Vote on papers for Tuesday, Apr 29 2025

The energy spectra of particles arriving at the ground is a significant observable in the analysis of extensive air showers (EAS). Energy distributions at ground were studied for primary particles (12C,56Fe, p, and 28Si) with high primary energies (10^17, 10^18, 10^19, and 10^20 eV) from two zenith angles (0 and 30 Deg.). 960 EAS were simulated using the Monte-Carlo program Aires (version 19.04.00) with three models of hadronic interaction (EPOS-LHC, QGSJET-II-04, and Sibyll2.3c). Good agreement was obtained by comparing the present results with results simulated using CORSIKA for primary iron at an energy of 10^20 eV. In this study we investigated various secondary particles that arrive at the ground and deposit a portion of their energy on ground detectors. These results show that the distinction in energy distribution at ground is greater for primary protons than carbon, iron, or silicon nuclei at higher energies and steeper zenith angles.

Tidal disruption events (TDEs) are X-ray and gamma-ray radiations emerging from the tidal disintegration of a star or substellar object that passes too close to a supermassive black hole (SMBH) at the center of a galaxy. In November 2010, a TDE designated as IGR J12580+0134 occurred in the galaxy NGC 4845, which was traced by follow-up XMM-Newton observations in January 2011. To identify a further TDE based on the radio outburst cycle, we requested NICER monitoring observations for nearly a year beginning in March 2023, which we studied here along with the previous XMM-Newton observations. We analyzed X-ray brightness changes using hardness analysis and principal component analysis (PCA), and conducted spectral analysis of the source continuum. The NICER observations revealed the presence of some X-ray flares during March--June 2023, which were much fainter than the TDE observed using XMM-Newton in 2011. The PCA component that mainly contributes to the X-ray outbursts during the TDE is a heavily absorbed power-law continuum emission, whereas there is a small contribution from collisionally ionized plasma in the soft excess, likely from a colliding wind or jet. Similarly, the PCA of the NICER data relates the X-ray flares to a power-law spectrum, albeit with a much lower absorbing column, and partially to soft collisional plasma. The faint X-ray flares captured by NICER could be associated with extremely weak accretion onto the SMBH resident in this galaxy, and thus, potentially a low-luminosity active galactic nucleus.

The elaborate observation of the single radio pulses of Vela pulsar around the pulsar glitch that occurred on December 12, 2016 reveals that the physical mechanism associated with this glitch exert a profound influence on the pulsar's magnetosphere. According to the evolution of these pulses, we propose a scenario regarding how the pulsar magnetic field might undergo alterations within the framework of the inner gap model. We deduce that the liberation of the free energy within Vela pulsar results in the emergence of new magnetic multipole components. The progressively developing multipole components cause the magnetic field lines in a section of the polar cap region to become increasingly curved, ultimately resulting in the observed pulse broadening and pulse missing. At last, we discuss the possible connection between magnetic variations and fast radio bursts according to the inspiration of the presented picture.

Classifying potentially hazardous asteroids (PHAs) is crucial for planetary defense and deep space navigation, yet traditional methods often overlook the dynamical relationships among asteroids. We introduce a Graph Neural Network (GNN) approach that models asteroids as nodes with orbital and physical features, connected by edges representing their similarities, using a NASA dataset of 958,524 records. Despite an extreme class imbalance with only 0.22% of the dataset with the hazardous label, our model achieves an overall accuracy of 99% and an AUC of 0.99, with a recall of 78% and an F1-score of 37% for hazardous asteroids after applying the Synthetic Minority Oversampling Technique. Feature importance analysis highlights albedo, perihelion distance, and semi-major axis as main predictors. This framework supports planetary defense missions and confirms AI's potential in enabling autonomous navigation for future missions such as NASA's NEO Surveyor and ESA's Ramses, offering an interpretable and scalable solution for asteroid hazard assessment.

Stars orbiting supermassive black holes can generate recurring accretion flares in repeating partial tidal disruption events (TDEs). Here we develop an efficient formalism for analyzing the time-dependent response of a star to the removal of a fraction ($\lesssim 10\%$) of its mass. This model predicts that mass loss results in a decrease in the average density of low-mass ($\lesssim 0.7 M_{\odot}$) stars. Contrarily, higher-mass stars increase in density, such that the change is more pronounced for larger mass losses, and stars with masses $\sim 1.5-2 M_{\odot}$ experience the largest such increase. We predict that the final energy of the star post-mass-loss (i.e., the ``surviving core'') is effectively given by the binding energy of the original star interior to the radius from which mass is removed, i.e., the final core energy is agnostic to the process that removes the mass and -- as a corollary -- tidal heating is comparatively insignificant. We find excellent agreement between our predictions and one-dimensional Eulerian simulations of a star undergoing mass loss, and three-dimensional Lagrangian simulations of partial TDEs. We conclude that 1) partially disrupted stars are not significantly heated via tidal dissipation, 2) evolved and moderately massive ($\gtrsim 1.5 M_{\odot}$) stars can most readily survive many repeated stripping events, and 3) progressively dimmer flares -- observed in some repeating partial TDE candidates -- could be explained by the increase in the density of the star post-mass-loss.

We present the mass-metallicity relation (MZR) for a parent sample of 604 galaxies at $z=5.34-6.94$ with [\text{O}~\textsc{iii}] doublets detected, using the deep JWST/NIRCam wide field slitless spectroscopic (WFSS) observations in 26 quasar fields. The sample incorporates the full observations of 25 quasar fields from JWST Cycle 1 GO program ASPIRE and the quasar SDSS J0100+2802 from JWST EIGER program. We identify 204 galaxies residing in overdense structures using friends-of-friends (FoF) algorithm. We estimate the electron temperature of $2.0^{+0.3}_{-0.4}\times10^4$ K from the Hg and $[\text{O}~\textsc{iii}]_{4363}$ lines in the stacked spectrum, indicating a metal-poor sample with median gas phase metallicity 12+$\log(\mathrm{O/H})=7.64^{+0.23}_{-0.11}$. With the most up-to-date strong line calibration based on NIRSpec observations, we find that the MZR shows a metal enhancement of $\sim0.2$ dex at high mass end in overdense environments. However, compared to the local Fundamental Metallicity Relation (FMR), our galaxy sample at $z>5$ shows a metal deficiency of $\sim0.2$ dex relative to FMR predictions. We explain the observed trend of FMR with a simple analytical model, and we favor dilution from intense gas accretion over outflow to explain the metallicity properties at $z>5$. Those high redshift galaxies are likely in a rapid gas accretion phase when their metal and gas contents are in a non-equilibrium state. According to model predictions, the protocluster members are closer to the gas equilibrium state than field galaxies and thus have higher metallicity and are closer to the local FMR. Our results suggest that the accelerated star formation during protocluster assembly likely plays a key role in shaping the observed MZR and FMR, indicating a potentially earlier onset of metal enrichment in overdense environments at $z\approx5-7$.

The spherical Jeans equation is commonly used to infer dark matter distributions in dwarf spheroidal satellites of the Milky Way to constrain the nature of dark matter. One of its assumptions is that of dynamical equilibrium while the dwarfs are under the influence of Galactic tides. We carry out tailored simulations of Carina, Draco, Fornax, Sculptor and Ursa Minor and analyse the accuracy of dark matter density profiles and annihilation rates (J-factors) recovered with the Jeans equation, using pyGravSphere. We find that tides do not significantly affect the quality of density profile inference when using a bound sample of stars in the 5 simulated dwarfs; however, pyGravSphere tends to underestimate the inner densities of dwarf galaxies, which, together with tidal mass loss, leads to an inference of flatter density slopes, although all of our dwarfs have cuspy Navarro-Frenk-White haloes. The recovered J-factors are generally underestimated. While the difference with the true J-factor is small, the error bars are often underestimated and must be at least of order 0.1 dex to encompass the true J-factor. We also test the accuracy of the Wolf et al. 2010 mass estimator and find that it can be sensitive to orbital stage and eccentricity. Still, for our sample of dwarf galaxies, the estimates agree with the truth within 10%. Consistency of our simulated dwarfs with the mass-concentration relation in LambdaCDM requires a light Milky Way, or limited action of tides, which may be in tension with a "tidal stirring" origin of dwarf spheroidals.

The James Webb Space Telescope continues to push back the redshift frontier to ever earlier cosmic epochs, with recent announcements of galaxy candidates at redshifts of $15 \lesssim z \lesssim 30$. We leverage the recent GUREFT suite of dissipationless $N$-body simulations, which were designed for interpreting observations in the high redshift Universe, and provide predictions of dark matter halo mass functions and halo growth rates for a state-of-the-art cosmology over a wide range of halo masses from $6 < z< 30$. We combine these results with an empirical framework that maps halo growth rate to galaxy star formation rate and then to rest-frame UV luminosity. We find that even if all of the photometrically selected $15 \lesssim z \lesssim 30$ galaxy candidates are real and actually at these extreme redshifts, there is no fundamental tension with $\Lambda$CDM, nor are exotic explanations required. With stellar light-to-mass ratios similar to those in well-studied lower redshift galaxies, our simple model can account for the observed extreme ultra-high redshift populations with star formation efficiencies that peak at values of 20-65 percent. Bursty star formation, or higher light-to-mass ratios such as are expected for lower metallicity stellar populations or a top-heavy Initial Mass Function, would result in even lower required star formation efficiencies, comparable to values predicted by high resolution numerical simulations of high-surface density star forming clouds.

Recent high-resolution observations indicate that the progenitors of globular clusters (GCs) at high redshifts had high average stellar surface densities above $10^5\, \mathrm{M}_\odot\, \mathrm{pc}^{-2}$. Studies of the internal structure and kinematics of the clusters, however, remain out of reach. Numerical simulations are necessary to decipher the origin of the zoo of spatio-kinematic features found in present-day GCs. Here we study star cluster formation in a star-by-star hydrodynamical simulation of a low-metallicity starburst occurring during a merger of two gas-rich dwarf galaxies. The simulation accounts for the multiphase interstellar medium, stellar radiation, winds and supernovae, and the accurate small-scale gravitational dynamics near massive stars. We also include prescriptions for stellar collisions and tidal disruption events by black holes. Gravitationally bound star clusters up to $\sim2\times10^5\, \mathrm{M}_\odot$ form dense with initial half-mass radii of $\sim0.1\unicode{x2013}1\, \mathrm{pc}$. The most massive cluster approaches the observed high-redshift surface densities throughout its hierarchical and dissipative assembly. The cluster also hosts a collisionally growing very massive star of $\sim1000\, \mathrm{M}_\odot$ that will eventually collapse, forming an intermediate mass black hole. The assembly leaves an imprint in the spatio-kinematic structure of the cluster. The younger half of stars is more centrally concentrated, rotates faster, and its velocity distribution is more radially biased at outer radii. The older population is more round in shape, rotates slowly, its velocity distribution is isotropic and its velocity dispersion is higher. These results provide a possible explanation for a subset of multiple population features observed in GCs such as NGC 104/47 Tuc.

The chemical feedback from stellar winds in low metallicity (Z) environments is key for understanding the evolution of globular clusters and the early Universe. With disproportionate mass lost from the most massive stars (M > 100Msun), and an excess of such stars expected at the lowest metallicities, their contribution to the enrichment of the early pristine clusters could be significant. In this work, we examine the effect of mass loss at low metallicity on the nucleosynthesis and wind yields of (very) massive stars. We calculate stellar models with initial masses ranging from 30 to 500Msun during core Hydrogen and Helium burning phases, at four metallicities ranging from 20% Zsun down to 1% Zsun. The ejected masses and net yields are provided for each grid of models. While mass-loss rates decrease with Z, we find that not only are wind yields significant, but the nucleosynthesis is also altered due to the change in central temperatures and therefore also plays a role. We find that 80-300Msun models can produce large quantities of Na-rich and O-poor material, relevant for the observed Na-O anti-correlation in globular clusters.

The Event Horizon Telescope (EHT) enables the exploration of black hole accretion flows at event-horizon scales. Fitting ray-traced physical models to EHT observations requires the generation of synthetic images, a task that is computationally demanding. This study leverages \alinet, a generative machine learning model, to efficiently produce radiatively inefficient accretion flow (RIAF) images as a function of the specified physical parameters. \alinet has previously been shown to be able to interpolate black hole images and their associated physical parameters after training on a computationally tractable set of library images. We utilize this model to estimate the uncertainty introduced by a number of anticipated unmodeled physical effects, including interstellar scattering and intrinsic source variability. We then use this to calibrate physical parameter estimates and their associated uncertainties from RIAF model fits to mock EHT data via a library of general relativistic magnetohydrodynamics models.

We explore the constraining power of future 21cm intensity mapping (IM) observations at the SKAO, focusing primarily on the sum of neutrino masses, $\Sigma m_\nu$. We forecast observations of the 21cm IM auto-power spectrum as well as the 21cm IM and galaxy surveys cross-correlation power spectrum. We construct different synthetic data sets of observations for the 21cm IM observables. For galaxy clustering, we consider two stage-IV surveys to mimic a DESI-like and Euclid-like cross-correlation signal. We study the impact of assuming three different fiducial values for the sum of neutrino masses, i.e. $\Sigma m_\nu = 0.06, 0.1, 0.4$ eV, in the synthetic data sets. To investigate the constraining power of the forecasted 21cm observations, we build a likelihood code. We find that the 21cm auto-power spectrum alone could provide an upper limit on the sum of neutrino masses of $\Sigma m_\nu < 0.287$ eV, at $95\%$ confidence level, for the case of the lowest fiducial value of $\Sigma m_\nu$. This result is comparable to the upper limits provided by cosmic microwave background (CMB) observations alone. When combining the 21cm auto-power spectrum synthetic data set with Planck 2018 CMB measurements, we find a tighter upper limit of $\Sigma m_\nu < 0.105$ eV, which improves on the constraints from Planck alone. We obtain a similar result with 21cm and galaxy clustering cross-correlation power spectrum, whose detection is more easily achieved as they are less affected by systematic effects. Combining with Planck 2018 data, we find the upper limits of $\Sigma m_\nu < 0.116$ eV and $\Sigma m_\nu < 0.117$ eV for the 21cm signal in cross-correlation with the DESI-like and Euclid-like surveys, respectively. These constraints are comparable to those obtained by combining Planck data with the 21cm auto-power spectrum synthetic data sets, thus supporting the case for 21cm cross-correlation detections.

Exoplanet imaging using the solar gravitational lens is an enticing prospect. The fundamental physical properties of the lens, including its angular resolution and light amplification, promise exceptional capabilities. These expectations, however, are tempered by the realization of numerous challenges, including imperfections of the lens itself, noise sources, the properties of the imaging target and difficult technical issues. We discuss, in particular, a subject not previously addressed, the impact of temporally varying surface features, notably a variable cloud cover, obscuring the target exoplanet. This has a substantial detrimental effect on image recovery, leading to our cautious assessment of the practical feasibility of using the Sun's gravitational field as an effective telescope.

The Sunyaev-Zeldovich (SZ) effect is a window into the astrophysical processes of galaxy clusters, and relativistic corrections (the "rSZ") promise to provide a global census of the gas feedback within clusters. Upcoming wide-field millimeter-wave surveys such as the Simons Observatory (SO), Fred Young Submillimeter Telescope, and CMB-S4 will make increasingly precise measurements of the SZ effect and its relativistic corrections. We present simulated full-sky maps of the rSZ effect and a fast code to generate it, for use in the development of analysis techniques and pipelines. As part of the websky simulation suite, our mock observations have semi-realistic cross-correlations with other large-scale structure tracers, offering insights into the formation and evolution of galaxy clusters and large-scale structure. As a demonstration of this, we examine what an SO-like experiment can learn from the rSZ effect. We find that high significance detections will be possible, provided that the instrumental systematics are under control, and that the evolution of cluster temperatures with mass and redshift can be probed in a manner complementary to X-ray measurements.

Galactic archeology has long been limited by a lack of precise masses and ages for metal-poor stars in the Milky Way's thick disk. However, with TESS providing a growing number of photometric observations, it is possible to calculate masses and ages for more solar-like oscillators than ever using asteroseismology. We have used the pySYD pipeline to determine global asteroseismic parameters and calculated the masses and ages of $506$ metal-poor ([M/H] $<$ -0.5) red giants observed by TESS. Our findings appear to show metallicity-dependent mass loss on the upper red giant branch and identify a set of "young" high-$\alpha$ stars that have been detected in other studies. We also find that $32.6\%$ of the metal-poor stars appear to be binary interaction products and four stars with stellar ages that could be from the Gaia Enceladus/Sausage system. In combination with existing ages from Kepler/K2, this data can be compared to galactic evolution models to better determine the formation history of the galaxy.

Forward modeling is often used to interpret substructures observed in protoplanetary disks. To ensure the robustness and consistency of the current forward modeling approach from the community, we conducted a systematic comparison of various hydrodynamics and radiative transfer codes. Using four grid-based hydrodynamics codes (FARGO3D, Idefix, Athena++, PLUTO) and a smoothed particle hydrodynamics code (Phantom), we simulated a protoplanetary disk with an embedded giant planet. We then used two radiative transfer codes (mcfost, RADMC-3D) to calculate disk temperatures and create synthetic 12CO cubes. Finally, we retrieved the location of the planet from the synthetic cubes using DISCMINER. We found strong consistency between the hydrodynamics codes, particularly in the density and velocity perturbations associated with planet-driven spirals. We also found a good agreement between the two radiative transfer codes: the disk temperature in mcfost and RADMC-3D models agrees within $\lesssim 3~\%$ everywhere in the domain. In synthetic $^{12}$CO channel maps, this results in brightness temperature differences within $\pm1.5$ K in all our models. This good agreement ensures consistent retrieval of planet's radial/azimuthal location with only a few % of scatter, with velocity perturbations varying $\lesssim 20~\%$ among the models. Notably, while the planet-opened gap is shallower in the Phantom simulation, we found that this does not impact the planet location retrieval. In summary, our results demonstrate that any combination of the tested hydrodynamics and radiative transfer codes can be used to reliably model and interpret planet-driven kinematic perturbations.

We report the first comprehensive census of the satellite dwarf galaxies around NGC~55 ($2.1$~Mpc) as a part of the DECam Local Volume Exploration DEEP (DELVE-DEEP) survey. NGC~55 is one of four isolated, Magellanic analogs in the Local Volume around which DELVE-DEEP aims to identify faint dwarfs and other substructures. We employ two complementary detection methods: one targets fully resolved dwarf galaxies by identifying them as stellar over-densities, while the other focuses on semi-resolved dwarf galaxies, detecting them through shredded unresolved light components. As shown through extensive tests with injected galaxies, our search is sensitive to candidates down to $M_V \lesssim -6.6$ and surface brightness $\mu \lesssim 28.5$ mag arcsec$^{-2}$, and $\sim 80\%$ complete down to $M_V \lesssim -7.8$. We do not report any new confirmed satellites beyond two previously known systems, ESO 294-010 and NGC~55-dw1. We construct the satellite luminosity function of NGC~55 and find it to be consistent with the predictions from cosmological simulations. As one of the first complete luminosity functions for a Magellanic analog, our results provide a glimpse of the constraints on low-mass-host satellite populations that will be further explored by upcoming surveys, such as the Vera C. Rubin Observatory's Legacy Survey of Space and Time.

A semi-analytic model is developed to study the effects of kappa-distributed lighter constituents and the associated kappa-modified polarization force on the classical Jeans instability in dust molecular clouds (DMCs). The constitutive electrons and ions are considered to follow a nonthermal kappa-velocity distribution law, while the constitutive massive dust grains are treated as the EiBI-gravitating fluids. A linearized quadratic dispersion relation is derived using spherical normal mode analysis. The resulting dispersion relation and its corresponding modified instability criteria are analyzed in the hydrodynamic and kinetic regimes. The oscillatory and propagating mode characteristics are illustratively analyzed. It is seen that the EiBI gravity introduces a new velocity term in the dispersion relation. In contrast, the nonthermal kappa-distributed constituents significantly enhance the polarization force against their respective Maxwellian counterparts. The kappa-modified polarization force and the negative EiBI gravity parameter have destabilizing influences, unlike the positive EiBI parameter. An enhanced polarization interaction parameter and a positive EiBI parameter reduce the real normalized frequency. Consequently, the phase velocity exhibits strong dispersion, increasing with wavenumber until reaching saturation, after which it transitions into a weakly dispersive regime. These findings provide new insights into the formation of smaller astrophysical structures via the non-local Jeans instability in the ultracompact HII regions of dense DMCs.

We present the instrument design and initial results for the Galactic Radio Explorer (GReX), an all-sky monitor for exceptionally bright transients in the radio sky. This instrument builds on the success of STARE2 to search for fast radio bursts (FRBs) from the Milky Way and its satellites. This instrument has deployments across the globe, with wide sky coverage and searching down to $32\,\mu\text{s}$ time resolution, enabling the discovery of new super giant pulses. Presented here are the details of the hardware and software design of the instrument, performance in sensitivity and other key metrics, and experience in building a global-scale, low-cost experiment. We follow this discussion with experimental results on validation of the sensitivity via hydrogen-line measurements. We then update the rate of Galactic FRBs based on a non-detection in $0.5\,\text{sky}\,\text{yr}$ of exposure, with twice the sensitivity of STARE2. Our results suggest FRB-like events are even rarer than initially implied by the detection of a MJy burst from SGR J1935+2154 in April 2020.

Planet formation is a hugely dynamic process requiring the transport, concentration and assimilation of gas and dust to form the first planetesimals and cores. With access to extremely high spatial and spectral resolution observations at unprecedented sensitivities, it is now possible to probe the planet forming environment in detail. To this end, the exoALMA Large Program targeted fifteen large protoplanetary disks ranging between ${\sim}1\arcsec$ and ${\sim}7\arcsec$ in radius, and mapped the gas and dust distributions. $^{12}$CO J=3-2, $^{13}$CO J=3-2 and CS J=7-6 molecular emission was imaged at high angular (${\sim}~0\farcs15$) and spectral (${\sim}~100~{\rm m\,s^{-1}}$) resolution, achieving a surface brightness temperature sensitivity of ${\sim}1.5$~K over a single channel, while the 330~GHz continuum emission was imaged at 90~mas resolution and achieved a point source sensitivity of ${\sim}\,40~\mu{\rm Jy~beam^{-1}}$. These observations constitute some of the deepest observations of protoplanetary disks to date. Extensive substructure was found in all but one disk, traced by both dust continuum and molecular line emission. In addition, the molecular emission allowed for the velocity structure of the disks to be mapped with excellent precision (uncertainties on the order of $10~{\rm m\,s^{-1}}$), revealing a variety of kinematic perturbations across all sources. From this sample it is clear that, when observed in detail, all disks appear to exhibit physical and dynamical substructure indicative of on-going dynamical processing due to young, embedded planets, large-scale, (magneto-)hydrodynamical instabilities or winds.

In this work, we apply an exploratory joint Bayesian transit detector (Taaki et al. 2020), previously evaluated using Kepler data, to the 2 min simple aperture photometry light curve data in the continuous viewing zone for the Transiting Exoplanet Survey Satellite (TESS) over three years of observation. The detector uses Bayesian priors, adaptively estimated, to model unknown systematic noise and stellar variability incorporated in a Neyman-Pearson likelihood ratio test for a candidate transit signal; a primary goal of the algorithm is to reduce overfitting. The detector was adapted to the TESS data and refined to improve outlier rejection and suppress false alarm detections in post-processing. The statistical performance of the detector was evaluated using transit injection tests, where the joint Bayesian detector achieves an 80.0 % detection rate and a 19.1% quasi-false alarm rate at a detection threshold {\tau} = 10; this is a marginal, although not statistically significant, improvement of 0.2% over a reference sequential detrending and detection algorithm. In addition, a full search of the input TESS data was performed to evaluate the recovery rate of known TESS objects of interest (TOI) and to perform an independent search for new exoplanet candidates. The joint detector has a 73% recall rate and a 63% detection rate for known TOI; the former considers a match against all detection statistics above threshold while the latter considers only the maximum detection statistic.

We provide a comprehensive analysis of Ion3, the most distant LyC leaker at $z=3.999$, using multi-band HST photometry and X-Shooter spectroscopy. Deep HST F390W imaging probe uncontaminated LyC flux blueward $\sim$880Å, while the non-ionizing UV 1500Å/2800Å~flux is probed with the F814W/F140W band. High angular resolution allows us to properly mask low-$z$ interlopers and prevent contamination of measured LyC radiation. We confirm the detection of LyC flux at SNR $\sim$3.5 and estimate the escape fraction of ionizing photons to be in the range $f_{\rm esc, rel}$ = 0.06 -- 1, depending on the adopted IGM attenuation. Morphological analysis reveals a clumpy structure made of two main components, with effective radii of R$_{\rm eff}$ $\sim$180 pc and R$_{\rm eff}$ < 100 pc, and a total estimated de-lensed area in the rest-frame 1600Å~of 4.2~kpc$^{2}$. We confirm the presence of faint ultraviolet spectral features HeII$\lambda$1640, CIII]$\lambda$1907,1909 and [NeIII]$\lambda$3968, with rest-frame EW(HeII) = (1.6$\pm$0.7)Å and EW(CIII]) = (6.5$\pm$3)Å. From [OII]$\lambda$$\lambda$3726,3729 and [CIII]$\lambda$1909/CIII]$\lambda$1906 we derive electron densities $n_{\rm e}^{\rm [OII]}$ = 2300$\pm$1900 cm$^{-3}$ and $n_{\rm e}^{\rm CIII]}$ > 10$^{4}$ cm$^{-3}$, corresponding to an ISM pressure log(P/k) > 7.90. Furthermore, we derive an intrinsic SFR(H$\alpha$) $\approx$ 77 M$_{\odot}$ yr$^{-1}$ (corresponding to $\Sigma_{\rm SFR} = 20$~M$_{\odot}$~yr$^{-1}$~kpc$^{-2}$ for the entire galaxy) and sub-solar metallicity $12+\rm log(O/H)$ = 8.02$\pm$0.20 using the EW(CIII]) as a diagnostic. The detection of [NeIII]$\lambda$3968 line and [OII]$\lambda$$\lambda$3726,3729, provide an estimate of the ratio [OIII]$\lambda$5007/[OII]$\lambda$$\lambda$3727,29 of O32 > 50 and high ionization parameter log$U$ > $-$1.5 using empirical and theoretical correlations.

We analyze the $^{12}$CO $J=3-2$ data cubes of the disks in the exoALMA program. 13/15 disks reveal a variety of kinematic substructures in individual channels: large-scale arcs or spiral arms, localized velocity kinks, and/or multiple faints arcs that appear like filamentary structures on the disk surface. We find kinematic signatures that are consistent with planet wakes in six disks: AA Tau, SY Cha, J1842, J1615, LkCa 15 and HD 143006. Comparison with hydrodynamical and radiative transfer simulations suggests planets with orbital radii between 80 and 310\,au and masses between 1 and 5 M$_\mathrm{Jup}$. Additional kinematic substructures limit our ability to place tight constraints on the planet masses. When the inclination is favorable to separate the upper and lower surfaces (near 45$^\mathrm{o}$, i.e. in 7/15 disks), we always detect the vertical CO snowline and find that the $^{12}$CO freeze-out is partial in the disk midplane, with a depletion factor of $\approx 10^{-3}$ - $10^{-2}$ compared to the warm molecular layer. In these same seven disks, we also systematically detect evidence of CO desorption in the outer regions.

Starburst galaxies are $\gamma$-ray sources. Canonically, their emission is driven by hadronic cosmic rays (CRs) interacting with interstellar gas, forming $\gamma$-rays via the decay of neutral pions. Charged pions are also formed in this process. They decay into secondary leptons, including electrons and neutrinos. Starburst galaxies are therefore also expected to be neutrino sources, and their high-energy $\gamma$-ray emission may include a secondary leptonic component. Leptonic $\gamma$-rays may also originate from electrons directly energized by shocks within the interstellar medium of galaxies, or from pulsars and their surrounding halos. In the Milky Way, pulsars/pulsar halos are the dominant $\gamma$-ray source class. They are associated with stellar remnants or old stellar populations, and are presumably abundant in old galaxies. In this work, we show that the collective high-energy emission from galaxies can account for only a fraction of extragalactic neutrinos, but can form a major component of the extragalactic $\gamma$-ray background. Contrary to the traditional view, a substantial fraction of this radiation may originate from leptonic processes, including from old, quiescent galaxies.

The Black Hole Explorer (BHEX) mission extends the submillimeter Very-Long-Baseline Interferometry (VLBI) to space. The preliminary baseline design of a shaped axial-symmetric displaced-axis dual-reflector antenna for the BHEX is presented. The main goal of the antenna design optimization is to maximize aperture efficiency given the geometric and mechanical constraints of a space-borne antenna.

The exoALMA Large Program targeted a sample of 15 disks to study gas dynamics within these systems, and these observations simultaneously produced continuum data at 0.9 mm (331.6 GHz) with exceptional surface brightness sensitivity at high angular resolution. To provide a robust characterization of the observed substructures, we performed a visibility space analysis of the continuum emission from the exoALMA data, characterizing axisymmetric substructures and nonaxisymmetric residuals obtained by subtracting an axisymmetric model from the observed data. We defined a nonaxisymmetry index and found that the most asymmetric disks predominantly show an inner cavity and consistently present higher values of mass accretion rate and near-infrared excess. This suggests a connection between outer disk dust substructures and inner disk properties. The depth of the data allowed us to describe the azimuthally averaged continuum emission in the outer disk, revealing that larger disks (both in dust and gas) in our sample tend to be gradually tapered compared to the sharper outer edge of more compact sources. Additionally, the data quality revealed peculiar features in various sources, such as shadows, inner disk offsets, tentative external substructures, and a possible dust cavity wall.

The exoALMA large program offers a unique opportunity to investigate the fundamental properties of protoplanetary disks, such as their masses and sizes, providing important insights in the mechanism responsible for the transport of angular momentum. In this work, we model the rotation curves of CO isotopologues $^{12}$CO and $^{13}$CO of ten sources within the exoALMA sample, and we constrain the stellar mass, the disk mass and the density scale radius through precise characterization of the pressure gradient and disk self gravity. We obtain dynamical disk masses for our sample measuring the self-gravitating contribution to the gravitational potential. We are able to parametrically describe their surface density, and all of them appear gravitationally stable. By combining dynamical disk masses with dust continuum emission data, we determine an averaged gas-to-dust ratio of approximately 400, not statistically consistent with the standard value of 100, assuming optically thin dust emission. In addition, the measurement of the dynamical scale radius allows for direct comparison with flux-based radii of gas and dust. This comparison suggests that substructures may influence the size of the dust disk, and that CO depletion might reconcile our measurements with thermochemical models. Finally, with the stellar mass, disk mass, scale radius, and accretion rate, and assuming self-similar evolution of the surface density, we constrain the effective $\alpha_S$ for these systems. We find a broad range of $\alpha_S$ values ranging between $10^{-5}$ and $10^{-2}$.

The ngVLA science requirements call for continuum image dynamic ranges of 45 dB and 35 dB at 8 and 27 GHz respectively. In interferometric aperture synthesis imaging, visibility amplitude and phase errors result in errors in the final images, limiting the dynamic range attained. In order to achieve the ngVLA dynamic range requirements it is necessary to limit the amplitude and phase errors to within appropriate levels. The relationship between the number of antennas N in an interferometric aperture synthesis array and the error in the constructed image has been previously derived and conventionally adopted to be a scaling of \approx N. In this short memo, we argue that this relationship may not hold everywhere in an image and derive the relationship in a more stringent limit. We derive a more stringent \sqrt N dependence as opposed to the previous, generally adopted N scaling and compare with existing simulations. This relationship is at the root of allowable amplitude and phase errors arising from practically every corrupting effect, e.g. antenna pointing, primary beam characteristics, tropospheric and ionospheric phase fluctuations and polarimetric imperfections, among others. Thus, it is central to ngVLA calibration requirements and strategies. We recommend the adoption of a conservative \sqrt N dependence as the basis to derive the requirements and to identify applicable strategies.

Quasars accreting at very high rates are believed to be prime movers of galactic evolution because of their high radiative and mechanical output. The study presented in this paper investigates a sample of six highly accreting quasars at redshifts \( z = 2-3 \) using near-infrared observations from the LUCI spectrograph at the Large Binocular Telescope (LBT). The aim is obtain a precise measure of the quasar systemic redshift and accretion parameters (black hole mass and Eddington ratio) primarily from the \hb\ line, \ and on second stance from other intermediate and low ionization lines. Outflow dynamical parameters (mass rate of outflowing gas, its kinetic power and momentum rate) were estimated from the \civ\ emission line that is perhaps the most easily accessible tracer of high-ionization winds from the accretion disk, obtained from the Sloan Digital Sky Survey. In addition, the joint analysis of the rest-frame optical and UV spectra allowed us to estimate the chemical composition of the broad line emitting gas. The high metal content of the outflowing gas ($Z \gtrsim 10 Z_\odot$) and the high values of thrust and kinetic power may induce a chemical feedback effect in the quasar host, in addition to mechanical feedback.

Understanding the impact of baryonic feedback on the small-scale ($k \gtrsim 1\,h\,$Mpc$^{-1}$) matter power spectrum is a key astrophysical challenge, and essential for interpreting data from upcoming weak-lensing surveys, which require percent-level accuracy to fully harness their potential. Astrophysical probes, such as the kinematic and thermal Sunyaev-Zel'dovich effects, have been used to constrain feedback at large scales ($k \lesssim 5\,h\,$Mpc$^{-1}$). The sightline-to-sightline variance in the fast radio bursts (FRBs) dispersion measure (DM) correlates with the strength of baryonic feedback and offers unique sensitivity at scales upto $k \sim 10\,h\,$Mpc$^{-1}$. We develop a new simulation-based formalism in which we parameterize the distribution of DM at a given redshift, $p(\mathrm{DM}|z)$, as a log-normal with its first two moments computed analytically in terms of cosmological parameters and the feedback-dependent electron power spectrum $P_\mathrm{ee}(k, z)$. We find that the log-normal parameterization provides an improved description of the $p(\mathrm{DM}|z)$ distribution observed in hydrodynamical simulations as compared to the standard $F$-parameterization. Our model robustly captures the baryonic feedback effects across a wide range of baryonic feedback prescriptions in hydrodynamical simulations, including IllustrisTNG, SIMBA and Astrid. Leveraging simulations incorporates the redshift evolution of the DM variance by construction and facilitates the translation of constrained feedback parameters to the suppression of matter power spectrum relative to gravity-only simulations. We show that with $10^4$ FRBs, the suppression can be constrained to percent-level precision at large scales and $\sim 10$\% precision at scales $k \gtrsim 10\,h\,$Mpc$^{-1}$ with prior-to-posterior $1\sigma$ constraint width ratio $\gtrsim 20$.

Physical and chemical conditions (kinetic temperature, volume density, molecular composition) of interstellar clouds are inherent in their mm-submm line spectra, making spectral line profiles powerful diagnostics of source conditions. We introduce a novel bottom-up approach employing Machine Learning (ML) algorithms to directly infer physical conditions from line profiles without using radiative transfer equations. We simulated HCN and HNC emission under representative dense molecular cloud and star-forming region conditions across five rotational transitions (J=1-0 to J=5-4) within 30-500 GHz. The generated data cloud was parameterized using line intensities and widths to infer the physical conditions of the analyzed regions. Three ML algorithms were trained, tested, and compared to unravel the excitation conditions of HCN and HNC and their abundance ratio. ML results obtained with two spectral lines, one for each isomer, were compared with a Local Thermodynamic Equilibrium (LTE) analysis for the cold source R CrA IRS 7B, yielding excitation temperatures and relative abundances in agreement with LTE. The optimized pipeline (training, testing, and prediction) can predict interstellar cloud properties from line profile inputs at lower computational cost than traditional methods. This work represents the first mapping of spectral line profiles to physical conditions by charting isomer abundance ratios and excitation temperatures. Our bottom-up approach, based on simulated and semiempirical spectra, offers a new tool to interpret line observations and estimate interstellar conditions using ML methods.

Rotation measure (RM) and dispersion measure (DM) are characteristic properties of fast radio bursts (FRBs) that contain important information of their source environment. The time evolution of RM and DM is more inclined to be ascribed to local plasma in the host galaxy rather than the intergalactic medium or free electrons in the Milky Way. Recently a sudden drastic RM change was reported for an active repeating FRB 20220529, implying that some kind of mass ejection happened near the source. In this work I suggest that magnetar flare ejecta could play this role and give rise to the significant RM change. I introduce a toy structured ejecta model and calculate the contribution to RM and DM by a typical flare event. I find that this model could reproduce the RM behaviour of FRB 20220529 well under reasonable parameters, and similar sudden change is expected as long as this source maintains its activity.

This study investigates the metallicity distribution in M31 and M33 by using the near-infrared color index $J-K$ of tip-red-giant-branch (TRGB) of the member stars from \cite{2021ApJ...907...18R} after removing the foreground dwarf stars by the near-infrared $J-H/H-K$ diagram as well as the Gaia astrometric measurements. We employ the Voronoi binning technique to divide the galaxy into sub-regions, the PN method to determine the TRGB position in the $J-K$/$K$ diagram, and the bootstrap method to estimate the uncertainties. The TRGB positions are calculated to be $J-K = 1.195 \pm 0.002$ and $1.100 \pm 0.003$, and $K = 17.615 \pm 0.007$ and $18.185 \pm 0.053$ for M31 and M33 respectively as an entity, consistent with previous results. The $J-K$ gradient of M31 is found to be $-$0.0055 kpc$^{-1}$ at $R_{\rm GC}=(0, 24)$ kpc and $-$0.0002 kpc$^{-1}$ at $R_{\rm GC}=(24, 150)$ kpc. Notably, two dust rings are evident at 11.5 kpc and 14.5 kpc, in agreement with previous studies. The $J-K$ of M33 is analyzed in four directions and generally shows a trend of gradually decreasing from the inside to the outside, however, it shows an increasing trend of 0.022 kpc$^{-1}$ in the inner 0$-$2 kpc in the west. Through the color$-$metallicity relation of TRGB, the metallicity gradient of M31 turns to be $-0.040 \pm 0.0012$ dex kpc$^{-1}$ with $R_{\rm GC}<30$ kpc and $-0.001 \pm 0.0002$ dex kpc$^{-1}$ with $R_{\rm GC}>30$ kpc, and for M33, $-$0.269 $\pm$ 0.0206 dex kpc$^{-1}$ with $R_{\rm GC}<9$ kpc.

Simulations of Galactic CR transport were performed with the software GALPROP, with the resulting gamma-ray flux calculated up to the PeV regime. The impact of altering parameters such as the number and distribution of CR sources, the distribution of infrared radiation between stars, and the distribution and strength of the Galactic magnetic field (GMF), were investigated. For the first time the modelling variation in the TeV predictions due to uncertainties in the Galactic distributions was quantified. Additionally, the modelling variation from considering a stochastic placement of the CR sources was quantified up to 1 PeV. The simulation results were compared to the most detailed Galactic TeV gamma-ray survey: the H.E.S.S. Galactic plane survey (HGPS). The GALPROP predictions were broadly compatible with the large-scale emission from the HGPS after accounting for both the catalogued sources and estimates of the unresolved source fraction. At 1 TeV the gamma-ray emission from CR electrons was found to contribute $\sim$50\% to the large-scale emission. The GMF was found to be an important modelling consideration above 1 TeV as it impacted the large-scale emission by approximately a factor of two. Additionally, the CR electron flux at Earth above 1 TeV was found to vary by over a factor of ten over a period of a few million years due. The GALPROP models were found to agree with observations of the diffuse gamma rays in the TeV regime by H.E.S.S., and the PeV regime by LHAASO, extending the demonstrated accuracy of GALPROP into the TeV--PeV regime. The results will also inform the next generation of experiments, such as the Cherenkov telescope array (CTA), on possible observation strategies and background considerations. It was also found that the proposed CTA Galactic plane survey will be sensitive enough to observe the large-scale diffuse gamma-ray emission in the TeV regime.

The advent of JWST has marked a new era in exoplanetary atmospheric studies, offering higher-resolution data and greater precision across a broader spectral range than previous space-based telescopes. Accurate analysis of these datasets requires advanced retrieval frameworks capable of navigating complex parameter spaces. We present NEXOTRANS, an atmospheric retrieval framework that integrates Bayesian inference using UltraNest/PyMultiNest with four machine learning algorithms: Random Forest, Gradient Boosting, K-Nearest Neighbor, and Stacking Regressor. This hybrid approach enables a comparison between traditional Bayesian methods and computationally efficient machine learning techniques. Additionally, NEXOTRANS incorporates NEXOCHEM, a module for solving equilibrium chemistry. We applied NEXOTRANS to JWST observations of the Saturn-mass exoplanet WASP-39 b, spanning wavelengths from 0.6 microns to 12.0 microns using NIRISS, NIRSpec PRISM, and MIRI. Four chemistry models-free, equilibrium, modified hybrid equilibrium, and modified equilibrium-offset chemistry-were explored to retrieve precise Volume Mixing Ratios (VMRs) for H2O, CO2, CO, H2S, and SO2. Absorption features in both NIRSpec PRISM and MIRI data constrained SO2 log VMRs to values between -6.67 and -5.31 for all models except equilibrium chemistry. High-altitude aerosols, including ZnS and MgSiO3, were inferred, with constraints on their VMRs, particle sizes, and terminator coverage fractions, providing insights into cloud composition. For the best-fit modified hybrid equilibrium model, we derived super-solar elemental abundances of O/H = 7.94 (+0.18/-0.18) x solar, C/H = 10.96 (+0.42/-0.41) x solar, and S/H = 3.98 (+0.29/-0.35) x solar, along with a C/O ratio of 1.17 (+0.03/-0.03) x solar, demonstrating NEXOTRANS's potential for atmospheric characterization in the JWST era and beyond.

The gravitational potential is established as a critical determinant of gas-phase metallicity (12+log(O/H)) in low-redshift galaxies, whereas its influence remains unconfirmed at high redshifts. We investigate the correlation between gas-phase metallicity and effective radius ($R_{\rm e}$) for a sample of galaxies with redshifts ranging from 1 to 7, drawn from JADES (JWST Advanced Deep Extragalactic Survey) Data Release 3. We calculate the metallicities using four strong-line methods: ${\rm N2S2H\alpha}$, ${\rm R23}$, ${\rm N2}$, and ${\rm O3N2}$, respectively. After taking out the evolution of size, we find that the offsets of mass-size relation ($\Delta \log R_{\rm e}$) are significantly negatively correlated with the offset of mass-metallicity relation ($\Delta \log({\rm O/H})$) for the four metallicity tracers. Regardless of the metallicity tracer used, we obtain Spearman rank $p-$values much less than 0.01, rejecting the null hypothesis that the observed correlation is statistically nonsignificant and attributable to random chance. This is also true for galaxies with $z>3$, with $p-$values less than 0.05 for the four metallicity tracers. We for the first time find evidence of size playing a key role in determining gas-phase metallicity towards cosmic dawn, suggesting that the gravitational potential influences their material-exchange processes with the surrounding environment at very early universe.

Next-generation gravitational wave detectors (GWDs) such as the Cosmic Explorer and Einstein Telescope demand extensive ultra-high vacuum systems, making material cost and performance critical considerations. This study investigates the potential of ferritic stainless steel as a cost-effective alternative to the commonly used austenitic stainless steel for UHV components, focusing on the analysis of outgassing rates pre and post-bakeout at 80°C and 150°C for 48 hours. The tested ferritic stainless steels exhibit significantly lower hydrogen content than standard AISI 304L steel. After bakeout, the hydrogen outgassing rates - measured down to 10$^{-15}$ mbar l s$^{-1}$ cm$^{-2}$ - are three orders of magnitude lower than those of similarly conditioned austenitic stainless steels. These results highlight ferritic stainless steel as a promising, economical, and high-performance candidate for future GWDs vacuum systems.

In their final stages before undergoing a core-collapse supernova, massive stars may experience mergers between internal shells where carbon (C) and oxygen (O) are consumed as fuels for nuclear burning. This interaction, known as a C-O shell merger, can dramatically alter the internal structure of the star, leading to peculiar nucleosynthesis and potentially influencing the supernova explosion and the propagation of the subsequent supernova shock. Our understanding of the frequency and consequences of C-O shell mergers remains limited. This study aims to identify for the first time early diagnostics in the stellar structure which will lead to C-O shell mergers in more advanced stages. We also assess their role in shaping the chemical abundances in the most metal poor stars of the Galaxy. We analyze a set of 209 of stellar evolution models available in the literature, with different initial progenitor masses and metallicities. We then compare the nucleosynthetic yields from a subset of these models with the abundances of odd-Z elements in metal-poor stars. We find that the occurrence of C-O shell mergers in stellar models can be predicted with good approximation based on the outcomes of the central He burning phase, specifically, from the CO core mass ($\rm M_{CO}$) and the $\rm ^{12}C$ central mass fraction ($\rm X_{C12}$): 90$\%$ of models with a C-O merger have $\rm X_{C12}< 0.277$ and $\rm M_{CO}< 4.90 M_{\odot}$, with average values $\rm M_{CO} = 4.02 M_{\odot}$ and $\rm X_{C12}= 0.176$. Additionally, we confirm that the Sc-rich and K-rich yields from models with C-O mergers would solve the long-standing underproduction of these elements in massive stars. Our results emphasize the crucial role of C-O shell mergers in enriching the interstellar medium, particularly in the production of odd-Z elements.

In this manuscript, we report evidence to support the dependence of D{\it n}4000 (4000Å~ break strength to trace stellar ages) on central AGN activity traced by narrow emission line properties in local Type-2 AGN in SDSS DR16. Based on the measured D{\it n}4000 and flux ratios of [O~{\sc iii}] to narrow H$\beta$ (O3HB) and [N~{\sc ii}] to narrow H$\alpha$ (N2HA) and narrow H$\alpha$ line luminosity $L_{H\alpha}$, linear dependence of the D{\it n}4000 on the O3HB, N2HA and $L_{H\alpha}$ in the local Type-2 AGN can provide clues to support the dependence of D{\it n}4000 on properties of narrow emission lines. Linear correlations between the D{\it n}4000 and the O3HB and N2HA can be found in the local Type-2 AGN, with Spearman rank correlations about -0.39 and 0.53. Meanwhile, stronger dependence of the D{\it n}4000 on the $L_{H\alpha}$ can be confirmed in Type-2 AGN, with Spearman rank correlation coefficient about -0.7. Moreover, combining the $L_{H\alpha}$ and the N2HA, a more robust and stronger linear correlation can be confirmed between the D{\it n}4000 and the new parameter $LR=0.2\log(L_{H\alpha})-0.5\log(\rm N2HA)$, with Spearman rank correlation coefficient about -0.76 and with smaller RMS scatters. After considering necessary effects, the dependence of D{\it n}4000 on $LR$ is stable and robust enough for the local Type-2 AGN, indicating the $LR$ on the narrow emission lines can be treated as a better indicator to statistically trace stellar ages of samples of more luminous AGN with weaker host galaxy absorption features.

Recently, blazar 4C +27.50 was found to be flaring in gamma-rays since its detection with Fermi-LAT in 2008. For the first time, a dedicated temporal and spectral study of the blazar 4C +27.50 has been performed in this work to understand the nature of this object. We used the Bayesian block algorithm to identify four flaring states and one quiet state in the 2-year-long Fermi-LAT light curve. Simultaneous broadband flaring episodes have been observed, and a significant correlation is seen between optical and $\gamma$-ray emission, suggesting the co-spatial origin of the broadband emission. The variation of fractional variability amplitude with respect to frequency shows a nearly double hump structure similar to broadband SED. The fastest flux doubling time in the 1-day binned $\gamma$-ray light curve is found to be about 7.8 hours. A curvature in $\gamma$-ray spectra has been observed, possibly caused by a stochastic particle acceleration process rather than radiative cooling. No evident correlation was found in the $\gamma$-ray flux-index plot, but a clear harder-when-brighter trend is observed in the X-ray flux-index plot. A one-zone leptonic model has been implemented to understand broadband emission during the quiet and flaring states, and the variation of the jet parameters is been investigated. A gradual increment in BLR and Disk energy density has been observed from a quiet to the flaring state. Broadband SED modeling suggested that an enhancement in the magnetic field, particle energy, and bulk Lorentz factor might have caused the flaring events.

Rotating primordial black holes (PBHs) in the early universe can emit particles through superradiance, a process particularly efficient when the particle's Compton wavelength is comparable to the PBH's gravitational radius. Superradiance leads to an exponential growth of particle occupation numbers in gravitationally bound states. We present an analysis of heavy bosonic dark matter (DM) production through three gravitational mechanisms: Hawking radiation, superradiant instabilities, and ultraviolet (UV) freeze-in. We consider PBHs that evaporate before Big Bang Nucleosynthesis (BBN). For both scalar and vector DM, our analysis incorporates the evolution of a second superradiant mode. We demonstrate that the growth of a second superradiant mode causes the decay of the first mode, and thus the second mode cannot further enhance the DM abundance beyond that already achieved by the first mode. Our study also reveals that while superradiance generally enhances DM production, gravitational wave (GW) emission from the superradiant cloud may significantly modify this picture. For scalar DM, GW emission reduces the parameter space where superradiance effectively augments relic abundance. For vector DM, rapid GW emission from the superradiant cloud may yield relic abundances below those achieved through Hawking radiation alone. These findings demonstrate that multiple-mode effect and GW emission play critical roles in modeling DM production from PBHs in the early universe.

The Hard X-ray Modulation Telescope (\insight) detected GRB 221009A, the brightest gamma-ray burst observed to date, with all its three telescopes, i.e. High Energy telescope (HE, 20-250 keV), Medium Energy telescope (ME, 5-30 keV), and Low Energy telescope (LE, 1-10 keV). Here we present the detailed observation results of all three telescopes of \insight~ on the prompt emission of GRB 221009A. After dead-time and data saturation correction, we recovered the light curves of HE, ME and LE telescopes and find that they generally track the GECAM-C low gain light curves that are free of data saturation issues. Particularly, the ME light curve matches the GECAM-C light curve in low gain mode above 400 keV, while the LE light curve is more consistent with the GECAM-C above 1.5 MeV. Based on simulation, we find that the signals recorded by the ME and LE are actually caused by the secondary particles produced by the interaction between GRB gamma-ray photons and the material of the satellite. Interestingly, the consistency between ME and LE light curves and GECAM-C demonstrates that ME and LE data could be used to characterize the GRB properties. Espeically, the high time resolution light curve of ME allowed us, for the first time, to calculate the minimum variability timescale (MVT = 0.10 s) of the main burst episode of GRB 221009A.

The gas-phase oxygen abundance of the circumnuclear regions around supermassive black holes (SMBH) has been claimed to be affected by the presence of an Active Galactic Nucleus (AGN). However, there is currently no consensus on the mechanism driving this effect. In this work, we explore whether the interplay between AGN activity and the Ram Pressure Stripping (RPS) can influence the metallicity distributions of nearby (z < 0.07) galaxies. To this aim, we measure the spatially resolved gas-phase oxygen abundances of 10 stripped AGN hosts from the GASP survey, as well as 52 AGN hosts found in the field, which are undisturbed by the effects of ram pressure, drawn from the MaNGA DR15. We find that the metal distributions in these two samples do not differ significantly. Only 2 out of the 10 RP-stripped AGNs present lower oxygen abundances at any given radius than the rest of the AGN sample. Overall, this result highlights that the AGN-RPS interplay does not play a significant role in shaping the metallicity distributions of stripped galaxies within 1.5 times the galaxy's effective radius (r < 1.5 Re). However, larger samples are required to draw more definitive conclusions. By including a control sample of SF galaxies, we observe that the AGN hosts are more metal-enriched than SF galaxies at any given radius. More than that, the steepness of the gradients in the nuclear regions (r < 0.5 Re) is greater in AGN hosts than in SF galaxies. These results favor the hypothesis that the AGN activity is causing metal pollution in the galaxy's nuclear regions.

Large-scale (i.e., $\gtrsim {\rm kpc}$) and micro-Gauss scale magnetic fields have been observed throughout the Milky Way and nearby galaxies. These fields depend on the geometry and matter-energy composition, can display complicated behavior such as direction reversals, and are intimately related to the evolution of the source galaxy. Simultaneously, gravitational-wave astronomy offers a new probe into astrophysical systems, for example the Laser Interferometer Space Antenna (LISA) will observe the mergers of massive (i.e., $M ~> 10^6$ M$_{\odot}$) black-hole binaries and provide extraordinary constraints on the evolution of their galactic hosts. In this work, we show how galactic, large-scale magnetic fields and their electromagnetic signatures are connected with LISA gravitational-wave observations via their common dependence on the massive black-hole binary formation scenario of hierarchical galaxy mergers. Combining existing codes, we astrophysically evolve a population of massive binaries from formation to merger and find that they are detectable by LISA with signal-to-noise ratio $\sim 10^3$ which is correlated with quantities from the progenitors' phase of circumbinary disk migration such as the maximum magnetic field magnitude $|\mathbf{B}| \approx 7 \,\mu$G, polarized intensity, and Faraday rotation measure. Interesting correlations result between these observables arising from their dependencies on the black-hole binary total mass, suggesting a need for further analyses of the full parameter space. We conclude with a discussion on this new multi-messenger window into galactic magnetic fields.

While the origins of ultra-high energy (UHE) cosmic rays (CRs) remain shrouded in uncertainty, several important milestones have been reached in recent years in the experimental study of CRs with energy above 1018 eV. Within the vast expanse of intergalactic space, turbulent magnetic fields (TMFs) are believed to pervade, and these fields could exert a significant influence on the journey of UHECRs across the expanding Universe, which is currently undergoing acceleration. Thus, it is imperative to incorporate these considerations into our theoretical framework to gain a deeper understanding of the empirical observations related to UHECRs. In light of this, our research delves into the impact of UHE particle diffusion in the presence of TMFs, all within the context of the f(R) gravity power-law model. Based on this f(R) model, we explore the diffusive behavior of UHECR protons, particularly focusing on their density enhancement throughout their propagation and their energy spectrum. We found that the f(R) gravity model considered here plays an effective role in the propagation of CRs and the results have lain within our range of interest. Also, we compare our results for flux with observational data like the Pierre Auger Observatory (PAO) and Telescope Array (TA).

When a (non-)Abelian gauge field acquires an isotropic background configuration during inflation, strong gravitational waves (GWs) with parity-violating polarization, known as chiral GWs, can be produced in addition to the intrinsic unpolarized GWs. However, previous studies have analyzed individual models, leaving the generality of this phenomenon unclear. To perform a model-independent analysis, we construct an effective field theory (EFT) of chiral GWs by extending the EFT of inflation and incorporating gauge fields. The resulting action unifies inflationary models with a $SU(2)$ gauge field, such as chromo-natural inflation and gauge-flation, and ones with a triplet of $U(1)$ gauge fields, systematically encompassing all possible GW production mechanisms consistent with the symmetry breaking induced by the gauge field background. We find that chiral GWs are generically and inevitably produced, provided that the effective energy density of the background gauge field is positive and the gauge kinetic function is not fine-tuned to a specific time dependence. This EFT offers a useful foundation for future phenomenological studies as well as for deepening our theoretical understanding of chiral GWs.

The planet-hunting ALMA large program exoALMA observed 15 protoplanetary disks at ~0.15" angular resolution and ~100 m/s spectral resolution, characterizing disk structures and kinematics in enough detail to detect non-Keplerian features (NKFs) in the gas emission. As these features are often small and low-contrast, robust imaging procedures are critical for identifying and characterizing NKFs, including determining which features may be signatures of young planets. The exoALMA collaboration employed two different imaging procedures to ensure the consistent detection of NKFs: CLEAN, the standard iterative deconvolution algorithm, and regularized maximum likelihood (RML) imaging. This paper presents the exoALMA RML images, obtained by maximizing the likelihood of the visibility data given a model image and subject to regularizer penalties. Crucially, in the context of exoALMA, RML images serve as an independent verification of marginal features seen in the fiducial CLEAN images. However, best practices for synthesizing RML images of multi-channeled (i.e. velocity-resolved) data remain undefined, as prior work on RML imaging for protoplanetary disk data has primarily addressed single-image cases. We used the open source Python package MPoL to explore RML image validation methods for multi-channeled data and synthesize RML images from the exoALMA observations of 7 protoplanetary disks with apparent NKFs in the 12CO J=3-2 CLEAN images. We find that RML imaging methods independently reproduce the NKFs seen in the CLEAN images of these sources, suggesting that the NKFs are robust features rather than artifacts from a specific imaging procedure.

Characterising the population and internal structure of sub-galactic halos is critical for constraining the nature of dark matter. These halos can be detected near galaxies that act as strong gravitational lenses with extended arcs, as they perturb the shapes of the arcs. However, this method is subject to false-positive detections and systematic uncertainties: particularly degeneracies between an individual halo and larger-scale asymmetries in the distribution of lens mass. We present a new free-form lens modelling code, developed within the framework of the open-source software \texttt{PyAutoLens}, to address these challenges. Our method models mass perturbations that cannot be captured by parametric models as pixelized potential corrections and suppresses unphysical solutions via a Matérn regularisation scheme that is inspired by Gaussian process regression. This approach enables the recovery of diverse mass perturbations, including subhalos, line-of-sight halos, external shear, and multipole components that represent the complex angular mass distribution of the lens galaxy, such as boxiness/diskiness. Additionally, our fully Bayesian framework objectively infers hyperparameters associated with the regularisation of pixelized sources and potential corrections, eliminating the need for manual fine-tuning. By applying our code to the well-known `Jackpot' lens system, SLACS0946+1006, we robustly detect a highly concentrated subhalo that challenges the standard cold dark matter model. This study represents the first attempt to independently reveal the mass distribution of a subhalo using a fully free-form approach.

We investigate the impact of repulsive self-interaction in ultralight dark matter (ULDM) on dynamical friction in circular orbits in ULDM halos and its implications for the Fornax dwarf spheroidal (dSph) galaxy's globular clusters. Using the Gross-Pitaevskii-Poisson equations, we derive the dynamical friction force considering soliton density profiles for both non-interacting and strongly self-interacting ULDM. Our results show that self-interactions reduce the dynamical friction effect further than both the non-interacting ULDM and standard cold dark matter models. Furthermore, we derive the low Mach number approximation to simplify the analysis in the subsonic motion, where the tangential component of dynamical friction dominates. Applying these findings to the Fornax dSph, we calculate the infall timescales of globular clusters, demonstrating that strong self-interaction can address the timing problem more effectively. We constrain the parameter space for ULDM particle mass and self-coupling constant, which are consistent with other constraints from astronomical and cosmological observations.

In this work we constrain the bounce energy scale $\rho_{s\downarrow}^{1/4}$ in a generic framework of bouncing cosmologies using the nanohertz stochastic gravitational-wave background recently detected by pulsar timing arrays (NANOGrav 15-yr, EPTA DR2, PPTA DR3, IPTA DR2). A full Bayesian fit of the analytic SGWB spectrum for this bounce scenario reveals, for the first time, two distinct posterior branches in $(\rho_{s\downarrow}^{1/4},w_1)$: one near $w_1\approx0.3$ and one at $w_1\gg1$, where $w_1$ is the contraction phase equation of state. We find that the bouncing model attains larger Bayes factors against each of six conventional SGWB sources (SMBHBs, inflationary GWs, cosmic strings, domain walls, first order phase transitions, scalar induced GWs), demonstrating strong preference of current PTA data for the bounce hypothesis. Compared to the more generic dual inflation bounce scenario, the concrete bounce realization yields smaller Bayes factors, indicating that PTA measurements impose tighter constraints when the bounce scale is explicit. Moreover, the two posterior branches illuminate distinct theoretical frontiers. The right branch ($w_1\gg1$) violates the dominant energy condition (DEC), thereby providing direct empirical impetus for models with novel early Universe physics, e.g. ghost condensates, higher-derivative or modified gravity operators, and extra dimensional effects. Independently, both branches infer $\rho_{s\downarrow}^{1/4}$ above the Planck scale $M_\mathrm{pl}$, demonstrating that current PTAs already probe trans-Planckian regimes. Together, these findings offer a rare observational window into UV completions of cosmology. We further describe how normalizing flow based machine learning can accelerate such Bayesian analyses as PTA data volumes increase.

Super-Eddington accretion has been proposed to explain the existence of black holes (BHs) with masses exceeding a billion solar masses within the first billion years after the Big Bang. We present a novel accretion disc-based sub-grid model for BH mass and spin evolution in the super-Eddington regime, implemented in the hydrodynamics code GIZMO. In our model, motivated by results of radiation-hydrodynamics simulations of accretion discs, the growth of the BH is mediated by a sub-grid accretion disc, comprising an inner photon-trapping region described by simulation-based fitting formulae and an outer thin $\alpha$-disc with three regions. We incorporate a self-consistent spin evolution prescription that transitions between the Bardeen-Petterson effect and inner thick-disc precession, depending on the accretion rate. We perform a suite of idealised simulations of a BH embedded in a gaseous circumnuclear disc and a spherically distributed stellar component to explore the conditions under which super-Eddington accretion can be sustained in the environment of a realistic galactic nucleus. Simulations with misaligned gas inflows onto an initially aligned BH-disc system yield very high Eddington ratios, triggered by the rapid removal of disc angular momentum via inflows. Mildly super-Eddington accretion can also be maintained when the BH is misaligned with the disc, as the Lense-Thirring effect reduces the disc angular momentum. These results highlight the importance of angular momentum misalignment in enabling super-Eddington accretion and suggest that such episodes are difficult to trigger unless the system resides in a highly dynamical environment -- a condition more likely to occur in high-redshift galaxies. Our model potentially provides a way to grow moderate-mass BH seeds to the sizes required to explain the bright high-redshift quasars.

Of the many discoveries uncovered by the Gaia astrometric mission, some of the most exciting are related to nearby dispersed stellar structures. We analyze one such structure in the Milky Way disk, OCSN-49, a coeval stellar stream with 257 identified members spanning approximately 30$^\circ$ across the sky. We obtained high-resolution spectroscopic data for four members that span the stream's extent, finding these four stars to have solar metallicities and remarkably homogeneous chemistry. Through a combination of isochrone fitting, lithium abundance analysis, and gyrochronology, we find a consistent stellar age of 400--600 Myr. Integrating stellar orbits backwards reveals that OCSN-49 converged to a single point at a much younger age. By integrating unbound model stars forward and comparing them to the current phase-space distribution of OCSN-49, we derive a dynamical age of 83$\pm$1 Myr, inconsistent with the age of the stellar population. The discrepancy between the kinematic and stellar age indicators is naturally explained by a disruptive event that unbound OCSN-49 roughly 500 Myr into its lifetime. Based on rate estimates, disruption due to a passing giant molecular cloud (GMC) is the most likely culprit. Assuming a single encounter, we find that a nearly head-on collision with a fairly massive GMC ($\sim$10$^5$ M$_\odot$) was necessary to unbind the cluster, although encounters with multiple GMCs may be responsible. To our knowledge, OCSN-49 serves as the first known remnant of a catastrophically disrupted open cluster and therefore serves as a benchmark for further investigating cluster disruption in the Milky Way.

Accretion disk winds are commonly observed in active galactic nuclei (AGN). The winds may be associated with the changing spectral properties of such sources, yet such connections have not been studied in detail so far. This paper presents detailed calculations of accretion disk winds and their impact on the observed spectrum of AGN, emphasizing recent observations of Mrk 817. The model consists of a radial and time-dependent mass outflow rate with a half-ejection radius of 50Rg and a variability timescale of 100 days. The resulting spectral energy distribution (SED) is characterized by a large drop in the ionizing luminosity and less significant changes in the optical luminosity. The time-dependent intensities of the broad emission lines and the spectrum emitted by the wind material reflect these variations. For Mrk 817, the variability timescale of the 1500-5500A continuum, the thermal time of the disk at the locations where most of this radiation is emitted, and the range of radii over which most of the mass outflow is taking place are all in agreement with the black hole mass and the radial-dependent accretion rate through the disk. This suggests a general connection between time-dependent disk winds, SED shape, thermal timescale, and optical-UV variability in AGN.

Icy ocean worlds attract significant interest for their astrobiological potential due to subsurface oceans, organics, and chemical energy sources. We quantify thermodynamic viability of metabolism-relevant reactions at pressure-temperature conditions of Enceladus, Europa, Titan, Ganymede, and the Lost City Hydrothermal Field for comparison. We examine the tricarboxylic acid (TCA) cycle and a plausible prebiotic reaction network leading to it, using DEWPython (based on the Deep Earth Water model) and SUPCRT to compute equilibrium constants and Gibbs free energy changes across temperatures from 0-1200°C and pressures between 1 bar-60 kbar. We found that across most oceanic P-T profiles, certain TCA cycle species accumulate (citrate, succinate) while others diminish (fumarate, oxaloacetate), suggesting ocean worlds' conditions may not thermodynamically favor a unidirectional TCA cycle, requiring additional energy to overcome bottlenecks. Similar bottlenecks exist at Lost City, which is inhabited. In the prebiotic network, pyruvate and acetate show remarkable stability, feeding the TCA cycle through citrate production, bypassing the oxaloacetate bottleneck. Formation of most TCA cycle species from inorganic compounds (CO$_2$ + H$_2$) is highly favored throughout ocean world geotherms, except for oxaloacetate. While based on uncertain chemical concentrations, our non-equilibrium thermodynamic predictions are relatively insensitive to activity changes and may aid interpretation of future mission data. [ABRIDGED]

The gas masses of protoplanetary disks are important but elusive quantities. In this work we present new ALMA observations of N2H+ (3-2) for 11 exoALMA disks. N2H+ is a molecule sensitive to CO freeze-out and has recently been shown to significantly improve the accuracy of gas masses estimated from CO line emission. We combine these new observations with archival N2H+ and CO isotopologue observations to measure gas masses for 19 disks, predominantly from the exoALMA Large program. For 15 of these disks the gas mass has also been measured using gas rotation curves. We show that the CO + N2H+ line emission-based gas masses typically agree with the kinematically measured ones within a factor 3 (1-2{\sigma}). Gas disk masses from CO + N2H+ are on average a factor 2.3(+0.7,-1.0) x lower than the kinematic disk masses, which could suggest slightly lower N2 abundances and/or lower midplane ionization rates than typically assumed. Herbig disks are found to have ISM level CO gas abundances based on their CO and N2H+ fluxes, which sets them apart from T-Tauri disks where abundances are typically 3-30x lower. The agreement between CO + N2H+ -based and kinematically measured gas masses is promising and shows that multi-molecule line fluxes are a robust tool to accurately measure disk masses at least for extended disks.

Extracting robust inferences on physical quantities from disk kinematics measured from Doppler-shifted molecular line emission is challenging due to the data's size and complexity. In this paper we develop a flexible linear model of the intensity distribution in each frequency channel, accounting for spatial correlations from the point spread function. The analytic form of the model's posterior enables probabilistic data products through sampling. Our method debiases peak intensity, peak velocity, and line width maps, particularly in disk substructures that are only partially resolved. These are needed in order to measure disk mass, turbulence, pressure gradients, and to detect embedded planets. We analyse HD 135344B, MWC 758, and CQ Tau, finding velocity substructures 50--200 ${\rm m s^{-1}}$ greater than with conventional methods. Additionally, we combine our approach with discminer in a case study of J1842. We find that uncertainties in stellar mass and inclination increase by an order of magnitude due to the more realistic noise model. More broadly, our method can be applied to any problem requiring a probabilistic model of an intensity distribution conditioned on a point spread function.

We use high resolution N-body dark matter simulations and L-Galaxies semi-analytical galaxy formation models to explore the high-$z$ galaxy properties and estimate the budget of ionizing photons. The parameters within L-Galaxies are obtained using a Markov Chain Monte Carlo (MCMC) method with high-$z$ galaxy observations from JWST and other telescopes. We consider two versions of L-Galaxies with and without dust correction on galaxy UV luminosities. With the best-fit parameters, both L-Galaxies 2015 and L-Galaxies 2020 reproduce well observations of UV luminosity functions, stellar mass functions, star formation rate densities and ionizing photon emission efficiency. With the assumption of escape fraction of $20\%$, all models produce more ionizing photons than the number of Hydrogen atoms in the Universe at $z>6$. The inclusion of dust correction within MCMC results in higher star formation efficiency, which predicts $\sim 50\%$ more ionizing photons, with better consistency between the predicted stellar mass functions and observations.

The gas surface density is one of the most relevant physical quantities in protoplanetary disks. However, its precise measurement remains highly challenging due to the lack of a direct tracer. In this study, we report the spatially-resolved detection of pressure-broadened line wings in the CO $J=3-2$ line in the RX J1604.3-2130 A transition disk as part of the exoALMA large program. Since pressure-broadened line wings are sensitive to the total gas volume density, we robustly constrain the radial dependence of the gas surface density and midplane pressure in the region located $50-110$ au from the central star, which encompasses the dust ring of the system. The peak radius of the midplane pressure profile matches the dust ring radial location, directly proving radial dust trapping at a gas pressure maximum. The peak gas surface density is $18-44\ {\rm g\ cm^{-2}}$} and decreases at radii interior to and exterior of the dust ring. A comparison of the gas and dust surface densities suggests that the disk turbulence is as low as $\alpha_{\rm turb} \sim 2\times10^{-4}$. Despite dust trapping, the gas-to-dust surface density ratio at the ring peak is { $70-400$}, which implies already-formed protoplanets and/or less efficient dust trapping. The gas surface density drop at radii interior to the ring is consistent with a gas gap induced by a Jupiter-mass planet. The total gas mass within $50 < r < 110$ au is estimated to be $\sim 0.05-0.1\ M_\odot$ ($50-100\ {M_{\rm Jup}}$), suggesting that planetary system formation is possible.

We hypothesize strong (transonic) twin toroidal recirculation zones above and below the accretion disk midplane, rather close-in to the protosun, to be the source of chondrules and calcium-aluminum inclusions (CAIs). The recirculation zones act as centrifugal separators. In the case of chondrules, we suggest this happens during Class II (T~Tauri) stage of protostellar accretion, and in the case of CAIs, during an earlier higher-$\dot M$ phase of accretion. The recirculation zones advect and raise dust and solid aggregates above the midplane, making a ``mushroom-cap,'' and they also generate weak standing oblique shocks that heat and fuse protochondrules. We do not model the emission of these shocks, but point out that they will produce Doppler-broadened, possibly twin-peaked line emission with width of the order of $\simeq 200\ {\rm km\ s^{-1}}$. For concreteness, we focus on chondrules in the paper. Small ($\lessapprox 10 {\rm\ \mu m}$) diameter protochondrules are evaporated by the standing shocks, whereas large ($\gtrapprox 1\ {\rm cm}$) protochondrules are too heavy to be entrained and accelerated by the outer recirculation zone and outflow. Intermediate-size protochondrules, however, are centrifugally ejected and carried by high-speed diffuse gas outflow to the outer regions of the disk, where they rain down. The recirculation-induced dust mushroom caps will create significant IR continuum emission. We suggest they coincide with observed inner ``puffed-up'' dust rims. We also suggest that the recent interferometric inferences of arcs or ellipses in the sub-AU continuum IR of low-mass Class II protostars may be observations of corresponding chondrule-producing recirculation zones in those systems.

This study investigates the morphological feature distances among various spectral types of galaxies from the Sloan Digital Sky Survey (SDSS), including strong and weak Active Galactic Nuclei (AGN), Quasi-Stellar Objects (QSO), quiescent, and star-forming galaxies. We evaluated the clustering and relative distances of these spectral types in the multidimensional morphological feature space. The results indicate that AGN and QSOs are more closely associated with quiescent galaxies than with star-forming ones, indicating a potential regulation of star formation by AGN activity. Furthermore, the analysis underlines the role of AGN feedback in the dwarf regime having $\sim$10~50% closer distances from AGN types to the quiescent type than to the SF type in the dwarf regime $-18 > M_r > -20$, compared to $<$15% closer in the massive regime $M_r < -21$. The continuous probability analysis for being Hubble types of the spectral types upholds the distance analysis results having a range of the probability distribution of AGN types similar to quiescent type, especially in dwarf galaxies.

We study star formation rate (SFR) indicators and dust attenuation of 74 nearby star-forming galaxies on kiloparsec scales, based on GALEX far-ultraviolet (FUV) and WISE mid-infrared (MIR) images with CALIFA optical integral field spectroscopic data. We obtain hybrid SFR indicators by combining the observed FUV and MIR luminosities and calibrate them using the dust-corrected H$\alpha$ luminosity as a reference SFR. The simple linear combination appears to follow well the reference SFR, but the calibration residual shows a significant dependence on the specific SFR (sSFR), which can be removed by employing the combination coefficient or conversion offset that varies with the sSFR. In the plane of gas versus stellar attenuation, the median trend line's slope ($\approx$ stellar-to-gas attenuation ratio) changes from 0.44 to 1.0 with increasing attenuation. The differential attenuation, defined as the deviation of stellar attenuation from the median trend line, is strongly correlated with the SFR surface density and sSFR, compatible with the two-component dust model. The differential attenuation seems to be affected by both local and global factors.

We investigate neutrino signals associated with black hole formation resulting from the gravitational collapse of massive stars, motivated by the candidate failed supernova M31-2014-DS1 in the Andromeda Galaxy (M31). By compiling numerical simulation results for stellar collapse, we predict the expected neutrino emission and compare these predictions with observational limits from Super-Kamiokande (SK). The simulations reveal a characteristic precursor signal consisting of a short, intense burst whose average neutrino energy rises rapidly and then ceases abruptly once the black hole forms. We examine several nuclear equations of state, specifically the Lattimer \& Swesty, Shen, Togashi, and SFHo models, to evaluate how the emission depends on neutron-star properties and nuclear-physics uncertainties. Comparison of the predicted event counts with SK's non-detection of neutrinos coincident with M31-2014-DS1 already rules out part of the model space and highlights the sensitivity of current neutrino detectors to both progenitor mass and the EOS. These findings demonstrate the capability of neutrino astronomy to probe core collapse and black hole formation in failed supernova scenarios.

Pulsar scintillation observations have revealed ubiquitous discrete scintillation screens in the interstellar medium. A major obstacle in identifying the nature of these screens is the uncertainty in their distances, which prevents precise correlation with known structures in the Milky Way. We used the Five-hundred-meter Aperture Spherical radio Telescope (FAST) to observe PSR B1237+25, PSR 1842+14, and PSR 2021+51. We detected 10 scintillation arcs in PSR B1237+25, 1 in PSR 1842+14, and at least 6 in PSR 2021+51. By modeling the annual modulation of these scintillation arcs, we constrained the distances of the scintillation screens, as well as the anisotropic scattering directions and the projected velocities in those directions. The scintillation screens are distributed throughout the entire paths between Earth and the pulsars. Among these, the distance to the main scintillation screen toward PSR B1237+25 is $267^{+32}_{-28}$ pc, the scintillation screen toward PSR B1842+14 is at a distance of $240^{+210}_{-120}$ pc, and the main scintillation screen toward PSR B2021+51 is located at $887^{+167}_{-132}$ pc. Several screens in our sample appear at distances coinciding with the Local Bubble boundary, particularly the brightest scintillation arc toward PSR B1237+25. We provide a substantial sample of scintillation screen measurements, revealing the rich plasma density fluctuation structures present in the Milky Way.

Solar wind forecasting plays a crucial role in space weather prediction, yet significant uncertainties persist due to incomplete magnetic field observations of the Sun. Isolating the solar wind forecasting errors due to these effects is difficult. This study investigates the uncertainties in solar wind models arising from these limitations. We simulate magnetic field maps with known uncertainties, including far-side and polar field variations, as well as resolution and sensitivity limitations. These maps serve as input for three solar wind models: the Wang-Sheeley-Arge (WSA), the Heliospheric Upwind eXtrapolation (HUXt), and the European Heliospheric FORecasting Information Asset (EUHFORIA). We analyze the discrepancies in solar wind forecasts, particularly the solar wind speed at Earth's location, by comparing the results of these models to a created "ground truth" magnetic field map, which is derived from a synthetic solar rotation evolution using the Advective Flux Transport (AFT) model. The results reveal significant variations within each model with a RMSE ranging from 59-121 km/s. Further comparison with the thermodynamic Magnetohydrodynamic Algorithm outside a Sphere (MAS) model indicates that uncertainties in the magnetic field data can lead to even larger variations in solar wind forecasts compared to those within a single model. However, predicting a range of solar wind velocities based on a cloud of points around Earth can help mitigate uncertainties by up to 20-77%.

Extremely-Low Lunar Orbits (eLLOs) (altitudes $\leq 50$ km) exhibit severe perturbations due to the highly non-spherical lunar gravitational field, presenting unique challenges to orbit maintenance. These altitudes are too low for the existence of stable `frozen' orbits, and naive stationkeeping methods, such as circularization, perform poorly. However, mission designers have noticed a particular characteristic of low lunar orbits, which they have found useful for stationkeeping and dubbed the "translation theorem", wherein the eccentricity vector follows a predictable monthly pattern that is independent of its starting value. We demonstrate this feature results from the low orbital eccentricity combined with the dominant effect of a particular subset of sectoral and tesseral harmonics. Subsequently, automated stationkeeping strategies for eLLOs are presented, utilizing this theorem for eccentricity vector control. Several constraints within the eccentricity vector plane are explored, including circular, annular, and elevation-model derived regions, each forming distinct stationkeeping strategies for varying orbital configurations. Subsequently, the optimal control profiles for these maneuvers within the eccentricity plane are obtained using Sequential Convex Programming (SCP). The proposed strategies offer computational simplicity and clear advantages when compared to traditional methods and are comparable to full trajectory optimization.

We explore constraints on the size of cool gas clouds in the circumgalactic medium (CGM) obtainable from the presence, or lack thereof, of refractive scattering in fast radio bursts (FRBs). Our refractive analysis sets the most conservative bounds on parsec-scale CGM clumpiness as it does not make assumptions about the turbulent density cascade. We find that the bulk of low-redshift cool CGM gas, constrained to have densities of $n_{\rm e} \lesssim 10^{-2}\,{\rm cm^{-3}}$, likely cannot produce two refractive images and, hence, scattering. It is only for extremely small cloud sizes $\lesssim 0.1$ pc (about a hundred times smaller than the so-called shattering scale) that such densities could result in detectable scattering. Dense $n_{\rm e} \gtrsim 0.1\,{\rm cm^{-3}}$ gas with shattering-scale cloud sizes is more likely to inhabit the inner several kiloparsecs of the low-redshift CGM: such clouds would result in multiple refractive images and large scattering times $\gtrsim 1 - 10$ ms, but a small fraction FRB sightlines are likely to be affected. We argue that such large scattering times from an intervening CGM would be a signature of sub-parsec clouds, even if diffractive scattering from turbulence contributes to the overall scattering. At redshift $z\sim 3$, we estimate $\sim 0.1\%$ of FRBs to intersect massive proto-clusters, which may be the most likely place to see scattering owing to their ubiquitous $n_{\rm e} \approx 1\,{\rm cm^{-3}}$ cold gas. While much of our discussion assumes a single cloud size, we show similar results hold for a CGM cloud-size distribution motivated by hydrodynamic simulations.

The origin of merging binary black holes detected through gravitational waves remains a fundamental question in astrophysics. While stellar evolution imposes an upper mass limit of about 50 solar mass for black holes, some observed mergers--most notably GW190521--involve significantly more massive components, suggesting alternative formation channels. Here we investigate how heavy black holes merging within Active Galactic Nucleus (AGN) disks can become. Using a comprehensive semi-analytic model incorporating 27 binary and environmental parameters, we explore the role of AGN disk conditions in shaping the upper end of the black hole mass spectrum. We find that AGN disk lifetime is the dominant factor, with high-mass mergers (>200 solar mass) only possible if disks persist for ~40 Myr. The joint electromagnetic observation of an AGN-assisted merger could therefore lead to a direct measurement of the age of an AGN disk.

Very Long Baseline Interferometry (VLBI) combines the signals of telescopes distributed across thousands of kilometres to provide some of the highest angular resolution images of astrophysical phenomena. Due to computational expense, typical VLBI observations are restricted to a single target and a small (few arcseconds) field-of-view per pointing. The technique of wide-field VLBI was born to enable the targeting of multiple sources and has been successful in providing new insights into Active Galactic Nuclei, the interstellar medium, supernovae, gravitational lenses and much more. However, this technique is still only employed in a few experiments, restricting the scientific potential of VLBI observations. In this conference proceeding, we outline new developments in wide-field VLBI, including an end-to-end correlation and calibration workflow, distributed correlation, and new calibration routines. These developments aim to enable wide-field VLBI to be a standard observing mode on all major VLBI arrays.

Aims. Our goal is to characterize the chemistry and physical conditions of the circumstellar envelopes (CSEs) of Asymptotic Giant Branch (AGB) binary candidate stars with UV-excess and X-ray emission, in particular, to identify the effects of the internal X-ray emission in the abundance of certain key molecules. Methods. We observed the 86.0-94.0 and 260.0-272.5 GHz spectral ranges searching for rotational transitions of the X-ray sensitive molecule $HCO^{+}$ in four AGB stars, two of them detected in both UV and X-ray emission and the other two detected only in UV. We derived the CSEs's physical parameters from previous CO observations and determined the molecular abundances of the detected species using radiative transfer models. We developed chemical kinetics models that account for the effects of internal X-ray emission (as well as UV radiation) and compared our predictions with observations. Results. We report the detection of $HCO^{+}$ in the X-ray emitting C-rich AGB T\,Dra, while it remains undetected in the spectra of the other three sources. In T\,Dra we also detect SiO, HCN, HNC, $HC_{3}N$, $SiC_{2}$, $C_{2}H$ and SiS. For the other targets only HCN and SiO are detected. The high fractional abundance of $HCO^{+}$ derived for T\,Dra ($[1.5-3.0]\times 10^{-8}$) is in good agreement with the predictions from our chemical kinetics models including the effects of internal X-ray emission, and one order of magnitude higher than the values expected for C-rich AGB stars. Additionally, we identify abundance enhancements for HNC, and $HC_{3}N$ alongside a depletion of CO in the innermost regions of T\,Dra's envelope. Conclusions. An internal X-ray source can significantly alter molecular abundances in AGB CSEs, enhancing $HCO^{+}$, $N_{2}H^{+}$, HNC, and $HC_{3}N$ while depleting parent species like CO. UV radiation has a weaker effect unless the envelope is optically thin or porous.

Interstellar complex organic molecules (iCOMs) may have a link to prebiotic species, key building blocks for life. In Galactic star-forming (SF) regions, spatial variations of iCOMs emission could reflect the source physical structure or different chemical formation pathways. Investigating iCOMs in extragalactic SF regions may thus provide crucial information about these regions. As an active extragalactic SF region, the central molecular zone (CMZ) of the nearby galaxy NGC 253 provides an ideal template for studying iCOMs under more extreme conditions. We aim to investigate the emission of a few selected iCOMs and understand if a difference between the iCOMs could reflect on the source's chemical or physical structure. Using the high angular resolution ($\sim 27$ pc) observations from the ALCHEMI ALMA large program, we imaged the emission of selected iCOMs and precursors; CH$_3$CHO, C$_2$H$_5$OH, NH$_2$CHO, CH$_2$NH, and CH$_3$NH$_2$. We estimated the iCOMs gas temperatures and column densities using a rotational diagram analysis, and by performing a non-LTE analysis for CH$_2$this http URL iCOM emission concentrates mostly towards the inner part of the CMZ of NGC 253 and can be reproduced with two gas components. Different emission processes can explain iCOM emission towards the CMZ of NGC 253: at Giant Molecular Cloud (GMC) scales ($\sim 27$ pc), the iCOMs could trace large-scale shocks whilst at smaller scales (few pc), both shock and heating processes linked with ongoing star formation may be involved. Using column density correlation trends and known formation pathways, we find that more than one formation path could be involved to explain the iCOM emission. Finally, we found chemical differences between the GMCs, such as a decrease of abundance for the N-bearing species towards one of the GMCs or different excitation conditions for NH$_2$CHO and CH$_3$CHO towards two of the GMCs.

The accurate determination of chemical abundances in stars plays a pivotal role in understanding stellar structure and evolution, nucleosynthesis, and the chemical enrichment history of the Milky Way. Benchmark stars with precise and accurate atmospheric parameters and abundances are indispensable for calibrating spectroscopic surveys and testing stellar atmosphere models. This study focuses on the compilation of high-quality spectra and the determination of LTE chemical abundances of iron-peak and $\alpha$ elements for the third version of the Gaia FGK Benchmark Stars (GBSv3). We compiled spectra of the GBSv3 from public archives and complemented these with our own observations. We use fundamental atmospheric parameters from Soubiran et al. 2024 to derive the chemical abundances and perform a spectroscopic analysis using the public code iSpec. We compile a homogeneous spectral library of high-resolution (42,000) and high signal-to-noise ($>100$) normalised spectra for 202 stars: including the 192 GBSv3, 9 stars with indirect measurement of the angular diameter from previous GBS versions, and the Sun. Using four radiative transfer codes, we derive chemical abundances of 13 chemical species (Fe I, Fe II, Mg I, Si I, Ca I, Ti I, Ti II, Sc II, V I, Cr I, Mn I, Co I, Ni I). We make an in-depth study of several sources of error. The GBSv3 contributes to the legacy samples of spectroscopic reference stars with improved statistics and homogeneity. The compiled high-resolution spectral library and the determination of abundances for iron-peak and $\alpha$ elements, together with an extensive discussion of the linked uncertainties, provides a sample of reference abundances to the community.

While delta Scuti stars are the most numerous class of kappa-mechanism pulsators in the instability strip, the short periods and small peak-to-peak amplitudes have left them understudied and underutilized. Recently, large-scale time-domain surveys have significantly increased the number of identified delta Scuti stars. Notably, the Tsinghua University-Ma Huateng Telescopes for Survey (TMTS), with its high-cadence observations at 1-minute intervals, has identified thousands of delta Scuti stars, greatly expanding the sample of these short-period pulsating variables. Using the delta Scuti stars from the TMTS catalogs of Periodic Variable Stars, we cross-matched the dataset with Pan-STARRS1, 2MASS, and WISE to obtain photometric measurements across optical and infrared bands. Parallax data, used as Bayesian priors, were retrieved from Gaia DR3, and line-of-sight dust extinction priors were estimated from a three-dimensional dust map. Using PyMC, we performed a simultaneous determination of the 11-band P-L relations of delta Scuti stars, which not only yields precise measurements of these relations, but also greatly improves constraints on the distance moduli and color excesses, as evidenced by the reduced uncertainties in the posterior distributions. Furthermore, our methodology enables an independent estimation of the color excess through the P-L relations, offering a potential complement to existing 3-D dust maps. Moreover, by cross-matching with LAMOST DR7, we investigated the influence of metallicity on the P-L relations. Our analysis reveals that incorporating metallicity might reduce the intrinsic scatter at longer wavelengths. However, this result does not achieve 3 sigma significance, leaving open the possibility that the observed reduction is attributable to statistical fluctuations.

Stars with very low levels of magnetic activity provide an opportunity for a more quantitative comparison with the Sun during its Maunder minimum. We employ spectra from the RAVE survey in a search for particularly low-activity stars with the goal of identifying candidates for so-called Maunder-minimum stars. Spectra were used to measure the relative flux in the cores of the Ca II infrared-triplet (IRT) lines. Those were converted to absolute emission-line fluxes and were corrected with target fluxes from high-resolution STELLA and ultra-high-resolution PEPSI spectra. Absolute Ca II IRT fluxes for a total of 78111 RAVE dwarf stars are presented and compared with fluxes of the 123 stars from our high-resolution STELLA+PEPSI sample. RAVE fluxes appear higher than the STELLA and PEPSI fluxes by on average 19% for IRT-1, 21% for IRT-2, and 25% for IRT-3 due to their lower spectral resolution. Our sample also spans a metallicity [Fe/H] range relative to the Sun of -1.5 to +0.5 dex. We confirm the strong dependency of IRT fluxes on metallicity and quantify it to be at most $\pm$14% in the B-V range 0.53-0.73. Without a metallicity correction, practically all very-low-activity RAVE dwarfs show a super-solar metallicity. After correcting for spectral resolution and for metallicity, we find 13 RAVE stars out of 13326 (0.1%) that fall well below our empirical lower flux bound from high-resolution versus B-V. For solar B-V, this relates to a photospheric uncorrected radiative loss in the IRT lines of log R_IRT=-4.13 (~20% below the solar-minimum value in late 2016). However, 11 targets turned out to be evolved stars based on their Gaia DR3 parallaxes. Two stars, TIC 352227373 (G2V) and TYC 7560-477-1 (G7V), are our only Maunder-minimum candidates from the present search. Contrary to the initial suggestion from the Mount-Wilson H&K Survey, we conclude that such stars are very rare.

The motion of neutron stars (NSs) in the Galaxy is largely dependent on natal kicks received by the NSs during supernova explosions. Thus, the measured peculiar velocities of NS high-mass X-ray binaries (HMXBs) provide valuable clues to natal kicks, which also play an important role in the evolution of HMXBs. In this work, we collect proper motions, radial velocities and parallaxes for 36 NS HMXBs to derive their peculiar velocities at the birth of the NSs. We then use binary population synthesis to simulate the velocities of NS HMXBs with various choices of the kick velocity distribution for both core-collapse and electron-capture supernovae. Comparing the simulated and measured velocities, orbital periods, and eccentricities, we show that the natal kick distribution that can best match the observations is characterized by a bimodal Maxwellian distribution with $\sigma_1$ = 320 km s$^{-1}$ (for core-collapse supernovae) and $\sigma_2$ = 80 km s$^{-1}$ (for electron-capture supernovae) and the He core mass for the latter in the range of $(1.83-2.25)$ $M_{\odot}$. Our findings provide useful insights for further population synthesis and binary evolution studies of NS binaries.

We investigate the evolutionary histories of a population of high mass, high redshift, quiescent galaxies in the cosmohydrodynamical simulation Thesan; studying the characteristic properties of their haloes and environments over the epoch of reionisation. Thesan employs a modified version of the Arepo moving-mesh code utilised in IllustrisTNG, whose explicit handling of ionising radiation couples haloes and galaxies with cosmic reionisation. This results in a regime of rapid growth and quenching, producing nine massive quiescent galaxies at $z = 5.5$, in a $95.5\text{cMpc}^3$ volume, with no counterpart in IllustrisTNG. We find that the rapid assembly of stellar mass is attributed to smooth accretion of mass onto their haloes in dense environments, particularly from massive neighbouring structures; while these galaxies exhibit fast-growing potential wells hosting massive central black holes. With insignificant merger activity, we find AGN feedback to be the primary source of quenching. We find megaparsec-scale densities and halo masses to continue growing after quenching, suggesting that massive quiescent galaxies will be found in some of the largest haloes and densest regions of space by observations. With an unprecedented plethora of massive quiescent galaxies found in JWST data, these reionisation simulations may provide the paradigm for the evolutionary histories of these galaxies, while constraining the relatively unknown physics of reionisation. Despite the rarity of simulated massive quiescent galaxies, their identification in Thesan enables identification of halo and environmental properties most conducive to their quenching, hopefully guiding future efforts into the study of analogous systems in deep observational surveys and large-volume N-body simulations.

SHARK-NIR is a new compact instrument for coronagraphic imaging, direct imaging, and coronagraphic spectroscopy in the near-infrared wavelengths mounted at LBT. Taking advantage of the telescope's adaptive optics system, it provides high contrast imaging with coronagraphic and spectroscopic capabilities and is focused on the direct imaging of exoplanets and circumstellar discs. We present SHINS, the SHARK-NIR instrument control software, mainly realized with the TwiceAsNice framework from MPIA - Heidelberg and the ICE framework using the C++ programming language. We describe how we implemented the software components controlling several instrument subsystems, through the adaptation of already tested libraries from other instruments at LBT, such as LINC-NIRVANA. The scientific detector comes with its own readout electronic and control software interfaced with our software through INDI. We describe the C++ core software Observation Control Software, responsible for dispatching commands to the subsystems, also implementing a software solution to avoid a potential collision between motorized components, fully transparent to final users. It exposes an ICE interface and can be controlled by clients developed in different languages. Observation, calibration, and maintenance procedures are implemented by means of template scripts, written in python language, controlling Observation Control Software through its ICE interface. These templates and their parameters are configured using "ESO-style", XML Observation Blocks prepared by observers, or in general SHARK-NIR users. The high-level control is carried out by REST HTTP APIs implemented in a python back-end, also acting as a web server for the several browser-based front-end GUIs. Finally, we present the first scientific results obtained by SHARK-NIR using coronagraphic mode.

Magnetic reconnection is a pivotal mechanisms in the energization and heating of cosmic plasmas, yet the exact process of energy transfer during these events remain elusive. Traditional models, which focus on acoustic and magnetohydrodynamic waves and micro/nano-flares, fall short of explaining the extreme heating of the solar corona and the origins of the supersonic solar wind. In this study, we provide compelling observational evidence from Wind spacecraft data supporting the Raghav effect, a mechanism where interactions between the magnetic moments of charged particles and dynamic magnetic fields result in abrupt kinetic energy changes. Our analysis demonstrates that the observed proton plasma heating is consistent with theoretical predictions, establishing the Raghav effect as a universal mechanism for particle energization. This discovery offers a unified framework for understanding energy dynamics across a wide range of astrophysical magnetised plasma environments.

The HMYSO G24.33+0.14 (G24), has recently been observed to undergo an accretion burst since September 2019, lasting approximately two years. By utilizing 1.3 mm observational data from the NOrthern Extended Millimeter Array (NOEMA) in March 2020 and the Atacama Large Millimeter/submillimeter Array (ALMA) in September 2019, we have examined the physical environment changes in gas and dust within G24 region during the decay phase of the accretion burst. Following the burst, the continuum emission in the inner core region of G24 diminished by approximately 20%, while the emission in the outer region exhibited an increase by a factor of ~30%. This pattern indicates that the heat wave, triggered by the accretion burst, radiated outward from the core's interior to its periphery over the half-year period, with a calculated propagation speed of 0.08-0.38 times the speed of light. Moreover, the methanol emission intensity in this area has experienced a notable decline, with the rate of flux reduction correlating positively with the energy of the upper energy states. This, in conjunction with the analysis of methanol molecular line rotation temperature diagrams for different emitting regions, further substantiates that the core region of G24 cooled down, contrasted with the persistent heating in the outer region following the burst.

The Hubble tension, characterized by discrepant measurements of the Hubble constant from early and late universe probes, remains one of the most significant challenges in cosmology. Building upon our previous analysis of individual parameter transitions in SH0ES data, we investigate the impact of simultaneous transitions in multiple Cepheid and SNIa calibration parameters at specific cosmic distances. We allow various combinations of transitions in Cepheid absolute magnitude ($M^W_H$), period-luminosity relation slope ($b_W$), metallicity coefficient ($Z_W$), and SNIa absolute magnitude ($M_B$). Our comprehensive analysis reveals a consistent preferred transition distance of approximately 23 Mpc across different parameter combinations. The most statistically favored model allows simultaneous transitions in $b_W$, $Z_W$, and $M_B$, yielding $\Delta \text{AIC} \simeq -9.2$ and $\Delta \text{BIC} \simeq -3.0$ compared to the baseline SH0ES model. This provides strong evidence for inhomogeneities in standard candle calibrations. We demonstrate that the post-transition SNIa absolute magnitude aligns more closely with CMB-based constraints, resulting in a reduced Hubble constant value that alleviates the tension. Our findings suggest that the Hubble tension might be resolved through proper modeling of calibration parameter inhomogeneities rather than requiring new physics beyond $\Lambda$CDM.

We present high-contrast imaging observations of seven protoplanetary disks at 4um using the ERIS on the VLT. This study focuses on detecting scattered light from micron-sized dust particles and assessing the potential of the vAPP coronagraph for disk and planet characterization. Observations were performed in pupil-stabilized mode with the vAPP coronagraph. Data were reduced using reference differential imaging and angular differential imaging techniques, incorporating principal component analysis for point-source detection. Contrast curves and detection limits were computed for planetary companions and disk features. The infrared disk signal was resolved in all systems, with first-time 4um detections around AS 209 and Elias 2-24, revealing mostly axisymmetric structures extending up to 60au. Two gaps were detected in the radial profiles of TW Hya (22au, 35au) and AS 209 (50au, 100au). For Elias 2-24, scattered light emission matched ALMA observations of inner disk structures, marking their first mid-infrared detection. In the case of HD 100546, the vAPP uncovered flared disk structures and faint spiral arms consistent with previous observations. HD 163296 shows a bright inner dust ring, confirming disk asymmetries and features, but we did not detect any planet candidate within the achieved contrast limits. The disk around PDS 70 exhibits clear features, with faint structures detected within the cavity. The observations achieved contrasts enabling the detection of planets down to 800 K, but no companions were detected, implying either low-mass planets, cooler formation scenarios, or a large dust extinction of Av>20 mag. The vAPP performed robustly for imaging structures in protoplanetary disks at 4um, providing critical insights into disk morphology and constraints on planet formation processes. No planetary-mass companions with temperatures >1000K are present in our sample.

Synchrotron circular polarization of a non-thermal power-law electron distribution in gamma-ray bursts (GRBs) has been studied. However, some numerical simulations have shown that the resulting distribution of electrons is a combination of a thermal component and a non-thermal power-law component. In this paper, we investigate synchrotron circular polarization using such a hybrid energy distribution of relativistic thermal and nonthermal electrons within a globally toroidal magnetic field in GRB prompt optical emission. Our results show that compared to the solely nonthermal electron model, the synchrotron circular polarization degree (PD) in the hybrid electron model can vary widely in the optical band, depending on different parameters. The lower the electron temperature, the higher the circular PD. The time-averaged circular PD in the hybrid electron model can be higher than $\sim 1\%$ when the electron temperature is as low as $\sim 10^{10}$ K, while in the solely nonthermal electron model is usually lower than $\sim 1\%$. We further calculate the radiative transfer of the circular and linear polarization in the optical band. Our results show that both of the circular and linear PDs decrease with the increase of optical depth, but the linear PDs decline faster than the circular PDs. To further examine the physical mechanisms of both radiation and particle acceleration, we expect that instruments will be capable of measuring the circular polarization of GRB prompt optical emission in the future.

Comets, during their journeys into the inner solar system, deliver volatile gases, organics, and particulates into their comae that provide crucial information for assessing the physico-chemical conditions in the outer disk from which they formed. Here we present observational and modeling results of a JWST NIRSpec and MIRI MRS integral-field-unit (IFU) spatial-spectral study of the inner coma of the Oort Cloud comet C/2017 K2 (PanSTARRS) at a heliocentric distance of 2.35 au. We find the comet is hyperactive (water ice active fraction greater than or equal to 86%), with a nucleus radius of $<$4.2 km, exhibiting strong emission from H$_{2}$O, $^{12}$CO, $^{13}$CO, and CO$_{2}$ as well as CN, H$_2$CO, CH$_3$OH, CH$_4$, C$_2$H$_6$, HCN, NH$_2$, and OH prompt emission. The water ortho-to-para ratio is greater than or equal to 2.75. The modeled dust composition (relative mass fraction of the sub-micron grains) in the coma is dominated by amorphous carbon ($\simeq 25$%), amorphous Mg:Fe olivine ($\simeq 19$%), amorphous Mg:Fe pyroxene ($\simeq 16$%), and Mg-rich crystalline olivine ($\simeq 39$%) and the crystalline mass fraction of the sub-micron grains in the coma is, $f_{cryst} \simeq 0.384 \pm 0.065$. Analysis of residuals in 3 to 8 $\mu$m region of the spectral energy distribution strongly suggests the presence of polycyclic aromatic hydrocarbon (PAHs) species in the coma.

Turbulent gas motions drive planet formation and protoplanetary disk evolution. However, empirical constraints on turbulence are scarce, halting our understanding of its nature. Resolving signatures of the large-scale perturbations driven by disk instabilities may reveal clues on the origin of turbulence in the outer regions of planet-forming disks. We aim to predict the observational signatures of such large-scale flows, as they would appear in high-resolution Atacama Large Millimeter/submillimeter Array observations of CO rotational lines, such as those conducted by the exoALMA Large Program. Post-processing 3D numerical simulations, we explored the observational signatures produced by three candidate (magneto-)hydrodynamical instabilities to operate in the outer regions of protoplanetary disks: the vertical shear instability (VSI), the magneto-rotational instability (MRI), and the gravitational instability (GI). We found that exoALMA-quality observations should capture signatures of the large-scale motions induced by these instabilities. Mainly, flows with ring, arc, and spiral morphologies are apparent in the residuals of synthetic velocity centroid maps. A qualitative comparison between our predictions and the perturbations recovered from exoALMA data suggests the presence of two laminar disks and a scarcity of ring- and arc-like VSI signatures within the sample. Spiral features produced by the MRI or the GI are still plausible in explaining observed disk perturbations. Supporting these scenarios requires further methodically comparing the predicted perturbations and the observed disks' complex dynamic structure.

Asteroseismology gives us the opportunity to better characterize binaries and their products, and shed light on their role in Galactic populations. We estimate occurrence rates, mass distributions, and evolutionary states of asteroseismic binaries, exhibiting solar-like oscillations from both components, and of products of binary interactions with detectable solar-like oscillations. Additionally, we explore the effects of mass accretion or loss on apparent age-metallicity relations. Using the TRILEGAL code, we simulate Kepler's field of view adopting the Eggleton and Moe & Di Stefano distributions of initial binary parameters, and run an additional simulation with non-interacting binaries for comparison. We find that asteroseismic binaries require an initial mass ratio close to one, and even small mass transfer events can prevent the detection of oscillations from both components. The fraction of asteroseismic binaries for red giant stars with detectable oscillations ranges from 0.5\% for non-interacting binaries to a minimum of 0.06% when taking interactions into account. Moreover, asteroseismic binaries composed of two red clump stars are not expected at separations $\leq 500~\text{R}_\odot$ due to the interplay of stellar evolution and binary interactions. Finally, we estimate that at least ~1% of the Kepler red giants with detectable oscillations have undergone significant mass accretion or loss, potentially affecting Galactic age-metallicity relations, although there is a strong dependence on the assumed initial binary parameters. Comparing predicted and observed asteroseismic binaries, as well as over- and under-massive stars, offers a way to constrain key binary evolution assumptions, and to reduce uncertainties in mass-transfer modeling.

In the past decade, the Atacama Large Millimeter/submillimeter Array (ALMA) has revealed a plethora of substructures in the disks surrounding young stars. These substructures have several proposed formation mechanisms, with one leading theory being the interaction between the disk and newly formed planets. In this Letter, we present high angular resolution ALMA observations of LkCa~15's disk that reveal a striking difference in dust and CO emission morphology. The dust continuum emission shows a ring-like structure characterized by a dust-depleted inner region of $\sim$40 au in radius. Conversely, the CO emission is radially smoother and shows no sign of gas depletion within the dust cavity. We compare the observations with models for the disk-planet interaction, including radiative transfer calculation in the dust and CO emission. This source is particularly interesting as the presence of massive planets within the dust cavity has been suggested based on previous NIR observations. We find that the level of CO emission observed within the dust cavity is inconsistent with the presence of planets more massive than Jupiter orbiting between 10-40 au. Instead, we argue that the LkCa~15 innermost dust cavity might be created either by a chain of low-mass planets, or by other processes that do not require the presence of planets.

The exoALMA Large Program was designed to search for subtle kinematic deviations from Keplerian motion, indicative of embedded planets, in high angular and spectral resolution Band 7 observations of $^{12}$CO, $^{13}$CO and CS emission from protoplanetary disks. This paper summarizes the calibration and imaging pipelines used by the exoALMA collaboration. With sources ranging in diameter from 2.4" to 13.8" when probed by $^{12}$CO, multiple antennae configurations were required to maximally recover all spatial information (including the ACA for 7 sources). Combining these datasets warranted particular care in their alignment during calibration and prior to imaging, so as not to introduce spurious features that might resemble the kinematic deviations being investigated. Phase decoherence was found in several datasets, which was corrected by an iterative self-calibration procedure, and we explored the effects of the order of operations of spatial alignment, flux scaling, and self-calibration. A number of different imaging sets were produced for the continuum and line emission, employing an iterative masking procedure that minimizes bias due to non-Keplerian motions in the disk.

The "cosmic shoreline", a semi-empirical relation that separates airless worlds from worlds with atmospheres as proposed by Zahnle & Catling (2017), is now guiding large-scale JWST surveys aimed at detecting rocky exoplanet atmospheres. We expand upon this framework by revisiting the shorelines using existing hydrodynamic escape models applied to Earth-like, Venus-like, and steam atmospheres for rocky exoplanets, and we estimate energy-limited escape rates for CH4 atmospheres. We determine the critical instellation required for atmospheric retention by calculating time-integrated atmospheric mass loss. Our analysis introduces a new metric for target selection in the Rocky Worlds DDT and refines expectations for rocky planet atmosphere searches in Cycle 4. Exploring initial volatile inventory ranging from 0.01% to 1% of planetary mass, we find that its variation prevents the definition of a unique clear-cut shoreline, though non-linear escape physics can reduce this sensitivity to initial conditions. Additionally, uncertain distributions of high-energy stellar evolution and planet age further blur the critical instellations for atmospheric retention, yielding broad shorelines. Hydrodynamic escape models find atmospheric retention is markedly more favorable for higher-mass planets orbiting higher-mass stars, with carbon-rich atmospheres remaining plausible for 55 Cancri e despite its extreme instellation. Dedicated modeling efforts are needed to better constrain the escape dynamics of secondary atmospheres, such as the role of atomic line cooling, especially for Earth-sized planets. Finally, we illustrate how density measurements can be used to statistically test the existence of the cosmic shorelines, emphasizing the need for more precise mass and radius measurements.

Cloudy atmospheres produce electric discharges, including lightning. Lightning, in turn, provides sufficient energy to break down air molecules into reactive species and thereby affects the atmospheric composition. The climate of tidally locked rocky exoplanets orbiting M-dwarf stars may have intense and highly localised thunderstorm activity associated with moist convection on their day side. The distribution and structure of lightning-producing convective clouds is shaped by various climate parameters, of which a key one is atmospheric mass, i.e. surface air pressure. In this study, we use a global storm-resolving climate model to predict thunderstorm occurrence for a tidally locked exoplanet over a range of surface pressures. We compare two lightning parameterisations: one based on ice cloud microphysics and one based on the vertical extent of convective clouds. We find that both parameterisations predict that the amount of lightning monotonically decreases with surface pressure due to weaker convection and fewer ice clouds. The spatial distribution of lightning on the planet changes with respect to the surface pressure, responding to the changes in the large-scale circulation and the vertical stratification of the atmosphere. Our study provides revised, high-resolution estimates for lightning activity on a tidally locked Earth-like exoplanet, with implications for global atmospheric chemistry.

Giant Eruptions (GEs) are episodic high-rate mass loss events that massive stars experience in the late stage of evolutions before exploding as a core-collapse supernova. If it occurs in a binary system, the companion star can accrete part of the mass. We use numerical simulations to analyze how the companion responds to accretion and how its structure and evolution are altered. We run a grid of massive stars with masses from $20~\rm M_{\odot}$ to $60~\rm M_{\odot}$, and accretion rates from $\rm 10^{-4}$ to $\rm 0.1~M_{\odot}~\rm yr^{-1}$, over a duration of $20$ yrs. For accretion rates $\rm \lesssim 0.01~M_{\odot}~\rm yr^{-1}$ the star remains on the hotter side of the HR diagram with a minor increase in luminosity without expanding, as the accretion timescale exceeds the thermal time scale by a larger factor. Mass loss through stellar winds leads to a minor drop in luminosity shortly after the accretion phase as the star enters the recovery phase. For $\rm \gtrsim 0.01~M_{\odot}~\rm yr^{-1}$ the companion star experiences a sudden increase in luminosity by about one order of magnitude, inflates, and cools. Under the accreted gas layer the star retains its structure and continues to eject radiation-driven wind during the recovery phase, namely the time it takes to regain equilibrium. Eventually, the accreted material mixes with the inner layers of the star, and the star continues to evolve as a more massive star.

Supernova (SN) 1987A provides a unique window into the aftermath of a massive stellar explosion, offering key insights into the ejecta's morphology, composition, explosion mechanism, progenitor system, and circumstellar medium (CSM) interaction. We investigate large-scale ejecta asymmetries in SN 1987A. By comparing the simulations with JWST observations and making predictions for XRISM, we aim to refine our understanding of the explosion mechanism and the remnant's evolution. We performed 3D MHD simulations that trace the evolution of SN 1987A from the SN to the SNR, extending our predictions up to 5000 years into the future and considering the Ni-bubble effects. The simulation results are compared with JWST observations and used to predict XRISM spectra, to evaluate the accuracy of the modeled ejecta structure. Our simulations reproduce the large-scale Fe-rich ejecta morphology seen by JWST, revealing two clumps suggestive of a bipolar explosion. Ni-bubble effects in the first year boost Fe-rich ejecta expansion and their interaction with the reverse shock. However, discrepancies with JWST observations in clump velocities and spatial distribution suggest stronger explosion asymmetries than modeled. Since 2021, our models predict that shocked ejecta have contributed increasingly to X-ray emission, now rivaling shocked CSM and soon dominating as the latter fades. Future XRISM observations will trace the evolution of these ejecta structures, refining constraints on explosion geometry. Early remnant asymmetries from CSM interaction may persist for at least 100 years. Our results underscore the role of asymmetric core-collapse mechanisms in shaping SN 1987A's ejecta and constraining its explosion geometry. Future studies should explore more extreme asymmetries, in neutrino-driven core collapse or magneto-rotational SN models, to identify the origin of its bipolar Fe-rich structure.

A near-infrared (NIR) excess has been discovered in the emission of the representative fast blue optical transient (FBOT): AT 2018cow. It was suggested that this NIR excess could be emitted by the dust surrounding the source and, thus, could provide a probe into the nature of its progenitor. We develop a model to describe the influence of the FBOT emission on the environmental dust and, as a result, a dust-free evaporation cavity can be formed on a timescale of one day. Outside this cavity, the surviving dust grains can have different size distributions at different distances to the source. With such a special dust environment, we fit the multi-wavelength light curves of AT 2018cow by taking into account the evolutionary dust echo of the FBOT emission. It is found that the dust temperature can vary with time along with the evolution of the irradiating FBOT emission. Even at a fixed time, the dust temperature can be distributed in a wide range rather than having only a unique value. Furthermore, both the mass of the dust shell and its distance to the FBOT are found to be much larger than those derived with a direct empirical fitting of the NIR spectra but without considering the evolutionary relationship between the spectra.

Analysis of the gaseous component in protoplanetary disks can inform us about their thermal and physical structure, chemical composition, and kinematic properties, all of which are crucial for understanding various processes within the disks. By exploiting the asymmetry of the line emission, or via line profile analysis, we can locate the emitting surfaces. Here, we present the emission surfaces of the exoALMA sources in $^{12}$CO $J=3-2$, $^{13}$CO $J=3-2$, and CS $J=7-6$. We find that $^{12}$CO traces the upper disk atmosphere, with mean <$z/r$> values of $\approx$ 0.28, while $^{13}$CO and CS trace lower regions of the disk with mean <z/r> values of $\approx$ 0.16 and $\approx$ 0.18, respectively. We find that $^{12}$CO <$z/r$> and the disk mass are positively correlated with each other; this relationship offers a straightforward way to infer the disk mass. We derive 2-D $r-z$ temperature distributions of the disks. Additionally, we search for substructure in the surfaces and radial intensity profiles; we find evidence of localized substructure in the emission surfaces and peak intensity profiles of nearly every disk, with this substructure often being co-incident between molecular tracers, intensity profiles, and kinematic perturbations. Four disks display evidence of potential photo-desorption, implying that this effect may be common even in low FUV star-forming regions. For most disks, we find that the physical and thermal structure is more complex than analytical models can account for, highlighting a need for more theoretical work and a better understanding of the role of projection effects on our observations.

We use numerical simulations to explore biases that arise in dynamical estimates of the mean mass profile for a collection of galaxy clusters that have been stacked to make a composite. There are three types of bias. One arises from anisotropy of the kinematic pressure tensor and has been already well studied; a second arises from departures from equilibrium; and a third arises because of heterogeneity of the clusters used, from their individual non-sphericity, and because velocities used are measured with respect to centres that are, in general, accelerating. Here we focus on the latter two. We stack clusters to measure the pressure tensor and density profiles and then estimate the dynamical mass profile using the Jeans equation, and compare to the actual mean mass profile. The main result of this paper is an estimate of the bias, that can be used to correct the dynamical mass estimate, and we show how it depends on the cluster sample selection. We find that Jeans equation typically overestimates the true mass by about 20\% at the virial radius.

Gravitational microlensing of gamma-ray bursts (GRBs) provides a unique opportunity to probe compact dark matter and small-scale structures in the universe. However, identifying such microlensed GRBs within large datasets is a significant challenge. In this study, we develop a machine learning approach to distinguish Lensed GRBs from their Non-lensed counterparts using simulated light curves. A comprehensive dataset was generated, comprising labeled light curves for both categories. Features were extracted using the Cesium package, capturing critical temporal properties of the light curves. Multiple machine learning models were trained on the extracted features, with Random Forest achieving the best performance, delivering an accuracy of 94\% and an F1 score of 95\% (94\%) for Non-Lensed (Lensed) class. This approach successfully demonstrates the potential of machine learning for identifying gravitational lensing in GRBs, paving the way for future observational applications.

We present an analysis of the archival XMM-Newton observations of the Large Magellanic Cloud (LMC) supernova remnant N132D totaling more than 500ks. We focus on the high temperature plasma ($kt\sim 4.5$keV) that is responsible for the high energy continuum and exciting the Fe K emission. An image analysis shows that the Fe K emission is mainly concentrated in the southern part of the remnant interior to the region defined by the forward shock. This Fe K distribution would be consistent with an asymmetric distribution of the Fe ejecta and/or an asymmetric interaction between the reverse shock and the Fe ejecta. We compare the EPIC-pn and EPIC-MOS spectra in the 3.0 -- 12.0keV bandpass with a model based on RGS data plus a higher temperature component, in collisional ionization equilibrium (CIE), or non-equilibrium (NEI) (both ionizing and recombining). We find that the data are equally well-fitted by the CIE and ionizing models. Assuming the CIE and ionizing spectral models, the Fe in this high temperature component is significantly enhanced with respect to typical LMC abundances. We can place only an upper limit on the neutral Fe K line. We conclude that the Fe~K emission is due to ejecta heated by the reverse shock given the spatial distribution, relatively high temperature, and enhanced abundance. We estimate the progenitor mass based on the Ca/Fe and Ni/Fe mass ratios to be $13\le M_P \le 15 M_\odot$.

The ALMA large program exoALMA offers a unique window into the three-dimensional physical and dynamical properties of 15 circumstellar disks where planets may be actively forming. Here, we present an analysis methodology to map the gas disk structure and substructure encoded in 12CO, 13CO, and CS line emission from our targets. To model and characterize the disk structure probed by optically thin species, such as CS and, in some cases, 13CO, we introduce a composite line profile kernel that accounts for increased intensities caused by the projected overlap between the disk's front and back side emission. Our workflow, built on the Discminer modelling framework, incorporates an improved iterative two-component fitting method for inclined sources ($i>40^\circ$), to mitigate the impact of the disk backside on the extraction of velocity maps. Also, we report best-fit parameters for the Keplerian stellar masses, as well as inclinations, position angles, systemic velocities, rotation direction, and emission surfaces of the disks in our sample.

The availability of exquisite data and the development of new analysis techniques have enabled the study of emitting heights in proto-planetary disks. In this paper we introduce a simple model linking the emitting height of CO to the disk surface density and temperature structure. We then apply the model to measurements of the emitting height and disk temperature conducted as part of exoALMA, integrated with additional legacy measurements from the MAPS Large Programme, to derive CO column densities and surface density profiles (assuming a CO abundance) for a total of 14 disks. A unique feature of the method we introduce to measure surface densities is that it can be applied to optically thick observations, rather than optically thin as conventionally done. While we use our method on a sample of well studied disks where temperature structures have been derived using two emission lines, we show that reasonably accurate estimates can be obtained also when only one molecular transition is available. With our method we obtain independent constraints from $^{12}$CO and $^{13}$CO and we find they are in general good agreement using the standard $^{12}$C/$^{13}$C isotopic ratio. The masses derived from our method are systematically lower compared with the values derived dynamically from the rotation curve if using an ISM CO abundance, implying that CO is depleted by a median factor $\sim$20 with respect to the ISM value, in line with other works that find that CO is depleted in proto-planetary disks.

The key planet-formation processes in protoplanetary disks remain an active matter of research. One promising mechanism to radially and azimuthally trap millimeter-emitting dust grains, enabling them to concentrate and grow into planetesimals, is anticyclonic vortices. While dust observations have revealed crescent structures in several disks, observations of their kinematic signatures are still lacking. Studying the gas dynamics is, however, essential to confirm the presence of a vortex and understand its dust trapping properties. In this work, we make use of the high-resolution and sensitivity observations conducted by the exoALMA large program to search for such signatures in the $^{12}$CO and $^{13}$CO molecular line emission of four disks with azimuthal dust asymmetries: HD 135344B, HD 143006, HD 34282, and MWC 758. To assess the vortex features, we constructed an analytical vortex model and performed hydrodynamical simulations. For the latter, we assumed two scenarios: a vortex triggered at the edge of a dead zone and of a gap created by a massive embedded planet. These models reveal a complex kinematical morphology of the vortex. When compared to the data, we find that none of the sources show a distinctive vortex signature around the dust crescents in the kinematics.

The bulk motion of the gas in protoplanetary disks around newborn stars is nearly Keplerian. By leveraging the high angular and spectral resolution of ALMA, we can detect small-scale velocity perturbations in molecular line observations caused by local gas pressure variations in the disk, possibly induced by embedded protoplanets. This paper presents the azimuthally averaged rotational velocity and its deviations from Keplerian rotation ($\delta\upsilon_{\phi}$) for the exoALMA sample, as measured in the $^{12}$CO and $^{13}$CO emission lines. The rotation signatures show evidence for vertically stratified disks, in which $^{13}$CO rotates faster than $^{12}$CO due to a distinct thermal gas pressure gradient at their emitting heights. We find $\delta\upsilon_{\phi}$-substructures in the sample on both small ($\sim$10 au) and large ($\sim$100 au) radial scales, reaching deviations up to 15% from background Keplerian velocity in the most extreme cases. More than 75% of the rings and 80% of the gaps in the dust continuum emission resolved in $\delta\upsilon_{\phi}$ are co-located with gas pressure maxima and minima, respectively. Additionally, gas pressure substructures are observed far beyond the dust continuum emission. For the first time, we determined the gas pressure derivative at the midplane from observations and found it to align well with the dust substructures within the given uncertainties. Based on our findings, we conclude that gas pressure variations are likely the dominant mechanism for ring and gap formation in the dust continuum.

Fast-rotating Wolf-Rayet (WR) stars are potential progenitors of long gamma-ray bursts, but observational verification is challenging. Spectral lines from their expanding stellar wind obscure accurate rotational velocity measurements. Intrinsic polarization from wind rotation may help determine rotational speeds, requiring precise wind models. Our study aims to investigate the intrinsic polarization due to the rotational distortion of WR winds considering multiple scattering of photons and compare it to a single-scattering model, where we use an analytical expression of the polarization. We study the polarization signatures resulting from the prolate structure of rotating winds of two WR stars using a 3D Monte Carlo radiative transfer code Hyperion. We estimated the intrinsic polarization resulting from multiple scattering in WR winds for different rotational velocities, inclination angles, and mass-loss rates. Our results indicate that at a rotation rate of less than 50 % of the critical rate, the intrinsic polarization from multiple scattering is close to that of a single scattering model. However, at higher rotation velocities, the polarization from multiple scattering increases with inclination up to 40$^\circ$, while it decreases for inclinations higher than about 60$^\circ$. This dependence is inconsistent with the single-scattering model. We also discuss the effect of the mass-loss rate on the polarization and find that the polarization changes linearly with the mass-loss rate. However, it is important to note that the relationship between polarization and mass-loss rate may vary for different types of stars. The results have implications for future studies of stellar winds and mass loss and may help to improve our understanding of the complex environments of massive stars. Our research offers valuable information on the complex polarization patterns observed in stellar winds.

We confront the star formation rate in different dark matter (DM) models with UV luminosity data from JWST up to $z\simeq25$ and legacy data from HST. We find that a transition from a Salpeter population to top-heavy Pop-III stars is likely at $z\simeq10$ and that beyond $z=10-15$ the feedback from supernovae and active galactic nuclei is progressively reduced, so that at $z\simeq25$ the production of stars is almost free from any feedback. We compare fuzzy and warm DM models that suppress small-scale structures with the CDM paradigm, finding that the fuzzy DM mass $> 4.5 \times 10^{-22}{\rm eV}$ and the warm DM mass $> 1.5\, {\rm keV}$ at the 95\% CL. The fits of the star formation rate parametrization do not depend strongly on the DM properties within the allowed range. We find no preference over CDM for enhanced matter perturbations associated with axion miniclusters or primordial black holes. The scale of the enhancement of the power spectrum should be $> 27\,{\rm Mpc}^{-1}$ at the 95\% CL, excluding axion miniclusters produced for $m_a < 7.5 \times 10^{-17}\,{\rm eV}$ or heavy primordial black holes that constitute a fraction $f_{\rm PBH}$ of DM in the range $10^{-4} (m_{\rm PBH}/10^4 \,M_{\odot})^{-0.09} < f_{\rm PBH} < 8.7\times 10^{-3} (m_{\rm PBH}/10^4\, M_{\odot})^{-1}$.

We investigate the properties of cosmological ionization fronts during the Epoch of Reionization using the CROC simulations. By analyzing reionization timing maps, we characterize ionization front velocities and curvatures and their dependence on the density structure of the intergalactic medium (IGM). The velocity distribution of ionization fronts in the simulations indicates that while the barrier-crossing analytical model captures the overall shape in high-velocity regions, it fails to reproduce the low-velocity tail, highlighting the non-Gaussian nature of the IGM's density field. Ionization front velocities are inversely correlated with local density, propagating faster in underdense regions and more slowly in overdense environments. Faster ionization fronts also lead to higher post-ionization temperatures, reaching a plateau at $\sim 2 \times 10^4$ K for velocities exceeding 3000 km/s. Examining curvature statistics further establishes a connection between ionization front structure and the normalized density contrast $\nu$, with trends in overdense regions aligning well with barrier-crossing model predictions, while deviations appear in underdense environments due to model limitations. These results provide a detailed characterization of ionization front dynamics and their interaction with the underlying density field, bridging small-scale reionization physics with large-scale observables such as the 21 cm signal and the IGM's thermal history.

It is widely believed that the parameter space for Higgs-portal dark matter that achieves the relic abundance through thermal freeze-out has already been tightly constrained, typically at masses on the order of ${\cal O}(10-100)$ GeV. We point out the possibility that the multiple Higgs production due to its self-interaction dramatically changes this picture. We show that the multiplicity can be as large as ${\cal O}(200)$ for the parameters of the Standard Model Higgs, independently of the kinematics of the particle production process. Consequently, heavy Higgs-portal dark matter of $m_\chi\gtrsim{\cal O}(1)$ TeV can achieve the required relic abundance in the same mechanism with that for canonical weakly interacting massive particle models.

Next-generation gravitational-wave observatories will reach farther into the universe than currently possible, revealing black-hole mergers from early stellar binary systems such as Population III stars, whose properties are currently poorly constrained. We develop a method to infer the properties of their progenitor populations from gravitational-wave catalogs. Using Bayesian deep learning, we train an emulator for population-synthesis predictions of black-hole merger properties across redshift as a function of the initial stellar mass function, crucially accounting for systematic uncertainty due to the finite number of training simulations. Combined with a nonparametric model for star formation history, we analyze catalogs containing both Population I/II and III sources simulated with full Bayesian parameter estimation for a detector network of Cosmic Explorer and Einstein Telescope with one year of observing time. We demonstrate our ability to separate these two populations at high redshifts where both make comparable contributions to the black-hole merger rate, excluding a Population III merger rate of zero at nearly 100% credibility. Moreover, we can place meaningful constraints on the Population III progenitor distributions; in particular, we constrain the spectral index of the initial mass function to within roughly +/-0.5 of the true value and the log of the star formation rate density to within ~25% over redshifts 10 to 20. By leveraging astrophysics-informed and astrophysics-agnostic models, we demonstrate the discriminative power of our combined inference approach and highlight the potential of next-generation gravitational-wave observatories to uncover the details of high-redshift stellar populations.

The use of quasi-circular waveforms in matched-filter analyses of signals from eccentric binary neutron star mergers can lead to biases in the source's parameter estimation. We demonstrate that significant biases can be present already for moderate eccentricities $e_{0} \gtrsim 0.05$ and LIGO-Virgo-Kagra signals with signal-to-noise ratio $\gtrsim 12$. We perform systematic Bayesian mock analyses of unequal-mass non-spinning binary neutron star signals up to eccentricities $e_0 \sim 0.1$ using quasi-circular effective-one-body waveforms with spins. We find fractional signal-to-noise ratio losses up to tens of percent and up to 16-$\sigma$ deviations in the inference of the chirp mass. The latter effect is sufficiently large to lead to an incorrect (and ambiguous) source identification. The inclusion of spin precession in the quasi-circular waveform does not capture eccentricity effects. We conclude that high-precision observations with advanced (and next generation) detectors are likely to require standardized, accurate, and fast eccentric waveforms.

The nonlinear gravitational-wave (GW) memory effect$\unicode{x2014}$a permanent shift in the GW strain that arises from nonlinear GW interactions in the wave zone$\unicode{x2014}$is a prediction of general relativity which has not yet been observed. The amplitude of the GW memory effect from binary-black-hole (BBH) mergers is small compared to that of primary (oscillatory) GWs and is unlikely to be detected by current ground-based detectors. Evidence for its presence in the population of all the BBH mergers is more likely, once thousands of detections are made by these detectors. Having an accurate and computationally efficient waveform model of the memory signal will assist detecting the memory effect with current data-analysis pipelines. In this paper, we build on our prior work to develop analytical time-domain and frequency-domain models for the dominant nonlinear memory multipole signal ($l=2$, $m=0$) from nonspinning BBH mergers in quasicircular orbits. The model is calibrated for mass ratios between one and eight. There are three parts to the time-domain signal model: a post-Newtonian inspiral, a quasinormal-mode-based ringdown, and a phenomenological signal during the late inspiral and merger (which interpolates between the inspiral and ringdown). The time-domain model also has an analytical Fourier transform, which we compute in this paper. We assess the accuracy of our model using the mismatch between our waveform model and the memory signal computed from the oscillatory modes of a numerical-relativity surrogate model. We use the advanced LIGO sensitivity curve from the fourth observing run and find that the mismatch increases with the total mass of the system and is of order $10^{-2}\unicode{x2013}10^{-4}$.

The Quantum Chromodynamics phase diagram at large densities and low temperature can be probed both by neutron stars and low-energy heavy-ion collisions. Heavy-ion collisions are nearly isospin symmetric systems whereas neutron stars are highly isospin asymmetric since they are neutron-rich. The symmetry energy expansion is used to connect these regimes across isospin asymmetry. However, the current symmetry energy expansion does not account for strange particles. Here we include a finite strangeness to calculate isospin asymmetry and find that the symmetry energy expansion has a skewness term in the presence of strangeness for the case of weak equilibrium.

A search for solar axions and axion-like particles produced in the $p+d\rightarrow\rm{^3He}+A~(5.5\rm{ ~MeV})$ reaction was performed using the complete dataset of the Borexino detector (3995 days of measurement live-time). The following interaction processes have been considered: axion decay into two photons $({\rm A}\rightarrow2\gamma)$, inverse Primakoff conversion on nuclei $({\rm A}+Z\rightarrow\gamma+Z$), the Compton conversion of axions to photons $({\rm A}+e\rightarrow e+\gamma)$ and the axio-electric effect $({\rm A}+e+Z\rightarrow e+Z$). Model-independent limits on axion-photon ($g_{A\gamma}$), axion-electron ($g_{Ae}$), and isovector axion-nucleon ($g_{3AN}$) couplings are obtained: $|g_{A\gamma}\times g_{3AN}| \leq 2.3\times 10^{-11} \rm{GeV}^{-1}$ and $|g_{Ae}\times g_{3AN}| \leq 1.9\times 10^{-13}$ at $m_A <$ 1 MeV (90\% c.l.). The Borexino results exclude new large regions of $g_{A\gamma}$, and $g_{Ae}$ coupling constants and axion masses $m_A$, and leads to constraints on the products $|g_{A\gamma}\times m_A|$ and $|g_{Ae}\times m_A|$ for the KSVZ- and the DFSZ-axion models.

The analytical theory of non-linear generation of large-scale magnetic turbulence in anisotropic magnetoactive plasma in the quasilinear approximation without taking into account the direct non-linear interaction of individual harmonics is constructed. It is shown that anomalous collisions of particles due to scattering on small-scale fluctuations of the developed Weibel turbulence lead to instability of long-wave harmonics, which are stable in the linear approximation. The non-linear growth of such harmonics at a given anisotropy of the particle velocity distribution, consistent with the dynamics of short-wave perturbations at the saturation stage and possible anisotropic particle injection, occurs in the superexponential regime and corresponds to an explosive-type instability. The growth law of the large-scale magnetic field is found analytically and the critical time of explosive instability is estimated.

We investigate the dynamics of the dilaton-inspired scalar field, formally rewritten by means of a Brans-Dicke Lagrangian, within the framework of \emph{geometrical trinity of gravity}. In this respect, we perform a stability analysis by adopting a non-flat Friedmann-Robertson-Walker (FRW) metric and considering the well-established exponential potential in three distinct gravitational frameworks: general relativity, teleparallel gravity, and symmetric-teleparallel gravity. By comparing the scalar field behaviors across these theories, we highlight the role of curvature, torsion, and non-metricity in shaping cosmic evolution. Our analysis reveals that, both in general relativity and teleparallel gravity, the dilaton-inspired field can drive the accelerated expansion of the universe, effectively behaving as cosmological constant at late times. In contrast, within the symmetric teleparallel gravity scenario, performing a complete linear stability analysis is prevented by the use of the non-coincident gauge. Nevertheless, the latter paradigm introduces complexity into the autonomous system, resulting in a structurally different analysis. For general relativity and teleparallel scenarios, we remark the regions of attractor solutions and unphysical domains in which we do not expect the viability of our dilaton-inspired Lagrangian. However, within the framework of symmetric-teleparallel gravity, the stability analysis reveals no attractor points for the chosen set of free parameters. In support of these findings, physical conclusions, kinematical studies, and consequences on Friedmann dynamics are thus explored.

Supermassive black hole binary mergers serve as prominent sources of the stochastic gravitational wave background (SGWB), detectable by pulsar timing arrays (PTAs). If dark matter-induced friction is present in the vicinity of these mergers, it can lead to suppression in the nanohertz frequency range of the SGWB spectrum. In particular, ultralight dark matter (ULDM) forming compact solitonic cores around supermassive black holes can imprint signatures in PTA observations. Our analysis places limits on the mass and self-interaction strength of ULDM, demonstrating that soliton-induced dynamical friction can significantly alter the SGWB spectrum. PTAs have the potential to exclude certain ULDM mass ranges while probing the effects of self-interactions, offering a novel avenue to investigate the fundamental properties of ULDM.

In prior work, conducted since 2017, two celestial pointing directions have been observed to be associated with the measurement of anomalous high counts of narrow bandwidth, short duration, polarized radio frequency pulse pairs. The prior experimental work utilized up to three geographically-spaced synchronized radio telescopes, a single-dish radio telescope, and a radio interferometer. The experimental work reported here examines full right ascension coverage at one declination, utilizing the interferometer, during 124.1 days. Results suggest the possible presence of an additional anomalous celestial pointing direction. Seven standard deviations of noise-modeled shifts of mean polarized pulse pair count were observed in three celestial directions. Indications of interferometer space delay aliasing were observed. A phase noise test, celestial source identification methods and associated measurements were used to seek potential explanations of the unusual observed phenomena.

We study cosmic strings in the complex symmetron model, a scalar-tensor theory with a spontaneously broken local $U(1)$ symmetry in low matter density regions. Using numerical simulations, we show that these strings preferentially attach to matter halos, leading to the stabilization of string loops. While the requirement for screening of fifth-force interactions in the solar system limits observable signatures in theories with universal coupling to matter, analogous topological defects in the dark sector may still influence cosmic structure formation, offering a novel avenue to constrain dark-sector interactions.

Binary neutron star inspirals detected as gravitational waves carry information on components' masses and tidal deformabilities, but not radii, which are measured by electromagnetic observations of neutron stars. An expression for neutron-star radii as a function of gravitational-wave only data would be advantageous for the multi-messenger astronomy. Using pySR, a symbolic regression method trained on TOV solutions to piecewise polytropic EOS input, an approximate symbolic expression for neutron-star radius as a function of mass and tidal deformability is obtained. The approximation is tested on piecewise polytropic EOS NS data, as well as on NS sequences based on various non-polytropic EOSs based on realistic theories of dense matter, achieving consistent agreement between the ground truth values and the approximation for a broad range of NS parameters covering current astrophysical observations, with average radii differences of few hundred meters. Additionally, the approximation is applied to GW170817 gravitational-wave mass and tidal deformability posteriors, and compared to reported inferred radius distributions.

We investigate how neutrinos may acquire small electric charges within the Standard Model framework while preserving electromagnetic gauge invariance. Instead of gauging the standard hypercharge generator $Y$, a linear combination of $Y$ and a new generator $X$ from a gaugable global $U(1)_X$ symmetry is embedded, under which neutrinos transform non-trivially. We demonstrate that minimal scenarios based on flavor-dependent $U(1)_X$ symmetries, such as $X = L_\alpha - L_\beta$, are incompatible with current neutrino oscillation data. In contrast, we have shown that only flavor-universal $U(1)_X$ symmetries-such as $U(1)_{B-L}$, which shifts both quark and lepton charges, and $U(1)_L$, which modifies only the lepton sector-can generate tiny neutrino charges consistent with observed masses and mixing. We also discuss the necessary connection between such charges and the Dirac nature of neutrinos. By analyzing the phenomenological implications in detail, our findings emphasize that constraints on neutrino charges should be evaluated within the specific framework of the $U(1)_X$ symmetry under consideration, rather than assuming a generic approach, as is often the case.