. In the first ~45 d, AT 2024wpp radiated $>10^{51}$ erg, surpassing AT 2018cow by an order of magnitude and requiring a power source beyond the radioactive $^{56}$Ni decay of traditional supernovae. Like AT 2018cow, the UV-optical spectrum of AT 2024wpp is dominated by a persistently blue thermal continuum throughout our monitoring, with blackbody parameters at peak of T>30,000 K and $R_{\rm{BB}}/t\approx0.2-0.3c$. A temperature of $\gtrsim$20,000 K is maintained thereafter without evidence for cooling. We interpret the featureless spectra as a consequence of continuous energy injection from a central source of high-energy emission which maintains high ejecta ionization. After 35 d, faint (equivalent width <10 Å) H and He spectral features with kinematically separate velocity components centered at 0 km s$^{-1}$ and -6400 km s$^{-1}$ emerge, implying spherical symmetry deviations. A near-infrared excess of emission above the optical blackbody emerges between 20-30 d with a power-law spectrum $F_{\rm\nu,NIR}\propto\nu^{-0.3}$ at 30 d. We interpret this distinct emission component as either reprocessing of early UV emission in a dust echo or free-free emission in an extended medium above the optical photosphere. LFBOT asphericity and multiple outflow components (including mildly relativistic ejecta) together with the large radiated energy are naturally realized by super-Eddington accretion disks around neutron stars or black holes and their outflows.

We present X-ray (0.3--79 keV) and radio (0.25--203 GHz) observations of the most luminous Fast Blue Optical Transient (LFBOT) AT\,2024wpp at $z=0.0868$, spanning 2--280 days after first light. AT 2024wpp shows luminous ($L_{\rm X} \approx 1.5 \times 10^{43}\, \rm erg\,s^{-1}$), variable X-ray emission with a Compton hump peaking at $\delta t \approx 50$ days. The X-ray spectrum evolves from a soft ($F_{\nu} \propto \nu^{-0.6}$) to an extremely hard state ($F_{\nu} \propto \nu^{1.26}$) accompanied by a re-brightening at $\delta t \approx 50$\,days. The X-ray emission properties favor an embedded high-energy source shining through asymmetric expanding ejecta. We detect radio emission peaking at $L_{\rm 9\,GHz} \approx 1.7 \times 10^{29}\,\rm erg\,s^{-1}\,Hz^{-1}$ at $\delta t \approx 73$ days. The spectral evolution is unprecedented: the early millimeter fluxes rise nearly an order of magnitude during $\delta t \approx 17-32$ days followed by a decline in spectral peak fluxes. We model the radio emission as synchrotron radiation from an expanding blast wave interacting with a dense environment ($\dot{M} \sim 10^{-3}\, \rm M_{\odot}\,yr^{-1}$ for $v_{\rm w} = 1000\,\rm km\,s^{-1}$). The inferred outflow velocities increase from $\Gamma \beta c \approx 0.07\, \rm to\,0.42c$ during $\delta t \approx 32-73$ days, indicating an accelerating blast-wave. We interpret these observations as a shock propagating through a dense shell of radius $\approx 10^{16}$\,cm, then accelerating into a steep density profile $\rho_{\rm CSM}(r) \propto r^{-3.1}$. All radio-bright LFBOTs exhibit similar circumstellar medium (CSM) density profiles ($\rho_{\rm CSM} \propto r^{-3}$), suggesting similar progenitor processes. The X-ray and radio properties favor a progenitor involving super-Eddington accretion onto a compact object launching mildly-relativistic disk-wind outflows.

Efforts are underway to measure the global 21 cm signal from neutral hydrogen, which is a powerful probe of the early universe, using NASA radio telescopes on the far side of the Moon. Physics-based models of the signal are computationally expensive to perform Bayesian multi-parameter inferences, for which we have developed novel, publicly-available neural network emulators utilizing a Long Short-Term Memory (LSTM) network and a Kolmogorov-Arnold Network (KAN). $\texttt{21cmLSTM}$ is currently the most accurate emulator in the community by leveraging the signal's temporally-correlated structure, and $\texttt{21cmKAN}$ maintains similar accuracy while training 75 times faster, by learning expressive functional transformations. Each emulator can fit realistic mock signals and obtain unbiased physical parameter constraints, with $\texttt{21cmKAN}$ able to complete end-to-end training and inference in under 30 minutes. The implementation of machine learning tools like these in data analysis pipelines is important to fully exploit upcoming measurements of the cosmological 21 cm signal.

We present the stellar dynamical mass of the central black hole in the nearby Seyfert galaxy MCG$-$06-30-15 using the Schwarzschild orbit-superposition method implemented in the open-source code FORSTAND. We obtained spatially resolved $K$-band nuclear stellar spectra for this galaxy with SINFONI on the VLT. We extracted the bulk stellar kinematics using Gauss$-$Hermite (GH) parameterization of the line-of-sight velocity distributions. A multicomponent surface brightness profile of the galaxy was determined from an $HST$ medium-band $V$ image. Our best-fit models indicate a black hole mass of $M_{BH}=(4.4\pm1.4) \times 10^7 M_{\odot}$ and a stellar mass-to-light ratio of $M/L$=($3.0\pm0.3$) $M_{\odot}$/$L_{\odot}$, within 1$\sigma$ confidence intervals. Our constraint on $M_{BH}$ agrees with an upper limit on the mass from stellar dynamics based on the Jeans Anisotropic Method, but is $\sim$10 times larger than the reported mass from reverberation mapping. However, our best-fit $M_{BH}$ may be systematically biased high due to the counter-rotating disk in the nucleus of MCG$-$06-30-15 and the inability of the GH parameterization to fully describe such a complicated set of stellar kinematics. In addition, a dynamical $M_{BH}$ value depends heavily on the assumed source distance, which is not yet accurately constrained for this galaxy. MCG$-$06-30-15 is only the fourth galaxy in which we can compare $M_{BH}$ from stellar dynamical modeling with that from reverberation mapping. A direct comparison of $M_{BH}$ allows us to identify and investigate the possible sources of bias associated with different mass measurement techniques, which may influence our understanding of black hole and galaxy coevolution across cosmological timescales.

We have analyzed the aromatic infrared bands (AIBs) in the 6-11.2 $\mu$m range around the Wolf-Rayet binary WR140 (d=1.64 kpc) obtained with the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer (MRS). In WR140's circumstellar environment, we have detected AIBs at 6 $\mu$m and 7.7 $\mu$m which are attributed to C-C stretching modes. These features have been detected in the innermost dust shell (Shell1; ~2100 au from WR140), the subsequent dust shell (Shell2; ~5200 au), and ``off-shell'' regions in the MRS coverage. The 11.2 $\mu$m AIB, which is associated with the C-H out-of-plane bending mode, has been tentatively detected in Shell2 and the surrounding off-shell positions around Shell2. We compared the AIB features from WR140 to spectra of established AIB feature classes A, B, C, and D. The detected features around WR140 do not agree with these established classes. The peak wavelengths and full width half maxima (FWHMs) of the 6 $\mu$m and 7.7 $\mu$m features are, however, consistent with those of R Coronae Borealis (RCB) stars with hydrogen-poor conditions. We discuss a possible structure of carbonaceous compounds and environments where they form around WR140. It is proposed that hydrogen-poor carbonaceous compounds initially originate from the carbon-rich WR wind, and the hydrogen-rich stellar wind from the companion O star may provide hydrogen to these carbonaceous compounds.

The e$^+$ e$^-$ annihilation line at 511 keV provides a unique probe for studying the distribution and origin of positrons in our Galaxy. The SPI spectrometer on INTEGRAL has observed this gamma-ray line for two decades. We analyze 20 years of INTEGRAL/SPI observations to produce the most sensitive all-sky map of the 511 keV line emission to date, aiming to reveal new features and provide refined measurements of known sources. We perform image deconvolution using the RL algorithm and employ bootstrap analysis to evaluate statistical uncertainties of fluxes from regions of interest. Systematic uncertainties in parameter choices are also considered. We utilize GPU acceleration to enable this computationally intensive analysis. The reconstructed image successfully recovers the basic morphological features reported in model-fitting studies: a bright central component, a broad bulge, and an elongated disk component along the Galactic plane. We also report hints of new spatial features in the reconstructed image, including an asymmetric structure in the broad bulge emission and 511 keV emission potentially associated with massive stars from the Sco-Cen and other OB associations. While the significance of these new features is marginal ($\sim 2\sigma$), they are spatially consistent with $^{26}$Al emission from massive stars in that region, suggesting that this 511 keV emission originates from its $\beta^{+}$ decay. Our 20-year dataset provides the most detailed 511 keV emission map to date, reproducing global structures suggested in model-fitting approach while revealing hints of new spatial features. These findings provide insights into the origin of Galactic positrons and propagation of low-energy positrons in the interstellar medium. Future MeV gamma-ray observations, such as COSI, are expected to confirm the reported features and shed further light on the nature of positrons in our Galaxy.

In clustered star-forming regions, stellar feedback-such as HII regions/photon-dominated regions (PDRs), and protostellar jets/outflows-shapes cloud structures and influences star formation. Using high-resolution ALMA millimeter and JWST infrared data, we analyze the cloud structure and the impact of stellar feedback in the nearest dense cluster-forming region Oph A. All 6 known Class 0/I and 2 of 6 Flat Spectrum/Class II objects are detected in the 1.3 mm dust continuum. Additionally, we newly detected 7 substellar cores, three of which show compact near-infrared emission, suggesting they are young substellar objects. The remaining cores, with masses of 0.01 Msun and high densities, are likely gravitationally bound. They appear connected by faint CO finger-like structures extending from the triple Class 0 system VLA1623-2417 Aa+Ab+B, suggesting they may have been ejected from the close binary VLA1623 Aa+Ab. 12CO and near-infrared data reveal multiple protostellar outflows. From the comparison, we identified several new outflows/jets, and shocked structures associated to the GSS30 large bipolar bubble. Strong 12CO emission traces the eastern edge of the Oph A ridge, forming part of the expanding HII/PDR bubble driven by the nearby Herbig Be star S1. The northern ridge appears blown out, with warm gas flowing toward GSS 30, injecting additional turbulent momentum. Several C18O striations in the S1 bubble align with magnetic fields, and position-velocity diagrams show wave-like patterns, possibly reflecting magnetohydrodynamic waves. Stellar feedback significantly influences Oph A's cloud structure.

We investigate how the pulsation frequencies of axial gravitational-wave modes ($w$-modes) in a non-rotating neutron star depend on its composition, particularly when including quarkyonic matter and fermionic dark matter. These modes emerge from the coupling between the star's fluid component and the gravitational field of general relativity, which are highly damped and characterized by complex frequencies with comparable real and imaginary parts. Using a relativistic mean field formalism for the nucleonic component, we modeled the neutron star's interior, while the exterior is analyzed through the complex-coordinate method to determine the $w$-modes. Our study employs a realistic equation of state, based on different physical assumptions and covering a broad area of observational constraints, starting from finite nuclei to nuclear matter with extreme conditions. The numerical findings demonstrate that axial $w$-modes provide valuable insights into the properties of neutron star matter, highlighting their significance in probing the star's internal structure.

(abridged) Recent analyses have reported low lithium but high beryllium abundances on the solar surface; however, standard solar models (SSMs) predict Li abundances that are ~30$\sigma$ away from the observed value. In this study, we aim to develop solar models and compare them with the Li and Be abundance constraints. We examine the effect of protosolar accretion and turbulent mixing below the base of the surface convective zone. We compute ~200 solar evolutionary models for each case to optimize input parameters using target quantities, similar to the SSM framework. We confirm that turbulent mixing helps reproduce the surface Li and Be abundances within ~0.6$\sigma$ by enhancing burning. It suppresses gravitational settling, leading to a better matching of the He surface abundance ($\lesssim$0.3$\sigma$) and a smaller compositional gradient. We derive a new protosolar helium abundance $Y_{\rm proto}=0.2651\pm0.0035$. Turbulent mixing decreases the central metallicity ($Z_{\mathrm{center}}$) by $\approx$4.4%, even though accretion increases $Z_{\rm center}$ by $\approx$4.4%, as suggested by our previous study. Unfortunately, the reduction in $Z_{\rm center}$ implies that our models do not reproduce constraints on observed neutrino fluxes by $6.2\sigma$ for $^8{\rm B}$ and $2.7\sigma$ for CNO. Including turbulent mixing in solar models appears indispensable to reproduce the observed atmospheric abundances of Li and Be. However, the resulting tensions in terms of neutrino fluxes, even in the models with the protosolar accretion, show that the solar modeling problem remains, at least partly. We suggest that improved electron screening, as well as other microscopic properties, may help alleviate this problem. An independent confirmation of the neutrino fluxes measured by the Borexino experiment would also be extremely valuable.

This paper proposes that the ion temperature is several times the local electron temperature in the hot onset phase and at the above-the-loop region of solar flares. The paper considers: the evidence of spectral line Doppler widths ("non-thermal" broadening); evidence for "universal" ion and electron temperature increase scaling relations for magnetic reconnection in the solar wind, Earth's magnetopause, Earth's magnetotail and numerical simulations; and thermal equilibration times for onset and above-the-loop densities, which are much longer than previous estimates based on soft X-ray flare loops. We conclude that the ion temperature is likely to reach 60 MK or greater and that it may represent a substantial part of spectral line widths, significantly contributing to solving the long-standing issue of the excess nonthermal broadening in flare lines.

In this work, we test the validity of $T_e$ - $T_e$ relations in resolved (10-200~pc) measurements of four nearby, low-metallicity (7.25 $\leq$ 12+log(O/H) $\leq$ 8.33), low-mass (10$^{6.78}$ $\leq$ M$_*$/M$_\odot$ $\leq$ 10$^{8.7}$), starburst (10$^{-4.5}$ $\leq$ sSFR $\leq$ 10$^{-0.3}$) galaxies. We obtain VLT/X-Shooter spectra of NGC~5253, NGC~0625, SBS~0335-052E and IC~2828, targeting regions within these galaxies with bright point-like sources and diffuse gas. Our observations are designed to extend from the galaxy midplane into extraplanar gas likely belonging to galactic winds. We measure electron temperatures from five different auroral lines: [NII]~$\lambda$5755, [OII]~$\lambda\lambda$7319,30, [SII]~$\lambda\lambda$4069,76, [SIII]~$\lambda$6312, and [OIII]~$\lambda$4363. We compare the resulting $T_e$ - $T_e$ relations with previous studies of HII regions in nearby spiral galaxies. Our results show that $T_e$ - $T_e$ relations in low-metallicity starburst galaxies do not significantly deviate from $T_e$ - $T_e$ relations in HII regions of local spiral galaxies. We do not find significant differences in the diffuse, extraplanar gas. These results suggest that auroral lines provide a reliable metallicity diagnostic not only for high-redshift galaxies but also for the extended diffuse gas in extreme environments like outflows.

We review recent findings from a detailed simulation study of the merging cluster El Gordo and present new results inferred from weak lensing data. We found that the observed spatial offsets between the different mass components are well reproduced in merging simulations that include self-interacting dark matter (DM), with an elastic cross-section per unit mass of approximately \sigma_DM/m_X ~ 4 -5 cm^2/gr. Moreover, a relative line-of-sight peculiar velocity on the order of several hundred km/s is found between the two stellar components of the colliding subclusters. These findings strongly suggest the possibility that, in a very energetic cluster collision, DM could possess collisional properties. However, the self-interacting DM merger model presented here is not without difficulties. The values found for \sigma_DM/m_X being in conflict with the current upper bounds on cluster scales. As a solution to this tension we argue that in major cluster mergers the physical modeling of DM interactions, based on the scattering of DM particles, should be considered too simplistic. Additionally, the DM halos of the post-collision clusters have cored density profiles with core radii r_c ~ 300 kpc. Consequently, the associated reduced tangential shear lensing profiles consistently tend to zero at angles \theta <~ 40^{''}. This result is inconsistent with what is deduced from the measured profiles. These profiles exhibit a diverging behavior when \theta --> 0, as predicted by an NFW mass model. We argue that such contradictions cannot be easily reconciled within the DM models presented so far as an alternative to the collisionless paradigm. However, we suggest that this tension can be used as a unique test bed to probe new DM physics.

Abridged. HE 1327-2326 (HE 1327), with [Fe/H]=-5.2, is one of the most metal-poor stars detected and a candidate to be the offspring of the first stars. Numerous efforts have been made to match its abundance pattern. However, no model satisfactorily explains its entire surface chemical composition. The high CNO pattern with [N/Fe]>[C/Fe]>[O/Fe], the light element 'slide' (between Na and Si), and the presence of Sr and Ba in HE 1327 is reminiscent of those asymptotic giant branch (AGB) stars that undergo third dredge-up, hot bottom burning, and s-processing, suggesting that AGBs may have been progenitors of the star. We assume that, where HE 1327 formed, the interstellar medium was well-mixed, and adopt an initial stellar composition based on the observed chemical evolution of the early universe. We calculated models of hyper-metal-poor AGB stars and compared their yields to the observed abundances of HE 1327. Our 3 Msun models match 13 of the 14 measured elements in HE1327. They are also consistent with the seven elements with upper limits. The only discrepancy is O, underproduced by 0.5-1.0 dex. Unlike the SN models, the AGB models also match Sr and Ba. Our model predicts high abundances of P and Pb, which would be useful in testing the AGB scenario. We propose that HE 1327 is the oldest known object that shows nucleosynthetic evidence of the first AGB stars. With lifetimes as short as 200 Myr, these stars may have formed and polluted the universe very early. Recent Pop III star formation simulations support their formation, and their strong N production is qualitatively consistent with recent JWST observations showing high N/O ratios just 440 Myr after the Big Bang. Importantly, our results also suggest that the interstellar medium may have shown some degree of homogeneity and mixing even at these early epochs.

Although the majority of star-forming galaxies show a tight correlation between stellar mass and dust extinction, recent James Webb Space Telescope observations have revealed a peculiar population of Highly Extincted Low-Mass (HELM) galaxies, which could revolutionise our understanding of dust production mechanisms. To fully understand the dust content of these galaxies, which are a minority of the overall galaxy population, far-infrared observations over large areas are pivotal. In this paper, we derive the expected PRIMAger, the far-IR (24-235$\mu m$) imaging camera proposed for the Probe far-IR Mission for Astrophysics, fluxes for a set of photometric candidates HELM galaxies. Taking into account a deep survey of 1000h over $1\rm\, deg^{2}$, we expect to detect around $3.1 \times 10^4$ HELM sources in at least one PRIMAger filter, 100 of which are at z=1-1.5. For 32% of this sample, there will be observations in at least four PRIMAger filters, covering at least the 90 to $240\mu m$ wavelength range, which will allow us to obtain a detailed fit of the dust emission and estimate the dust mass.

This study examines the resolved Kennicutt Schmidt (rKS) relation, defined as the connection between the star formation rate surface density (Sigma SFR) and the molecular gas mass surface density (Sigma H2) in the high-density central regions of three nearby barred spiral galaxies hosting AGN: NGC 1365, NGC 1433, and NGC 1566. Utilising high-resolution archival data from AstroSat/UVIT for UV imaging and the Atacama Large Millimeter/submillimeter Array (ALMA) for CO(2-1) molecular gas mapping, we explore recent star formation and gas distribution with a spatial resolution of about 120 to 132 pc. Our findings reveal a sublinear rKS law, with slopes ranging from about 0.17 to 0.71. Notably, NGC 1566 exhibits a robust rKS relation consistent with previous studies, while NGC 1365 and NGC 1433 show weaker correlations. These differences are likely due to the smaller number of identified star-forming regions in these galaxies compared to NGC 1566, as well as the central molecular gas concentrations and varying star formation activity in their bars and nuclear regions. These results also support the idea that the rKS relation deviates from linearity in extreme environments, such as starburst galaxies and galactic centres. Additionally, we find a generally low median star formation efficiency (SFE) within the bars of these galaxies, suggesting that while bars may drive nuclear starbursts and contribute to bulge growth, they do not significantly increase SFE. Furthermore, a negative correlation between SFE and Sigma H2 is observed across the sample, both within and outside the bar regions, suggesting that higher Sigma H2 may lead to lower SFE in the central regions of these galaxies. Our findings highlight that Sigma H2 plays a primary role in shaping the observed trends in SFE, rather than the presence of a bar itself.

Modern cosmology is based on the cosmological principle, which states that the Universe is statistically homogeneous and isotropic. When applied in its strict -- rather than statistical -- sense, the cosmological principle leads to the Friedmann--Lemaître--Robertson--Walker (FLRW) model, which serves as background spacetime. This background is used to predict: (1) the dynamics of cosmic expansion; and (2) the kinematics of light propagation through the Universe, which dictates the interpretation of cosmological observations. In this lecture, we shall discuss the performance of the FLRW model for those purposes, and present some results on the so-called backreaction and fitting problems.

Magnetar outbursts are among the most noteworthy manifestations of magnetism in neutron stars. They are episodes in which the X-ray luminosity of a strongly magnetised neutron star swiftly rises by several orders of magnitude to then decay over the course of several months. In this work, we present simulations of outbursts as a consequence of localised heat deposition in a magnetised neutron star crust, and the subsequent surface cooling. In particular, we employed a magnetothermal evolution code adapted to the study of short-term phenomena; that is, one including in its integration domain the outer layers of the star, where heat diffusion is faster. This choice entailed the development and use of heat blanketing envelope models that are thinner than those found in the literature as the surface boundary ondition. We find that such envelopes can support a higher surface temperature than the thicker ones (albeit for less time), which can account for the typical luminosities observed in outbursts even when coming from small hotspots (few km in radius). We study several parameters related to the energetics and geometry of the heating region, concluding that the cooling of a crustal hotspot found in the outer part of the crust can account for the luminosity evolution observed in outbursts both in terms of peak luminosity and timescales. Finally, we discuss the key observables that must be studied in future observations to better constrain the nature of the underlying mechanism.

When compact objects -- neutron stars and black holes -- are formed in a supernova explosion, they may receive a high velocity at formation, which may reach or even exceed $\approx{1000}$~km~s$^{-1}$ for neutron stars and hundreds of km~s$^{-1}$ for black holes. The origin of the kick is intimately related to supernova physics. A better understanding of kick properties from astronomical observations will shed light on the unsolved problems of these explosions, such as the exact conditions leading to exotic electron capture and ultra-stripped supernovae. Compact object kicks are profoundly important in several areas of astrophysics. First, being a result of supernova explosions, the kick velocity distribution must be explained in the framework of the supernova mechanism. Second, the kick magnitudes and directions influence many aspects of the evolution of binary systems, including the rate of compact object coalescences observable through gravitational waves. Third, the evolution of isolated neutron stars depends on their spatial velocities relative to the surrounding medium. Finally, knowledge of the kick velocity distribution is significant in predicting future observational results and their interpretation. For example, it is expected that the Roman space telescope will discover many microlensing events related to neutron stars and black holes; accurate estimates require precise kinematic properties of these compact objects.

The Earth--Moon system has been experiencing impacts from asteroids and comets for billions of years. The Moon, as an airless body, has preserved a distinct record of these events in form of impact craters and ejecta deposits, offering valuable insights into the impact history and surface evolution of the Moon. However, the ancient impact relics can only provide limited information to the lunar interior structure, with an absence of the Moon's immediately dynamic response to the impact events. With human lunar exploration entering an era of sustained presence, e.g., lunar research station and human return, we propose a new concept to probe the lunar subsurface and interior by investigating the future asteroid impacts in real time. This can be achieved by integrating 1) ground- and space-based telescopes, 2) lunar-based seismometers and rovers, and 3) in-situ investigations around the impact sites. A promising opportunity arises with the possible lunar impact of the 60-m-sized asteroid 2024~YR4 in 2032 (impact probability $\sim$4.3\%), an event of once-in-ten-thousand-years rarity. Comprehensive observations of such events would greatly enhance our understanding of the Moon's structure and evolution, and have significant implications for the future lunar resource utilization and planetary defense missions.

We present a catalogue of dense cores identified in James Clerk Maxwell Telescope (JCMT) Gould Belt Survey SCUBA-2 observations of nearby star-forming clouds. We identified 2257 dense cores using the getsources algorithm, of which 59% are starless, and 41% are potentially protostellar. 71% of the starless cores are prestellar core candidates, suggesting a prestellar core lifetime similar to that of Class 0/I YSOs. Higher-mass clouds have a higher fraction of prestellar cores compared to protostars, suggesting a longer average prestellar core lifetime. We assessed completeness by inserting critically-stable Bonnor--Ebert spheres into a blank SCUBA-2 field: completeness scales as distance squared, with an average mass recovery fraction of $73\pm6$% for recovered sources. We calculated core masses and radii, and assessed their gravitational stability using the Bonnor-Ebert criterion. Maximum starless core mass scales with cloud complex mass with an index $0.58\pm 0.13$, consistent with the behaviour of maximum stellar masses in embedded clusters. We performed least-squares and Monte Carlo modelling of the core mass functions (CMFs) of our starless and prestellar core samples. The CMFs can be characterised using log-normal distributions: we do not sample the full range of core masses needed to create the stellar Initial Mass Function (IMF). The CMFs of the clouds are not consistent with being drawn from a single underlying distribution. The peak mass of the starless core CMF increases with cloud mass; the prestellar CMF of the more distant clouds has a peak mass $\sim 3\times$ the log-normal peak for the system IMF, implying a $\sim 33$% prestellar core-to-star efficiency.

Context. PSR J0312$-$0921 and PSR J1627$+$3219 are black widow pulsars with orbital periods of 2.34 and 3.98 hours. They were recently detected in the radio and $\gamma$-rays. Aims. Our goals are to estimate the fundamental parameters of both binary systems and their components. Methods. We performed first phase-resolved multi-band photometry of both objects with the 10.4-m Gran Telescopio Canarias and fitted the obtained light curves with a model assuming direct heating of the companion by the pulsar. Archival X-ray data obtained with the Swift and XMM-Newton observatories were also analysed. Results. For the first time, we firmly identified both systems in the optical. Their optical light curves show a rather symmetric single peak per orbital period and a peak-to-peak amplitude of $\gtrsim$2 mag. We also identified the X-ray counterpart to J1627$+$3219, while for J0312$-$0921 we set an upper limit on the X-ray flux. Conclusions. We estimated the masses of the pulsars, companion temperatures and masses, Roche lobe filling factors, orbital inclinations, and the distances to both systems. PSR J0312$-$0921 has a very light ($\approx$0.02 M$_\odot$) companion which possibly has one of the lowest ($\approx$1600 K) `night-side' temperatures among the known black widow systems. We found that the distances to J0312$-$0921 and J1627$+$3219 are about 2.5 and 4.6 kpc, respectively. This likely explains their faintness in X-rays. The X-ray spectrum of PSR J1627$+$3219 can be described by the power-law model, and its parameters are compatible with those obtained for other black widows.

We report on polarimetric observations of V572 Vel (Nova Vel 2025) conducted on June 26th and July 21st, 2025, shortly after its nova eruption was discovered. Our measurements in the I$_C$ band revealed an average linear polarization of 1.60$\pm$0.03\% at position angle of 132.2\degr. To distinguish between intrinsic and interstellar polarization, we also measured 86 field stars in the nova's vicinity, finding an average polarization of 1.25$\pm$0.61\% at a nearly identical position angle of 132\degr. The strong consistency between the nova's polarization and that of the surrounding field stars suggests that the observed polarization is predominantly interstellar in origin. We found no significant evidence of an intrinsic polarization component, which would typically arise from an asymmetric distribution of ejected material. Further multi-band observations are recommended to confirm these findings.

Due to the non-linearity of the QUMOND field equations, in the modelling of binaries so far the two-body system is replaced by an effective one-body system, where the central particle contains the total mass of both binary components and is orbited by a massless test particle. In this work, the discrepancy between the effective one-body treatment and the complete two-body solution in QUMOND is quantified. Particles are treated as limits of Dirac sequences. Then, the QUMOND contribution to the total kinematical acceleration of a particle is expressed as a Green's integral which is calculated numerically. In the non-linear transition regime the kinematical acceleration of the effective one-body system with a total mass of 2 Msun is up to a factor of 1.44 higher than the Newtonian acceleration, whereas the acceleration is only boosted by a factor of 1.2--1.3 in the two-body system in the case of the simple transition function.

The emission-line binary ALS 8814 was recently proposed as a Be star + black hole (BH) binary based on large-amplitude radial velocity (RV) variations of a Be star and non-detection of spectroscopic features from a luminous companion. We reanalyze low- and medium-resolution LAMOST spectra of ALS 8814 and show that the system's spectroscopic variability is considerably more complex than previously recognized. Inspection of the system's trailed spectra reveals the presence of a second set of absorption lines that move in anti-phase with the Be star. In addition, the emission and absorption lines exhibit inconsistent RV variability, suggesting that they trace different stars. Using spectral disentangling, we recover the spectrum of a rapidly rotating companion whose broad, shallow lines were previously undetected. Time-variability in the emission lines complicates interpretation of the disentangled spectrum, such that the physical parameters of the components are still uncertain, but we find with simulations that emission line variability alone is unlikely to explain all signatures of the companion. The system's high Gaia RUWE value suggests a third luminous companion, making ALS 8814 a likely hierarchical triple. Although it is unlikely to contain a BH, the system is unusual, with the largest RV semi-amplitude observed in any known classical Be star and a companion that does not appear to be stripped. More extensive spectroscopic monitoring and high-resolution imaging will be necessary to fully characterize the system's orbital architecture, stellar parameters, and evolutionary status.

In three previous Papers we analysed the origin of the properties of halo substructure found in simulations. This was achieved by deriving them analytically in the peak model of structure formation, using the statistics of nested peaks (with no free parameter) plus a realistic model of subhalo stripping and shock-heating (with only one parameter). However, to simplify the treatment we neglected dynamical friction (DF). Here, we revisit that work by including it. That is done in a fully analytic manner, i.e. avoiding the integration of subhalo orbital motions. This leads to simple accurate expressions for the abundance and radial distribution of subhaloes of different masses, which disentangle the effects of DF from those of tidal stripping and shock-heating. This way we reproduce and explain the results of simulations and extend them to haloes of any mass, redshift and formation times in the desired cosmology.

(Sub-)millimetre single-dish telescopes feature faster mapping speeds and access larger spatial scales than their interferometric counterparts. However, atmospheric fluctuations tend to dominate their signals and complicate recovery of the astronomical sky. Here we develop a framework for Gaussian process-based sky reconstruction and separation of the atmospheric emission from the astronomical signal based on Numerical Information Field Theory (\texttt{NIFTy}). To validate this novel approach, we use the \textit{maria} software to generate synthetic time-ordered observational data mimicking the MUSTANG-2 bolometric array. This approach leads to significantly improved sky reconstructions versus traditional methods.

Interstellar objects provide a direct window into the environmental conditions around stars other than the Sun. The recent discovery of 3I/ATLAS, the second interstellar comet ever observed, offers a unique opportunity to investigate the physical and chemical properties of interstellar objects and to compare them with those of comets in our own Solar System. In this Letter we present the results of a 10-night spectroscopic and photometric monitoring campaign with the 2.4 m Hiltner and 1.3 m McGraw-Hill telescopes at the MDM Observatory. The campaign was conducted between August 8 and 17 while 3I/ATLAS was inbound at heliocentric distances of 3.2 - 2.9 au. Our observations captured the onset of optical gas-driven activity. Nightly spectra reveal a weak CN emission feature in the coma of 3I/ATLAS, absent during the first nights but steadily strengthening thereafter. We measure a CN production rate of $\sim$8$\times$10$^{23}$ s$^{-1}$, towards the lower end of activity observed in Solar System comets. Simultaneous photometry also indicates a small but measurable increase in the coma's radial profile and increasing $r$-band $Af\rho$ with values in the order of $\sim300$ cm. Our upper limit on the C$_2$-to-CN ratio ($\log Q(\mathrm{C}_2)/Q(\mathrm{CN})<-1.05$) places 3I/ATLAS among the most carbon-chain depleted comets known. The derived gas-to-dust production ratio of $\log Q (\mathrm{CN})/Af\rho<21.49$ is likewise at the low end of the Solar System comet distribution. Further observations of 3I/ATLAS are required to verify the apparent carbon-chain depletion and to explore whether such composition represents a recurring trait of the interstellar comet population.

Quasi-periodic eruptions (QPEs) are X-ray transients characterized by nearly regular recurring flares from galactic nuclei. Recent observations have confirmed that some QPEs occur in galactic centers that experienced a tidal disruption event (TDE) a few years earlier. This may be reasonably explained if QPEs are produced when a star orbiting a supermassive black hole passes through an accretion disk formed by the TDE. Based on this scenario, we investigate the expected QPE signatures in the early stages of TDEs, taking into account the time evolution of the accretion disk. In the early phase, the disk is in a super-Eddington accretion state. The interaction between the star and such a slim disk results in QPEs with durations of $\sim 100-1000\,{\rm s}$ and temperatures of $\sim 1-100\,{\rm keV}$, which are significantly shorter and hotter than those of the currently detected QPE population. These events are detectable with current X-ray telescopes, but their small duty cycle ($\lesssim1\,\%$) and the potential presence of a massive disk wind may make detection challenging. We encourage early-time and long-term monitoring TDEs showing X-rays to capture these QPEs, as such detections would provide valuable insights into the disk formation process in TDEs.

JWST has uncovered a diverse population of extreme near-infrared dropouts, including ultra high-redshift ($z>15$) galaxy candidates, dust-obscured galaxies challenging dust production theories, sources with strong Balmer breaks - possibly compact AGN in dense environments - and cold, sub-stellar Galactic objects. This work presents Capotauro, a F356W-dropout in the CEERS survey with F444W AB magnitude of $\sim27.68$ and a sharp $>3$ mag flux drop between $3.5{-}4.5\,\mu$m, undetected below $3.5\,\mu$m. We combine JWST/NIRCam, MIRI, and NIRSpec/MSA data with HST/ACS and WFC3 observations to perform a spectro-photometric analysis of Capotauro using multiple SED-fitting codes. Our setup tests $z\geq15$ as well as $z<10$ dusty, Balmer-break or strong-line galaxy solutions, and the possibility of Capotauro being a Milky Way sub-stellar object. Among extragalactic options, our analysis favors interpreting the sharp drop as a Lyman break at $z\sim32$, consistent with the epoch of formation of the first stars and black holes, with only $\sim0.5\%$ of the posterior volume at $z<25$. Lower-redshift solutions struggle to reproduce the extreme break, suggesting that if Capotauro lies at $z<10$, it must show a non-standard combination of strong dust attenuation and/or Balmer breaks, making it a peculiar interloper. Alternatively, its properties match a very cold (Y2-Y3 type) brown dwarf or a free-floating exoplanet with a record-breaking combination of low temperature and large distance ($T_{\mathrm{eff}}<300\,\mathrm{K}$, $d\gtrsim130\,\mathrm{pc}$, up to $\sim2\,\mathrm{kpc}$). While current data cannot determine its nature, Capotauro emerges as a remarkably unique object in all plausible scenarios, and a compelling target for follow-up.

Investigations of intrinsic alignments suggest a link between the alignment of a central galaxy's major axis with the galaxy distribution and its internal galaxy-halo shape alignment. In contrast, blue central galaxies typically exhibit almost no alignment signal, owing to a stronger internal misalignment with their halo. We investigated how the internal alignment between the principal axes of the stellar and dark matter components evolves over time as a function of the total mass of central galaxies at z=0. In particular, we aim to understand why disk-dominated, blue central galaxies often show weak or absent alignment signals with the galaxy distribution in their group and in the larger-scale cosmic structure. We used data from the IllustrisTNG300-1 run and selected a sample of bright central galaxies at z=0. We computed the principal axes of the stellar and dark matter components, along with their angular momenta, to obtain the various alignment angles analyzed in this study. Also, we used the merger trees to determine the number of major mergers between z=20 and z=0, and to track their shapes along their main branch. We examined secondary dependencies of the galaxy-halo alignment on properties such as color and merger history. We analyzed how shape alignments relate to the dynamical coupling between the angular momentum directions of the stellar and dark matter components. The results show that massive centrals tend to align with the shape of their inner halo, and they are typically red and have undergone numerous mergers. Lower-mass red centrals, and those that have experienced many mergers exhibit the strongest evolution toward alignment. Blue centrals, in contrast, are more strongly influenced by the link between the stellar and dark matter angular momenta, such that they evolve toward either alignment or misalignment with both the shape and angular momentum of the inner halo.

Cycle 1 JWST observations of Cepheids in SN Ia hosts resolved their red-giant-dominated NIR backgrounds, sharply reducing crowding and showing that photometric bias in lower-resolution HST data does not account for the Hubble tension. We present Cycle 2 JWST observations of >100 Cepheids in NGC 3447, a unique system that pushes this test to the limit by transitioning from low to no background contamination. NGC 3447, an SN Ia host at D~25 Mpc, is an interacting pair comprising (i) a spiral with mixed stellar populations, typical of H0 calibrators, and (ii) a young, star-forming companion (NGC 3447A) devoid of old stars and hence stellar crowdinga rare "perfect host" for testing photometric bias. We detect ~60 long-period Cepheids in each, enabling a "three-way comparison" across HST, JWST, and background-free conditions. We find no component-to-component offset (sigma<0.03 mag; a calibration independent test), and a 50% reduction in scatter to ~0.12 mag in the background-free case, the tightest seen for any SN Ia host. Across Cycles 1-2 we also measure Cepheids in all SH0ES hosts observed by JWST (19 hosts of 24 SNe Ia; >50% of the sample) and find no evidence of bias relative to HST photometry, including for the most crowded, distant hosts. These observations constitute the most rigorous test yet of Cepheid distances and provide strong evidence for their reliability. Combining JWST Cepheid measurements in 19 hosts (24 SNe Ia) with HST data (37 hosts, 42 SNe Ia) yields H0 = 73.49 +/- 0.93 km/s/Mpc. Including 35 TRGB-based calibrations (from HST and JWST) totals 55 SNe Ia and gives H0 = 73.18 +/- 0.88 km/s/Mpc, ~6 sigma above the LambdaCDM+CMB expectation.

We explore whether Local Group dwarf spheroidal (dSph) galaxies might have hosted Earth-like planets dwelling unexposed for several billions of years to major galactic threats to life, such as supernovae and gamma-ray bursts. To this aim, we developed a novel semiempirical model that exploits the observed chemical abundances and star formation histories of a selected sample of local dSphs, to explore whether their stars may have (i) reached the minimum metallicity to trigger planet formation and (ii) avoided exposure to destructive events long enough to provide time for possible biological development. From our work two scenarios emerge. If planet formation is possible for ${\rm[Fe/H]}\lesssim-1$, then in all dSphs with $5\times10^{3}L_{\odot}\leq L_V\leq2\times10^{7}L_{\odot}$ a fraction $\approx0.1\%-10\%$ of stars might have safely hosted terrestrial planets for more than $1$ Gyr. In this scenario, ancient ultra-faint dwarf galaxies (UFDs, $L_V\leq10^{5}L_{\odot}$) would have been the first to reach this condition in the history of the Local Group. Conversely, if planets form for ${\rm[Fe/H]}\geq-0.6$ then they should not exist in UFDs, while only $\approx0.001\%-0.1\%$ of stars in dSphs with $L_V\geq3\times10^{5}L_{\odot}$ would host planets dwelling in safe conditions for long times. Interestingly, we find a "luminosity sweet spot" at $L_V\sim10^{6}L_{\odot}$ where dSphs in our sample safely host terrestrial planets up to $4$ Gyr and in any planet formation scenario explored. In conclusion, planet formation at low metallicity is key to understanding which types of galaxies might have formed Earth-like planets that dwelt unexposed to galactic threats over several billions of years, first in the history of the Local Group.

We present a combined HST and JWST 0.2 - to - 5 $\mu$m analysis of the spectral energy distributions (SEDs) of emerging young star clusters (eYSCs) in four nearby galaxies from the Feedback in Emerging extrAgalactic Star clusTers (FEAST) survey: M51, M83, NGC 628, and NGC 4449. These clusters, selected for their bright Pa$\alpha$ and 3.3 $\mu$m polycyclic aromatic hydrocarbon (PAH) emission, are still associated to their natal gas cloud and have been largely missed in previous HST optical campaigns. We modeled their SEDs using the CIGALE fitting code and identified: i) a systematic flux excess at 1.5 - 2.5 $\mu$m that is not accounted for by current stellar population models; ii) the preference for a set of dust model parameters that is not aligned with expectations from self-consistent analyses of star-forming regions, suggesting model shortcomings also in the 3 - 5 $\mu$m. The near-infrared (NIR) excess is most prominent in low-mass ($\leq 3000$ M$_\odot$) and young ($\leq 6$ Myr) clusters. Additionally, we see that the SED fitting analysis wrongly assigns ages $\geq 6$ Myr to a fraction of strong Pa$\alpha$ emitters with equivalent widths suggestive of significantly younger ages. A parallel analysis with the slug code suggests that stochastic initial mass function (IMF) sampling of pre-main-sequence stars combined with extinction might partially reduce the gap. We conclude that the inclusion of young stellar object SEDs, along with more realistic sampling of the cluster IMF, might be needed to fully account for the stellar population and dust properties of eYSCs.

Achieving a complete picture of galaxy evolution is a primary goal of extragalactic astrophysics. To accomplish this ambitious task, a wealth of multi-wavelength surveys have been devoted to assess the cosmic evolution of the cold gas and of the stellar mass across cosmic time. In this cosmic census, one elusive component is represented by interstellar dust. In this work, we exploit the IR mission PRIMA (covering wavelengths from 24 $\mu$m to 235 $\mu$m) to perform a deep survey (1000h on 1 deg$^2$) aimed at estimating the still poorly known dust mass function (DMF) at $z \sim 0.5 - 5$. We consider the spectro-photometric realization of the SPRITZ simulation and we compute the dust masses using single temperature Modified Grey Body functions. We show how PRIMA alone, thanks to its unprecedented sensitivities, will constrain the DMF at $z < 1.5$, in terms of mass and faint-end slope. At $z > 1.5$, we stress the key synergy with current or future sub-millimeter facilities, such as the JCMT/SCUBA-2, AtLAST, LMT and ALMA telescopes, that will allow us to probe the R$-$J regime of PRIMA selected galaxies. Finally, PRIMA, thanks to its large photometric coverage, will be able for the first time to constrain strictly the warm dust properties of a two component dust model.

Within hierarchical triple stellar systems, there exists a tidal process unique to them, known as tertiary tides. In this process, the tidal deformation of a tertiary in a hierarchical triple drains energy from the inner binary, causing the inner binary's orbit to shrink. Previous work has uncovered the rate at which tertiary tides drain energy from inner binaries, as a function of orbital and tidal parameters, for hierarchical triples in which the orbits are all circular and coplanar. However, not all hierarchical triples have orbits which are circular and coplanar, which requires an understanding of what happens when this condition is relaxed. In this paper, we study how eccentricities affect tertiary tides, and their influence on the subsequent dynamical evolution of the host hierarchical triple. We find that eccentricities in the outer orbit undergo tidal circularisation as quickly as binary tidal synchronisation, and are therefore trivial, but that eccentricities in the inner binary completely change the behaviour of tertiary tides, draining energy from the outer orbit as well as the inner orbit. As with the circular orbit case, tertiary tides become significant when the tertiary is large enough to come close to filling its Roche Lobe, and dominate tidal evolution when interactions between the inner binary pair are weak. Empirical equations that approximate this behaviour are provided for ease of implementing this process in other stellar evolution codes, and the implications of these results are discussed.

The cosmic evolution of obscured star formation, dust properties and production mechanisms, and the prevalence of dust-obscured AGN out to high redshifts are currently some of the hot topics in astrophysics. While much progress has been made in the early days with Spitzer and Herschel, these facilities have not reached the necessary depths to observe the mid-IR light of high-redshift (z > 3) galaxies. Recently, the James Webb Space Telescope (JWST) has filled in the blue side of the rest-frame mid-IR. The Atacama Large (Sub)Millimeter Array (ALMA), on the other hand, provides excellent sensitivity in the far-IR regime, allowing the study of dust and gas properties at high redshifts. Filling the wavelength gap between JWST and ALMA is crucial to progress our understanding of early galaxy evolution - and this will be an important goal in the next decades. The Probe far-IR Mission for Astrophysics (PRIMA), with sensitive imaging and spectroscopic capabilities at 24-240$\mu$m and currently in Phase A study, will achieve this and provide insights into early galaxy evolution, Black Hole growth, and dust production mechanisms. Here we present PRIDES, a possible deep and wide-area survey over 1.6 square-degrees of the COSMOS field with PRIMA to study these science cases.

Striations are diffuse, linear, quasi-periodic, and magnetized structures located in the outskirts of molecular clouds. These structures seem to play an important role during the earliest stages of star formation. Theoretical models suggest that magnetic fields play an important role in the formation of striations. With its unprecedented resolution and sensitivity, the polarization module of the PRIMAger instrument onboard the PRIMA space observatory will enable studies related to the magnetic properties of striations in nearby molecular clouds. We plan to target three nearby ($\lesssim 350$ pc) molecular clouds (the Polaris Flare, Taurus, and Musca) with prominent striations that are strongly coupled to the large-scale magnetic field properties, as traced by low-resolution sub-millimeter polarization data. We will search for the unique imprint of the passage of magnetohydrodynamic waves in the polarization angle maps, which traces the magnetic field morphology, in bands 3 (172$\mu$m) and 4 (235$\mu$m) of PRIMAger. Each of the target regions is approximately 1 square degree in size. All three regions combined, can be mapped to more than five-sigma detection in averaged polarized intensity in $\sim 59$ hours. The proposed survey promises to provide important information on the early phases of star formation.

The Roman Space Telescope will be instrumental for characterizing the physical properties of galaxies and understanding their evolution across time. However, a complete view of galaxy star formation activity will only be possible with the addition of far-infrared observations that a telescope such as PRobe far-Infrared Mission for Astrophysics (PRIMA) will be able to provide. Indeed, PRIMA's far-infrared camera will be highly sensitive to dust emission, whereas Roman will probe the stellar emission in rest-frame optical and ultraviolet of distant galaxies. Our aim here is to evaluate the advantage of combining large PRIMA and Roman extragalactic surveys to retrieve the physical properties of galaxies and compare them with what we would obtain using either dataset separately. To do so, we use the Code Investigating Galaxy Emission photometric modeling code to generate a far-ultraviolet to a far-infrared synthetic set of dusty star-forming galaxies at redshifts from 1.5 to 2.5, simulating the observations from the main extragalactic surveys of PRIMA and Roman. We find that the PRIMA + Roman observations can reliably retrieve the star formation rate, stellar masses, and dust luminosity.

The behaviour of fast radio bursts (FRBs) at radio frequencies <400 MHz is not well understood due to very few detections, with only two known sources detected below 300 MHz. Characterising low-frequency emission of FRBs is vital for understanding FRB emission mechanisms and circumburst environments. We robustly characterise the 150 MHz activity CHIME-detected FRB sources relative to their 600 MHz activity -- using their non-detection in 473 h of archival observations from the Low Frequency Array (LOFAR) Tied-Array All-Sky Survey (LOTAAS), and 252 h of LOFAR observations of 14 repeating FRB sources, the largest sub-300 MHz targeted FRB campaign to date. In the LOTAAS data, we search for repeat bursts from 33 CHIME/FRB repeaters, 10 candidate repeaters and 430 apparent non-repeaters. Their non-detection yields a population-level constraint on the statistical spectral index $\alpha_{s, 150MHz/600MHz}>-0.9$, indicating that FRB spectral indices are, on average, flatter than known spectral indices from pulsars. From the targeted campaign, we find that the prolific repeater FRB 20201124A shows a positive $\alpha_s>0.55$, implying reduced low-frequency activity, unlike the typically negative $\alpha_{s}$ seen from FRBs at higher frequency bands. We explore free-free absorption in the circumburst environment as a cause of the non-detection at 150 MHz. The non-detection of FRB 20201124A is consistent with either a very young $\sim10$ yr old supernova remnant, or a typical HII region. Our simulations indicate that LOFAR2.0 can detect 0.3-9 FRBs per week, and up to 4 FRBs at redshifts in the range $1<z<3$. Such detections will provide robust constraints on cosmological parameters due to their clean environments. Our results guide future low-frequency FRB searches by showing how even non-detections can place meaningful constraints on the repetition rates and circumburst environments of FRBs.

Satellite kinematics offers a powerful method to infer dynamical halo masses and has been demonstrated to yield tight constraints on the galaxy-halo connection. However, previous studies have assumed that the halos in which the satellites orbit are composed solely of dark matter, neglecting the role of baryons. Here, we develop an analytical model incorporating stars, gas, and the adiabatic response of dark matter to assess the impact of baryonic effects on the inference from satellite kinematics. The model covers halos in the mass range $10^{12}-10^{15}M_\odot$ and is tuned to agree with well-established observational scaling relations. In addition, the model uses simple functional forms for the mass fractions of ejected baryons and diffuse halo stars, calibrated to the median trends in the EAGLE hydrodynamical simulations. We find that baryonic effects mainly result in a reduction of the satellite line-of-sight velocity dispersion due to the ejection of baryons and the resulting response of the dark matter halo. The effect is minimal (less than 1%) for the most massive halos, but reaches ~5-6% for halos in the mass range $10^{12}-10^{13}M_\odot$, and up to 8% in extreme cases. We propose a simple formalism for correcting the satellite line-of-sight velocity dispersion for baryonic effects, and for marginalizing over the uncertainties. We integrate this correction function into BASILISK, a Bayesian hierarchical inference method applied to satellite kinematics data extracted from large redshift surveys, and find that this shifts central galaxies to higher inferred halo masses at fixed luminosity by up to ~0.3 dex. In a forthcoming work, we demonstrate that these few-percent level baryonic effects can have a non-negligible impact on the inference of cosmological parameters, motivating a novel approach to constraining the efficiency of feedback processes associated with galaxy formation.

This paper develops a few science cases, using the PRIMA far-IR probe, aimed at achieving several breakthroughs in our understanding of the dust properties and their evolution. We argue that the specific observational capabilities of PRIMA, namely its unprecedented sensitivity over the whole far-IR range and the possibility to obtain continuous spectra between wavelengths 24 and 235 microns, are essential to progress in our understanding of the physics of the interstellar medium and galaxy evolution. Our science cases revolve around observations of nearby galaxies. We discuss the importance of detecting the IR emission of the diffuse interstellar medium of these galaxies, including very low-metallicity systems. We also discuss the opportunity of detecting various solid-state features to understand the mineralogy of interstellar grains. Finally, we stress the unique opportunity brought by the possible simultaneous measures of both the dust continuum and the far-IR fine-structure gas lines. These science cases could be distributed in a few large programs.

Observations of atmospheres of polluted white dwarfs provide insights into the elemental composition of accreted exoplanets and exo-asteroids. However, they poorly constrain the abundance of ice-forming volatile elements due to the properties of white dwarf atmospheres. Instead of focusing solely on atmospheric observations, we propose observing circumstellar water ice and vapor disks formed by the tidal disruption of icy bodies using the future PRobe far-Infrared Mission for Astrophysics (PRIMA) far-infrared enhanced survey spectrometer. PRIMA has the potential to measure volatile abundances in colder circumstellar regions inaccessible by shorter-wavelength observations. We employ a simple disk emission model with disk parameter ranges inferred from previous observations and disk evolution simulations. We find the 44-$\mu$m water ice feature promising for observing icy disks. For white dwarfs within 60 pc, 1-hour PRIMA observations could detect water ice with a mass above $10^{20}$ g, representing a potential lower limit of circumstellar disk mass. Water vapor rotational lines also abundantly emerge within the PRIMA wavelength coverage, and 5-hour observations for white dwarfs within 20 pc could detect water vapor with a total disk mass $\gtrsim 10^{20}$ g, depending on the H$_2$/H$_2$O ratio. 19 metal polluted white dwarfs within 20 pc and 210 within 60 pc could be optimal targets for water vapor and ice observations, respectively.

We derive and analyse the star formation histories of 393 intermediate-redshift (0.1 $\leq$ z $\leq$ 0.9) galaxies with stellar masses between $\sim$10$^{8}$ - 10$^{12}$ M$_{\odot}$. We probe a cosmic time of approximately 6 Gyr and a range of environments, from field (low-density systems) to rich groups (high-density systems). We find that the galaxies' stellar mean ages, metallicities, and star formation rates (SFRs) follow similar trends to galaxies as those characterising the nearby Universe. We modelled the derived SFRs, quantifying and characterising the number of star-forming episodes (SFEs). We found that more than 85$\%$ of the galaxies have more than one event of star formation, typically described with an exponentially decaying SFR and subsequent Gaussian-like episode(s) of star formation. We also observe that massive galaxies have fewer SFEs than low-mass systems and that they form their stellar mass and reach quiescence faster than lower mass galaxies. Moreover, the history of mass assembly for the most massive galaxies in the sample can be described with only one episode of star formation in the early Universe, which we detected as an exponential decrease that was longer in duration than subsequent SF events. This early event has typically been completed by z$\sim$3 and it accounts for a high fraction of the total stellar mass, from $\sim$40$\%$ for low-mass galaxies to more than 50$\%$ for higher-mass galaxies. We also analysed the dependence of stellar population parameters with the various environments probed by the sample, finding no significant correlations between different group environments; however, our field galaxies are generally distinct from group galaxies in terms of the mass, metallicity, stellar ages, and formation timescales. We discuss possible biases in the sample selection and examine how representative our galaxies are of the overall galaxy population.

A long-range force acting only in the dark sector can displace the stellar component of satellite galaxies relative to their dark matter (DM) halos, thereby \emph{breaking} the weak equivalence principle (WEP) between DM and baryons. We investigate observational signatures of such WEP breaking using $N$-body simulations of a Fornax-like Milky Way (MW) satellite, implementing a fifth force between DM particles of amplitude $\beta$ relative to Newtonian gravity (with a screening length much larger than the MW halo size). We find that $\beta \gtrsim 0.6$ strips and unbinds the bulk of the stellar component, leaving at most a negligible bound remnant that fails to match the observed stellar content, surface-brightness, and line-of-sight velocity-dispersion profiles of Fornax. By contrast, $\beta \lesssim 0.2$ yields only mild stellar stripping and remains broadly consistent with current photometric and kinematic constraints within our modeling assumptions.

The PRobe far-Infrared Mission for Astrophysics (PRIMA) is an infrared observatory for the next decade, currently in Phase A, with a 1.8m telescope actively cooled to 4.5K. On board, an infrared camera, PRIMAger, equipped with ultra-sensitive kinetic inductance detector (KID) arrays, will provide observers with coverage of mid-infrared to far-infrared wavelengths from 24 to 264 microns. PRIMAger will offer two imaging modes: the Hyperspectral mode will cover the 24-84 microns wavelength range with a spectral resolution R=8, while the Polarimetric mode will provide polarimetric imaging in 4 broad bands, from 80 to 264 microns. These observational capabilities have been tailored to answer fundamental astrophysical questions such as black hole and star-formation co-evolution in galaxies, the evolution of small dust grains over a wide range of redshifts, and the effects of interstellar magnetic fields in various environments, as well as to open a vast discovery space with versatile photometric and polarimetric capabilities. PRIMAger is being developed by an international collaboration bringing together French institutes (Laboratoire d'Astrophysique de Marseille and CEA) through the center National d'Etudes Spatiales (CNES, France), the Netherlands Institute for Space Research (SRON, Netherlands), and the Cardiff University (UK) in Europe, as well as the Jet Propulsion Laboratory (JPL) and Goddard Space Flight Center (GSFC) in the USA.

We present a dynamical and chemical study of the centre of a massive early-type strong-lens galaxy ESO286-G022 (SNL-1). Analysing new data obtained through the adaptive-optics-assisted Narrow-Field Mode of VLT/MUSE, we aim to measure the mass distribution and internal properties of SNL-1 at $\sim 50\ {\rm pc}$ resolution. In particular, we aim to address the tension in the reported IMF measurements of SNL-1 between strong-lens/dynamical and spectral-fitting techniques. We fit a triaxial orbital dynamical model to the measured stellar kinematics, including constraining the mass of the (resolved) central supermassive black-hole. The dynamical model is consistent with the mass-to-light ratio expected for a Kroupa-like IMF. We also employ a highly-flexible spectral-fitting technique, which instead favours a Salpeter-like IMF (low-mass slope $\alpha\approx 2.3$) over the same spatial region. To conclude, we discuss possible origins of this discrepancy, both intrinsic and technical.

We present new JWST/NIRCam observations of the interacting dwarf galaxy system NGC 4485/NGC 4490 (a.k.a. Arp 269), obtained as part of the Cycle 1 Feedback in Emerging extrAgalactic Star clusTers (FEAST) program. NGC 4485 and NGC 4490 form the closest known pair of interacting late-type dwarf galaxies (at $\sim 7.4$ Mpc), excluding the Magellanic Clouds. Near-infrared color-magnitude diagrams (CMDs) reveal a wide range of stellar populations in both galaxies, including young ($\lesssim 200$ Myr) upper main sequence stars, core helium-burning stars, and oxygen-rich asymptotic giant branch (AGB) stars. We also identify intermediate-age ($\sim 200$ Myr -- $1$ Gyr) carbon-rich AGB stars and a well-populated old ($\gtrsim 1$ Gyr) red giant branch (RGB). The CMDs show two distinct bursts of star formation beginning $\sim 30$ Myr and $\sim 200$ Myr ago, the latter consistent with the most recent pericenter passage predicted by N-body simulations. The spatial distribution of stars reveals a tidal bridge extending from NGC 4485 and connecting to the disk of NGC 4490. Compact star-forming regions are seen along NGC 4490's spiral arms, possibly originating from its infrared nucleus. A significant metallicity gradient is observed in the young stellar populations forming the bridge. These findings suggest that during the last pericenter passage, gas was stripped from NGC 4485 via tidal forces or ram pressure, accreted by NGC 4490, and mixed with in-situ material, fueling ongoing star formation. This system provides a unique nearby laboratory for studying how tidal interactions shape the star formation and chemical enrichment history of dwarf galaxies.

The UV-optical dust attenuation curve is key to interpreting the intrinsic properties of galaxies and provides insights into the nature of dust grains and their geometry relative to stars. In this work, we constrain the UV-optical slope of the stellar attenuation curve using a spectroscopic-redshift sample of ~3300 galaxies at z~1-9, to characterize the diversity and redshift evolution of stellar attenuation curves and to gain insight into dust production and evolution at high redshifts. The sample is constructed from three JWST/NIRCam grism surveys in GOODS and A2744 fields, with a wealth of JWST/NIRCam and HST photometry. With constraints from spectroscopic redshifts and emission line fluxes, we use the Prospector SED fitting code with a flexible dust model. We find that the attenuation curve slope varies strongly with Av at all redshifts, becoming flatter at higher attenuation. We find no strong correlation between attenuation curve slope and size or axis ratio, and the trends with stellar mass and star-formation rate are largely driven by their correlation with Av. We find strong evidence that at fixed Av, the curve becomes flatter with increasing redshift. On average, the attenuation curves derived here are shallower than those at z~0 and than the SMC curve. The highest redshift galaxies at z=7-9 (124 galaxies, a significantly larger sample than in previous studies) show slopes even flatter than the Calzetti curve, implying reduced UV obscuration and lower IR luminosities than expected from an SMC dust curve, by as large as an order of magnitude. Hydrodynamical simulations that couple dust growth to gas chemical enrichment successfully reproduce the different loci of high- and low-redshift galaxies in the slope-Av diagram, suggesting that dust in high-redshift galaxies is increasingly dominated by large grains produced in supernova ejecta with limited ISM processing at early times.

High-resolution, wide-area mapping of magnetic field geometries within molecular clouds, and the star-forming filaments and cores within them, is crucial in order to understand the role of magnetic fields in the star formation process. We therefore propose an unbiased survey of star-forming molecular clouds within 0.5 kpc of the Earth in polarized light with the PRIMAger Polarimetry Imager. We will map magnetic fields over entire molecular clouds at linear resolutions of $\sim10^{-3}-10^{-2}$ pc ($\sim10^{3}-10^{4}$ au) in PRIMAger Bands PPI1 - PPI4, thereby resolving magnetic field structure both within individual star-forming filaments and cores, and in the most diffuse regions of molecular clouds. These multi-wavelength polarimetric observations will allow us to systematically investigate both the wide range of open questions about the role of magnetic fields in star formation and the evolution of the interstellar medium, and interstellar dust grain properties. The time required to map the area observed by the \textit{Herschel} Gould Belt Survey (160 deg$^{2}$) to the cirrus confusion limit in polarized light is 170 hours. This will give a 5-$\sigma$ detection of 20% polarized low-density cirrus emission, with surface brightnesses in polarized intensity of 1.0-2.4\,MJy/sr across the PRIMAger bands, and will ensure detection of polarized emission at all higher column densities. This time estimate can be simply scaled up in order to map magnetic fields in a larger sample of molecular clouds, including more distant regions of higher-mass star formation.

We present the science drivers for the Far-Infrared Enhanced Survey Spectrometer (FIRESS), one of two science instrument on the PRobe Infrared Mission for Astrophysics (PRIMA). FIRESS is designed to meet science objectives in the areas of the origins of planetary atmospheres, the co-evolution of galaxies and supermassive black holes, and the buildup of heavy elements in the Universe. In addition to these drivers, FIRESS is envisioned as a versatile far-infrared spectrometer, capable of addressing science questions in most areas of astrophysics and planetary astronomy as part of a dominant General Observer (GO) program with 2/3 of the current science cases using FIRESS. We summarize how the instrument design choices and parameters enable the main science drivers as well as a broad and vibrant GO program.

We relate the optical attenuation inferred by the Balmer decrement, $A_{V\mathrm{,BD}}$, and by the SED-fitting, $A_{V\mathrm{,SED}}$, to the dust distribution and gas surface density throughout the disc of galaxies, down to scales smaller than 0.5 kpc. We investigate five nearby star-forming spirals with available FUV to sub-mm observations, along with atomic and molecular gas surface density maps and optical integral-field spectroscopic data. We use the CIGALE SED-fitting code to map the dust mass surface density ($\Sigma_\mathrm{dust}$) and $A_{V,\mathrm{SED}}$ of different stellar populations. For each pixel, we independently estimate the attenuation from the BD. We find that both $\Sigma _\mathrm{dust}$ and $A_{V,\mathrm{BD}}$ trace better the molecular and total gas mass surface density, rather than the atomic gas. Since regions sampled in this study have high molecular fractions, atomic gas surface densities, indicative of molecular gas shielding layers, decrease as the mean dust-to-gas ratio increases from galaxy to galaxy. The fitted attenuation towards young stars, $A^\mathrm{young}_{V,\mathrm{SED}}$, is in good agreement with $A_{V,\mathrm{BD}}$ and it can then be used to trace the attenuation in star forming galaxies where integral-field observations are not available. We estimate the ratio of $A_{V,\mathrm{BD}}$ over the total stellar $A_{V,\mathrm{SED}}$ and find it slightly larger than what has been found in previous studies. Finally, we investigate which dust distribution reproduces better the estimated $A_{V,\mathrm{BD}}$ and $A_{V,\mathrm{SED}}$. We find that the attenuation towards old stars is consistent with the expectations for a standard galactic disc, where the stellar and dust distributions are mixed, while $A_{V, \mathrm{BD}}$ and the $A^\mathrm{young}_{V, \mathrm{SED}}$ are between the values expected for a foreground dust screen and a mixed configuration.

Studies of the water content and isotopic composition of water-rich asteroids and comets are of key interest for understanding the late accretion stage of the Solar System cometary and chondritic materials. The PRobe far-infrared Mission for Astrophysics (PRIMA) can make an important contribution to solving this long-standing problem by carrying out direct measurements of the D/H ratio in a significant sample of Oort cloud and Kuiper belt comets, sampling the isotopic composition of the present-day outer Solar System. This would allow comparisons between different comet reservoirs, and with inner Solar System measurements in meteorites, as well as searching for correlations with physical parameters, such as hyperactivity, providing quantitative constraints on the dynamical and chemical models of the early Solar System.

Study of interstellar elemental depletion poses an important problem in the interstellar matter that at least a quarter of the total oxygen ($\sim 160$ ppm relative to hydrogen) is not accounted for in any known form of oxygen in the translucent or dense interstellar medium (ISM). Detailed analysis of the absorption feature of water ice at 3 $\mu$m suggests that one fifth of the missing oxygen may reside in 3 $\mu$m-sized water ice grains. However, the 3 $\mu$m feature becomes complex and weak for grains larger than 3 $\mu$m, and thus the NIR spectroscopy is not the best means to study the presence of large ice grains reliably. Here we show that sensitive observations of the far-infrared (FIR) features of water ice at 44 and 62 $\mu$m enable us to constrain the amount of crystalline water ice grains up to 5 $\mu$m or even larger sizes unambiguously. Oxygen is one of the key elements in the ISM chemistry, and [O I] 63 $\mu$m is a dominant cooling line in the neutral ISM. Understanding the actual form of the missing oxygen in the ISM is crucial for the study of the ISM and star-formation process. To detect the FIR features of the crystalline water ice over the expected strong continuum, a sensitive FIR spectrograph represented by PRIMA/FIRESS is indispensable. Since the feature is broad, the low spectral resolution of $R \sim 130$ is sufficient, but accurate relative calibration better than 1% is required.

Transition-edge sensor (TES) bolometers operate under strong electrothermal feedback, wherein power deposited on the bolometer is compensated by a corresponding change in electrical power dissipation. We present a comprehensive analysis of Johnson noise suppression that extends previous theoretical frameworks to the general case of AC-biased linear circuits with arbitrary parasitic impedances. Using a Thévenin-equivalent circuit formulation -- consisting of an ideal voltage source and complex series impedance external to the bolometer thermal island -- we derive analytical expressions for the noise-equivalent current in the presence of both bolometer and parasitic Johnson noise sources. Our analysis demonstrates that while the electrothermal feedback loop effectively suppresses Johnson noise originating from the bolometer resistance, it provides no suppression of Johnson noise from external series resistance. In the limit of high loop gain, the bolometer Johnson noise contribution vanishes while the parasitic contribution remains unsuppressed.

Recent measurements made by the Alpha Magnetic Spectrometer (AMS) have detected accurate positron flux for energy range 1-1000 GeV. The energy spectrum can be best described by two source terms: the low-energy background diffusion term and an unknown high-energy source term. In this article, we discuss the possibility of the emission of positrons originating from dark matter annihilation in two nearby black hole X-ray binaries A0620-00 and XTE J1118+480. We show that the dark matter density spikes around these two black holes can best produce the observed AMS-02 high-energy positron flux due to dark matter annihilation with rest mass $m_{\rm DM} \approx 8000$ GeV via the $W^+W^-$ annihilation channel. This initiates a new proposal to account for the unknown high-energy source term in the AMS-02 positron spectrum.

It is presented that the Probe far-Infrared Mission for Astrophysics (PRIMA) has a high potential to study particle acceleration phenomena associated with jets emanating from active galactic nuclei. A special focus is put on hot spots of radio galaxies because they are widely regarded as the jet-terminal shock where particles are accelerated via the diffusive shock acceleration. To investigate the particle acceleration condition in the hot spots, it is of prime importance to evaluate their magnetic field strength. As a useful indicator of the magnetic field, we propose to adopt a synchrotron spectral feature called the cooling break, of which the frequency is determined by the mutual balance between the synchrotron radiative cooling and the adiabatic one. Referring to the standard physical parameter of the hot spots, the cooling break is expected to reside in or slightly below the far-infrared range covered with PRIMA. The feasibility of the PRIMA observations to measure the far-infrared flux density and to constrain their cooling break frequency is discussed for nearby well-studied hot spots. An affordable observational strategy with PRIMA is described. A possible application of the method to lobes of radio galaxies is also briefly discussed.

Within a Bayesian statistical framework, we jointly estimate the source and lens parameters and evaluate the relative evidence between the lensed and unlensed models. This work focuses on the wave optics effects induced by a point mass (PM) lens on gravitational waves (GW) from equal-mass massive binary black holes (MBHB), and assesses the capability of the space-based GW detector Taiji to detect such effects. Specifically, we investigate the impact of the redshifted lens mass MLz in the range [3e5, 3e7] solar masses, impact parameter y in [10, 50], source redshift zs in [4, 6], and total source mass Ms in [1e5, 1e7] solar masses on parameter estimation and model selection. Our results show that, for the cases we studied, larger MLz increases the waveform mismatch MM, which directly enhances the waveform difference and the corresponding signal-to-noise ratio (SNR), thereby improving the ability to discriminate between the lensed and unlensed models. In contrast, for y > 50, both MM and SNR are too small to allow effective model discrimination in these cases. Parameter estimation further indicates that for y < 50, the degeneracy between the luminosity distance and MLz can be effectively broken. Although the Bayes factor decreases as zs increases, lensing signatures remain identifiable up to zs = 6. The role of Ms depends on the overlap of the GW signal with the detector sensitive band. Overall, effective model discrimination requires MM greater than or equal to 1e-7 (corresponding to SNR greater than 5).

Recently, the youngest transiting planet was discovered around the T Tauri star, IRAS 04125+2902, in the Taurus-Auriga star-forming region. This system is crucial for understanding the early stages of planet formation. We used Atacama Large Millimeter/submillimeter Array Band 6 data to investigate the IRAS 04125+2902 system in detail. The dust continuum emission reveals a ring-gap transitional disk structure with an inclination of 35.6$^{\circ}$. In addition, two-dimensional super-resolution imaging based on Sparse Modeling and the one-dimensional modeling of disk brightness distribution suggest the existence of an inner emission, which may be attributed to an inner disk, although free-free emission from the central star is not ruled out. Furthermore, we identified the $^{12}$CO $J$=2-1 emission, and the dynamical mass of the central star is estimated to be 0.7-1.0 $M_{\odot}$. The asymmetry of the dust ring and the velocity distortion around the central star are, if at all, weak, suggesting that the inner disk, if it exists, is not highly inclined with respect to the outer disk. Radiative transfer calculations of dust continuum emission suggest that the inner and the outer disk may be misaligned by $\sim$10$^\circ$, which may be confirmed in future observations with higher resolution and sensitivity. Our results suggest that IRAS 04125+2902 is a dynamically complex system, where the binary orbit, outer disk, inner disk, and planetary orbit are mutually misaligned, providing insight into the early orbital evolution of young systems.

Acetamide (CH$_{3}$CONH$_{2}$), a key interstellar amide and a methyl derivative of formamide (NH$_{2}$CHO), has been sparsely detected, limiting insights into its prebiotic relevance. We present the first systematic survey for acetamide toward 52 hot molecular cores using ALMA Band 6 data. Acetamide has been detected in 10 cores, markedly expanding the inventory of known emitters. The derived column densities of acetamide range from $(2.5\pm0.9)\times10^{14}$ to $(1.5\pm0.6)\times10^{16}$ cm$^{-2}$, compared to formamide's $(1.1\pm0.1)\times10^{15}$ to $(6.9\pm0.4)\times10^{16}$ cm$^{-2}$. The nearly constant abundance ratios (~3-9) and strong abundance correlation between the two amides across sources suggest a chemically linked formation pathway, likely on grain surfaces. The presence of peptide-like molecules in these regions implies that complex organic species can survive star formation processes, offering a potential pathway toward prebiotic chemistry. These findings constrain the dominant grain surface formation routes of acetamide, confirm its broader prevalence in highmass star-forming regions, and underscore the importance of targeted amide surveys in tracing the chemical evolution toward prebiotic complexity.

Planetary radii are derived for 218 exoplanets orbiting 161 M dwarf stars. Stellar radii are based on an analysis of APOGEE high-resolution near-IR spectra for a subsample of the M-dwarfs; these results are used to define a stellar radius-M$_{\rm K_{\rm s}}$ calibration that is applied to the sample of M-dwarf planet hosts. The planetary radius distribution displays a gap over R$_{\rm p}$$\sim$1.6-2.0 R$_{\oplus}$, bordered by two peaks at R$_{\rm p}$$\sim$1.2-1.6 R$_{\oplus}$ (super-Earths) and 2.0-2.4 R$_{\oplus}$ (sub-Neptunes). The radius gap is nearly constant with exoplanetary orbital period (a power-law slope of m=$+0.01^{+0.03}_{-0.04}$), which is different (2-3$\sigma$) from m$\sim$$-$0.10 found previously for FGK dwarfs. This flat slope agrees with pebble accretion models, which include photoevaporation and inward orbital migration. The radius gap as a function of insolation is approximately constant over the range of S$_{\rm p}$$\sim$20-250 S$_{\oplus}$. The R$_{\rm p}$-P$_{\rm orb}$ plane exhibits a sub-Neptune desert for P$_{\rm orb}$$<$2d, that appears at S$_{\rm p}$$>$120 S$_{\oplus}$, being significantly smaller than S$_{\rm p}$$>$650 S$_{\oplus}$ found in the FGK planet-hosts, indicating that the appearance of the sub-Neptune desert is a function of host-star mass. Published masses for 51 exoplanets are combined with our radii to determine densities, which exhibit a gap at $\rho_{\rm p}$$\sim$0.9$\rho_{\oplus}$, separating rocky exoplanets from sub-Neptunes. The density distribution within the sub-Neptune family itself reveals two peaks, at $\rho_{\rm p}$$\sim$0.4$\rho_{\oplus}$ and $\sim$0.7$\rho_{\oplus}$. Comparisons to planetary models find that the low-density group are gas-rich sub-Neptunes, while the group at $<$$\rho_{\rm p}$$>$$\sim$0.7$\rho_{\oplus}$ likely consists of volatile-rich water worlds.

Mergers of double white dwarfs are considered significant potential progenitors of type Ia supernovae. Although there is no direct observational evidence to definitively determine the formation pathways of SNe Ia, studying the physical properties of DWDs provides valuable insights into their evolutionary processes, interaction modes, and merger mechanisms, which are essential for understanding the explosion mechanisms of SNe Ia. This study aims to identify DWD candidates through spectroscopic radial velocity measurements and analyze their physical properties based on DESI EDR. We crossmatched DESI EDR with the Gaia EDR3 to select DA. We measured the spectroscopic RV using the cross-correlation function and assessed the significance of RV variability using a chi-squared-based variability method. Spectroscopic Teff and log g were derived by fitting the hydrogen Balmer lines, with 3D convection corrections applied. Orbital periods and semi-amplitudes were obtained through a Lomb-Scargle analysis of the RV time series. We interpolated WD cooling models and applied Monte Carlo simulations to calculate masses, cooling ages, radii, and their associated uncertainties. We also analyzed their photometric and spectral energy distribution properties to derive photometric temperatures and radii, which were then compared with the corresponding spectroscopic parameters. We identified 33 DA DWD candidates with significant RV variability, including 28 new discoveries. Among them, we found an extremely low-mass DWD candidate and a potential triple system. For these candidates, we measured key physical parameters including Teff, log g, mass, and radius, and estimated the orbital periods based on the available data. Of these, 17 candidates exhibit relatively clear periodic RV variability in the current data, and we report their best-fitting periods and RV semi-amplitudes.

We present observations and detailed modeling of a protoplanetary disk around the T Tauri star, V1098 Sco. Millimeter wavelength data from the Atacama Large Millimeter Array (ALMA) show a ring of large dust grains with a central cavity that is filled with molecular gas. Near-infrared data with the Very Large Telescope (VLT) detect the scattered starlight from the disk surface and reveal a large shadow that extends over it's entire southern half. We model the ALMA continuum and line data to determine the outer disk geometry and the central stellar mass. Using radiative transfer models, we demonstrate that a misaligned inner disk, tilted in both inclination and position angle with respect to the outer disk, can reproduce the salient scattered light features seen with the VLT. Applying an image threshold algorithm to compare disk morphologies and training a neural network on a set of high signal-to-noise models, we forward model the data and determine the inner disk geometry. We find that the rotation axes of the inner and outer disks are misaligned by 38 degrees and constrain the mass and location of a perturbing planetary or substellar companion. The technique of simulation based inference that is illustrated here is broadly applicable for radiative transfer modeling of other objects.

Recently, the Large High Altitude Air Shower Observatory (LHAASO) published measurements of the all-particle CR energy spectrum and the mean logarithmic mass of CRs with unprecedented accuracy in 0.3-30 PeV. The mean logarithmic mass shows a nonmonotonic change with energy, a feature observed for the first time. In this work, we present a new approach to describe the mechanisms of formation of this feature. The key elements of this approach are the non-classical diffusion model of cosmic rays developed by the authors in which the knee in the observed spectrum occurs naturally without the use of additional assumptions, as well as power-law asymptotics before and after the knee, and a soft spectrum of particle generation in cosmic ray source. To obtain a more complete picture of the spectrum formation in the region of the knee and the sources that form it, we carried out calculations of the spectra of the main groups of nuclei in the energy range of 1 TeV-100 PeV. It is shown that the behavior of the all-particle spectrum and mass composition in the knee region is determined by local pevatrons located at a distance of 750-900 pc from the Earth. The energy of the knee practically coincides with the knees in the spectra of protons and helium nuclei. The contribution of the light components $p$+He is about 70%, the CNO group provides $\sim$13%. The energy spectrum index of the light components is -2.61 before the knee. The nonmonotonic change in the mean logarithmic mass is due mainly to a decrease in the contribution of the CNO group in the energy range of 0.3-3 PeV.

One of the main open issues in galaxy formation and evolution is the early assembly of the most massive galaxies and their contribution to the stellar mass and star formation rate densities at early epochs. Massive red sources already in place at z > 2 to 3 have been found in deep Spitzer-IRAC and ALMA surveys. They are often called optically and near-IR dark, or HST-dark, being undetected even in the deepest HST frames. The submillimeter (i.e., ALMA) detection of these sources confirms their high-z dusty nature: they are massive (e.g., log(M*/Msun) > 10) and dusty star-forming galaxies with estimated redshifts in the 2.5 to 7 range. They seem to lie mostly below the main sequence (MS) of star-forming galaxies and show gas depletion times <1 Gyr. Imaging with the PRIMA/PRIMAger instrument over the full 25 to 265 micron range will allow us to characterize their still uncovered spectral energy distributions between JWST and ALMA spectral windows, probing their dust content and properties (e.g., temperature, mass), whereas spectroscopic observations with FIRESS will be the key to investigate the nature of their powering source (e.g., AGN or star formation) and to study the physics of their ISM, by detecting and measuring fine structure lines in the mid- and far-IR domain.

The properties of interstellar dust grains are being scrutinized more than ever before, with the advent of large facilities. Infrared emission from dust grains is a powerful asset than can help constrain their physical and chemical properties. Among these, the relative ratio of carbon-rich to silicate-rich grains remains one that has not yet been investigated thoroughly, due to the lack of dedicated instruments and modeling limitations. In this paper, we quantify the modeling degeneracies inherent to constraining the far-infrared (far-IR) slope of the dust emission spectral energy distribution. Used as a proxy for the silicate-to-carbon ratio, we find that recovering the far-IR slope is affected by the estimate of the local radiation field, and the input abundances of different grain species. We show that PRIMA's Hyperspectral Imaging will lead to better constrained local radiation fields which will aid -- together with PRIMA's polarization capabilities -- to better constrain the silicate-to-carbon ratio in M31, and how it spatially varies within the galaxy.

This paper presents a study on the distinguishability of dark matter and Modified Newtonian Dynamics (MOND) at galactic scales based on the stability criterion proposed by Efstathiou, Lake, and Negroponte (ELN criterion). First, we test the statistical validity of this stability criterion against the presence of bars within the SPARC and CALIFA databases, successfully identifying $\sim 70\%$ of barred galaxies. Then, we employ a series of N-body galaxy simulations to exhibit a direct observable difference between the dark matter and MOND theoretical frameworks, at least in gas-poor galaxies. We present N-body models that satisfy the stability requirement of the ELN criterion, and so are stable against bar formation in the presence of a dark matter halo, and that do actually exhibit bar instabilities in MOND. On the other hand, the question of how to inhibit bar formation in gas-poor galaxies in MOND is posed, and requires a detailed investigation of the external field effect.

We present the first simultaneous detection of four distinct highly ionized $z=0$ absorbing phases using Chandra and XMM-Newton grating spectra toward the blazar PKS 2155$\hbox{-}$304. We detect the MgXII K$\alpha$ absorption line for the first time in the circumgalactic medium (CGM) of the Milky Way. Along with MgXII K$\alpha$, we detect SiXIV K$\alpha$ absorption, which are the tell-tale signatures of the hot 'super-virial' gas in the CGM. Both from the model-independent calculations and hybrid-ionization modeling, we infer four phases at distinct temperatures, hot 'super-virial' ($5.4^{+1.9}_{-0.8} \times 10^7$ K), warm-hot 'virial' ($1.8^{+0.3}_{-0.2} \times 10^6$ K), warm 'sub-virial' ($2.2\pm 0.5 \times 10^5$ K), and cool phase ($<1.7 \times 10^5$ K). The warm-hot and hot phases are $\alpha$-enhanced, and [C/O] and [Ne/O] are super-solar in the warm-hot phase, while [Mg/O] and [Si/O] are super-solar in the hot phase. The low-ionization lines are blue-shifted (v$_{\rm los} \approx -100$ km s$^{-1}$), whereas the high-ionization lines are red-shifted. It suggests a scenario of infalling sub-virial, quasi-static virial, and outflowing super-virial phases along this sightline. Earlier studies on individual sightlines were confined to the Northern Hemisphere. Our sightline is located in the Southern hemisphere, demonstrating that hot super-virial gas is also present at Southern Galactic latitudes as well. This confirms a more widespread distribution of the super-virial gas across both hemispheres.

We present a systematic search for broad-line active galactic nuclei (AGNs) in the ALPINE-CRISTAL-JWST sample of 18 star-forming galaxies ($M_\star>10^{9.5}~M_{\odot}$) at redshifts $z=4.4-5.7$. Using JWST/NIRSpec IFU, we identify 7 AGN candidates through the detection of broad \Ha\ emission lines from 33 aperture spectra centred on photometric peaks. These candidates include one highly robust AGN detection with FWHM $\sim$ 2800 \kms\ and six showing broad components with FWHM $\sim 600-1600$ \kms, with two in a merger system. We highlight that only broad-line detection is effective since these candidates uniformly lie within narrow emission-line ratio diagnostic diagrams where star-forming galaxies and AGNs overlap. The broad-line AGN fraction ranges from 5.9\% to 33\%, depending on the robustness of the candidates. Assuming that the majority are AGNs, the relatively high AGN fraction is likely due to targeting high-mass galaxies, where simulations demonstrate that broad-line detection is more feasible. Their black hole masses range from $10^6$ to $10^{7.5}~M_{\odot}$ with $0.1 \lesssim L_{\rm bol}/L_{\rm Edd}\lesssim 1$. Counter to previous JWST studies at high redshift that found overmassive black holes relative to their host galaxies, our candidates lie close to or below the local $M_{\rm BH}-M_\star$ scaling relations, thus demonstrating the effect of selection biases. This study provides new insights into AGN-host galaxy co-evolution at high redshift by identifying faint broad-line AGNs in galaxy samples, highlighting the importance of considering mass-dependent selection biases and the likelihood of a large population of AGNs being undermassive and just now being tapped by JWST.

The properties of galaxies are known to have been influenced by the large-scale structures that they inhabit. Theory suggests that galaxies acquire angular momentum during the linear stage of structure formation, and hence predict alignments between the spin of halos and the nearby structures of the cosmic web. In this study, we use the largest catalog of galaxies publicly available - the Siena Galaxy Atlas - to study the alignment of the spin normals of elliptical and spiral galaxies with filaments constructed by applying the Bisous process on galaxies ($z \le$ 0.2) from SDSS - DR12. Our sample comprises 32517 disk and 18955 elliptical galaxies that are within 2 Mpc of any filament spine. We find that the spin normals of elliptical galaxies exhibit a strong perpendicular alignment with respect to the orientation of the host filaments, inconsistent with random distributions by up to $\approx$ 13 $\sigma$. The spin axis of spiral galaxies shows a much weaker but nonzero alignment signal with their host filaments of $ \approx$ 2.8$\sigma$ when compared with random. These numbers depend on exactly how the significance is measured, as elucidated in the text. Furthermore, the significance of the alignment signal is examined as a function of distance from the filament spine. Spiral galaxies reach a maximum signal between 0.5 and 1 Mpc. elliptical galaxies reach their maximum significance between 0.2 and 0.5 Mpc. We also note that with a tailored selection of galaxies, as a function of both i) distance from the filaments \& as a ii) function of absolute luminosity, the alignment significance can be maximized.

Sulfur is known to undergo severe depletion when moving from diffuse clouds to the denser regimes of the interstellar medium in molecular clouds. The form in which sulfur gets depleted onto dust grains, however, remains a mystery. One possibility is that sulfur gets locked in interstellar dust in the form of sulfide minerals. Recently, metal sulfides such as NaS and MgS have been detected in a shocked molecular cloud in the Galactic Center, suggesting that these molecules could represent an important reservoir of sulfur in dust grains. In this contribution, we discuss the prospect of observing metal sulfides such as MgS and FeS in absorption experiments carried out with the FIRESS instrument onboard PRIMA using its low resolution observing mode. Our estimates show that the molecular bands of MgS and FeS found between 20 and 50 ${\mu}$m could be detected in absorption with S/N ${\geq}$ 5 for sources brighter than 200 mJy in just 1 h of observing time against low-mass protostellar objects. This science case, therefore, has the potential to unveil the main reservoir of sulfur in interstellar dust, constraining in what form sulfur is incorporated into minor bodies of our solar system.

We analyse 77 \textit{Fermi} sources and their potential low-energy counterparts previously proposed in the literature. These sources were classified as active galactic nuclei, mainly blazars, based on optical spectroscopy. The main goals of this work are to examine these associations, classify the blazars based on their multi-wavelength spectral energy distributions (SEDs), and identify potential masquerading BL Lac objects. Through SED analysis, we assess whether the multi-wavelength emission follows the characteristic double-peaked curve of blazars. Additionally, we propose the region of origin of the emission at different wavelengths, investigate the correlation between $\gamma$-ray and lower-energy emission, and classify objects as low-, intermediate-, high- or extreme high synchrotron peaked (LSP, ISP, HSP, E-HSP) blazars. We search for masquerading BL Lacs, a class of flat-spectrum radio quasars where broad emission lines are swamped by non-thermal jet emission. The multi-wavelength analysis revealed that the 64 radio-loud sources in our sample exhibit an SED with a double-peak structure, typically ascribed to jet activity. Based on the synchrotron peak, 46 are HSP, 11 as ISP, and 7 as LSP. We also found 9--18 masquerading BL Lac candidates ($\approx$15--30\% of the radio-loud sample). For the 13 radio-quiet UGSs, the SEDs do not exhibit the double-peak structure typical of jetted AGN. Further analysis ruled out star formation as the origin of the observed $\gamma$-ray emission, making its reconciliation with lower-energy emission challenging. We explored alternative counterparts, identifying low-energy matches for 7 sources, with no plausible counterparts found for the others.

JWST observations of the secondary eclipse of TRAPPIST-1 b at 12.8 and 15 microns revealed a very bright dayside. These measurements are consistent with an absence of atmosphere. Previous 1D atmospheric modeling also excludes -- at first sight -- CO2-rich atmospheres. However, only a subset of the possible atmosphere types has been explored and ruled out to date. Recently, a full thermal phase curve of the planet at 15 microns with JWST has also been observed, allowing for more information on the thermal structure of the planet. We first looked for atmospheres capable of producing a dayside emission compatible with secondary eclipse observations. We then tried to determine which of these are compatible with the observed thermal phase curve. We used a 1D radiative-convective model and a 3D global climate model (GCM) to simulate a wide range of atmospheric compositions and surface pressures. We then produced observables from these simulations and compared them to available emission observations. We found several families of atmospheres compatible at 2-sigma with the eclipse observations. Among them, some feature a flat phase curve and can be ruled out with the observation, and some produce a phase curve still compatible with the data (i.e., thin N2-CO2 atmospheres, and CO2 atmospheres rich in hazes). We also highlight different 3D effects that could not be predicted from 1D studies (redistribution efficiency, atmospheric collapse). The available observations of TRAPPIST-1 b are consistent with an airless planet, which is the most likely scenario. A second possibility is a thin CO2-poor residual atmosphere. However, our study shows that different atmospheric scenarios can result in a high eclipse depth at 15 microns. It may therefore be hazardous, in general, to conclude on the presence of an atmosphere from a single photometric point.

The interacting transient SN 2016cvk (ASASSN-16jt) is a member of the peculiar SN 2009ip-like events. We present our follow-up data and aim to draw conclusions about the physical nature of the progenitor system. Our spectrophotometric data set of SN 2016cvk covers the ultraviolet, optical, and near-infrared wavelength region extending to +1681 d from the light curve peak; the data is analysed and compared to other SN 2009ip-like transients. Archival data reveals pre-outbursts of the progenitor with the first detection at -1219 d. The light curve evolution of SN 2016cvk consists of two consecutive luminous events A and B with peak magnitudes of M_V < -15.6 and M_r = -18.3 mag, respectively. The spectra are dominated by Balmer emission lines that have a complex, multi-component evolution similar to other SN 2009ip-like targets. SN 2016cvk is among the first detected SN 2009ip-like events that show early `flash ionisation' features of C III, N III, and He II, lasting for 16 +/- 5 d. Our late-time +405 d spectrum shows forbidden [Ca II], [Fe II], and [O I] features with the latter detected particularly clearly for a SN 2009ip-like event. The evolution of SN 2016cvk is similar to other SN 2009ip-like transients, with some uncommon traits. The lack of a double-peaked structure in the Balmer lines is likely caused by differences in the circumstellar medium structure or viewing angle. The flash features in the early spectra propose abundances consistent with a red, yellow, or blue supergiant progenitor rather than for example a luminous blue variable. The detection of [O I] in the +405 d spectrum suggests possible evidence of nucleosynthesised material generated in a SN explosion.

We report JWST/MIRI 15 $\mu$m phase curves of TRAPPIST-1 b and c, revealing thermal emission consistent with their irradiation levels, assuming no efficient heat redistribution. We find that TRAPPIST-1 b shows a high dayside brightness temperature (490 $\pm$ 17 K), no significantly detectable nightside emission ($F_{\rm b, Night, max}$ = $39_{-27}^{+55}$ ppm), and no phase offset -- features consistent with a low-albedo, airless ultramafic rocky surface. TRAPPIST-1 c exhibits a lower dayside brightness temperature (369 $\pm$ 23 K), and a nightside flux statistically indistinguishable from that of TRAPPIST-1 b ($F_{\rm c, Night, max}$ = $62_{-43}^{+60}$ ppm). Atmosphere models with surface pressures $\geq$1 bar and efficient greenhouse effects are strongly disfavoured for both planets. TRAPPIST-1 b is unlikely to possess any substantial atmosphere, while TRAPPIST-1 c may retain a tenuous, greenhouse-poor O$_2$-dominated atmosphere or be similarly airless with a more reflective surface. These results suggest divergent evolutionary pathways or atmospheric loss processes, despite similar compositions. These measurements tightly constrain atmosphere retention in the inner TRAPPIST-1 system.

The time variable far-IR/mm sky is largely unexplored. However, when PRIMA launches, next generation ground-based CMB experiments, including Simons Observatory and CMB-S4, will be operating. These will survey large areas of the sky for transient mm sources as a byproduct of their observations, producing regular mm-transient alerts. The results from current experiments show they can detect a wide variety of mm transients ranging from Galactic stars to extragalactic sources associated with AGNs and other energetic phenomena, and moving Solar System objects such as asteroids. These results, and theoretical predictions, indicate that future mm/submm facilities will detect many kinds of transient, including flaring stars, protostars, GRBs, TDEs, neutron star mergers, FBOTs, and SNe. New classes of mm-variable may be uncovered by CMB experiments, and transient searches at other wavelengths, such as the optical LSST survey, will produce additional targets to followup with PRIMA. Predicted rates for extragalactic mm transients to be detected by CMB experiments range from 10s to 1000s of events over the lifetime of these projects. CMB-S4 is most relevant for PRIMA, producing $\sim$100 extragalactic transients per year. Galactic transients and variable sources will also be detected, but the most common Galactic transients, flaring stars, operate on such short timescales that direct follow-up with PRIMA will not be feasible. Variable accretion rates in forming protostars, conversely, produce long term brightness variations that will be ideal monitoring targets. The addition of mid- and far-IR data points for all these sources can determine much about their radiation mechanisms and underlying physics. PRIMA followup of representative examples of various mm-transient and variable sources will thus have a powerful impact on our understanding of a wide range of astrophysical phenomena.

We present an improved matched filter method for detecting large ionized regions in 21 cm observations of the Epoch of Reionization. In addition to detection, the method constrains the properties of these regions, offering insights into the underlying source populations. Extending a previously developed Bayesian framework, we replace the spherical filter with an eight-parameter spheroidal filter, enabling a more flexible characterization of ionized bubbles. This enhancement significantly improves both detectability and recovery of bubble orientations. For a representative reionization scenario with mean ionization fraction $0.4$ at $z=7$, we find that a $10\sigma$ detection of the largest ionized region can be achieved with $\sim 1$, $2$, and $30$ h of observations using the SKA-low AA4, AA$^{\star}$, and AA2 configurations, respectively. Our method can help identify regions in the observed field that host large ionized bubbles, making them prime targets for deeper follow-up observations.

Context. Magneto-asteroseismology is a novel technique allowing for more precise determinations of internal properties of magnetic pulsating stars, but requires an accurate characterisation of the surface magnetic field, not previously possible with Zeeman-Doppler Imaging (ZDI) due to the time-dependent surface velocity of pulsating stars. Aims. We aim to develop a new version of ZDI, which creates an additional surface velocity map, that includes the time-dependent velocities of surface elements due to pulsations. Methods. We present a new code, PIMMS: Pulsation-Informed Magnetic Mapping of Stars, which uses a surface-integrated line profile model that accounts for the additional Doppler shifts of local lines caused by pulsations. It is then possible to fit this model to spectropolarimetric observations, reconstructing maps of the surface brightness, magnetic field, and the velocity field due to the combination of pulsation and rotation. In this paper, we present and test PIMMS extensively, to understand its limitations and data requirements. Results. We find that PIMMS can accurately reproduce the magnetic fields and brightness distributions of realistic models of pulsating hot stars. The required number of observations is higher than that required for ZDI of a non-pulsating star due to the additional velocity map that must be disentangled from surface brightness variations. PIMMS is now ready to be applied to real stars.

Plasma upflows with a Doppler shift exceeding -10 km/s at active region (AR) boundaries are considered potential sources of the nascent slow solar wind. We investigate the driving mechanisms of a pair of coronal upflow regions on the western and eastern peripheries of an AR, which have different magnetic topologies and surroundings. It is aimed to explore how these upflows couple to the lower atmosphere. Using observations of the Fe XII 19.51 nm line from Hinode, we identified two upflow regions at the western and eastern boundaries of a decaying AR. Context images for the two regions were obtained by the High Resolution Imager (HRI) telescope of the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter mission. Other instruments on Solar Orbiter and other observatories provide diagnostics to the lower atmosphere. Potential Field Source Surface (PFSS) extrapolations were used to examine the magnetic field configuration associated with the AR upflows. The eastern upflow region, located over the AR moss, displays small-scale dynamic fibril structures, whereas the western region hosts fan-like loops. We found blueshifted Ne VIII emission at the eastern site, in contrast to redshifted Ne VIII profiles in the west. Magnetic field extrapolations reveal a pseudostreamer topology connecting both these regions. Moreover, low transition-region lines show systematically reduced redshift below the eastern footpoint. The observations support the scenario in which both upflows are driven by pressure imbalances created by coronal reconnection, leading to a continuous upflow above approximately 0.6 MK (i.e., Ne VIII line formation temperature). Meanwhile, mass flows in the lower transition region beneath the eastern upflow region appear to respond passively to the pressure-driven coronal upflows.

The QCD phase transition in the early universe may provide primordial black hole nuclei for globular clusters. We consider the accretion and star formation that follow, once 1000 solar mass nuclei have formed. When such a nucleus has formed, it remains. Whether these are common in the oldest globular clusters is one decidedly challenging question for the model, which is, as yet, unanswered; another is a possible contribution to the cosmic gravitational radiation background.

We conducted long-term monitoring of the doubly imaged gravitationally lensed quasar SDSS J1001+5027 consisting of spectro-photometric observations separated by $\sim$120 days (time delay between both quasar images), as well as test and auxiliary data. This monitoring approach allowed us to reliably find a strong microlensing-induced chromatic variation of the quasar continuum in the period 2022$-$2025. The ongoing microlensing event has caused the delay-corrected spectral flux ratio in 2025 to have a dramatic changing look, opening the door to very promising observations of the system in the coming years. These future follow-up observations of such a rare event are expected to provide critical information to discuss, among other things, the structure of the inner accretion flow towards the central supermassive black hole in SDSS J1001+5027.

Although dark matter in galaxies may consist of elementary particles different from those that make up ordinary matter and that would be smoothly distributed (still undetected), the so-called primordial black holes (PBHs) formed soon after the initial Big Bang are also candidates to account for a certain fraction of mass in galaxies. In this paper, we focused on the main lensing galaxy ($z$ = 0.260) of the doubly imaged gravitationally lensed quasar FBQ 0951+2635 ($z$ = 1.246) for probing possible PBH populations. Assuming that the mass of the galaxy is due to smoothly distributed matter (SDM), stars, and PBHs, the 16-yr observed microlensing variability was compared in detail with simulated microlensing signals generated by 90 different physical scenarios. Among other details, the simulated signals were sampled as the observed one, and the observed variability in its entirety and over the long term were used separately for comparison. While none of the scenarios considered can reproduce the overall observed signal, the observed long-term variability favours a small mass fraction in PBHs with a mass of the order of the mean stellar mass. Furthermore, it is possible to obtain strong constraints on the galaxy mass fraction in Jupiter-mass PBHs, provided that a reverberation-based measurement of the source size is available and relatively small. To constrain the mass fraction in $\sim$10 $\rm{M_{\odot}}$ PBHs, light curves five times longer are probably required.

Gravitational lensing magnification bias is a valuable tool for studying mass density profiles, with submillimetre galaxies (SMGs) serving as ideal background sources. The satellite distribution in galaxy clusters also provides insights into their mass this http URL study aims to investigate the signal drop in mass density profiles from magnification bias measurements, assessing the role of satellite galaxies through observational data and lensing simulations. Using a stacking technique, we analyze the radial distribution of satellites in clusters and measure the magnification bias on background SMGs via angular cross-correlations. A gravitational lensing simulator aids in interpreting the results. Our analysis confirms that satellite distributions align with a Navarro-Frenk-White profile on large scales but exceeding it in the inner part. However, the lack of a similar signal drop at $\sim$10 arcseconds as in the lensing measurements suggests a strong lensing effect from massive central galaxies. The study provides new insights into the mass density profiles derived from gravitational lensing and their relation to satellite distributions within galaxy clusters. The introduction of a gravitational lensing simulator helps explain the emergence of an ``Einstein Gap'' induced by strong lensing effects associated to a change in the apparent position of the sources that suppresses the expected signal. These findings provide a deeper understanding of how satellite galaxies influence gravitational lensing and offer a framework for improving mass density profile estimations in future studies.

The South Pole Telescope Shirokoff Line Intensity Mapper (SPT-SLIM) experiment is a pathfinder for demonstrating the use of on-chip spectrometers for millimeter Line Intensity Mapping. We present spectral bandpass measurements of the SLIM spectrometer channels made on site using a Fourier Transform Spectrometer during SPT-SLIMs first deployment the 2024-2025 austral summer observing season. Through this we demonstrate a technique for measuring the narrow band passes of the SPT-SLIM filterbanks that improves beyond the intrinsic resolution of a Fourier Transform Spectrometer.

We explore mid-infrared (MIR) variability in local ultraluminous infrared galaxies (ULIRGs; infrared luminsoity $L_{\rm IR}>10^{12}\ L_\odot$) utilizing the $\sim$11 years of photometry from the NEOWISE multi-epoch catalog of {\it Wide-field Infrared Survey Explorer} ({\it WISE}). We identify 30 variable ULIRGs with statistically significant MIR variability. The variability is observed on timescales of a few years, implying that the MIR-emitting regions are compact ($\lesssim 1$ pc). The difference between maximum and minimum $W2$ (4.6 ${\rm \mu}$m) band luminosity ($\Delta L_{\rm W2}$) of the 30 variable ULIRGs range from $\Delta L_{W2}$ = $7\times10^{42}$ to $5\times 10^{44}$ erg s$^{-1}$. The $\Delta L_{W2}$ of 25 variable ULIRGs out of 30 are greater than $\Delta L_{W2}$ = $1\times10^{43}$ erg s$^{-1}$, surpassing the MIR luminosity {range} observed in known supernovae (SNe; $L_{\rm 3.6\ {\rm \mu m}}$ and $L_{\rm 4.5\ {\rm \mu m}}$ < 10$^{42.3}$ erg s$^{-1}$). Therefore, the MIR variabilities in these 25 ULIRGs are most likely driven by tidal disruption events (TDEs) or intrinsic changes in their active galactic nuclei (AGN) torus emission. Our sample includes hard X-ray detected AGNs (e.g., UGC 05101) and previously reported TDE candidates (IRAS F01004-2237, IRAS 05189-2524). All 25 also exhibit at least one AGN signature(s) besides the MIR variability, suggesting that even if the MIR variability originates from TDEs, the black holes responsible are likely AGNs. Our results suggest that MIR variability is an effective tool for detecting buried AGNs and highlights the intense nuclear activity in ULIRGs.

CTAO's (Cherenkov Telescope Array Observatory) largest telescopes type, the LST (Large-Sized Telescope), are being installed at the northern site of the Cherenkov Telescope Array (CTA) at the Observatorio del Roque de los Muchachos on the Canary island of La Palma. Their aim is to capture the lowest-energy gamma rays of the observatory. The hereby proposed readout electronics architecture, serving as a proof-of-concept for its advanced camera upgrade, relies on a custom high-channel count fast sampling hardware digitizer board acting as a Front-End. The design includes a versatile pre-amplification stage and high-speed serial links for streaming JESD204C-compliant data at rates approaching 12 Gb/s per lane. The data get transferred to Back-End electronics for a first data-processing and trigger before being transmitted to event-building servers through 10 Gb/s Ethernet links. The performance of the link is exploited by implementing RDMA communication in hardware, thanks to a RoCEv2 core written in Bluespec SystemVerilog, enabling the possibility of transfer data directly to processing units without CPU intervention. Hardware design and characterization of the Front End board are reported, as well as a detailed description and tests of the Back End RDMA firmware.

We present measurements of optical turbulence (OT) power inside the telescope dome using an instrument registering fluctuations of intensity of a bright star at a plane conjugated to -2 km below the pupil of the telescope - Domecam. The measurements were conducted at the 2.5-m telescope of Caucasian Mountain Observatory of Sternberg Astronomical Institute Lomonosov Moscow State University in period 2022-2024 in different ambient conditions. The instrument was validated against Multi Aperture Scintillation Sensor. Using simultaneous observations with a speckle imager mounted at 2.5-m telescope, we demonstrate that dome OT power measured with Domecam can be converted into delivered image quality (DIQ) assuming von Karman model with outer scale of 0.57 +/- 0.1 m for dome turbulence. Dome turbulence increases median of expected distribution of DIQ for the 2.5-m telescope from 0.90'' to 1.12''.

Our understanding of the generation of magnetic fields in intermediate-mass and massive OBA stars remains limited. Some theories have proposed that their magnetic fields could be a result of strong binary interactions, including stellar mergers. Blue stragglers, which lie well beyond the main sequence turn-off point on the colour-magnitude diagram of stellar clusters, are widely theorised to be merger products or interacting binaries and therefore can be considered excellent test targets to get insights into the origin of magnetic fields in stars with radiative envelopes. We search for the presence of magnetic fields in a sample of blue and yellow stragglers listed in the Gaia DR2-based catalogue of blue stragglers in open clusters. We measured the mean longitudinal magnetic field from HARPSpol spectra of five blue stragglers and three yellow stragglers using the least-squares deconvolution technique. We present the first observational evidence that blue and yellow stragglers possess magnetic fields of the order of a hundred to a few hundred Gauss. The targets in our sample belong to open clusters of very different ages and metallicities, but we do not detect any relationship between the presence or strength of the detected magnetic field and the cluster characteristics. For the first time, using high-resolution spectropolarimetric observations, a definite detection of a magnetic field is achieved in a Be-shell star, HD61954. The two yellow stragglers, HD62329 and HD65032, appear to be members in binary systems, whereas the blue straggler HD62775 is possibly a triple system. HD62329 and HD65032 exhibit in their spectra weak Nd III 6145 lines, which are usually prominent in magnetic Ap and Bp stars.

We present a 3D hydrodynamical simulation of a wind-accreting high-mass microquasar, from 30 binary separations (d) to 256 black hole (BH) gravitational radii, over one-sixth of a full orbit in time, with system parameters inspired by Cyg X-1. The simulation allows key system components to emerge naturally as inter-dependent quasi-stationary parts of an inherently multi-scale flow. The BH accretion disk is highly eccentric, with spirally shaped accreting and decreting zones. Its flow field is consistent with elliptical orbits confocal at the BH. The disk structure relates to its feeding: a cold 3D accretion cone channels matter from opposite the L1 point and within 2/3d from the BH toward the disk. Above and below the disk, a polytropic atmosphere establishes, with temperatures one-tenth of the virial temperature. A hot cocoon of shocked wind material engulfs the BH accretion structure on scales of d/10. We hypothesize that the shocks may accelerate particles and the atmosphere may up-scatter photons to GeV energies and beyond. An Archimedian spiral is apparent out to at least 10d, as the orbiting BH perturbs the homogeneous donor star wind. Our simulation offers a coherent cross-scale perspective that allows us to contextualize observations, interpretations, and specific models.

The growth of supermassive black holes (SMBHs) remains a central problem in astrophysics, with current observations providing only limited constraints on the underlying mechanisms. One possible growth channel is stellar accretion via the Hill's mechanism, wherein a SMBH tidally breaks up a passing binary star, capturing and eventually accreting a member of the binary. We adopt a model to predict capture rates from parameters that include the central number density of stars, the stellar velocity dispersion, the binary fraction, and black hole mass. We then use this model to estimate the growth of SMBHs across a range of galactic environments. In a data set of 30 galaxies of various types and masses, we identify two candidates with SMBHs for which stellar accretion may be a driver of recent growth. Closer to home, a recent analysis of observed hypervelocity stars from the Large Magellanic Cloud (LMC) implicates binary star interactions with a massive black hole. Every hypervelocity star produced in this way leaves a bound partner that may be accreted, providing an active growth channel for the LMC's black hole.

We present the first detailed spectroscopic analysis of the heavily extincted bulge globular cluster Terzan 2 (Ter 2) based on high-resolution near-infrared spectra obtained as part of the CAPOS (the bulge Cluster APOgee Survey) project. CAPOS focuses on surveying clusters within the Galactic Bulge, using the APOGEE-2S spectrograph, part of the SDSS-IV survey, a component of the second generation Apache Point Observatory Galactic Evolution Experiment (APOGEE-2). For the spectral analysis, we use the Brussels Automatic Code for Characterizing High accUracy Spectra (BACCHUS) code which provides line-by-line elemental abundances. We derive abundances for Fe-peak (Fe, Ni), $\alpha$-(O, Mg, Si, Ca, Ti), light-(C, N), odd-Z(Al), and the s-process element (Ce) for four members of the cluster. Our analysis yields a mean metallicity of [Fe/H]= $-$0.84 $\pm$ 0.04, with no evidence for an intrinsic variation. We detect a significant abundance variation only in C and N, indicating the presence of multiple populations. Ter 2 exhibits a typical $\alpha$-enrichment, that follows the trend of Galactic GCs. Additionally, our dynamical analysis reveals that Terzan 2 is a bulge globular cluster with a chaotic orbit that is influenced by the Galactic bar but not trapped by it, displaying both prograde and retrograde motions within the inner bulge region. Overall, the chemical patterns observed in Terzan 2 are in good agreement with those of other CAPOS bulge clusters of similar metallicity.

We present realistic eccentricity distributions for extreme mass ratio inspirals (EMRIs) forming via the two-body relaxation channel in nuclear star clusters, tracking their evolution up to the final plunge onto the central Schwarzschild massive black hole (MBH). We find that EMRIs can retain significant eccentricities at plunge, with a distribution peaking at $e_\mathrm{pl} \approx0.2$, and a considerable fraction reaching much higher values. In particular, up to $20\%$ of the forming EMRIs feature $e_\mathrm{pl} > 0.5$ for central MBH masses $M_\bullet$ in the range $10^5 \mathrm{M_\odot} \leq M_\bullet \leq 10^6 \mathrm{M_\odot}$, partially due to EMRIs forming at large semi-major axes and "cliffhanger EMRI", usually neglected in literature. This highlights the importance of accounting for eccentricity in waveform modeling and detection strategies for future space-based gravitational wave observatories such as the upcoming Laser Interferometer Space Antenna (LISA). Furthermore, we find that the numerical fluxes in energy and angular momentum currently implemented in the FastEMRIWaveforms (FEW) package may not adequately sample the full parameter space relevant to low-mass MBHs ($M_\bullet < 10^6 \mathrm{M_\odot}$), potentially limiting its predictive power in that regime. Specifically, for $M_\bullet=10^5 \mathrm{M_\odot}$ we find that about $75\%$ ($50 \%$) of EMRIs at 2 years (6 months) from plunge fall outside the currently available flux parameter space. Our findings motivate the development of extended flux grids and improved interpolation schemes to enable accurate modeling of EMRIs across a broader range of system parameters.

Line-intensity mapping (LIM) traces the large-scale distribution of matter by measuring fluctuations in aggregate line emission from unresolved galaxies and the intergalactic medium, providing a powerful probe of both astrophysics and cosmology. However, interpreting LIM data is limited by our ability to disentangle the signal of a target spectral line from continuum emission and interloper lines, which are emissions from other redshifts that fall within the observed frequency band. Astrophysical modeling uncertainties further complicate matters, leaving the relative amplitudes of the map components poorly understood. In this paper, we present a neural-network (NN) approach to separate the three map components at the level of the angular power spectrum, explicitly accounting for uncertainties in their relative amplitudes. As test cases, we generate SPHEREx-like maps with variable interloper line luminosities across multiple frequency channels, with and without pixel-wise scatter and continuum contributions. We find that cross-channel correlations are essential for robust NN performance when scatter is present. The NN exhibits a hierarchy in residual errors: brighter components yield smaller residuals, and the dimmest the highest. Without continuum emission, the network recovers the target power spectrum to within $2.5\%$, while partially correcting the interloper spectra. With continuum included, the NN accurately reconstructs the power spectra of the continuum and target line, within $2\%$ and $6\%$, respectively, but fails to recover those of the interlopers. Reducing pixel-level scatter further improves performance, lowering residual errors to $1\%$ (continuum) and $3\%$ (target line).

Type Ia supernovae (SNe) occur when a white dwarf (WD) is disrupted by runaway thermonuclear burning. The nature and observable signatures of the mechanism triggering the explosion are still debated. In this work, we study how supernova remnants (SNRs) are impacted by the `double detonation' explosion mechanism, or a helium shell detonation in a sub-Chandrasekhar WD followed by a core detonation. We evolve double detonation SN models to the remnant phase (up to several centuries) and measure the size of substructures formed in the SNR as a result of turbulent activity. We compare our results to small-scale substructures seen in high-resolution optical observations of the SNR 0509-67.5. Substructures dominated by iron in that SNR are observed to be about $40\%$ larger than those dominated by sulfur. This has been shown to be a definitive signature of the explosion of a sub-Chandrasekhar WD by Mandal et al. Comparisons against our suite of SNR models with a range of core and shell masses suggest that the specific substructure sizes in SNR 0509-67.5 are most consistent with the double detonation explosion of a WD with a carbon-oxygen core mass and a helium shell mass of $1M_{\odot}$ and $>0.05M_{\odot}$, respectively.

The James Webb Space Telescope's (JWST) discovery of an unexpectedly high abundance of UV-bright galaxies at redshifts $z > 10$ poses a significant challenge to the standard $\Lambda$CDM cosmology. This work tests whether this tension can be resolved solely by modifying the cosmological background, without invoking significant evolution in the astrophysical properties of early galaxies. We investigate an alternative framework featuring the presence of an anti-de Sitter vacuum in the dark energy sector, a model that naturally arises in quantum gravity models like string theory and can enhance early structure formation. Using a self-consistent semi-analytical model that couples galaxy evolution with reionization, we confront this scenario with a wide range of observations. We first show that while a model tailored to fit the high-$z$ UV luminosity functions (UVLFs) shows promise, it is in strong tension with well-established cosmological constraints from the CMB and other low-redshift probes. Conversely, models within this framework that are consistent with these constraints provide only a modest boost to structure formation and fail to reproduce the observed JWST galaxy abundances at $z > 10$. While these models remain consistent with the cosmic reionization history, our primary result is that this class of cosmological modifications is insufficient on its own to explain the galaxy excess. Our study underscores the critical importance of holistic testing for any beyond-$\Lambda$CDM proposal; apparent success in one observational regime does not guarantee overall viability. By demonstrating the limitations of a purely cosmological solution, our results strengthen the case that evolving astrophysical properties are a necessary ingredient for solving the challenge of early galaxy formation.

The incidence of quasar absorption systems and the space density of their galaxies are proportional, the proportionality factor being the mean absorbing cross section. In this paper we use redshift parameterizations of these two statistics to predict the cosmic evolution of an equivalent-width ($W_r$) radial profile model, tailored for the low-ionization species Mg II and O I. Our model provides an excellent match with well-sampled, low-redshift Mg II equivalent-width/impact-parameter pairs from the literature. We then focus on the evolution of various quantities between the Reionization and Cosmic Noon eras. Our findings are: (1) The extent of Mg II and hence the amount of cool ($T\sim 10^4$ K), enriched gas in the average halo decreases continuously with cosmic time after $z \approx 6$--$8$. This effect is more pronounced in $W_r^{2796}\lesssim 0.3$ Å systems (outermost layers of the model) and, in general, affects O I more than Mg II, probably due to the onset of photoionization by the UV background. (2) The line density of $W_r^{2796}\gtrsim 1$ Å systems (model inner layers) constantly increases in synchrony with the star formation rate density until it reaches a peak at Cosmic Noon. The line density of $W_r^{2796}\lesssim 0.3$ Å systems, on the other hand, remains constant or decreases over the same period. (3) At the end of Reionization, the filling factor is low enough that the winds have not yet reached neighboring halos. This implies that the halos are self-enriched, as suggested by semi-analytic models. We discuss how these statistical predictions can be reconciled with early metal enrichment models and offer a practical comparison point for future analyses of quasar absorption lines at $z>6$.

Barium (Ba) stars belong to binary systems that underwent mass transfer events. As a consequence, their envelopes were enriched with material synthesized in the interiors of their evolved companions via \textit{slow} neutron-capture nucleosynthesis, the $s$-process. As post-interacting binaries, Ba stars figure as powerful tracers of the $s$-process. In this study, we conduct a classical local thermodynamic equilibrium analysis for a sample of 180 Ba giant stars to find complementary insights for the $s$-process, in form of elemental abundances of carbon, nitrogen, and oxygen, as well as the $^{12}\rm{C}/^{13}\rm{C}$ ratio. We found carbon abundances systematically larger than those observed in normal giants, with [C/Fe] ratios ranging within from $-0.30$ to $+0.60$~dex. As expected, the [C/Fe] ratios increase for lower metallicity regimes and are strongly correlated with the average $s$-process abundances. Nitrogen abundances have a flat behavior around $\rm{[N/Fe]}\sim+0.50$~dex and are moderately correlated with sodium abundances. Except for HD~107541, the entire sample shows $\rm{C/O}<1$. We found $^{12}\rm{C}/^{13}\rm{C}<20$ for $\sim80\%$ of the sampled stars and $^{12}\rm{C}/^{13}\rm{C}>60$ for three objects.

The kinetic field theory is developed without assumptions of statistical homogeneity and isotropy. In a solvable toy model with short-ranged interactions, we compare first-order perturbation theory to an iterated mean-field approximation scheme, demonstrating that the mean-field theory maintains positivity and captures collapse dynamics, allowing analytic estimates of blow-up times. In a self-gravitating sheet model, the first-order perturbation theory is shown to reproduce critical phenomena. This work suggests a path toward convergence analysis of the mean-field approximation and applications to more complex inhomogeneous systems.

The integrated luminosity from the features of the polycyclic aromatic hydrocarbons (PAHs) exceeds the luminosity from atomic and molecular emission lines in the star-forming regions in galaxies and is a potential tracer of galaxy-scale star formation and molecular gas content of the high-redshift universe. We simulate the observable PAH spectra using the PRobe far-Infrared Mission for Astrophysics far-infrared enhanced survey spectrometer (FIRESS) and investigate the capability of the FIRESS low-resolution spectroscopy for observing PAH emission spectrum from high-redshift galaxies. Our investigation suggests that (1) PRIMA observations of PAH emission are $\gtrsim10$ times more efficient at detecting galaxies than the VLA observations of CO(1-0) for galaxies with the same infrared luminosity, (2) PRIMA/FIRESS can detect the PAH emission from galaxies with $L_{IR}\sim10^{12}L_{\odot}$ up to the end of reionization (and possibly beyond, if $L_{IR}\sim10^{13}L_{\odot}$), (3) the PAH band ratios measured from a full spectral fitting and from a simple flux "clipping" method are different and vary depending on the interstellar radiation field strength, and (4) PRIMA/FIRESS can also be used as the PAH mapping instrument to measure star formation and redshift of the galaxies in high-redshift protoclusters.

Imaging X-ray polarimetry with IXPE has demonstrated the scientific potential of the technique but also revealed the need for significant detector upgrades, particularly with the read-out ASIC that images photoelectron tracks and possibly the multiplication stage. Building on this experience, we are developing a next generation three-dimensional photoelectron track polarimeter based on the GridPix detector, originally developed for axion and axion-like-particle searches. We report on the current status of prototype development and preparations for the ion-irradiation tests. Preliminary proton beam irradiation runs at the Bonn Isochronous Cyclotron facility of the University of Bonn verified both this generation of ASIC's tolerance to high radiation doses present in space and the capability of the cyclotron facility to operate at sufficiently low rates for controlled tests.

Giant stars have been shown to be rich hunting grounds for those aiming to detect giant planets orbiting beyond ~0.5 AU. Here we present two planetary systems around bright giant stars, found by combining the radial-velocity (RV) measurements from the EXPRESS and PPPS projects, and using a Bayesian framework. HIP18606 is a naked-eye (V=5.8 mags) K0III star and is found to host a planet with an orbital period of ~675 days, a minimum mass (Msini) of 0.8 MJ, and a circular orbit. HIP111909 is a bright (V=7.4 mags) K1III star, and hosts two giant planets on circular orbits with minimum masses of Msini=1.2 MJ and Msini=0.8 MJ, and orbital periods of ~490 d and ~890 d, for planets b and c respectively, strikingly close to the 5:3 orbital period ratio. Analysis of 11 known giant star planetary systems arrive at broadly similar parameters to those published, whilst adding a further two new worlds orbiting these stars. With these new discoveries, we have found a total of 13 planetary systems (including three multiple systems) within the 37 giant stars that comprise the EXPRESS and PPPS common sample. Periodogram analyses of stellar activity indicators present possible peaks at frequencies close to proposed Doppler signals in at least two planetary systems, HIP24275 and HIP90988, calling for more long-term activity studies of giant stars. Even disregarding these possible false-positives, extrapolation leads to a fraction of 25-30% of low-luminosity giant stars hosting planets. We find the mass-function exponentially rises towards the lowest planetary masses, however there exists a ~93% probability that a second population of giant planets with minimum masses between 4-5 MJ, is present, worlds that could have formed by the gravitational collapse of fragmenting proto-planetary disks. Finally, our noise modelling reveals a lack of statistical evidence for the presence of correlated noise...(Abridged)

Coronal mass ejections (CMEs) are known drivers of large-scale waves in the low corona. However, wave dynamics in the extended corona and inner heliosphere remain largely unexplored. Here, we report the first observational and numerical evidence of coherent global compressive oscillations in the outer corona and inner heliosphere, revealed by white-light SOHO/LASCO C3 data and an MHD simulation. Analyzing the CME event of 2012 July 23 using Spectral Proper Orthogonal Decomposition (SPOD), we isolate two distinct wave signatures: (1) a directional fast-mode shock-like compressive wave that dissipates completely within ~3 hours, and (2) a large-scale global circular wavefront consistent with fast-mode MHD behavior, lasting ~7 hours and extending across the LASCO C3 field of view, marking the first detection of such a global oscillation. Our findings reveal a previously unrecognized component of CME-driven wave activity, providing new constraints on the dynamics of the extended corona and inner heliosphere.

We present the architectural concept for the Far-Infrared Enhanced Survey Spectrometer (FIRESS) for the Probe Mission for far-IR Astrophysics (PRIMA). FIRESS spans the 24--235 micron range with four R ~ 100 slit-fed grating modules, each coupling to a 24 (spatial) by 84 (spectral) pixel array of kinetic inductance detectors (KIDs). All four arrays are read out simultaneously, and a point source of interest can be coupled to two of the four bands at a time. A Fourier transform module can be engaged over a portion of the FIRESS slits to create a high-resolution mode in which the light is intercepted, processed by the interferometer then reinserted into the path to the grating modules for detection. We provide a simulation and description of the technique that will be used to obtain high-resolution spectra. We identify the most important system requirements imposed by the detector system, finding that they are met with the existing design. Finally, we present our performance modeling, including both direct estimates given our current design status, as well as durable guidelines for developing general-observer programs.

Magnetic fields are a fundamental part of the interstellar medium (ISM) and remain a challenge for building a comprehensive understanding of galactic properties. Their study requires far-infrared polarimetric observations, which provide an unrivaled probe of the dynamics, magnetization, and structure of the coldest and densest interstellar gas and dust at small scales in galaxies, where mass and star formation reside. We use high-resolution magnetohydrodynamical simulations of a face-on Milky Way-like galaxy and show that the alignment of magnetic fields with ISM structures and the turbulence at 100 pc scales decrease with increasing magnetization. We make predictions for extragalactic observations by the proposed PRobefarInfrared Mission for Astrophysics (PRIMA) telescope, comparing them with Stratospheric Observatory For Infrared Astronomy (SOFIA) observations similar to those of the Survey of extragALactic magnetiSm with SOFIA (SALSA). PRIMA will be able to better measure magnetic alignment trends inaccessible by SOFIA. We find that PRIMA will better sample magnetic turbulence, especially in dense environments, and will be able to measure the unresolved intrinsic magnetic field orientations to approximately 6 deg precision. PRIMA will also be capable of resolving observables such as the polarized fraction or the magnetic alignment down to scales comparable to the resolution of our simulations (about 10 pc) for galaxies up to 0.5 Mpc away. The polarization-dispersion relation shows that PRIMA observations will suffer from significantly reduced beam depolarization. Furthermore, PRIMA will recover the correlation between increasing the magnetic alignment parameter and local polarization fraction. Overall, observations of local galaxies with PRIMA will better characterize interstellar magnetism and constrain ISM and galaxy models, advancing our understanding of magnetism in the universe.

We combine new spectroscopic observations of the ultra faint dwarf galaxy (UFD) Boötes I (Boo I) from the Southern Stellar Stream Spectroscopic Survey ($S^{5}$) with $\sim$15 years of archival spectroscopic data to create the largest sample of stellar kinematics and metallicities to date in any Milky Way UFD. Our combined sample includes 148 members extending out to $\sim$7 half-light radii ($r_h$), including 24 newly confirmed members, 18 binary candidates, 15 RR Lyrae stars, and 92 [Fe/H] measurements. Using this larger and more spatially extended sample, we provide updated constraints on Boo I's systemic properties, including its radial population gradients. Properly accounting for perspective rotation effects in a UFD for the first time, we detect a $4\sigma$ line-of-sight velocity gradient of $1.2\pm0.3$ km s$^{-1}$ $r_h^{-1}$ aligned along Boo I's orbit and discuss its potential tidal origins. We also infer a metallicity gradient of $-0.10\pm0.02$ dex $r_h^{-1}$ in agreement with previous studies. Using an axisymmetric Jeans model, we provide updated constraints on Boo I's dark matter density profile, which weakly favor a cusped ($\gamma=1.0^{+0.5}_{-0.6}$) dark matter profile. Lastly, we re-analyze Boo I's metallicity distribution function with a one-zone galactic chemical evolution model and place new constraints on its rapid, inefficient star formation and strong galactic outflows.

It has been suggested that, if the free-fall time of star-forming clouds is shorter than the lifetime ($\approx 3 $ Myr) of massive stars exploding as supernovae (SN), a large fraction of the cloud gas can be converted into stars during an allegedly `feedback-free' phase. Here, we show that radiation pressure from Ly$\alpha$ photons produced in the pre-SN phase can instead erase feedback-free conditions, and severely limit the star formation efficiency (SFE). We find that, for a constant star formation rate, all clouds with gas surface density $(37-1.7 \times 10^5)\ M_\odot\ \rm pc^{-2}$ have $\epsilon_* < 0.08$. Higher SFE values can only be reached if Ly$\alpha$-driven shells fragment and form stars. While advanced RHD simulations are required to establish the importance of this effect, adopting an optimistic guess, we find that the SFE increases with cloud surface density, rising from $\epsilon_*=0.023$ at $\Sigma_g = 37\ M_\odot\ \mathrm{pc^{-2}}$ to $\epsilon_*=0.27$ at $\Sigma_g = 1.7 \times 10^5\ M_\odot\ \mathrm{pc^{-2}}$. Given the optimistic assumptions adopted, these numbers should be regarded as upper limits. We conclude that Ly$\alpha$ radiation pressure strongly limits the SFE, even at solar metallicities, erasing the possibility that a feedback-free star formation mode with $\epsilon_* \gtrsim 0.4$ exists in the pre-SN phase. This conclusion remains valid even when other effects such as dust destruction of Ly$\alpha$ photons, presence of HII regions, velocity gradients, atomic recoil, and turbulence are considered.

Dissociative electron attachment (DEA) to the HNC$_3$ is modeled theoretically using a first-principles approach. In HNC$_3$+$e^-$ collisions, there is a low-energy resonance, which has a repulsive character along the H+NC$_3$ coordinate and becomes a bound electronic state of the HNC$_3^-$ anion near the equilibrium of HNC$_3$. The anion state dissociates without a potential barrier towards C$_3$N$^-$+H. The cross section and the rate coefficient of the process were computed. The obtained rate coefficient at low temperatures is $5\times 10^{-9}$cm$^3$/s at 300~K. Such a value of the DEA rate coefficient makes the DEA process by three orders of magnitude more efficient in producing negative molecular ions in the interstellar space than the radiative electron attachment (REA). It is suggested that negative molecular carbon-chain ions, observed in the interstellar medium, are produced by DEA rather than REA.

We investigate heat propagation in rigidly rotating bodies within the theory of general relativity. Using a first-order gradient expansion, we derive a universal partial differential equation governing the temperature evolution. This equation is hyperbolic, causal, and stable, and it naturally accounts for both rotational and gravitational Tolman-Ehrenfest effects. Any other first-order theory consistent with established physics (including the parabolic theories used in neutron star cooling models) must be equivalent to our formulation within an error that is of higher order in gradients. As a case study, we analyze heat transfer in solid cylinders rotating around their symmetry axis, so that the tangential speed approaches the speed of light on the surface. We also compute the relativistic rotational corrections to the cooling law of black bodies.

Gravitational lensing offers a powerful probe into the properties of dark matter and is crucial to infer cosmological parameters. The Legacy Survey of Space and Time (LSST) is predicted to find O(10^5) gravitational lenses over the next decade, demanding automated classifiers. In this work, we introduce GraViT, a PyTorch pipeline for gravitational lens detection that leverages extensive pretraining of state-of-the-art Vision Transformer (ViT) models and MLP-Mixer. We assess the impact of transfer learning on classification performance by examining data quality (source and sample size), model architecture (selection and fine-tuning), training strategies (augmentation, normalization, and optimization), and ensemble predictions. This study reproduces the experiments in a previous systematic comparison of neural networks and provides insights into the detectability of strong gravitational lenses on that common test sample. We fine-tune ten architectures using datasets from HOLISMOKES VI and SuGOHI X, and benchmark them against convolutional baselines, discussing complexity and inference-time analysis.

With the aim of incorporating an intercultural perspective into Physics teacher training programs, we ask ourselves which current disciplinary contents could begin to be addressed from this perspective. We started out by exploring the current state of the field exclusively in relation to intercultural science education, focusing on direct relationships with Physics. We present here a synthesis of publications from the past five years that we have found so far. These publications were categorized based on their approach, whether related to theoretical dimensions or to the practical implementation. We develop the following categories: reflections on practical implementation, boundary objects, and practical implementation experiences. We find coincidences that allow us to identify the concept of the celestial sphere as the one that would facilitate the incorporation of an intercultural perspective into Physics teacher training programs.

We present a two-stage upgrade to the PySTAMPAS pipeline that boosts the search for long-duration (10 to 10^3 s) transients in gravitational-wave detector data. First, a denoising scheme combines complex 2D wavelet shrinkage with an adaptive pixel threshold to suppress noise while retaining signal power. Second, a KDTree nearest-neighbour algorithm clusters surviving pixels in O(log n) time, replacing the standard clustering approach. Tests with one week of LIGO O3b data show a large reduction in false-alarm rate and up to a factor-of-two improvement in search sensitivity. The computational time is also significantly reduced. These gains extend the sensitivity of all-sky, all-time searches to weaker and shorter transients, enabling rapid and deeper analyses in forthcoming LIGO-Virgo-KAGRA observation campaigns.

Small-scale scalar perturbations amplified during inflation can induce primordial gravitational waves through tensor-scalar interactions. A long-standing controversial issue is whether the one-loop corrections to tensor perturbations exist on large scales. Firstly, we demonstrate through direct one-loop calculations that one-loop corrections cancel each other out on large scales. We then proceed from the symmetry of the interacting system and directly prove, based on the Ward identity, the absence of one-loop corrections on large scales-without the need for specific loop diagram calculations. This is consistent with the results we previously obtained for scalar perturbations.

The paper analyzes the thermodynamic properties of a special state of charged black holes, in which the event horizon becomes point-like and coincides with the singularity. It is shown that for such states, called black points, in contrast to Reissner-Nordström black holes, the third law of thermodynamics in Planck's formulation is fulfilled. It is also shown that the formation of a black point is not a first-order phase transition. Considerable attention is paid to the special state of a black point with a doubly degenerate horizon, similar to the extreme state of a Reissner-Nordström black hole.

It was recently proposed that predictions of Lorentz-breaking space-time foam models from string theory may be compatible with the suggestion of light-speed variation from gamma-ray burst studies. Our analysis of foam-modified kinematics shows that despite the subluminal photon velocities explaining photon time delays one may, and in certain circumstances does, keep intact the electromagnetic showers essential for the detection and identification of cosmic photons. In contrast to other~(mostly phenomenological) approaches to Lorentz violations with modified dispersions leading to drastic changes on the formation length for the cascade development in the atmosphere and in detectors, there is the possibility that the dispersion effect in the present string foam model avoids such modifications and the theory naturally escapes the shower formation constraints from recent observations.

These lectures aim to highlight the remarkable symbiosis that currently exists between the physics of the very small and the physics of the very large, using the unsolved puzzle of the nature of Dark Energy as a vehicle for so doing. The lectures first summarize what we know observationally about the properties of Dark Energy (and the Dark sector more broadly) and then discuss several approaches to explain them. Along the way this involves determining the types of interactions that would on general grounds be expected to be present in the low-energy limit of fundamental theories involving the many hierarchy of scales we see around us. This includes (but is not limited to) a discussion of technical naturalness (and `t Hooft naturalness) as well as the arguments for their use as a criterion for distinguishing amongst candidate theories. Some recent approaches I find promising are briefly summarized at the end.

Magnetic reconnection is one of the most important magnetic energy conversion processes observed in laboratory and space plasmas. It describes the breaking and joining of magnetic field lines, leading to the release of magnetic energy and the acceleration of charged particles. Finding regions where fast reconnection occurs is key to understanding this process. However, identifying such reconnection events within a turbulent environment in three dimensions remains a challenge. In this work, we develop a new framework for identifying magnetic reconnection using 3D turbulent plasma simulations. First, we apply bifurcation lines from fluid visualization to magnetic fields and show that they can be identified with X-lines of magnetic reconnection. For reconnection configurations with magnetic guide fields, we introduce a novel concept of quasi X-lines (QXL). Using the spatial information of X-lines in numerical simulations, we present a local technique to estimate the reconnection rate, obtaining a distribution that features a local maximum near the normalized value 0.1. Additionally, we provide an alternative tool to highlight current sheets in turbulent plasma by measuring magnetic shear layers as the second invariant of the shear strain tensor. These methods, avoiding traditional reliance on global methods, electric fields and current density, offer a new perspective to the quantitative study of magnetic reconnection in plasmas with complex magnetic field topologies. Validated across various plasma simulation models, including kinetic particle-in-cell (PIC) and resistive magnetohydrodynamics (MHD), our approach enables efficient exploration of magnetic field dynamics in turbulent plasma environments.

We investigate the effects that arise from the inclusion of Weylian boundary terms in the Einstein gravitational field equations in the Big Bang Nucleosynthesis (BBN) framework. With the help of the generalized Friedmann equations for a Universe with a Weylian boundary, obtained for a Friedmann-Lemaitre-Robertson-Walker FLRW metric, three distinct cosmological models can be constructed. The cosmological evolution is determined by a dissipative scalar field, and by the Weyl vector coming from the boundary. Several cosmological scenarios are obtained via the appropriate splitting of the generalized energy conservation equation. In the present work we obtain relevant constraints on these models by using the BBN data. In particular, the effects on the BBN that arise in the post warm-inflationary era will be examined by theoretically evaluating the measured abundances of relic nuclei (Hydrogen, Deuterium, Helium-3, Helium-4, and Lithium-7). We consider firstly the primordial mass fraction estimates, and their deviations due to changes in the freezing temperature, which impose an upper limit on the effective energy density obtained from the modified Friedmann equations. The deviation from the standard energy density of the radiative plasma is therefore constrained by the abundances of the Helium-4 nuclei. Secondly, an upper limit will be considered in a numerical analysis performed through the usage of the \texttt{PRyMordial} software package, with the help of which we calculate the primordial abundances of the light elements by evaluating the thermonuclear rates within the considered modified gravity framework. Finally, an MCMC analysis will validate the cosmological model with Weylian boundary contributions, imposing relevant constraints on the initial conditions of the cosmos. The methodology is implemented in the python code \texttt{genesys}, which is available on GitHub.

Black Hole (BH) Quasi-Normal Modes (QNMs) and Greybody Factors (GBFs) are key signatures of BH dynamics that are crucial for testing fundamental physics via gravitational waves. Recent studies of the BH pseudospectrum have revealed instabilities in QNMs. Here, we introduce a new perspective using hidden symmetries in the BH dynamics, specifically the Korteweg-de Vries (KdV) integrals - an infinite series of conserved quantities. By analyzing modified BH potentials, we find strong evidence that KdV integrals are valuable indicators for detecting instabilities in QNMs and GBFs.

This study examines how inflationary dynamics are affected by $f(R)$ theories with a non-minimal coupling between matter and curvature. Both positive and negative corrections to the minimal coupling of General Relativity are considered, and a robust numerical method is developed that evolves the metric and the inflaton field in this modified theory beyond slow-roll. Through a stability analysis, we find that positive models are inherently unstable during slow-roll, whereas negative ones can accommodate a stable attractor de Sitter solution. Using the amplitude of the scalar power spectrum from the latest data releases, we constrain the scale of the non-minimal coupling to be above $10^{13}$ GeV. In light of the 2018 Planck, BICEP/Keck and the recent Atacama Cosmology Telescope data for the scalar spectral index and tensor-to-scalar ratio, strong constraints on the coupling strength force the effects of these modified theories to be, at most, slightly above the perturbative level. Furthermore, we determine that the choice of the perfect fluid matter Lagrangian does not impact the inflationary observables at the pivot scale. Finally, we present the predicted observables for different inflationary potentials and show that even though classical gravity is still preferred by the data, there are areas of the parameter space that are viable for non-minimally coupled inflationary models.

We compare two time series analysis methods, the Discrete Fourier Transform (DFT) and our Discrete Chi-square Method (DCM). DCM is designed for detecting many signals superimposed on an unknown trend. The solution for the non-linear DCM model is an ill-posed problem. The backbone of DCM is the Gauss-Markov theorem that the least squares fit is the best unbiased estimator for linear regression models. DCM is a simple numerical time series analysis method that performs a massive number of linear least squares fits. We show that our numerical solution for the DCM model fulfills the three conditions of a well-posed problem: existence, uniqueness and stability. The Fisher-test is used to identify the best DCM model from all alternative tested DCM models. The correct DCM model must also pass our Predictivity-test. Our analyses of seven different simulated data samples expose the weaknesses of DFT and the efficiency of DCM. The DCM signal and trend detection depend only on the sample size and the accuracy of data. DCM is an ideal forecasting method because the time span of observations is irrelevant. We recommend fast sampling of large high quality datasets and the analysis of those datasets using numerical DCM parallel computation Python code.

Inflationary expansion of space-time provides us with an efficient particle production mechanism in the Early Universe. The fermion production efficiency depends critically on the particle mass, which is generated via the Yukawa coupling and sensitive to the corresponding scalar field value. During inflation, scalar fields experience large quantum fluctuations driving the average field values to the Hubble scale and above. This applies, in particular, to the Higgs field, making the Standard Model fermions very heavy and facilitating their production. Using the Bogolyubov coefficient approach, we compute the corresponding fermion abundance taking into account time dependence of the mass term. We find that the Standard Model fermion and the right-handed neutrino production grows dramatically compared to the naive estimate based on the low energy masses. The inflationary production mechanism can be the leading source of the right handed neutrinos, if they gain a Majorana mass from the Yukawa coupling to a light scalar. We also find a lower bound on the mass of fermionic dark matter, which can be produced by inflation.

Alexei Starobinsky is one of the main authors of inflationary cosmology. Here I will discuss the Starobinsky model and its generalizations, including the theory of $\alpha$-attractors. I will then describe the current status of these models in light of the latest observational results from ACT, SPT, and DESI.

We present the first study of how dark matter environments influence nonlinear gravitational memory from intermediate-mass-ratio binaries. Incorporating dark matter effects-gravitational potential, dynamical friction, and accretion-we compute nonlinear memory for both bound and unbound orbits under dark matter minispikes and Navarro-Frenk-White profiles. For quasi-circular orbits within a minispike profile, we further account empirically for the evolution of the dark matter density. Our findings reveal significant deviations from the vacuum case, with important implications for the detectability of gravitational memory by future gravitational wave observatories. These results underscore the role of astrophysical environments in shaping gravitational memory, strengthening its interpretation as a hereditary imprint of past binary evolution and providing a novel bridge between dark matter physics and memory effects.

The ringdown phase of a gravitational wave signal from a binary black hole merger offers a unique laboratory for testing general relativity in the strong-field regime and probing the properties of the final remnant black hole. In this study, we analyze the ringdown of GW231123 and find strong evidence for a multimode quasinormal spectrum. Our analysis employs two time-domain methodologies: a full Bayesian inference and an enhanced F-statistic framework, which we extend to enable the calculation of Bayesian evidence and the reconstruction of posterior distributions for all model parameters. We report a statistically significant detection of the $\ell|m|n=200$ mode, with a $\log_{10}$(Bayes factor) of $5.3$, commencing at $12\,M$ after the peak amplitude--a time well within the accepted linear regime. This two-mode analysis yields a redshifted final mass of $305.6^{+35.7}_{-47.3}M _{\odot}$ and a final spin of $0.84^{+0.07}_{-0.14}$ at $90\%$ credibility, from a ringdown signal with a network signal-to-noise ratio of approximately $14.5$. Furthermore, a test of the no-hair theorem performed using the two detected modes reveals no deviation from the predictions of general relativity. These results highlight the power of the F-statistic methodology to uncover nuanced features in gravitational wave signals, thereby providing novel insights into the fundamental properties of black holes.

The expansion history and content of the Universe between the end of inflation and the onset of Big Bang Nucleosynthesis is mostly unknown. In this paper, we study gravitational waves (GWs) induced by matter isocurvature fluctuations in a generic perfect fluid background as a novel probe of the physics of the very early Universe. We analytically compute the induced GW kernel and analyze the spectral GW energy density for a sharply peaked isocurvature power spectrum. We show that the spectral shape of the GW signal is sensitive to the equation of state parameter $w$ of the perfect fluid dominating the early Universe after inflation. We find that the GW amplitude is enhanced for a soft equation of state. Our framework can be applied to dark matter isocurvature and models leading to early matter-dominated eras, such as primordial black holes and cosmological solitons.

We present constraints on sub-GeV dark matter (DM) through the mechanism of being boosted by cosmic rays (CRs). We utilize the nuclear recoil data from the LUX-ZEPLIN (LZ) experiment for this purpose. Without the mechanism of boosted dark matter (BDM), sub-GeV DM particles are cold enough to produce detectable nuclear recoil in the LZ experiment above the detector threshold. We choose to work with the leading components of cosmic rays to take into account the boost due to them towards the cold DM. In the present discussion we worked on models consisting of a Dirac fermion $\chi$ with a new $U(1)'$ gauge symmetry and DM particles have non-zero coupling to the nucleons as per the model parameters. Specific examples of the energy dependence of the scattering cross section have been invoked through the secluded dark photon model and $U(1)_{B-L}$ model. Additionally, we present the upper bound on the interaction cross section due to the Earth shielding effect in the light of a systematic analysis of the energy loss by the BDM while traveling to the underground detector through the Earth's crust.

We investigate the structural and oscillation properties of dark matter (DM) admixed strange quark stars (DMSQSs). The strange quark matter (SQM) is described with the well-known Nambu-Jona-Lasino (NJL) model and the self-interacting fermionic DM is included in a systematic manner. The self-interaction of DM is of four-Fermi type and the overall DM density is considered as a function of the baryon density of SQM with two free parameters ($\alpha$, $\rho_{sc}$). This work is the first to consider four-Fermi interactions between fermionic DM and SQM in DMSQSs. Certain experiments like LZ, XENON, DarkSide, CRESST, and LHC have almost ruled out the possibility of contact interaction between SQM and massive DM (in GeV order). Recently, the quest for sub-GeV DM has garnered significant attention. We show that recent astrophysical constraints on the structural properties of compact stars also do not support the presence of massive DM in DMSQSs. On the other hand, we find sub-GeV DM to successfully concur with such observational constraints. We also calculate the fundamental $f$-mode frequency ($f_f$) of the DMSQSs, which shows universality with compactness, mean density, and tidal deformability. Further, we investigate the prospect of detection of $f_f$ with respect to the projected sensitivity of upcoming gravitational wave detectors like aLIGO, A+, Cosmic Explorer, and Einstein Telescope. In our DMSQS model, the three free parameters are $\alpha$, $\rho_{sc}$, and the ratio of repulsive to attractive interaction in SQM ($G_V/G_S$), which are optimized by Bayesian analysis in light of various recent astrophysical data.

We perform a physics-informed Bayesian analyses of the equation of state of hybrid neutron stars that incorporates color-flavor-locked quark matter modeled by a three-flavor non-local Nambu-Jona-Lasinio framework with vector repulsion and diquark pairing. Contrary to the model-agnostic Bayesian analyses our scheme allows for distinguishing between the scenarios of neutron stars with quark cores and without them. The used quark model realizes asymptotic conformality at high densities in accordance with perturbative QCD. The hadronic sector is described by the density-dependent relativistic functional DD2Y-T, which satisfies chiral effective field theory constraints and includes hyperonic degrees of freedom. We construct a large set of candidate hybrid EOSs by varying the vector and diquark couplings and apply a Maxwell construction for the quark-hadron phase transition. Observational constraints from recent NICER pulsar mass-radius measurements and tidal deformability from GW170817 are incorporated into the likelihood. Depending on whether the observational data from the black widow pulsar PSR J0952-0607 and the HESS J1731-347 object are included to the analysis or not, the posterior distribution favors vector and diquark couplings around $(\eta_V,\eta_D)\simeq (0.82,0.40)$ or $(\eta_V,\eta_D)\simeq (0.64,0.36)$, respectively. This corresponds to equations of state that support two-solar-mass neutron stars with superconformal speed of sound and relatively low onset densities for deconfinement. Our findings indicate that the most probable hybrid EOSs are statistically preferred over the purely hadronic baseline. The corresponding probabilities of agreeing with the observational data differ by one or two orders of magnitude depending on the data set used. This suggests that quark cores may exist in all observed neutron stars.