Papers for Friday, Jul 11 2025

The LiteBIRD satellite mission aims at detecting Cosmic Microwave Background $B$ modes with unprecedented precision, targeting a total error on the tensor-to-scalar ratio $r$ of $\delta r \sim 0.001$. Operating from the L2 Lagrangian point of the Sun-Earth system, LiteBIRD will survey the full sky across 15 frequency bands (34 to 448 GHz) for 3 this http URL current LiteBIRD baseline configuration employs 4508 detectors sampling at 19.1 Hz to achieve an effective polarization sensitivity of $ 2 \mu\mathrm{K-arcmin}$ and an angular resolution of 31 arcmin (at 140 GHz).We describe the first release of the official LiteBIRD simulations, realized with a new simulation pipeline developed using the LiteBIRD Simulation this http URL pipeline generates 500 full-sky simulated maps at a Healpix resolution of nside=512. The simulations include also one year of Time Ordered Data for approximately one-third of LiteBIRD's total detectors.

The Decadal Survey on Astronomy and Astrophysics 2020 highlights the importance of advancing research focused on discovering and characterizing habitable worlds. In line with this priority, our goal is to investigate how planetary systems evolve through atmospheric escape and to develop methods for identifying potentially Earth-like planets. By leveraging the ultraviolet (UV) capabilities of the Habitable Worlds Observatory (HWO), we can use transit spectroscopy to observe atmospheric escape in exoplanets and explore the processes that shape their evolution, assess the ability of small planets to retain their atmospheres, and search for signs of Earth-like atmospheres. To achieve this, we support the development of a UV spectrograph with moderate- to high-resolution capabilities for point-source observations, coverage of key spectral features in the 100-300 nm range, and detectors that can register high count rates reliably. This article is an adaptation of a science case document developed for the Characterizing Exoplanets Steering Committee within HWO's Solar Systems in Context Working Group.

The instrument payload of the future Habitable Worlds Observatory (HWO) will span a wide range of wavelengths, including the ultraviolet (UV) region that cannot be easily accessed from the ground (< 350 nm). Along with its primary mission to characterize the habitability of candidate exo-Earths, HWO will be well suited for observations of potentially habitable icy ocean worlds in our Solar System, in particular with an integral field spectrograph (IFS). Here, we discuss future HWO observations of ocean worlds including Ceres, Europa, Enceladus, Ariel, and Triton. We explore the observational requirements for capturing ongoing and sporadic geyser activity and for measuring the spectral signatures of astrobiologically-relevant compounds, including water, salts, organics, and other bioessential components. We consider the key observing requirements for an IFS, including wavelength coverage, resolving power (R), angular resolution, and field-of-view (FOV). We also outline some of the potential measurements that would define incremental, substantial, and breakthrough progression for characterizing habitability at ocean worlds, primarily focusing on UV and visible (VIS) wavelengths (90 - 700 nm). Our investigation concludes that a UV/VIS IFS on HWO could make some groundbreaking discoveries, in particular for detection and long-term monitoring of geyser activity and interior-surface exchange of components critical for understanding habitability at ocean worlds.

Recent JWST observations of massive galaxies at z > 2 have detected blueshifted absorption in Na I D and other resonant absorption lines, indicative of strong gas outflows in the neutral phase. However, the measured mass outflow rates are highly uncertain because JWST observations can only probe the column density of trace elements such as sodium, while most of the gas is in the form of hydrogen. The conversion between the column density of sodium and that of hydrogen is based on observations of gas clouds within the Milky Way, and has not been directly tested for massive galaxies at high redshift. In order to test this conversion, we study a unique system consisting of a massive quiescent galaxy (J1439B) at z = 2.4189 located at a projected distance of 38 physical kpc from the bright background quasar QSO J1439. The neutral outflow from the galaxy is observed as a sub-damped Lyman-alpha absorber in the spectrum of the background quasar, which enables a direct measurement of the hydrogen column density from Lyman transitions. We obtain new near-infrared spectroscopy with Magellan/FIRE and detect Na I D and other resonant absorption lines from Mg II, Mg I, and Fe II. We are thus able to derive new, empirical calibrations between the column density of trace elements and the hydrogen column density, that can be used to estimate the mass and the rate of neutral gas outflows in other massive quiescent galaxies at high redshift. The calibration we derive for Na I is only 30% lower than the local relation that is typically assumed at high redshift, confirming that the neutral outflows observed with JWST at z > 2 are able to remove a large amount of gas and are thus likely to play a key role in galaxy quenching. However, using the local calibration for Mg II yields an order-of-magnitude discrepancy compared to the empirical calibration, possibly because of variations in the dust depletion.

We present a detailed spectropolarimetric study of the Sco-like Z-source GX 349+2, simultaneously observed with the Imaging X-ray Polarimetry Explorer (IXPE) and Nuclear Spectroscopic Telescope Array (NuSTAR). During the observations GX 349+2 was found mainly in the normal branch. A model-independent polarimetric analysis yields a polarisation degree of $1.1\% \pm 0.3\%$ at a polarisation angle of $29° \pm 7°$ in the 2--8 keV band, with ${\sim}4.1\sigma$ confidence level significance. No variability of polarisation in time and flux has been observed, while an energy-resolved analysis shows a complex dependence of polarisation on energy, as confirmed by a spectropolarimetric analysis. Spectral modeling reveals a dominant disc blackbody component and a Comptonising emitting region, with evidence of a broad iron line associated with a reflection component. Spectropolarimetric fits suggest differing polarisation properties for the disc and Comptonised components, slightly favouring a spreading layer geometry. The polarisation of the Comptonised component exceeds the theoretical expectations, but is in line with the results for other Z-sources with similar inclination. A study of the reflection's polarisation is also reported, with polarisation degree ranging around 10% depending on the assumptions. Despite GX 349+2's classification as a Sco-like source, these polarimetric results align more closely with the Cyg-like system GX 340+0 of similar inclination. This indicates that polarisation is governed primarily by accretion state and orbital inclination, rather than by the subclass to which the source belongs.

We present JWST NIRSpec/G395H transmission spectroscopy observations of GJ 357 b, a warm ($T_{\mathrm{eq}} \approx 525$ K) super-Earth ($1.2\ \mathrm{R_{\oplus}} $, $1.84\ \mathrm{M_{\oplus}} $) orbiting a nearby M3-type star, with a median precision of 18 ppm and 27 ppm in NRS1 and NRS2, respectively. These precisions are obtained by binning the spectrum into 53 spectroscopic channels with a resolution of 60 pixels (around 0.02 $\mu$m) each. Our analysis of the transmission spectrum reveals no detectable atmospheric spectral features. By comparing the observed spectrum with 1D forward models, we rule out atmospheres with mean molecular weights (MMW) lower than 8 g/mol to $3 \sigma$, as well as atmospheres with metallicities less than 300x solar. The lack of a low MMW primary atmosphere is consistent with a primordial H$_2$ rich atmosphere having escaped, given the planet's $\gtrsim5$ Gyr age, relatively low surface gravity (log g = 3.09), and its likely history of substantial incident extreme ultraviolet radiation. We conclude that GJ 357 b most likely possesses either a high-MMW secondary atmosphere, perhaps rich in oxidized gases like CO$_2$, or is a bare rock with no atmosphere. Upcoming scheduled JWST thermal emission observations could help distinguish between these scenarios by detecting signatures indicative of atmospheric heat redistribution or molecular absorption.

The orbital eccentricity-radius relation for small planets is indicative of the predominant dynamical sculpting processes during late-stage orbital evolution. Previous studies have shown that planets orbiting Sun-like stars exhibit an eccentricity-radius trend such that larger planets have higher orbital eccentricities, and that radius gap planets may have modestly higher orbital eccentricities than planets on either side of the radius gap. In this work, we investigate the trend for a sample of smaller M dwarf stars. For a sample of 236 single- and multi-transit confirmed planets or candidates discovered by the TESS and Kepler missions, we constrain orbital eccentricity for each planet from the transit photometry together with a stellar density prior. We investigate the binned eccentricity-planet radius relation for the combined planet sample and present evidence for a positive eccentricity-radius relationship with elevated eccentricities for planets larger than 3.5 R_earth, similar to the trend for planets orbiting Sun-like stars. We find modest evidence that single-transit M dwarf planets near the radius gap exhibit higher eccentricity, consistent with trends for Sun-like stars. However, we see no evidence for an increased eccentricity near the radius gap among multi-transit M dwarf planets. We discuss implications for these results in the context of predominant atmospheric loss mechanisms: namely, supporting evidence for photoevaporation in M dwarf planets vs. planet-planet collisions or giant impacts in FGK dwarf planets.

The James Webb Space Telescope (JWST) observations have identified a class of compact galaxies at high redshifts ($4 \lesssim z \lesssim 11$), dubbed "little red dots" (LRDs). The supermassive black holes (SMBHs) of $10^{5-8}{\rm\,M}_{\odot}$ in LRDs favor a heavy-seed origin. We propose a mechanism for their formation: Clusters of primordial black holes, formed through long-short mode coupling on small scales in the early Universe, undergo sequential mergers over extended timescales. This mechanism can evade cosmic microwave background distortions and result in heavy-seed SMBHs via runaway mergers. We employ Monte Carlo simulations to solve the Smoluchowski coagulation equation and determine the runaway merging timescale. The resulting stochastic gravitational wave background offers a distinct signature of this process, and the forming SMBHs can be highly spinning at their formation due to the spin residual of the cluster from tidal fields. This mechanism may explain the rapidly spinning SMBHs in LRDs under the assumption of obscured active galactic nuclei.

We search a sample of 5,685,060 isolated sources in the All Sky Automated Survey for SuperNovae (ASAS-SN) with 14.5<g<15 mag for slowly varying sources with brightness changes larger than ~0.03 mag/year over 10 years. We find 426 slowly-varying systems. Of these systems, 200 are identified as variables for the first time, 226 are previously classified as variables, and we find equal numbers of sources becoming brighter and fainter. Previously classified systems were mostly identified as semi-regular variables (SR), slow irregular variables (L), or unknown (MISC or VAR), as long time scale variability does not fit into a standard class. Much like Petz & Kochanek 2025, the sources are scattered across the color magnitude diagram and can be placed into 5 groups that exhibit distinct behaviors. There are also six AGN. There are 262 candidates (~62 percent) that also show shorter time scale periodic variability, mostly with periods longer than 10 days. The variability of 66 of these candidates may be related to dust. Combining the new slow variable candidates with the candidates from Petz & Kochanek 2025, we have found a total of 1206 slow variables.

We present GokuNEmu, a ten-dimensional neural network emulator for the nonlinear matter power spectrum, designed to support next-generation cosmological analyses. Built on the Goku $N$-body simulation suite and the T2N-MusE emulation framework, GokuNEmu predicts the matter power spectrum with $\sim 0.5 \%$ average accuracy for redshifts $0 \leq z \leq 3$ and scales $0.006 \leq k/(h\,\mathrm{Mpc}^{-1}) \leq 10$. The emulator models a 10D parameter space that extends beyond $\Lambda$CDM to include dynamical dark energy (characterized by $w_0$ and $w_a$), massive neutrinos ($\sum m_\nu$), the effective number of neutrinos ($N_\text{eff}$), and running of the spectral index ($\alpha_\text{s}$). Its broad parameter coverage, particularly for the extensions, makes it the only matter power spectrum emulator capable of testing recent dynamical dark energy constraints from DESI. In addition, it requires only $\sim $2 milliseconds to predict a single cosmology on a laptop, orders of magnitude faster than existing emulators. These features make GokuNEmu a uniquely powerful tool for interpreting observational data from upcoming surveys such as LSST, Euclid, the Roman Space Telescope, and CSST.

The Transiting Exoplanet Survey Satellite (TESS) has been highly successful in detecting planets in close orbits around low-mass stars, particularly M dwarfs. This presents a valuable opportunity to conduct detailed population studies to understand how these planets depend on the properties of their host stars. The previously observed radius valley in Sun-like stars has not been unambiguously detected among M dwarfs, and how its properties varies when compared with more massive stars remains uncertain. We use a volume-limited sample of low mass stars with precise photometric stellar parameters from the bioverse catalog of TESS Objects of Interest (TOIs) confirmed planets and candidates within 120 pc. We detect the radius valley around M dwarfs at a location of 1.64 $\pm$ 0.03 $R_{\oplus}$ and with a depth of approximately 45${\%}$. The radius valley among GKM stars scales with stellar mass as $R_p \propto M_*^{0.15\pm 0.04}$. The slope is consistent, within 0.3$\sigma$, with those around Sun-like stars. For M dwarfs, the discrepancy is 3.6$\sigma$ with the extrapolated slope from the Kepler FGK sample, marking the point where the deviation from previous results begins. Moreover, we do not see a clear shift in the radius valley between early and mid M dwarfs. The flatter scaling of the radius valley for lower-mass stars suggests that mechanisms other than atmospheric mass loss through photoevaporation may shape the radius distribution of planets around M dwarfs. Comparison of the slope with various planet formation and evolution models matches well with pebble accretion models including waterworlds, indicating a potentially different regime of planet formation that can be probed with exoplanets around the lowest mass stars.

Dense star clusters are thought to contribute significantly to the merger rates of stellar-mass binary black holes (BBHs) detected by the LIGO-Virgo-KAGRA collaboration. We combine $N$-body dynamic models of realistic dense star clusters with cluster formation histories to estimate the merger rate distribution as a function of primary mass for merging BBHs formed in these environments. It has been argued that dense star clusters -- most notably old globular clusters -- predominantly produce BBH mergers with primary masses $M_p\approx30\,M_{\odot}$. We show that dense star clusters forming at lower redshifts -- and thus having higher metallicities -- naturally produce lower-mass BBH mergers. We find that cluster BBH mergers span a wide range of primary mass, from about $6\,M_{\odot}$ to above $100\,M_{\odot}$, with a peak near $8\,M_{\odot}$, reproducing the overall merger rate distribution inferred from gravitational wave detections. Our results show that most low-mass BBH mergers (about $95\%$ with $M_p\lesssim 20\,M_{\odot}$) originate in metal-rich ($Z \sim Z_{\odot}$) dense star clusters, while more massive BBH mergers form predominately in metal-poor globular clusters. We also discuss the role of hierarchical mergers in shaping the BBH mass distribution. Gravitational wave detection of dynamically-formed low-mass BBH mergers -- potentially identifiable by features such as isotropic spin distributions -- may serve as probes of cluster formation histories in metal-rich environments at low redshifts.

Accurate and efficient simulation-based emulators are essential for interpreting cosmological survey data down to nonlinear scales. Multifidelity emulation techniques reduce simulation costs by combining high- and low-fidelity data, but traditional regression methods such as Gaussian processes struggle with scalability in sample size and dimensionality. In this work, we present T2N-MusE, a neural network framework characterized by (i) a novel 2-step multifidelity architecture, (ii) a 2-stage Bayesian hyperparameter optimization, (iii) a 2-phase $k$-fold training strategy, and (iv) a per-$z$ principal component analysis strategy. We apply T2N-MusE to selected data from the Goku simulation suite, covering a 10-dimensional cosmological parameter space, and build emulators for the matter power spectrum over a range of redshifts with different configurations. We find the emulators outperform our earlier Gaussian process models significantly and demonstrate that each of these techniques is efficient in training neural networks or/and effective in improving generalization accuracy. We observe a reduction in validation error by more than a factor of five compared to previous work. This framework has been used to build the most powerful emulator for the matter power spectrum, GokuNEmu, and will also be used to construct emulators for other statistics in future.

Recent observational results from the DESI collaboration reveal tensions with the standard $\Lambda$CDM model and favor a scenario in which dark energy (DE) decays over time. The DESI DR2 data also suggest that the DE equation of state (EoS) may have been phantom-like ($w < - 1$) in the past, evolving to $w > - 1$ at present, implying a recent crossing of the phantom divide at $w = - 1$. Scalar field models of DE naturally emerge in ultraviolet-complete theories such as string theory, which is typically formulated in higher dimensions. In this work, we investigate a class of thawing scalar field models propagating on a (4+1)-dimensional phantom braneworld, and demonstrate that their effective EoS exhibits a phantom-divide crossing. Alongside the Hubble parameter and EoS of DE, we also analyse the evolution of the Om diagnostic, and demonstrate that the time dependence of these quantities is in excellent agreement with the DESI DR2 observations. Furthermore, we perform a comprehensive parameter estimation using Markov Chain Monte Carlo (MCMC) sampling, and find that the $\chi^2$ values for all our models are remarkably close to that of the widely used CPL parametrisation, indicating that our models fit the data very well.

Ultra-hot Jupiters are a class of gas-giant exoplanets that show a peculiar combination of thermochemical properties in the form of molecular dissociation, atomic ionization, and inverted thermal structures. Atmospheric characterization of gas giants lying in the transitional regime between hot and ultra-hot Jupiters can help in understanding the physical mechanisms that cause the fundamental transition in atmospheres between the two classes of hot gas giants. Using Doppler spectroscopy with IGRINS on Gemini South (1.4 to 2.5 $\mu$m), we present the day-side high-resolution spectrum of WASP-122b (T$_{\mathrm{day}}$=2258$ \pm$ 54 K), a gas-giant situated at this transition. We detect the signal from H$_{2}$O, based on which we find that WASP-122b has a significantly metal-depleted atmosphere with metallicity log$_{10}$[Z$_{\mathrm{P}}$/Z$_{\odot}$] = $-$1.48$\pm$0.25 dex (0.033$_{-0.016}^{+0.018}$ $\times$ solar), and solar/sub-solar C/O ratio = 0.36$\pm$0.22 (3$\sigma$ upper limit 0.82). Drastically low atmospheric metallicity pushes the contribution function to higher pressures, resulting in the planetary spectral lines to originate from a narrow region around 1 bar where the thermal profile is non-inverted. This is inconsistent with solar composition radiative convective equilibrium (RCTE) which predicts an inverted atmosphere with spectral lines in emission. The sub-solar metallicity and solar/sub-solar C/O ratio is inconsistent with expectations from core-accretion. We find the planetary signal to be significantly shifted in K$_{\mathrm{P}}$ and V$_{\mathrm{sys}}$, which is in tension with the predictions from global circulation models and require further investigation. Our results highlight the detailed information content of high-resolution spectroscopy data and their ability to constrain complex atmospheric thermal structures and compositions of exoplanets.

The polarization of starlight and thermal dust emission from aligned non-spherical grains provides a powerful tool for tracing magnetic field morphologies and strengths in diffuse interstellar medium to star-forming regions, and constraining dust grain properties and their alignment mechanisms. However, the physics of grain alignment is not yet fully understood. The alignment based on RAdiative Torques (RATs), known as RAT Alignment or RAT-A mechanism is the most acceptable mechanism. In this work, we investigate the grain alignment mechanisms in F13 (F13N and F13C) and F13S filamentary regions of the Cocoon Nebula (IC 5146) using polarized thermal dust emission observations from JCMT/POL-2 at 850 $\mu$m. We find that the polarization fraction decreases with increasing total intensity and gas column density in each region, termed as polarization hole. We investigate for any role of magnetic field tangling on the observed polarization hole by estimating the polarization angle dispersion function. Our study finds that the polarization hole is not significantly influenced by magnetic field tangling, but majorly due to decrease in RAT alignment efficiency of grains in denser regions. To test whether RAT-A mechanism can reproduce the observational results, we estimate minimum alignment size of grains using RAT theory. Our study finds strong evidence for RAT-A mechanism that can explain the polarization hole. We also find potential hints that the observed higher polarization fractions in some regions of F13 filament can be due to combined effects of both suprathermal rotation by RATs and enhanced magnetic relaxation, supporting the Magnetically-Enhanced RAT (M-RAT) mechanism.

Fifteen years of the Fermi Large Area Telescope (LAT) data in the halo region of the Milky Way (MW) are analyzed to search for gamma rays from dark matter annihilation. Gamma-ray maps within the region of interest ($|l| \le 60$ deg, $10 \le |b| \le 60$ deg) are modeled using point sources, the GALPROP models of cosmic-ray interactions, isotropic background, and templates of Loop I and the Fermi bubbles, and then the presence of a halo-like component is further examined. A statistically significant halo-like excess is found with a sharp peak around 20 GeV, while its flux is consistent with zero below 2 GeV and above 200 GeV. Examination of the fit residual maps indicates that a spherically symmetric halo component fits the map data well. The radial profile agrees with annihilation by the smooth NFW density profile, and may be slightly shallower than this, especially in the central region. Various systematic uncertainties are investigated, but the 20 GeV peak remains significant. In particular, the halo excess with a similar spectrum is detected even relative to the LAT standard background model, which does not depend on GALPROP or other model templates. The halo excess can be fitted by the annihilation spectrum with a mass $m_\chi \sim$ 0.5-0.8 TeV and annihilation cross section $\langle \sigma \upsilon \rangle \sim$ (5-8)$\times 10^{-25} \ \rm cm^3 \, s^{-1}$ for the $b\bar{b}$ channel. This cross section is larger than the upper limits from dwarf galaxies and the canonical thermal relic value, but considering various uncertainties, especially the density profile of the MW halo, the dark matter interpretation of the 20 GeV ``Fermi halo'' remains feasible. The prospects for verification through future observations are briefly discussed.

The IceCube Neutrino Observatory at the South Pole detects neutrinos from the entire sky, both of astrophysical and atmospheric origin, via the Cherenkov light emitted when these neutrinos interact in the ice, giving rise to rapidly moving charged particles. Neutrino events with vertices contained within the detector volume are useful for studying the neutrino flavor ratio, as they allow for a better reconstruction of the event morphology. The Medium Energy Starting Events (MESE) data sample is a selection of such events with energies of at least 1 TeV. This sample includes electron-, muon-, and tau-neutrino events, processed consistently. We use it to constrain the flavor ratio of astrophysical neutrinos at Earth, which in turn informs us of the flavor composition at the source itself. In this talk, we will present the results of this study, based on 11.4 years of IceCube data.

Surface radio antenna-based measurements of cosmic-ray air showers present significant computational challenges in accurately reconstructing physics observables, in particular, the depth of shower maximum, X$_{max}$. State-of-the-art template fitting methods rely on extensive simulation libraries, limiting scalability. This work introduces a technique utilizing graph neural networks to reconstruct key air-shower parameters, in particular, direction and shower-core, energy, and X$_{max}$. For training and testing of the networks, we use a CoREAS simulation library made for a future enhancement of IceCube's surface array with radio antennas. The neural networks provide a scalable framework for large-scale data analysis for next-generation astroparticle observatories, such as IceCube-Gen2.

The IceCube Neutrino Observatory is a multi-messenger observatory at the South Pole. As preparation for an enhancement of its surface array, IceTop, a prototype station consisting of elevated scintillation panels and radio antennas has been installed and is operating since 2020. The radio antennas detect emissions from cosmic-ray-induced air showers, and their precise orientation is essential for an accurate reconstruction of the air-shower properties. This work presents a novel method to determine the orientation by analyzing periodic variations of the Galactic background noise recorded by the antennas. In particular, we examine noise level variations correlated with the Earth's rotation and the apparent position of the Galactic Center. The method can provide a potential alternative or augment GPS-based measurements of the alignment of radio antennas at the South Pole.

The blazar Markarian 501 (Mrk 501) was observed on three occasions over a 4-month period between 2022 March and 2022 July with the Imaging X-ray Polarimetry Explorer (IXPE). In this paper, we report for the first time on the third IXPE observation, performed between 2022 July 9 and 12, during which IXPE detected a linear polarization degree of $\Pi_X=6\pm2$ per cent at a polarization angle, measured east of north, of $\Psi_X=143^\circ\pm11^\circ$ within the 2-8 keV X-ray band. The X-ray polarization angle and degree during this observation are consistent with those obtained during the first two observations. The chromaticity of the polarization across radio, optical, and X-ray bands is likewise consistent with the result from the simultaneous campaigns during the first two observations. Furthermore, we present two types of models to explain the observed spectral energy distributions (SEDs) and energy-resolved polarization: a synchrotron self-Compton model with an anisotropic magnetic field probability distribution in the emitting volume, as well as an energy-stratified shock model. Our results support both the shock scenario as well as support that small levels of magnetic field anisotropy can explain the observed polarization.

Adding to the large radial velocity survey of nearby solar-type stars (summary in Tokovinin, 2023a), spectroscopic orbits are determined for four hierarchical systems: HIP 49442 (inner and outer periods of 164.55 d and 34 yr, respectively), HIP 55691 (2.4 and 415 yr), HIP 61465 (86.8 d), and HIP 78662C (0.82 d). Each system is discussed individually. Seven Gaia orbits of low-mass dwarfs, each with two additional resolved (interferometric and wide) companions, i.e. potential quadruples, are tested by monitoring radial velocities; five orbits are confirmed and two are refuted. Five of these systems are quadruples of 3+1 hierarchy, one is quintuple, and one is triple. Strengths and limitations of the Gaia data on multiple systems and the need of complementary observations are highlighted.

We report on an unusual radio source J180526-292953, initially identified as a steep spectrum, polarized point source toward the Galactic bulge and found to coincide with the nearby K dwarf HD317101A. We conducted a multi-wavelength radio study utilizing new GMRT observations and archival data from ASKAP, MeerKAT, and the VLA. At 1.5 GHz, HD317101A exhibits highly polarized coherent emission with variable activity lasting several hours with an apparent period of 3.7 days, which is consistent with electron cyclotron maser (ECM) emission. The behavior at 3 GHz is distinctive, with a short burst lasting tens of seconds to minutes, a flat spectrum, and no detected polarization, possibly suggesting gyro-synchrotron emission. High-resolution optical spectroscopy from CHIRON/SMARTS confirms HD317101A as a mature, chromospherically inactive K7V star, while Gaia astrometry, combined with speckle imaging from Zorro/Gemini-S, indicates the presence of a close-in M5.5V companion. We evaluated three possible origins for the combined radio behavior: chromospheric activity, auroral emission (possibly from a star-planet interaction), or an ultra-long-period transient. The bulk of the evidence favors an auroral origin, but the dominant stellar source of the ECM emission remains uncertain. Future VLBI observations, long-term TESS monitoring, high resolution spectroscopy and further radio characterization will be key to distinguishing between various scenarios.

GRAND (the Giant Radio Array for Neutrino Detection) is a proposed next-generation observatory targetting primarily the detection of ultra-high-energy neutrinos, with energies exceeding about 100 PeV. GRAND is envisioned as a collection of large-scale ground arrays of self-triggered radio antennas that target the radio emission from extensive air showers initiated by UHE particles. Three prototype arrays are presently in operation: GRANDProto300 in China, with 65 units running since end of 2024, GRAND@Auger in Argentina with 10 units deployed on the site of the Pierre Auger Observatory, and GRAND@Nançay in France, a 4-unit setup installed at the Nançay radio-observatory and used for test purposes. The main objective of the GRAND prototype phase is to validate the detection principle and technology of GRAND, in preparation for its next phase, GRAND10k. GRAND10k will consist of two arrays of 10'000 antennas each, covering both the Northern and Southern hemispheres, to be deployed from 2030 on. Here we give an overview of the GRAND concept, its science goals, the status of the prototypes, their performances and first detection of cosmic rays, and the technical perspective they open for the future.

IceCube Upgrade, starting in the Antarctic summer season 2025/2026, will enhance the sensitivity of the current IceCube in the GeV range and improve understanding of the ice properties. Around 700 new modules will be deployed deep in the ice along seven strings, spaced $3\,\mathrm{m}$ vertically within a horizontal region of $100\,\mathrm{m}$. IceCube Upgrade mainly consists of two types of Cherenkov photon detectors, $\sim280$ Dual optical sensors in an Ellipsoid Glass for Gen2 (D-Eggs) and $\sim400$ multi-PMT Digital Optical Modules (mDOMs). Here, we present the status of mDOM production and acceptance testing for mass-produced mDOMs. The majority of the modules have already been produced, and all 128 modules on the first 2 strings have been successfully shipped to the South Pole after multiple steps of testing. Each mDOM contains 24 photomultipliers nearly isotropically distributed on the surface to achieve uniform photon sensitivity, making the integration and testing complicated. To reduce the amount of testing time, we have developed parallelized and automated software.

Despite extensive efforts, discovery of high-energy astrophysical neutrino sources remains elusive. We present an event-level simultaneous maximum likelihood analysis of tracks and cascades using IceCube data collected from April 6, 2008 to May 23, 2022 to search the whole sky for neutrino sources and, using a source catalog, for coincidence of neutrino emission with gamma-ray emission. This is the first time a simultaneous fit of different detection channels is used to conduct a time-integrated all-sky scan with IceCube. Combining all-sky tracks, with superior pointing-power and sensitivity in the northern sky, with all-sky cascades, with good energy-resolution and sensitivity in the southern sky, we have developed the most sensitive point-source search to date by IceCube which targets the entire sky. The most significant point in the northern sky aligns with NGC 1068, a Seyfert II galaxy, which shows a 3.5$\sigma$ excess over background after accounting for trials. The most significant point in the southern sky does not align with any source in the catalog and is not significant after accounting for trials. A search for the single most significant Gaussian flare at the locations of NGC 1068, PKS 1424+240, and the southern highest significance point shows results consistent with expectations for steady emission. Notably, this is the first time that a flare shorter than four years has been excluded as being responsible for NGC 1068's emergence as a neutrino source. Our results show that combining tracks and cascades when conducting neutrino source searches improves sensitivity and can lead to new discoveries.

The NASA Great Observatories Maturation Program is a development plan to efficiently and effectively develop large, strategic astrophysics missions. Suborbital rocket and balloon programs have long been a key development tool for enabling large missions in NASA astrophysics. We review the significance of these suborbital missions in the preceding decades to demonstrate their contributions to the Great Observatories Maturation Program for the Habitable Worlds Observatory and beyond. We show that suborbital instruments have obtained new science observations of astrophysical sources across the electromagnetic spectrum, matured high-priority component technologies, and served as a training ground for principal investigators of Explorer-class astrophysics satellites. A brief discussion of emerging CubeSat and SmallSat missions and their place in the NASA astrophysics portfolio is also provided.

Comets are primitive remnants of the early Solar System whose composition offers fundamental clues to their formation and evolution. High-resolution, broad-wavelength spectroscopy is crucial for identifying volatile species and constraining the physical conditions within the coma. We aim to characterize the gas composition and physical environment of the newly discovered comet C/2025 N1 through optical and near-infrared spectroscopy. We used a medium-resolution spectrum of comet C/2025 N1 with X-shooter at the ESO Very Large Telescope (VLT), covering the 300-2500 nm wavelength range. Standard data reduction and flux calibration were applied. It corresponds to a spectral slope at least a factor of $\sim1.86$ higher than that of 2I/Borisov. Although the object clearly shows activity, only upper limits to the production rates of OH and CN can be estimated: $8.0\times10^{24}$ s$^{-1}$ and $4.9\times10^{23}$ s$^{-1}$, respectively. We obtained red spectral slopes consistent with those of typical D-type asteroids and outer Solar System objects.

We have investigated the lensing event KMT-2024-BLG-0404. The light curve of the event exhibited a complex structure with multiple distinct features, including two prominent caustic spikes, two cusp bumps, and a brief discontinuous feature between the caustic spikes. While a binary-lens model captured the general anomaly pattern, it could not account for a discontinuous anomaly feature between the two caustic spikes. To explore the origin of the unexplained feature, we conducted more advanced modeling beyond the standard binary-lens framework. This investigation demonstrated that the previously unexplained anomaly was resolved by introducing an additional lens component with planetary mass. The estimated masses of the lens components are $M_{\rm p}= 17.3^{+25.5}_{-8.8}~M_{\rm E}$ for the planet, and $M_{\rm h,A}=0.090^{+0.133}_{-0.046}~M_\odot$ and $M_{\rm h,B}=0.026^{+0.038}_{-0.013}~M_\odot$ for the binary host stars. Based on these mass estimates, the lens system is identified as a planetary system where a Uranus-mass planet orbits a binary consisting of a late M dwarf and a brown dwarf. The distance to the planetary system is estimated to be $D_{\rm L} = 7.21^{+0.93}_{-0.97}$~kpc, with an 82\% probability that it resides in the Galactic bulge. This discovery represents the ninth planetary system found through microlensing with a planet orbiting a binary host. Notably, it is the first case where the host consists of both a star and a brown dwarf.

We present initial results from a planned 10 year survey of Ca II H & K emission, using observations made with the ARC 3.5m Telescope at Apache Point Observatory. The primary goal of the survey is to investigate activity cycles in low mass stars. The sample includes stars chosen from the legacy Mount Wilson survey carried out by Olin Wilson more than 50 years ago, together with newly identified planet-host stars and a select sample of early-mid M dwarfs. This paper presents the first four years of data, comprising 1040 observations of 271 stars, with a specific focus on K and M stars. We identify a subsample of 153 stars for continuing observations over the full 10 year survey. Early results indicate that our data are consistent with the MWO cycle periods over a time span of more than 50 years; that there is a bifurcation in activity in the late K range with separate populations of low and high activity stars at lower masses; and that M dwarf planet hosts tend to be mainly found in the population of low activity stars, even in the unbiased (by activity) TESS sample, potentially indicating a link between activity and planet formation. We have also found indications of possible cyclic variability in some of the lower mass stars in the sample. Our ultimate goal is to link the activity cycle and rotation periods in a robust sample of stars spanning FGKM spectral types and to investigate the implications for the underlying magnetic dynamo.

The theory of galaxy formation posits a clear correlation between the spin of galaxies and the orientation of the elements of the large-scale structure of the Universe, particularly cosmic filaments. A substantial number of observational and modelling studies have been undertaken with the aim of identifying the dependence of spin orientation on the components of the large-scale structure. However, the findings of these studies remain contradictory. In this paper, we present an analysis of the orientation of the spins of 2 861 galaxies with respect to the filaments of the large-scale structure of the Universe. All galaxies in our sample have an inclination to the line of sight greater than 85 degrees, enabling an unambiguous determination of the spin axis direction in space. We investigate the alignment of galaxy spin axes relative to cosmic web filaments as a function of various properties for galaxies. Our results reveal a statistically significant tendency for the galaxy spin axes to align along the filament axes of the large-scale structure.

These notes are very much work-in-progress and simply intended to showcase, in various degrees of details (and rigour), some of the cosmology calculations that class_sz can do. We describe the class_sz code in C, Python and Jax. Based on the Boltzmann code class, it can compute a wide range of observables relevant to current and forthcoming CMB and Large Scale Structure surveys. This includes galaxy shear and clustering, CMB lensing, thermal and kinetic Sunyaev and Zeldovich observables, Cosmic Infrared Background, cross-correlations and three-point statistics. Calculations can be done either within the halo model or the linear bias model. For standard $\Lambda$CDM cosmology and extensions, class_sz uses high-accuracy cosmopower emulators of the CMB and matter power spectrum to accelerate calculations. With this, along with efficient numerical integration routines, most class_sz output can be obtained in less than 500 ms (CMB $C_\ell$'s or matter $P(k)$ take $\mathcal{O}(1\mathrm{ms})$), allowing for fast or ultra-fast parameter inference analyses. Parts of the calculations are "jaxified", so the software can be integrated into differentiable pipelines.

We calculate the second order perturbations driven by oscillation modes of rotating stars. Assuming that the typical amplitude $a$ of oscillation modes is small, we expand the perturbed quantities as $Q=Q^{(0)}+Q^{(1)}+Q^{(2)}+\cdots$ where $Q^{(0)}$ represents the equilibrium state and $Q^{(1)}$ and $Q^{(2)}$ are the first order and second order perturbations in $a$, respectively. We assume that the first order perturbations are given by non-axisymmetric modes and the second order perturbations are axisymmetric. For the second order perturbations, we derive a set of linear partial differential equations, which have inhomogeneous terms due to the first order perturbations. For low frequency $g$- and $r$-modes and overstable convective (OsC) modes of main sequence stars, we calculate the second order velocity field $\mathbf{v}^{(2)}$ and find that prograde $g$-modes and OsC modes tend to accelerate and retrograde $r$-modes to decelerate $v_\phi^{(2)}$ in the surface equatorial regions where $v_\phi^{(2)}$ is the $\phi$ component of $\mathbf{v}^{(2)}$. Using the angular momentum conservation equation derived for waves, we discuss that low frequency $g$- and $r$-modes transport angular momentum between the inner and outer parts of the envelope. For OsC modes in the core resonantly coupled with envelope prograde $g$-modes, we find that they can transport angular momentum from the core to the outer envelope so that they tend to brake the core rotation. We also suggest that the OsC modes provide the outer envelope of rotating stars with the torque enough to support a decretion disc.

We present a strong lensing analysis and reconstruct the mass distribution of SPT-CL J0356-5337, a galaxy cluster at redshift z = 1.034. Our model supersedes previous models by making use of new multi-band HST data and MUSE spectroscopy. We identify two additional lensed galaxies to inform a more well-constrained model using 12 sets of multiple images in 5 separate lensed sources. The three previously-known sources were spectroscopically confirmed by Mahler et al. (2020) at redshifts of z = 2.363, z = 2.364, and z = 3.048. We measured the spectroscopic redshifts of two of the newly-discovered arcs using MUSE data, at z = 3.0205 and z = 5.3288. We increase the number of cluster member galaxies by a factor of three compared to previous work. We also report the detection of extended Lya emission from several background galaxies. We measure the total projected mass density of the two major sub-cluster components, one dominated by the BCG, and the other by a compact group of luminous red galaxies. We find M_BCG(< 80kpc) = 3.93+0.21-0.14 * 10^13Msun and M_LRG(< 80kpc) = 2.92+0.16 -0.23 * 10^13Msun, yielding a mass ratio of 1.35+0.16 -0.08. The strong lensing constraints offer a robust estimate of the projected mass density regardless of modelling assumptions; allowing more substructure in this line of sight does not change the results or conclusions. Our results corroborate the conclusion that SPT-CL J0356-5337 is dominated by two mass components, and is likely undergoing a major merger on the plane of the sky

As of early 2025, the GRAND Collaboration operates three prototype arrays: GRANDProto300 in China, GRAND@Nançay in France, and GRAND@Auger in Argentina. The GRAND@Auger prototype was established through an agreement between the GRAND and Pierre Auger Collaborations, repurposing ten Auger Engineering Radio Array (AERA) stations as GRAND detection units. This setup provides a unique opportunity for coincident air-shower detection, enabling direct event-by-event comparison between GRAND@Auger and the well-established Pierre Auger detectors. Such comparisons allow for a detailed assessment of the detection principle and reconstruction capabilities of GRAND. In this contribution, we present an overview of the commissioning and preliminary results of GRAND@Auger, including the measurement of the Galactic background noise and the detection of the first self-triggered candidate event in coincidence with the Pierre Auger Observatory. Both results underscore the role of GRAND@Auger in advancing the GRAND project and refining the techniques required for large-scale radio detection of ultra-high-energy particles.

The IceCube Neutrino Observatory, located at the geographic South Pole, uses the glacial ice volume to detect astrophysical neutrinos. Detection of the neutrinos from the northern sky provides the opportunity to use a large effective volume. However, as the cross-section increases with energy, most high-energy neutrinos are absorbed by the Earth. On the other hand, probing down-going PeV neutrinos from the southern sky becomes challenging because of the large cosmic ray induced muon backgrounds. This contribution presents a method for classifying atmospheric muon bundles and single muons by analyzing the lateral and longitudinal characteristics of through-going track-like events from the southern sky. Muons generated in cosmic ray air showers form muon bundles, exhibiting a lateral spread spanning tens of meters within IceCube. We explore the time residual feature for the observed Cherenkov light to separate bundles from single muons. We also utilize energy losses along the track, which lead to fluctuations in the light intensity: bundles follow a smooth pattern, whereas single muons are more stochastic. A Boosted Decision Tree algorithm is trained on simulated, well-reconstructed cosmic ray and neutrino events to classify neutrino-induced single muons and cosmic ray bundles.

The GRAVITY interferometer has achieved microarcsecond precision in near-infrared interferometry, enabling tracking of flare centroid motion in the strong gravitational field near the Sgr A*. It might be promising to serve as a unique laboratory for exploring the accretion matter near black holes or testing Einstein's gravity. Recent studies debated whether there is a non-Keplerian motion of the flares in the GRAVITY dataset. It motivates us to present a comprehensive analysis based on error estimation under the Bayesian framework. This study uses asctrometric flare data to investigate the possibility that the flares exhibit deviations from the circular Keplerian motion. By fixing the black hole mass of Sgr A* and using the averaged astrometric data from the four flares, our results find that the super-Keplerian orbit is favored at the near $1\sigma$ confidence level, where the non-Keperian parameter is $\omega/\omega_k=1.45^{+0.35}_{-0.38}$. By treating the black hole mass as a free parameter, both the averaged and individual data exhibit no significant evidence in favor of non-Keplerian motions, where the non-Keplerian parameter is close to $1$ within $1\sigma$ confidence level. We further analyze flares undergoing planar geodesic motion, where the orbital circularity parameter is $\gamma = 0.99_{-0.10}^{+0.07}$. This indicates that the astrometric data favor the circular orbits. Future improvements in astrometry precision might enable stronger constraints on the kinematical behavior of the flares, potentially offering insights into black hole physics or accretion matter in the strong-field regime.

The IceCube Neutrino Observatory is a cubic-kilometer detector located in the Antarctic ice at the geographic South Pole. It reads out over 5,000 photomultiplier tubes (PMTs) to detect Cherenkov light produced by secondary particles, enabling IceCube to identify both atmospheric and astrophysical neutrinos. One of the main challenges in this effort is effectively distinguishing between muons induced by neutrinos and those generated by cosmic-ray air showers. To address this challenge, the Advanced Northern Tracks Selection (ANTS) employs a graph convolutional neural network. This network is designed to utilize both the sensor data and the geometric arrangement of the detector's photomultiplier tubes (PMTs). By representing each module as a node in a graph and extracting features from each module, the network can capture and integrate both local and global features. This work details the implementation of the network architecture and highlights the improvements in background rejection efficiency compared to existing methods for selecting muon tracks.

The IceCube Neutrino Observatory searches for the origins of astrophysical neutrinos using various techniques to overcome the significant backgrounds produced by cosmic-ray air showers. One such technique involves combining the neutrino data with other cosmic messengers to identify spatial and temporal correlations. IceCube contributes to multi-messenger astrophysics (MMA) by providing alerts for interesting events observed in the detector. The Gamma-ray Follow-Up (GFU) cluster alert system is one stream that identifies potential neutrino flares in realtime, producing around 20 alerts per year. GFU-cluster alerts have been privately shared with Imaging Air Cherenkov Telescopes (IACTs) through memoranda of understanding since IceCube's predecessor, AMANDA. To preserve blindness to the full behavior of our data, the current system mutes updates from sources following the initial GFU-cluster alert sent, preventing further updates until the activity drops below the alert threshold. With growing knowledge of the potential environments that produce astrophysical neutrinos and to foster open collaboration, the GFU-cluster alerts will shift to be publicly shared. Additionally, the new alert platform will provide all above-threshold information such that the source behavior after the initial alert is not obscured. The above threshold data will be distributed through an interactive website that will update the community on the status of active GFU-cluster alerts. This presentation will introduce the new GFU-cluster platform and the accompanying website, soon to be accessible to the MMA community.

When ultra-high-energy cosmic rays (UHECRs) interact with ambient photon backgrounds, a flux of extremely-high-energy (EHE), so-called cosmogenic, neutrinos is produced. The observation of these neutrinos with IceCube can probe the nature of UHECRs. We present a search for EHE neutrinos using $12.6 \, \mathrm{years}$ of IceCube data. The non-observation of neutrinos with energies $\gtrsim 10 \, \mathrm{PeV}$ constrains the all-flavor neutrino flux at $1 \, \mathrm{EeV}$ to be below $E^2 \Phi_{\nu_e + \nu_\mu + \nu_\tau} \simeq 10^{-8} \, \mathrm{GeV} \, \mathrm{cm}^{-2} \, \mathrm{s}^{-1} \, \mathrm{sr}^{-1}$, the most stringent limit to date. This constrains the proton fraction in UHECRs of energy above $30 \, \mathrm{EeV}$ to be $\lesssim 70\%$ if the evolution of the UHECR sources is similar to the star formation rate. Our analysis circumvents uncertainties associated with hadronic interaction models in studies of UHECR air showers, which also suggest a heavy composition at such energies.

We analyse ESPRESSO data for the stars HD10700, HD20794, HD102365, and HD304636 acquired via its Guaranteed Time Observations (GTO) programme. We characterise the stars' radial velocity (RV) signals down to a precision of 10 cm/s on timescales ranging from minutes to planetary periods falling within the host's habitable zone (HZ). We study the RV signature of pulsation, granulation, and stellar activity, inferring the potential presence of planets around these stars. Thus, we outline the population of planets that while undetectable remain compatible with the available data. A simple model of stellar pulsations successfully reproduced the intra-night RV scatter of HD10700 down to a few cm/s. For HD102365 and HD20794, an additional source of scatter at the level of several 10 cm/s remains necessary to explain the data. A kima analysis was used to evaluate the number of planets supported by the nightly averaged time series of each of HD10700, HD102365, and HD304636, under the assumption that a quasi-periodic Gaussian process (GP) regression is able to model the activity signal. While a frequency analysis of HD10700 RVs is able to identify a periodic signal at 20d, when it is modelled along with the activity signal the signal is formally non-significant. ESPRESSO data on their own do not provide conclusive evidence for the existence of planets around these three stars. ESPRESSO is shown to reach an on-sky RV precision of better than 10 cm/s on short timescales (<1h) and of 40 cm/s over 3.5 yr. A subdivision of the datasets showcases a precision reaching 20-30 cm/s over one year. These results impose stringent constraints on the impact of granulation mechanisms on RV. In spite of no detections, our analysis of HD10700 RVs demonstrates a sensitivity to planets with a mass of 1.7M$_{\oplus}$ for periods of up to 100 d, and a mass of 2-5M$_{\oplus}$ for the star's HZ. (abridged)

The Giant Radio Array for Neutrino Detection (GRAND) aims to detect and study ultra-high-energy (UHE) neutrinos by observing the radio emissions produced in extensive air showers. The GRANDProto300 prototype primarily focuses on UHE cosmic rays to demonstrate the autonomous detection and reconstruction techniques that will later be applied to neutrino detection. In this work, we propose a method for reconstructing the arrival direction and energy with high precision using state-of-the-art machine learning techniques from noisy simulated voltage traces. For each event, we represent the triggered antennas as a graph structure, which is used as input for a graph neural network (GNN). To significantly enhance precision and reduce the required training set size, we incorporate physical knowledge into both the GNN architecture and the input data. This approach achieves an angular resolution of 0.14° and a primary energy reconstruction resolution of about 15%. Additionally, we employ uncertainty estimation methods to improve the reliability of our predictions. These methods allow us to quantify the confidence of the GNN predictions and provide confidence intervals for the direction and energy reconstruction. Finally, we explore strategies to evaluate the consistency and robustness of the model when applied to real data. Our goal is to identify situations where predictions remain trustworthy despite domain shifts between simulation and reality.

We present a multi-band study of the diffuse emission in the galaxy cluster Abell 3558, located in the core of the Shapley Supercluster. Using new MeerKAT UHF-Band and uGMRT Band-3 observations, and published MeerKAT L-band and ASKAP 887 MHz data, we perform a detailed analysis of the diffuse emission in the cluster centre. We complement with XMM-Newton X-ray information for a thorough study of the connection between the thermal and non-thermal properties of the cluster. We find that the diffuse radio emission in the cluster centre is more extended than published earlier, with a previously undetected extension spanning 100 kpc towards the north beyond the innermost cold front, increasing the total size of the emission to 550 kpc, and shows a clear spatial correlation with the X-ray features. The overall radio spectrum is steep ($\alpha_{\rm 400\,MHz}^{\rm 1569\,MHz}=1.18\pm0.10$), with local fluctuations which show several connections with the X-ray surface brightness, cold fronts, and residual emission. The point-to-point correlation between the radio and X-ray surface brightness is sub-linear, and steepens with increasing frequency. We discuss the classification of the diffuse emission considering its overall properties, those of the ICM, and the existing scaling laws between the radio and X-ray quantities in galaxy clusters. We conclude that it is a mini-halo, powered by turbulent (re)-acceleration induced by sloshing motions within the cluster region delimited by the cold fronts, and it supports the picture of a known minor merger between A\,3558 and the group SC\,1327--312 with mass ratio 5:1.

The ring structures of disk galaxies are vital for understanding galaxy evolution and dynamics. However, due to the scarcity of ringed galaxies and challenges in their identification, traditional methods often struggle to efficiently obtain statistically significant samples. To address this, this study employs a novel semi-supervised deep learning model, GC-SWGAN, aimed at identifying galaxy rings from high-resolution images of the DESI Legacy Imaging Surveys. We selected over 5,000 confirmed ringed galaxies from the Catalog of Southern Ringed Galaxies (CSRG) and the Northern Ringed Galaxies from the GZ2 catalog (GZ2-CNRG), both verified by morphology expert R. J. Buta, to create an annotated training set. Additionally, we incorporated strictly selected non-ringed galaxy samples from the Galaxy Zoo 2 dataset and utilized unlabelled data from DESI Legacy Surveys to train our model. Through semi-supervised learning, the model significantly reduced reliance on extensive annotated data while enhancing robustness and generalization. On the test set, it demonstrated exceptional performance in identifying ringed galaxies. With a probability threshold of 0.5, the classification accuracy reached 97\%, with precision and recall for ringed galaxies at 94\% and 93\%, respectively. Building on these results, we predicted 750,000 galaxy images from the DESI Legacy Imaging Surveys with r-band apparent magnitudes less than 17.0 and redshifts in the range 0.0005 < z < 0.25, compiling the largest catalog of ringed galaxies to date, containing 62,962 galaxies with ring structures. This catalog provides essential data for subsequent research on the formation mechanisms and evolutionary history of galaxy rings.

High-velocity stars are interesting targets to unveil the formation of the Milky Way. In fact they can be recently accreted from an infalling dwarf galaxies or they can be the result of a turbulent merging of galaxies. Gaia is providing the community a way to select stars for their kinematics and the radial velocity, one of the speed components, is derived from the Gaia RVS spectrum. High absolute radial velocity values are sensitive to be false positive. They are rare and as such they are more easily impacted than lower velocity stars, by contamination by very low SNR spurious measures. We here investigate a sample of 26 stars with Gaia absolute radial velocity in excess of 500___km/s with spectroscopic follow-up observations with UVES. For all but one star the extreme radial velocity is confirmed and these stars are all metal-poor and, as expected, enhanced in the elements. The complete chemical inventory confirm the large star-to-star scatter for the heavy elements and their on average larger ratio over iron with respect to the Sun, in agreement with the literature.

Magnetars are likely to be the origin of all fast radio bursts. The recent detection of circularly polarized bursts suggests that they might be generated deep inside magnetar magnetospheres. However, the mechanism behind the circular polarization remains uncertain. Here, we study the propagation of an intense radio pulse in a longitudinally magnetized electron-dominant plasma by particle-in-cell simulations. When the field strength of the radio pulse exceeds the background magnetic field, it can excite a nonlinear plasma wakefield and continually erodes due to energy transfer to the wake. Along the magnetic field, the plasma wakefield launched by the right-circularly polarized pulse is much stronger and more nonlinear than that by the left-circularly polarized pulse. Hence, the erosion rates of the two circularly polarized modes are significantly different. We discover that this asymmetric erosion can generate circularly polarized modes from a linearly polarized pulse at relativistic intensities, even when the cyclotron frequency is much higher than the radio frequency. Finally, we present a proof-of-principle simulation to demonstrate the generation of circularly polarization by this magneto-induced asymmetric erosion in the nonuniform environment of magnetar magnetospheres.

Understanding stars and their evolution is a key goal of astronomical research and has long been a focus of human interest. In recent years, theorists have paid much attention to the final interior processes within massive stars, as they can be essential for revealing neutrino-driven supernova mechanisms and other potential transients of massive star collapse. However, it is challenging to observe directly the last hours of a massive star before explosion, since it is the supernova event that triggers the start of intense observational study. Here we report evidence for a final phase of stellar activity known as a ``shell merger'', an intense shell burning in which the O-burning shell swallows its outer C-/Ne-burning shell, deep within the progenitor's interior moments before the supernova explosion. In the violent convective layer created by the shell merger, Ne, which is abundant in the stellar O-rich layer, is burned as it is pulled inward, and Si, which is synthesized inside, is transported outward. The remnant still preserves some traces of such Ne-rich downflows and Si-rich upflows in the O-rich layer, suggesting that inhomogeneous shell-merger mixing began just hours ($\lesssim 10^4$ s) before its gravitational collapse. Our results provide the first observational evidence that the final stellar burning process rapidly alters the internal structure, leaving a pre-supernova asymmetry. This breaking of spherical symmetry facilitates the explosion of massive stars and influences various supernova and remnant characteristics, including explosion asymmetries and the neutron star's kick and spin.

In this article, we have presented non-relativistic boundary conditions across a magnetohydrodynamic (MHD) shock front propagating in van der Waals gases. The expression for the strength of the non-relativistic MHD shock wave has been obtained, and the Rankine-Hugoniot (R-H) shock jump relations, or boundary conditions, for the pressure, the density, and the particle velocity across an MHD shock front have been derived in terms of a shock compression ratio. The simplified forms of shock jump relations have been written simultaneously for the weak and strong MHD shock waves in terms of the magnetic field strength, the non-idealness parameter, and the ratio of specific heats of the gas. Further, the case of weak shocks has been explored under two distinct conditions, viz., (i) when the applied magnetic field is weak and (ii) when the field is strong, respectively. The case of strong shocks has also been investigated under two distinct ways: (i) as in the purely non-magnetic case, when the ratio of densities on either side of the shock nearly equals $(\gamma+1)/(\gamma-1)$ or (ii) when the applied magnetic field is large. This is when the ambient magnetic pressure is large as compared with the ambient gas pressure. Finally, the effects on the shock strength and the pressure across the MHD shock front are studied due to the magnetic field strength and the non-idealness parameter of the gases. This study presents an overview of the influence of the magnetic field strength and the non-idealness parameter on the shock strength, the pressure, the density, and the particle velocity across the MHD shock front in van der Waals gases.

In massive binary-star systems, supernova explosions can significantly alter the orbit during the formation of compact objects. Some compact objects are predicted to form via direct collapse, a scenario with negligible mass loss and no baryonic ejecta emitted. In this scenario, most of the energy is released via neutrinos, and any resulting natal kick arises from asymmetries in their emission. Here I investigate stellar collapse leading to binary black hole (BH) formation, with a focus on how the natal kick influences the gravitational-wave-driven merger time. Broadly, I find three regimes. For low natal kicks, the effect on the time-to-coalescence is negligible. For moderate natal kicks, if the binary remains bound, up to 50% of binary BHs experience a decrease in their time-to-coalescence by more than an order of magnitude. For large natal kicks, although most binaries become unbound, those that remain bound may acquire retrograde orbits and/or lead to shorter time-to-coalescence. For binary BH mergers, large natal kicks ($\gtrsim100$ km/s) are hard to reconcile with both neutrino natal kicks and the complete collapse scenario. This suggests that retrograde orbits and shortened merger times could only arise in volatile BH formation scenarios or if spin-axis tossing is at work. Consequently, electromagnetic observations of BHs in massive star binaries within the Local Group offer a more effective means to probe the physics behind complete collapse. Another promising population for deciphering the complete collapse scenario is that of massive, wide binaries. Although Gaia may help shed light on these systems, longer observational baselines will likely be needed to fully understand the roles of neutrino natal kicks and stellar collapse in BH formation.

The intensity and energy spectrum of galactic cosmic rays in the heliosphere are significantly influenced by the 11-year solar cycle, a phenomenon known as solar modulation. Understanding this effect and its underlying physical mechanisms is essential for assessing radiation exposure and associated risks during space missions. Starting from a previously developed effective predictive model of solar modulation, validated using cosmic ray flux measurements from space-based detectors such as PAMELA and AMS-02, we build a generalizable forecasting strategy for the long-term evolution of cosmic ray fluxes. This strategy is based on identifying delayed cross-correlation relationships between solar proxies and the model's parameters. It integrates recent findings on time lags between cosmic ray fluxes and solar activity, and incorporates advanced time-series signal processing techniques. The framework not only performs well in reproducing observed data, but also shows strong potential for applications in space radiation monitoring and forecasting. By efficiently capturing the long-term variability of galactic cosmic rays, our approach contributes valuable insights for evaluating radiation risks, ultimately supporting safer and more effective space exploration.

The Euclid space telescope of the European Space Agency (ESA) is designed to provide sensitive and accurate measurements of weak gravitational lensing distortions over wide areas on the sky. Here we present a weak gravitational lensing analysis of early Euclid observations obtained for the field around the massive galaxy cluster Abell 2390 as part of the Euclid Early Release Observations programme. We conduct galaxy shape measurements using three independent algorithms (LensMC, KSB+, and SourceXtractor++). Incorporating multi-band photometry from Euclid and Subaru/Suprime-Cam, we estimate photometric redshifts to preferentially select background sources from tomographic redshift bins, for which we calibrate the redshift distributions using the self-organising map approach and data from the Cosmic Evolution Survey (COSMOS). We quantify the residual cluster member contamination and correct for it in bins of photometric redshift and magnitude using their source density profiles, including corrections for source obscuration and magnification. We reconstruct the cluster mass distribution and jointly fit the tangential reduced shear profiles of the different tomographic bins with spherical Navarro--Frenk--White profile predictions to constrain the cluster mass, finding consistent results for the three shape catalogues and good agreement with earlier measurements. As an important validation test we compare these joint constraints to mass measurements obtained individually for the different tomographic bins, finding good consistency. More detailed constraints on the cluster properties are presented in a companion paper that additionally incorporates strong lensing measurements. Our analysis provides a first demonstration of the outstanding capabilities of Euclid for tomographic weak lensing measurements.

FRB 20180916B is a repeating Fast Radio Burst (FRB) which produces bursts in a 5.1 day active window which repeats with a 16.34 day period. Models have been proposed to explain the periodicity using dynamical phenomena such as rotation, precession or orbital motion. Polarization Position Angle (PA) of the bursts can be used to distinguish and constraint the origin of the long term periodicity of the FRB. We aim to study the PA variability on short (within an observation) and long timescales (from observation to observation). We aim to compare the observed PA variability with the predictions of various dynamical progenitor models for the FRB. We use the calibrated burst dataset detected by uGMRT in Band 4 (650 MHz) which have been published in arXiv:2409.12584 . We transform the PA measured at 650 MHz to infinite frequency such that PAs measured in different observations are consistent, and finally measure the changes within and across active windows. We find that PA of the bursts vary according to the periodicity of the source. We constrain the PA variability to be within seven degrees on timescales less than four hours for all MJDs. In addition, we also tentatively note the PA measured at the same phase in the active window varies from one cycle to another. Using the findings, we constrain rotational, precession and binary progenitor models. Rotational model partially agrees with observed PA variability but requires further study to fully constrain. We robustly rule out all flavors of precessional models where either precession explains the periodicity of the FRB or the variability from one cycle to another. Lastly, we draw similarities between FRB 20180916B and a X-ray binary system, Her X 1, and explicitly note that both the sources exhibit a similar form of PA variability.

We investigate the stochastic gravitational wave background (SGWB) generated by the ringdown phase of primordial black holes (PBHs) formed in the early universe. As the ringdown signal is independent of the PBH formation mechanism, the resulting SGWB offers a model-independent probe of PBHs. We numerically compute the ringdown waveform and derive the corresponding SGWB. We show that such a signal could be detected by future pulsar timing arrays (PTAs) for PBHs heavier than the solar mass. Additionally, we evaluate the SGWB from binary PBH mergers and demonstrate that it lies within the sensitivity bands of next-generation ground-based interferometers such as Cosmic Explorer and Einstein Telescope, suggesting a multi-band observational strategy for probing the PBH dark matter scenario.

The subsurface meridional flow has long been recognized as a critical factor in driving the solar cycle. Specifically, the equatorward return flow in the tachocline is widely believed to be responsible for the formation of the sunspot butterfly diagram and determine the solar cycle period within the framework of flux transport dynamo (FTD) models. We aim to investigate whether the subsurface meridional flow also plays a significant role in the recently developed distributed-shear Babcock-Leighton (BL) dynamo model, which operates within the convection zone, rather than the tachocline. Various meridional flow configurations, including a deep single cell, a shallow single cell, and double cells, are applied in the distributed-shear BL dynamo model to explore the mechanisms driving the butterfly diagram and variations in the cycle period. Subsurface meridional flow plays a minimal role in the distributed-shear BL dynamo. A solar-like butterfly diagram can be generated even with a double-cell meridional flow. The diagram arises from the time- and latitude-dependent regeneration of the toroidal field, governed by latitude-dependent latitudinal differential rotation and the evolution of surface magnetic fields. The cycle period is determined by the surface flux source and transport process responsible for polar field generation, which corresponds to the $\alpha$-effect in the BL-type dynamo. The cycle period may exhibit varying dependence on the amplitude of the subsurface flow. The distributed-shear BL dynamo differs fundamentally from the FTD models, as it does not rely on the subsurface flux transport. This distinction aligns the distributed-shear BL dynamo more closely with the original BL dynamo and the conventional $\alpha\Omega$ dynamo. Although the subsurface meridional flow plays a negligible role in our distributed-shear BL dynamo, the poleward surface flow is essential.

Cosmic ray shower detection using large radio arrays has gained significant traction in recent years. With massive improvements in signal modelling and microscopic simulations, the analysis of incoming events is still severely limited by the simulation cost of radio emission to interpret the data. In this work, we show that a neural network can be used for simulating such radio pulses. We also demonstrate how such a neural network can be used for $X_\mathrm{max}$ reconstruction, while retaining comparable resolution to using full Monte-Carlo CORSIKA/CoREAS simulations for radio emission.

Stellar-mass binary black hole\,(BBH) mergers resulting from binary-single interactions\,(BSIs) in active galactic nucleus\,(AGN) disks are a potential source of gravitational wave\,(GW) events with measurable eccentricities. Previous hydrodynamical simulations have shown that ambient gas can significantly influence the dynamics of BSIs. However, due to limitations such as the use of purely Newtonian dynamics and small sample sizes, a direct estimation of the BBH merger probability during BSI has remained elusive. In this work, we directly quantify the merger probability, based on a suite of 1800 two-dimensional hydrodynamical simulations coupled with post-Newtonian \emph{N}-body calculations. Our results demonstrate that dense gas can enhance the merger probability by both shrinking the spatial scale of the triple system and increasing the number of binary-single encounters. These two effects together boost the merger probability by a factor of $\sim$5, from 4\% to as high as 20\%. Among the two effects, our analysis suggests that the increase in encounter frequency plays a slightly more significant role in driving the enhancement. Moreover, this enhancement becomes more significant at larger radial distances from the central SMBH, since the total gas mass enclosed within the Hill sphere of the triple system increases with radius. Finally, the BSI process in AGN disks can naturally produce double GW merger events within a timescale of $\sim$year, which may serve as potential observational signatures of BSI occurring in AGN disk environments.

The intensities of total, linearly polarized, and unpolarized synchrotron emission are measures for the strengths of total, ordered, and isotropic turbulent fields in the sky plane. Faraday rotation measures (RMs) provide a model of the regular field. The quadratic difference between ordered and regular field strengths yields the strength of the anisotropic turbulent field. - Based on observations of M31 at 3.6 cm, 6.2 cm, and 20.5 cm wavelengths and assuming equipartition between the energy densities of total magnetic fields and total cosmic rays, we measured average equipartition strengths of the magnetic field in the emission torus of M31 of 6.3\pm\0.2 \muG for the total, 5.4\pm0.2 \muG for the isotropic turbulent, and 3.2\pm0.3 \muG for the ordered field in the sky plane. The average strength of the axisymmetric regular field, Breg, is 2.0\pm0.5 \muG and remains almost constant between 7 kpc and 12 kpc radius. Quadratic subtraction of the component Breg,perp in the sky plane from the ordered field Bord,perp yields the strength of the anisotropic turbulent field Ban,perp, which is 2.7\pm0.7 \muG. - The average strength of the regular field is about 40% smaller than the equipartition strength of the ordered field, which is consistent with the assumption of equipartition. The almost constant ratio between regular and isotropic turbulent fields of about 0.39 is consistent with present-day dynamo models. The almost constant ratio between anisotropic and isotropic turbulent fields of about 0.57 indicates that anisotropic turbulent fields are generated by the shearing of isotropic turbulent fields. - The average magnetic energy density is about five times larger than the thermal energy density of the diffuse warm ionized gas, while the magnetic energy density is similar to the kinetic energy density of turbulent motions of the neutral gas.

Data collected so far by the Pierre Auger Observatory have enabled major advances in ultra-high energy cosmic ray physics and demonstrated that improved determination of masses of primary cosmic-ray particles, preferably on an event-by-event basis, is necessary for understanding their origin and nature. Improvement in primary mass measurements was the main motivation for the upgrade of the Pierre Auger Observatory, called AugerPrime. As part of this upgrade, scintillator detectors are added to the existing water-Cherenkov surface detector stations. By making use of the differences in detector response to the electromagnetic particles and muons between scintillator and water-Cherenkov detectors, the electromagnetic and muonic components of cosmic-ray air showers can be disentangled. Since the muonic component is sensitive to the primary mass, such combination of detectors provides a powerful way to improve primary mass composition measurements over the original Auger surface detector design. In this paper, the so-called Scintillator Surface Detectors are discussed, including their design characteristics, production process, testing procedure and deployment in the field.

SIMP-0136 is a T2.5 brown dwarf whose young age ($200\pm50$~Myr) and low mass ($15\pm3$~M$_{\rm Jup}$) make it an ideal analogue for the directly imaged exoplanet population. With a 2.4 hour period, it is known to be variable in both the infrared and the radio, which has been attributed to changes in the cloud coverage and the presence of an aurora respectively. To quantify the changes in the atmospheric state that drive this variability, we obtained time-series spectra of SIMP-0136 covering one full rotation with both NIRSpec/PRISM and the MIRI/LRS on board JWST. We performed a series of time-resolved atmospheric retrievals using petitRADTRANS in order to measure changes in the temperature structure, chemistry, and cloudiness. We inferred the presence of a ~250 K thermal inversion above 10 mbar of SIMP-0136 at all phases, and propose that this inversion is due to the deposition of energy into the upper atmosphere by an aurora. Statistical tests were performed in order to determine which parameters drive the observed spectroscopic variability. The primary contribution was due to changes in the temperature profile at pressures deeper than 10 mbar, which resulted in variation of the effective temperature from 1243 K to 1248 K. This changing effective temperature was also correlated to observed changes in the abundances of CO2 and H2S, while all other chemical species were consistent with being homogeneous throughout the atmosphere. Patchy silicate clouds were required to fit the observed spectra, but the cloud properties were not found to systematically vary with longitude. This work paints a portrait of an L/T transition object where the primary variability mechanisms are magnetic and thermodynamic in nature, rather than due to inhomogeneous cloud coverage.

The early spectra of the kilonova (KN) AT2017gfo following the binary neutron star merger GW170817 exhibit numerous features shaped by r-process nucleosynthesis products. Although a few species were tentatively detected, no third-peak elements were unambiguously identified, as the amount of atomic data required for radiative transfer modeling is immense. Although comprehensive atomic data, including atomic opacities, is now available for many elements, wavelength-calibrated data remains limited to a select few ions. To examine the atomic opacities of all singly and doubly ionized lanthanides, from La (Z = 57) to Yb (Z = 70), we perform atomic structure calculations using the FAC code. Our calculations incorporate an innovative optimization of the local central potential and the number of configurations considered, alongside a calibration technique aimed at enhancing agreement between theoretical and experimental atomic energy levels. We assess the accuracy of the computed data, including energy levels and electric dipole (E1) transition strengths, as well as their impact on KN opacities. We find that strong transitions ($\log(gf)>-1$) are in good agreement with both experiments and semi-empirical calculations. For ions with substantial experimental data, the computed opacities exhibit good agreement with prior calculations. By calibrating low-lying energy levels with experimental data, we have identified 66,591 transitions with experimentally calibrated wavelength information, rendering future lanthanide line identifications through radiative transfer modeling feasible. In total, our calculations encompass 28 ions, yielding 146,856 energy levels below the ionization threshold and 28,690,443 transitions among these levels.

Recent observations of DESI hint that dark matter (DM) may not be cold but have a non-zero equation of state (EoS) parameter, and that dark energy (DE) may not be a cosmological constant. In this work, we explore the possibility of a non-zero DM EoS parameter within the framework of dynamical DE. We perform analysis by using the latest baryon acoustic oscillation (BAO) data from DESI DR2, the cosmic microwave background (CMB) data from Planck, and the type Ia supernova (SN) data from DESY5 and PantheonPlus. When using the combination of CMB, BAO, and SN data, our results indicate a preference for a non-zero DM EoS parameter at the $2.8\sigma$ and $3.3\sigma$ level within the content of a constant DE EoS. In contrast, for a time-evolving DE EoS parameterized by $w_0$ and $w_a$, this preference decreases to $0.8\sigma$ and $1.1\sigma$. Furthermore, allowing a non-zero DM EoS yields best-fit values of $w_0$ and $w_a$ that exhibit smaller deviations from the $\Lambda$CDM expectations, and Bayesian evidence analysis shows a comparable preference for this model relative to $\Lambda$CDM. The overall results of this work indicate that a non-zero DM EoS parameter warrants further exploration and investigation.

The next generation neutrino telescope, IceCube-Gen2, will be sensitive to the astrophysical and cosmogenic flux of neutrinos across a broad energy range, from the TeV to the EeV scale. The planned design includes 8 cubic kilometers of ice instrumented with approximately 10,000 optical sensors, a surface array, and a radio array of antennas embedded in the ice laid out sparsely over 500 km^2. The radio array provides sensitivity to ultra-high energy neutrinos using independent radio stations that can trigger on Askaryan emission from neutrino interactions in the ice. In this contribution, we present the design for the radio array along with its planned implementation, which is expected to increase sensitivity to neutrinos with energies beyond 100PeV by at least an order of magnitude over existing arrays. Furthermore, we will quantify the expected science output by presenting measurement forecasts for the main science cases of diffuse flux and point source discovery, as well as cross-section and flavor measurements.

We propose a method for estimating the Fisher score--the gradient of the log-likelihood with respect to model parameters--using score matching. By introducing a latent parameter model, we show that the Fisher score can be learned by training a neural network to predict latent scores via a mean squared error loss. We validate our approach on a toy linear Gaussian model and a cosmological example using a differentiable simulator. In both cases, the learned scores closely match ground truth for plausible data-parameter pairs. This method extends the ability to perform Fisher forecasts, and gradient-based Bayesian inference to simulation models, even when they are not differentiable; it therefore has broad potential for advancing cosmological analyses.

Large-scale primordial perturbations have been well constrained by current cosmological observations, but the properties of small-scale perturbations remain elusive. This study focuses on second-order tensor-scalar induced gravitational waves (TSIGWs) generated by large-amplitude primordial scalar and tensor perturbations on small scales. We provide the analytical expressions for the kernel functions and the corresponding energy density spectra of second-order TSIGWs. By combining observations of SGWB across different scales, TSIGWs can be used to constrain small-scale primordial curvature perturbations and primordial gravitational waves. Furthermore, we discuss the feasibility of TSIGWs dominating the current PTA observations under various primordial power spectra scenarios. Our results indicate that TSIGWs generated by monochromatic primordial power spectra might be more likely to dominate the current PTA observations.

NASA's Kepler mission identified over 4000 extrasolar planets that transit (cross in front of) their host stars. This sample has revealed detailed features in the demographics of planet sizes and orbital spacings. However, knowledge of their orbital shapes - a key tracer of planetary formation and evolution - remains far more limited. We present measurements of eccentricities for 1646 Kepler planets, 92% of which are smaller than Neptune. For all planet sizes, the eccentricity distribution peaks at e=0 and falls monotonically toward zero at e=1. As planet size increases, mean population eccentricity rises from $\langle e \rangle = 0.05 \pm 0.01$ for small planets to $\langle e \rangle = 0.20 \pm 0.03$ for planets larger than $\sim$ 3.5 Earth-radii. The overall planet occurrence rate and planet-metallicity correlation also change abruptly at this size. Taken together, these patterns indicate distinct formation channels for planets above and below $\sim$ 3.5 Earth-radii. We also find size dependent associations between eccentricity, host star metallicity, and orbital period. While smaller planets generally have low eccentricities, there are hints of a noteworthy exception: eccentricities are slightly elevated in the ``radius valley,'' a narrow band of low occurrence rate density which separates rocky ``super-Earths'' (1.0-1.5 Earth-radii) from gas-rich ``sub-Neptunes'' (2.0-3.0 Earth-radii. We detect this feature at $2.1\sigma$ significance. Planets in single- and multi-transiting systems exhibit the same size-eccentricity relationship, suggesting they are drawn from the same parent population.

Neural networks (NNs) have a great potential for future neutrino telescopes such as IceCube-Gen2, the planned high-energy extension of the IceCube observatory. IceCube-Gen2 will feature new optical sensors with multiple photomultiplier tubes (PMTs) designed to provide omnidirectional sensitivity. Neural networks excel at handling high-dimensional problems and can naturally incorporate the increased complexity of these new sensors. Additionally, their fast inference time makes them promising candidates for handling the high event rates expected from IceCube-Gen2. This contribution presents potential applications of neural networks in the IceCube-Gen2 in-ice optical array. First, we introduce a method to simulate the IceCube-Gen2 optical modules' photon acceptance using a NN that leverages the modules' inherent symmetries. Secondly, we present the status of neutrino NN-based reconstruction efforts, including the adaptation of a novel IceCube technique that combines normalizing flows with transformer NNs. Finally, we describe current progress in noise cleaning applications based on node classification with graph neural networks (GNNs), a method that has already shown promising results for the forthcoming low-energy extension, IceCube-Upgrade.

The identification of potential sources of ultra-high-energy cosmic rays (UHECRs) remains challenging due to magnetic deflections and propagation losses, which are particularly strong for nuclei. In previous iterations of this work, we proposed an approach for UHECR astronomy based on Bayesian inference through explicit modelling of propagation and magnetic deflection effects. The event-by-event mass information is expected to provide tighter constraints on these parameters and to help identify unknown sources. However, the measurements of the average mass through observations from the surface detectors at the Pierre Auger Observatory already indicate that the UHECR masses are well represented through its statistical average. In this contribution, we present our framework which uses energy and mass moments of $\ln A$ to infer the source parameters of UHECRs, including the mass composition at the source. We demonstrate the performance of our model using simulated datasets based on the Pierre Auger Observatory and Telescope Array Project. Our model can be readily applied to currently available data, and we discuss the implications of our results for UHECR source identification.

Jet luminosity from active galaxies and the rate of star formation have recently been found to be uncorrelated observationally. We show how to understand this in the context of a model in which powerful AGN jets enhance star formation for up to hundreds of millions of years while jet power decreases in time, followed by a longer phase in which star formation is suppressed but coupled to jet power increasing with time. We also highlight characteristic differences depending on environment richness in a way that is also compatible with the observed SEDs of high redshift radio galaxies. While the absence of a direct correlation between jet power and star formation rate emerges naturally, our framework allows us to also predict the environment richness, range of excitation and redshift values of radio AGN in the jet power-star formation rate plane.

The LIGO Scientific, Virgo, and KAGRA collaboration has identified two binary neutron star merger candidates, GW170817 and GW190425, along with several binary black hole candidates. While GW170817 was confirmed as a BNS merger through its electromagnetic counterparts, GW190425 lacked such observations, leaving its classification uncertain. We examine the possibility that GW190425 originated from black holes that merged after dark matter accretion caused their progenitor neutron stars to implode. Using this event, we place constraints on dark matter parameters, such as its mass and interaction cross section. We simulate GW190425-like events and analyze them using future gravitational wave detector networks, including upcoming upgrades to current detector networks and next-generation observatories. We show that a network with A+ sensitivity can not classify a GW190425-like event with sufficient confidence. Detector networks with A# sensitivity can classify such events only if the neutron stars follow a relatively stiff equation of state, whose stronger tidal imprint differs measurably from a binary black hole waveform. Next-generation observatories like the Einstein Telescope and Cosmic Explorer recover the tidal signature even for soft, compact stars, enabling confident classification. Finally, we forecast the dark matter constraints that future gravitational wave networks could achieve for similar events.

Infrared (IR) radiation dominates dense, interstellar clouds, yet its effect on icy grains remains largely unexplored. Its potential role in driving the photodesorption of volatile species from such grains has recently been demonstrated, providing a crucial link between the solid state reservoir of molecules and the gas phase. In this work, we investigate IR-induced photodesorption of CO for astrophysically relevant ice systems containing perhydropyrene (PHP). This fully superhydrogenated version of pyrene is used as an analogue for large carbonaceous molecules such as polycyclic aromatic hydrocarbons (PAHs) and related species, as well as hydrogenated carbonaceous grains. The abundance and range of strong IR absorption bands of these carbonaceous species make them interesting candidates for IR-induced effects. We present IR spectroscopic and mass spectrometric measurements probing the effects of IR radiation on two ice systems: a layered ice with CO on top of PHP, and a CO:PHP mixed ice. These ices were irradiated with IR radiation from the FELIX IR Free Electron Laser (FEL) FEL-2. In accordance with previous studies, we confirm that direct excitation of CO is not an efficient pathway to CO desorption, indicating that another energy dissipation mechanism exists. We demonstrate that vibrational excitation of the PHP CH stretching modes leads to efficient CO photodesorption. The derived photodesorption yields are an order of magnitude higher for the layered than the mixed system and comparable to those previously obtained for CO photodesorption from CO on amorphous solid water upon excitation of H$_2$O vibrational modes. Our results indicate that IR excitation of carbonaceous molecules and grains in dense clouds could potentially play an important role in the desorption of volatile species such as CO from icy grains.

In fuzzy dark matter scenarios, the quantum wave nature of ultralight axion-like particles generates stochastic density fluctuations inside dark matter halos. These fluctuations, known as granules, perturb the orbits of subhalos and other orbiting bodies. While previous studies have simulated these effects using N-body techniques or modeled them statistically using diffusion approximations, we propose an alternative framework based on representing the perturbations as a Fourier series with random coefficients, which can be applied to individual orbits, not just populations. We extend the model to finite-size subhalos, identifying a critical length scale below which subhalos behave as point-mass particles. In contrast, larger subhalos exhibit suppressed perturbations from granules due to their extended mass profiles. Using FDM-Simulator, we validate our finite-size model by isolating granule accelerations and confirming their statistical effects on subhalo dynamics.

All gravitational-wave signals are inevitably gravitationally lensed by intervening matter as they propagate through the Universe. When a gravitational-wave signal is magnified, it appears to have originated from a closer, more massive system. Thus, high-mass outliers to the gravitational-wave source population are often proposed as natural candidates for strongly lensed events. However, when using a data-driven method for identifying population outliers, we find that high-mass outliers are not necessarily strongly lensed, nor will the majority of strongly-lensed signals appear as high-mass outliers. This is both because statistical fluctuations produce a larger effect on observed binary parameters than does lensing magnification, and because lensing-induced outliers must originate from intrinsically high-mass sources, which are rare. Thus, the appearance of a single lensing-induced outlier implies the existence of many other lensed events within the catalog. We additionally show that it is possible to constrain the strong lensing optical depth, which is a fundamental quantity of our Universe, with the detection or absence of high-mass outliers. However, constraints using the latest gravitational-wave catalog are weak$\unicode{x2014}$we obtain an upper limit on the optical depth of sources at redshift $1$ magnified by a factor of $5$ or more of $\tau(\mu\geq5,z=1)\leq 0.035 \unicode{x2014}$and future observing runs will not make an outlier-based method competitive with other probes of the optical depth. Future work will investigate the ability of the full inferred population of compact binaries to inform the distribution of lenses in the Universe, opening a unique opportunity to access the high-redshift Universe and constrain cosmic structures.

Spatially resolved observations of the Sun and the astronomical sample size of stellar bodies are the respective key strengths of solar and stellar observations. However, the large difference in object brightness between the Sun and other stars has led to distinctly different instrumentation and methodologies between the two fields. We produce and analyze synthetic full-disk spectra derived from 19 small area field-of-view optical observations of solar flares acquired by the Swedish 1-m Solar Telescope (SST) between 2011 and 2024. These are used to investigate what can and cannot be inferred about physical processes on the Sun from Sun-as-a-star observations. The recently released Numerical Empirical Sun-as-a-Star Integrator (NESSI) code provides synthetic full-disk integrated spectral line emission based on smaller field-of-view input, accounting for center-to-limb variations and differential rotation. We use this code to generate pseudo-Sun-as-a-star spectra from the SST observations. ...

We measure the angular power spectrum and bispectrum of the projected overdensity of photometric DESI luminous red galaxies, and its cross-correlation with maps of the Cosmic Microwave Background lensing convergence from \planck. This analysis is enabled by the use of the ``filtered-squared bispectrum'' approach, introduced in previous work, which we generalise here to the case of cross-correlations between multiple fields. The projected galaxy bispectrum is detected at very high significance (above $30\sigma$ in all redshift bins), and the galaxy-galaxy-convergence bispectrum is detected above $5\sigma$ in the three highest-redshift bins. We find that the bispectrum is reasonably well described over a broad range of scales by a tree-level prediction using the linear galaxy bias measured from the power spectrum. We carry out the first cosmological analysis combining projected power spectra and bispectra under a relatively simple model, and show that the galaxy bispectrum can be used in combination with the power spectrum to place a constraint on the amplitude of matter fluctuations, $\sigma_8$, an on the non-relativistic matter fraction $\Omega_m$. We find that data combinations involving the galaxy bispectrum recover constraints on these parameters that are in good agreement with those found from the traditional ``2$\times$2-point'' combination of galaxy-galaxy and galaxy-convergence power spectra, across all redshift bins.

We represent excursion sets of smooth random fields as unions of a topological basis consisting of a sequence of simply and multiply connected compact subsets of the underlying manifold. The associated coefficients, which are non-negative discrete random variables, reflect the randomness of the field. Betti numbers of the excursion sets can be expressed as summations over the coefficients, and the Euler characteristic and the sum of Betti numbers can also be expressed as their (alternating) sum. This enables understanding their statistical properties as sums (or differences) of discrete random variables. We examine the conditions under which each topological statistic can be asymptotically Gaussian as the size of the manifold and the resolution increase. The coefficients of the basis elements are then modeled as Binomial variables, and the statistical natures of Betti numbers, Euler character and sum of Betti numbers follow from this fundamental property. We test the validity of the modeling using numerical calculations, and identify threshold regimes where the topological statistics can be approximated as Gaussian variables. The new representation of excursion sets thus maps the properties of topological statistics to combinatorial structures, thereby providing mathematical clarity on their use for physical inference, particularly in cosmology.

We investigate the hyperonic equation of state within the non-linear derivative model that incorporates a momentum dependence on the interactions, with a special emphasis on properly establishing the conditions for hyperon appearance in neutron star matter. We demonstrate that hyperons can appear at finite momentum, forming a so-called ``moat" region, even when they are absent at lower momenta. Our study shows that this phenomenon significantly alters the composition and equation of state of hyperonic matter as compared to the cases when it is disregarded, highlighting the importance of accurately treating the momentum dependence of the baryon fields in dense matter.

Axion-like particles (ALPs), hypothetical particles beyond the Standard Model, are considered as promising dark matter candidates. ALPs can convert into photons and vice versa in a magnetic field via the Primakoff effect, potentially generating detectable oscillation in $\gamma$-ray spectra. This study analyzes 16.5 years of data from the Fermi Large Area Telescope (Fermi-LAT) on NGC 1275, the brightest galaxy in the Perseus cluster, to constrain the ALP parameter space. Our results improve the previous 95\% exclusion limits of the photon-ALP coupling $g_{a\gamma}$ by a factor of 2 in the ALP mass range of $4\times 10^{-10}\,\mathrm{eV}\lesssim m_{a}\lesssim 5\times 10^{-9}\,\mathrm{eV}$. Moreover, we investigate the projected sensitivity of the future Very Large Area $\gamma$-ray Space Telescope (VLAST) on searching for ALPs. We find that (i) the expected sensitivity on the ALP-photon coupling can be stronger than that from the upcoming International Axion Observatory (IAXO) in the ALP mass range of $2\times 10^{-11}\,\mathrm{eV}\lesssim m_{a}\lesssim 1\times 10^{-7}\,\mathrm{eV}$, with the best sensitivity of $g_{a\gamma}\sim 7\times 10^{-13}\,\mathrm{GeV^{-1}}$ at $m_{a}\sim 2\times 10^{-10}\,\mathrm{eV}$; (ii) VLAST can extend the sensitivity of the ALP masses below $5\times 10^{-12}\,\mathrm{eV}$, where the ALP-photon coupling $g_{a\gamma}\gtrsim 1.5\times 10^{-11}\,\mathrm{GeV^{-1}}$ will be excluded; (iii) the entire parameter space of ALP accounting for TeV transparency can be fully tested. These results demonstrate that VLAST will offer an excellent opportunity for ALPs searches.