Papers for Friday, Sep 05 2025

The radius valley -- a deficit of exoplanets between super-Earths and sub-Neptunes -- is a key diagnostic of planet formation and atmospheric evolution. We investigate how the radius valley depends on stellar type by analyzing an updated, transit-only sample of exoplanets from the NASA Exoplanet Archive. Planets are selected with $P < 100$ days and divided by host spectral class (M, K, G, F). We construct weighted radius distributions and apply statistical tests to quantify the valley depth. We recover a pronounced valley centered near $\sim 1.8\,R_\oplus$ for G/K stars, but shifted to $\sim 1.6\,R_\oplus$ for M dwarfs and $\sim 1.9\,R_\oplus$ for F stars. These results support the view that the radius valley is shaped by stellar-dependent processes such as photoevaporation, core-powered mass loss, and orbital migration.

[Abridged] The LiteBIRD mission aims to measure the Cosmic Microwave Background (CMB) polarization with unprecedented precision, targeting the detection of primordial B modes and a precise determination of the tensor-to-scalar ratio r. A central component of LiteBIRD are the polarization modulators based on Half-Wave Plates (HWP). In this work, we investigate systematic effects caused by a small, constant misalignment between the reflective HWP's rotation axis and optical axis, which mimics a wedge-like effect. This effect can introduce HWP-synchronous pointing errors, biasing polarization measurements and generating spurious B modes. Using the LiteBIRD simulation framework, we implement this wedge-like misalignment in time-ordered data and evaluate its impact on reconstructed maps and angular power spectra. Our results show that the contamination predominantly mimics lensing B modes rather than primordial tensor modes, and its impact is reduced when increasing the number of detectors. By estimating the resulting error on the tensor-to-scalar ratio, we set constraints on the maximum allowable wedge angle to ensure systematic effects remain below mission requirements. This study emphasizes the critical importance of precise optical alignment in CMB polarization experiments. Future work will address the additional effects of time-dependent HWP wobbling and more realistic scenarios with non-ideal detector pairs.

The orbits of stars around Sgr A*, the Milky Way's supermassive black hole, provide a unique laboratory for testing its environment with unprecedented precision. In this work, we compute the apsidal precession induced by extended matter distributions through Lagrange's equations and compare it with the measured precession of S2, reproducing and extending GRAVITY's constraints. In particular, we push bounds on boson clouds to larger gravitational couplings $\alpha$ and to the second-fastest superradiant mode. We also show that environments with mass of order $1\%$ of Sgr A* drive stellar orbits to decay by dynamical friction within a few Myr. The inner star cluster is however efficiently replenished, masking this effect observationally. We also show that orbital resonances from boson clouds have no impact on relevant timescales. While S2 currently provides the cleanest dataset, our framework is readily applicable to other stars that we identify as particularly promising, whose orbits will be measured with increasing accuracy, opening up new opportunities to probe the environment of Sgr A*.

The recent observations of highly accreting supermassive black holes (SMBH) at very high redshift ($>$4) with the James Webb Space Telescope (JWST) allowed us to shed light for the very first time on the early evolutionary phases of active galactic nuclei (AGN). Perhaps unsurprisingly, several of the physical properties observed in these new objects, including those known as little red dots (LRDs), are closely reminiscent of the low-mass and high-Eddington AGN in the local Universe, and in particular of the class of narrow-line Seyfert 1 (NLS1) galaxies. However, some differences also emerged, likely due to the radically different evolutionary path and the environment where LRDs and NLS1s live. In this work, we review the multiwavelength properties of local NLS1s and compare them with type 1 AGN found at high-$z$, showing that despite some differences, the study of NLS1s can be extremely useful to better understand the extreme accretion physics of high-$z$ quasars and the early stages of AGN evolution.

Over the last two decades, the Sun has been observed to be depleted in refractory elements as a function of elemental condensation temperature (\tcond) relative to $\sim 80\%$ of its counterparts. We assess the impact of Galactic chemical evolution (GCE) on refractory element--\tcond\ trends for 109,500 unique solar analogs from the GALAH, APOGEE, Gaia RVS, and \cite{bedell18} surveys. We find that a star's \feh\ and \alphafe\ are indicators of its \tcond\ slope (\rsq\ = $15 \pm 5$, $23 \pm 10\%$ respectively) while \teff\ and \logg\ contribute more weakly (\rsq\ = $9 \pm 5$, $13 \pm 16\%$). The Sun's abundance pattern resembles that of more metal-rich (0.1 dex) and $\alpha$-depleted stars ($-0.02$ dex), suggesting a connection to broader GCE trends. To more accurately model stars' nucleosynthetic signatures, we apply the K-process model from \cite{Griffith24}, which casts each star's abundance pattern as a linear combination of core-collapse and Type Ia supernovae contributions. We find the Sun appears chemically ordinary in this framework, lying within $0.5\sigma$ of the expected solar analog abundance distribution. We show that refractory element--\tcond\ trends arise because elements with higher \tcond\ have higher contributions from core-collapse supernovae. Refractory element depletion trends primarily reflect nucleosynthetic enrichment patterns shaped by GCE and local ISM inhomogeneities, with these processes accounting for $93\%$ of the observed variation within 2$\sigma$. This work highlights how abundance diversity due to local and global chemical enrichment may often mask and mimic population-scale signatures of planet-related processes.

We aim to study the clustering of metal absorption lines and the structures that they arise in as a function of cosmic time. We focus on C IV and Si IV absorption features that are identified along a given quasar sightline. We exploit the two-point correlation function (2PCF) to investigate the clustering of these structures as a function of their separation. We utilise the E-XQR-30 data to perform a novel analysis at z>5. We also draw on literature surveys (including XQ-100) of lower redshift quasars to investigate the possible evolution of this clustering towards cosmic noon (i.e., z~2-3). We find no significant evolution with redshift when considering the separation of absorbers in velocity space. Since we are comparing data across a large interval of cosmic time, we also consider the separation between absorbers in the reference frame of physical distances. In this reference frame, we find that the amplitude of the clustering increases with cosmic time for both C IV and Si IV on the scales of <1500 physical kpc. For the first time, we assess the 2PCF of C IV and Si IV close to the epoch of reionisation utilising the absorber catalogue from the E-XQR-30 survey. We compare this with lower redshift data and find that, on small scales, the clustering of these structures grows with cosmic time. We compare these results to the clustering of galaxies in the GAEA simulations. It appears that the structures traced by C IV are broadly comparable to the galaxies from the considered simulations. The clustering is most similar to that of the galaxies with virial masses M~10^10.5 M_sun. We require tailor-made simulations to investigate the full range of factors contributing to the observed clustering. Future ground-based spectrographs will further facilitate surveys of absorbers at this epoch with increased sensitivity.

We investigate the star formation activity and black hole scaling relations in a sample of 1451 AGN hosted by dwarf galaxies at redshift 0.5 to 0.9, drawn from the VIPERS survey. The sample comprises Seyferts and LINERs identified through emission-line diagnostics, as well as IR-selected AGN based on WISE colors. Using the parameter SFRnorm, defined as the ratio of the SFR of a galaxy hosting an AGN to the median SFR of star-forming galaxies of similar stellar mass and redshift, we compare AGN hosts to a control sample of non-AGN star-forming galaxies. We examine how SFRnorm varies with AGN power ([O III] luminosity), black hole mass, local environment, and stellar population age. We also analyze the MBH-Mstar relation and the evolution of the MBH/Mstar ratio, incorporating comparisons to X-ray AGN and high-redshift quasars (z > 4). Our key findings are: (i) all AGN populations show suppressed star formation at low AGN luminosities, with SFRnorm rising above unity at different luminosity thresholds depending on AGN type; (ii) LINERs show flat SFRnorm trends with MBH, remaining broadly consistent with unity; Seyferts display a mild increase with MBH, while IR AGN show a more pronounced positive trend; (iii) LINERs exhibit older stellar populations than Seyferts; (iv) at fixed stellar mass, Seyferts host more massive black holes than LINERs, with IR AGN falling in between; (v) the MBH/Mstar ratio is elevated relative to local scaling relations and remains approximately constant with redshift, in agreement with high-z AGN; (vi) the ratio decreases with stellar mass up to log(Mstar/Msun) approximately 11, beyond which it flattens toward values consistent with those of local, inactive galaxies, with this trend clearest for Seyferts and IR AGN. These results suggest that AGN in dwarf galaxies follow diverse evolutionary pathways shaped by gas availability, feedback, and selection effects.

Transient events associated with supermassive black holes provide rare opportunities to study accretion and the environments of supermassive black holes. We present a multiwavelength study of AT2020adpi (ZTF20acvfraq), a luminous optical/UV transient in the nucleus of the galaxy WISEA J231853.77$-$103505.6 ($z=0.26$) that exhibits the properties of an ambiguous nuclear transient. Near peak, its spectral energy distribution is well described by a power law ($\lambda L_\lambda \propto \lambda^{-\alpha}$, $\alpha = 0.44 \pm 0.04$), with a maximum $g$-band luminosity of $(3.6 \pm 0.6)\times10^{44}$ erg s$^{-1}$, which is consistent with luminous AGN flares. We detect a strong mid-infrared flare ($L_\mathrm{peak}^{\mathrm{MIR}} = (2.3 \pm 0.05)\times10^{44}$ erg s$^{-1}$) delayed by $\sim$240 rest-frame days, indicating a hot dust echo from material at $\sim$0.2 pc. The optical and near-infrared spectra show broad H, He I, [OIII] lines, as well as narrow Fe II, and prominent Mg II, which is a combination not typical of TDEs. Taken together, these features suggest AT2020adpi is an ambiguous nuclear transient, where an accretion episode was triggered by stellar disruption of an accretion disk or instabilities within an active nucleus. This source demonstrates the need for careful multiwavelength analysis to distinguish between extreme AGN variability and TDEs.

We study the phase shift that free-streaming neutrinos imprint on the 21-cm power spectrum during cosmic dawn, computing for the first time its effect on both density- and velocity-induced acoustic oscillations. Neutrinos are known to generate a characteristic phase shift in the acoustic oscillations of the photon-baryon plasma before recombination, a signature already detected in the cosmic microwave background (CMB) as well as the spectrum of baryon acoustic oscillations (BAOs) extracted from galaxy surveys. We show that in the 21-cm signal this phase shift is distinct from that observed in the CMB and BAO spectra, exhibiting a characteristic mode and redshift dependence arising from the additional contribution of the so-called velocity acoustic oscillations (VAOs), sourced by the baryon-dark matter relative velocities. Our results establish the phase of acoustic oscillations in the 21-cm spectrum as a promising new avenue for probing free-streaming light relics at cosmic dawn, complementary to existing CMB and BAO measurements.

Next-generation surveys are expected to uncover thousands of globular cluster (GC) stellar streams, motivating the need for a theoretical framework that produces realistic GC streams in a fully cosmological, Milky Way-like environment. We present $\textsf{CosmoGEMS}$, a star-by-star cosmological GC stream framework that self-consistently links small-scale cluster physics with large-scale Galactic dynamics. The initial phase-space positions of stream stars are informed by post-processed GC populations within the FIRE cosmological simulation. Escaped stars are orbit-integrated from their time of escape to the present day in a time-evolving Galactic potential extracted from the same simulation using a basis function expansion. We explore two example streams on different orbits. One forms a long, thin stream with a velocity dispersion consistent with Milky Way GC streams. However, it exhibits a clump and orbital-phase-dependent misalignments due to the evolving potential. The other stream develops both a thin component and a diffuse, shell-like structure, similar to features observed in streams like Jhelum. These results highlight the power of fully cosmological models in producing realistic stream morphologies and kinematics. Unlike idealized simulations, our models naturally incorporate time-dependent changes in the progenitor's orbit, including orbital plane evolution, which significantly affects stream structure. This challenges common assumptions in stream-finding algorithms and interpretation. $\textsf{CosmoGEMS}$ provides a key step toward connecting future stellar stream observations with the physics of globular cluster evolution and hierarchical galaxy formation in a cosmological context.

Gravitational wave standard sirens offer a promising avenue for cosmological inference, particularly in measuring the expansion history of the universe. Traditionally, bright sirens require an electromagnetic counterpart to determine the redshift of the emission source while dark sirens rely on the presence of complete galaxy catalogs over large sky regions. Spectral sirens, using GW data alone, can circumvent these limitations by leveraging features in the mass distribution of compact binaries. With the recent release of the Gravitational-Wave Transient Catalog 4 (GWTC-4.0), the number of significant binary black hole (BBH) merger candidates has increased to 153, enabling more robust population studies and cosmological constraints. This work builds upon previous spectral siren analyses by analyzing the latest BBH observations with parametric and non-parametric models. In particular, we consider a parametric approach using the Powerlaw + Peak and Broken Powerlaw + 2 Peaks models as well as a more flexible non-parametric model based on Gaussian processes. We find broad consistency in the inferred Hubble constant $H_0$ constraints across models. Our most constraining result is from the Gaussian Process model, which, combined with the GW170817 bright siren measurement, results in $H_0 = 69^{+7}_{-6} \ \mathrm{km\,s^{-1}\,Mpc^{-1}}$, a 10% precision measurement. For the Powerlaw + Peak and Broken Powerlaw + 2 Peaks we find fractional uncertainties of 17% and 13% respectively.

We use archival data from the Diffuse Infrared Background Experiment (DIRBE) to map the polycyclic aromatic hydrocarbon (PAH) 3.3 $\mu$m emission feature and analyze its correlation with AME in 98 compact sources identified by the Planck collaboration. We find that while FIR thermal dust emission continues to be a better tracer of AME in most of the considered regions, 17% of the AME sources are better correlated with emission from small PAHs as traced by DIRBE. Furthermore, of the 27 sources which were identified as highly significant AME detections in the Planck analysis, 37% prefer PAHs as an AME tracer. Further work is required to understand to what extent local interstellar conditions are affecting PAH emission mechanisms and to reveal the underlying carriers of AME.

Protoplanetary disks are the birthplaces of planets, and resolving their three-dimensional structure is key to understanding disk evolution. The unprecedented resolution of ALMA demands modeling approaches that capture features beyond the reach of traditional methods. We introduce a computational framework that integrates physics-constrained neural fields with differentiable rendering and present RadJAX, a GPU-accelerated, fully differentiable line radiative transfer solver achieving up to 10,000x speedups over conventional ray tracers, enabling previously intractable, high-dimensional neural reconstructions. Applied to ALMA CO observations of HD 163296, this framework recovers the vertical morphology of the CO-rich layer, revealing a pronounced narrowing and flattening of the emission surface beyond 400 au - a feature missed by existing approaches. Our work establish a new paradigm for extracting complex disk structure and advancing our understanding of protoplanetary evolution.

Context. kAndb is a substellar companion near the planet-brown dwarf boundary, orbiting a B9IV star at 50-100 au. Estimates of its age and mass vary, fueling a decade-long debate. Atmospheric parameters (Teff 1650-2050 K, log(g) 3.5-5.5) remain poorly constrained due to model differences and heterogeneous datasets. Aims. We refine the characterization of kAndb using mid-infrared data to capture its bolometric emission. Combined with NIR measurements, we constrain Teff, log(g), and radius to reduce uncertainties in age and mass. Methods. We obtained JWST/MIRI coronagraphic data (F1065C, F1140C, F1550C) and recalibrated NIR photometry with an updated ATLAS stellar model. MIRI color-magnitude diagrams (CMDs) probe the likelihood of species (CH4, NH3, silicates). We compared H and F1140C colors and magnitudes to isochrones to constrain age and mass. We modeled the spectral energy distribution with atmosphere models to refine Teff, radius, and log(g), and to constrain age and mass using evolutionary models. Results. Cloudy atmosphere models fit best, consistent with the L0/L2 spectral type and position near silicate-atmosphere field objects in the MIRI CMD. We derived an age of 47+-7 Myr and mass of 17.3+-1.8 MJup by weighted-mean model combination. Modeling yielded Teff = 1791+-68 K and radius = 1.42+-0.06 RJup, improving precision by 30%. Log(g) = 4.35+-0.07 dex represents a 70% improvement over the previous best value (4.75+-0.25). Conclusions. The new mass places kAndb just above the deuterium-burning limit. The age is 75% more precise and consistent with the Columba association (42 Myr). The Teff suggests silicate clouds, requiring spectroscopic confirmation. MIRI data were crucial to refining radius and temperature, which led to stronger constraints on age and mass and improving the overall characterization of kAndb.

We present a machine vision approach to quantify galaxy structure combining a variational autoencoder (VAE) framework with principal component analysis (PCA). Using mock gri-band images from the EAGLE simulation, the VAE finds that 35 features are needed to describe images. Adding the PCA, we identify an optimal range of 10-12 features needed to capture 99.9 per cent of the variance in galaxy morphology. The exact optimal number varies with galaxy complexity: disk-dominated galaxies require 12 features, bulge-dominated galaxies need 9, and intermediate systems require 10-11 features. Correlations between extracted PCA features and structural measurements reveal that the VAE prioritizes galaxy size during reconstruction, with half-light radius strongly correlating with the highest-ranked principal components. Subsequent features capture morphology-dependent characteristics: disk-dominated galaxies emphasize size, asymmetry, and position angle; bulge-dominated systems focus on size, concentration, and axis ratio; while intermediate galaxies show enhanced attention to Sérsic index, indicating greater emphasis on accurately reproducing both disk and bulge structures. The PCA process significantly reduces the entanglement of the features compared to the raw VAE latent features, decreasing the correlations with the half-light radius and the Sérsic index from 14.5\pm1.0 and 6.0\pm1.5 features, respectively, to only 2.0\pm1.0 components after PCA. Using UMAP technique, we construct 2D visualizations that preserve neighborhood relationships from the high-dimensional feature space. This demonstrates that machine vision can effectively distinguish galaxy populations across different morphological types, including systems with atypical structures that may be overlooked by traditional classification methods, providing a data-driven complement to conventional structural measurements.

Weakened magnetic braking (WMB) was originally proposed in 2016 to explain anomalously rapid rotation in old field stars observed by the Kepler mission. The proximate cause was suggested to be a transition in magnetic morphology from larger to smaller spatial scales. In a series of papers over the past five years, we have collected spectropolarimetric measurements to constrain the large-scale magnetic fields for a sample of stars spanning this transition, including a range of spectral types from late F to early K. During this time, we gradually improved our methods for estimating the wind braking torque in each of our targets, and for evaluating the associated uncertainties. Here, we reanalyze the entire sample with a focus on uniformity for the relevant observational inputs. We supplement the sample with two additional active stars to provide more context for the evolution of wind braking torque with stellar Rossby number (Ro). The results demonstrate unambiguously that standard spin-down models can reproduce the evolution of wind braking torque for active stars, but WMB is required to explain the subsequent abrupt decrease in torque as Ro approaches a critical value for dynamo excitation. This transition is seen in both the large-scale magnetic field and the X-ray luminosity, indicating weakened coronal heating. We interpret these transitions as evidence of a rotational threshold for the influence of Coriolis forces on global convective patterns and the resulting inefficiency of the global stellar dynamo.

Studies of cosmic microwave background (CMB) are often limited by foreground contamination. Foreground cleaning is performed either in harmonic or pixel space after data cuts have excluded sky areas of strong contamination. We present a nearly full-sky CMB temperature map with only 1% of pixels masked. To derive this map, we make use of six full-sky template maps at foreground-dominated frequencies from different experiments smoothed to $1^\circ$ and rely on the combination of these weighted maps to trace the morphology of foreground contamination. We do not impose any spectral index constraints, but only fit for template amplitudes at each target frequency. We clean WMAP and Planck maps at a set of target frequencies and conduct quality tests at the level of the maps, pixel histograms and power spectra to select four CMB maps that are cleaned with negligible foreground contamination and only 1% masked pixels and no inpainting. We recommend use of these cleaned CMB maps for low multipole ($\ell < 30$) studies.

We present a CMB temperature power spectrum measurement at large angular scales from WMAP and Planck maps that were cleaned of foregrounds using a template-based approach described in a companion paper. We recover essentially the full-sky CMB information at multipoles $\ell<30$ with only 1% of pixels near the Galactic plane masked and no inpainting. Notable features continue to appear: (a) a low quadrupole power compared to the best-fit Planck 2018 $\Lambda$CDM spectrum at $2.2\sigma$, (b) a dip in the range $20 \le \ell \le 27$, and (c) an overall $\ell<30$ power level low of the $\Lambda$CDM prediction derived from higher multipole moments. Given the different methodology from previous analyses and the nearly full-sky solution presented here, these features do not plausibly arise from foreground contamination, systematic errors, masking, or mode-mixing. Our overall $\ell<30$ amplitude constraint is consistent with published WMAP (77% sky fraction) and Planck (86%) results at $1.2\sigma$ and $0.6\sigma$, respectively, accounting for the improvement in statistical precision. We present a new $\ell<30$ likelihood for use with the Cobaya package. Parameter constraints from joint fits with the higher-multipole Planck data are consistent with the published Planck results, for example we find $H_0=67.35\pm0.54$ km s$^{-1}$ Mpc$^{-1}$ in a joint $\Lambda$CDM fit.

Unexpected features have been observed in the cosmic microwave background (CMB) temperature on large scales. We revisit these CMB anomalies using new foreground-cleaned CMB temperature maps derived in a companion paper from WMAP and Planck data, which are tailored to low-resolution analysis and require only minimal masking of $1\%$ of the sky. These maps allow us to assess the impact of foreground-cleaning methods and the choice of sky cut on the significance of five commonly studied CMB anomalies. We find a notable impact of the choice of galactic mask on the significance of two anomalies: the significance of the low real-space correlation function and of the local-variance asymmetry reduces from $\sim3\sigma$ for the Planck common mask with $26\%$ masked fraction to $\sim2\sigma$ for the $1\%$ mask. We find good agreement between the two sky cuts for the low northern variance, $\sim3\sigma$, and the parity asymmetry, $\sim2\sigma$. For the quadrupole-octopole alignment, we find good agreement between the $1\%$-mask result and the full-sky results in the literature, $\sim3\sigma$. Thus using a larger fraction of the sky enabled by improved foreground cleaning reduces the significance of two commonly studied CMB anomalies. Overall, for an alternative physical model to be convincingly favored over $\Lambda$CDM with statistically-isotropic Gaussian fluctuations, it would need to explain multiple CMB anomalies, or better describe some other type of measurement in addition to a CMB anomaly.

The compositions of the Solar System terrestrial bodies are fractionated from that of the Sun, where elemental depletions in the bulk rocky bodies correlate with element volatility, expressed in its 50% condensation temperature. However, because element volatility depends on disk gas composition, it is not mandated that elemental fractionation trends derived from the solar-terrestrial scenario apply to other planetary systems. Here, we expand upon previous efforts to quantify element volatility during disk condensation, and how this affects rocky planet compositional diversity. We simulate condensation sequences for a sample of 1000 initial disk compositions based on observed stellar abundances. We present parametrisations of how element 50% condensation temperatures depend on disk composition, and apply element fractionation trends with appropriate element volatilty to stellar abundances to simulate compositions of rocky exoplanets with the same volatile depletion pattern as the Earth, providing a robust and conservative lower limit to the compositional diversity of rocky exoplanets. Here we show that Earth-like planets emerge from low-C-to-O disks and graphite-bearing planets from medium-to-high-C-to-O disks. Furthermore, we identify an intermediate-C-to-O class of planets characterized by Mg and Si depletion, leading to relatively high abundances of Fe, Ca, and Al. We show that devolatilisation patterns could be adapted potentially with disk composition-dependent condensation temperatures to make predictions of rocky planet bulk compositions within individual systems. The outcomes of our analysis suggest that accounting for disk composition-dependent condensation temperatures means that we can expect an even broader range of possible rocky planet compositions than has previously been considered.

We present optical photometry and spectroscopy of SN 2019hnl. Discovered within ~26 hr of explosion by the ATLAS survey, SN 2019hnl is a typical Type IIP supernova with a peak absolute V band magnitude of -16.7+-0.1 mag, a plateau length of ~107 days, and an early decline rate of 0.0086+-0.0006 mag (50 days)^-1. We use nebular spectroscopy and hydrodynamic modeling with the SNEC, MESA, and STELLA codes to infer that the progenitor of SN 2019hnl was a M_ZAMS ~ 11M_solar red supergiant which produced 0.047+-0.007M_solar of 56Ni in the explosion. As a part of our hydrodynamic modeling, we reduced hydrogen envelope mass by scaling the mass loss within the "Dutch" wind scheme to fit our light curve, showing that the progenitor of a relatively typical Type IIP SN may experience partial stripping during their evolution and establish massive (~0.2M_solar) CSM environments prior to core collapse.

Some black holes in X-ray binaries accrete at rates far above the Eddington limit. In this supercritical regime, photons are trapped in a radiation-dominated, geometrically thick disk. The innermost regions form a complex environment of intense radiation, strong magnetic fields, and powerful outflows, where radiation-driven winds expel large amounts of mass. These conditions suppress primary relativistic electrons within the transparent funnel along the black hole's spin axis. We show that high-energy electrons can instead arise as secondary pairs from Bethe-Heitler interactions between relativistic protons and ambient photons. Using self-similar models of accretion disks with strong winds of ultraluminous X-ray sources (ULXs), we compute particle acceleration via magnetic reconnection and diffusive shocks, evaluate energy losses, and assess the efficiency and spectral imprint of Bethe-Heitler pair production. Our results suggest that secondary pairs can yield nonthermal radiation in the 0.1-100 MeV range with luminosities from $10^{34}$ up to $10^{38}$ erg s$^{-1}$. This emission could be detectable by future MeV instruments from Galactic ULXs, offering evidence of relativistic protons in their inner funnels and revealing misaligned, otherwise hidden, super-Eddington sources in the Milky Way.

The Large Magellanic Cloud (LMC) experiences disruption from tidal and ram-pressure forces as it travels through the halo of the Milky Way. In this project, we combine radio emission-line observations from the GASS and GASKAP surveys with UV absorption-line observations from the HST Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program to trace the material in front of the LMC. Along our 8 stellar sightlines near 30 Doradus, we observe gaseous structures likely associated with two arm-like features flowing in and around the LMC's disk. We detect the nearside gas in neutral, low, and medium ionization species. The lower-ionization species likely undergo both thermal and non-thermal broadening while the moderately-ionized phase is influenced by more non-thermal processes. The total integrated column density of AlIII decreases with increasing angular offset from 30 Doradus, with sightlines within 0.25 degrees containing more moderately ionized gas. We demonstrate from a Gaussian decomposition technique on the HI emission that both arms likely trace an additional 1.0 degree in Galactic longitude toward the 30 Doradus region than previously predicted. We constrain the orientation of the arms by suggesting that they likely converge around (l,b) =(280.5$^\circ$, -31.2$^\circ$) and at least partially cross in front of the LMC. Our observations are consistent with two competing origins of the arms: 1) outflowing material is swept back by tidal and ram-pressure forces or 2) tidally stripped inflows fuel the ongoing stellar activity inside the LMC. Future studies are needed to distinguish between these scenarios.

Magnetar giant flares (MGFs) are among the most luminous high-energy transients in the local universe, consisting of a short, intense MeV gamma-ray spike followed by a softer, pulsating X-ray tail and possibly delayed radioactive emission. While only three Galactic events have been firmly detected, several extragalactic candidates have recently been reported, motivating the need for sensitive, rapid-response gamma- and X-ray facilities to constrain their rates and energetics. We present a feasibility study of detecting MGFs with the Advanced X-ray Imaging Satellite (AXIS), focusing on two complementary pathways: (i) serendipitous discovery of the prompt gamma-ray spike within the field of view, and (ii) rapid follow-up of MGF tails in nearby galaxies. Using sensitivity rescaling and volumetric rate estimates, we find that serendipitous detection of prompt spikes during the mission lifetime is possible but unlikely, given their hardness and short duration. In contrast, AXIS's superior sensitivity, if accompanied by fast repointing capabilities, offer an extraordinary opportunity to detect pulsating X-ray tails out to about 20 Mpc, enabling the first extragalactic measurements of periodic modulations and potentially constraining emission geometry and fireball physics. Finally, we evaluate the detectability of soft X-ray line emission from r-process nucleosynthesis in MGFs, finding that such signals are extremely faint and confining the detection to Galactic distances. Our study offer a general framework for assessing the detectability of short transients with future missions.

Classical T Tauri stars (CTTS) exhibit strong variability over timescales of minutes to decades. However, much theoretical work assumes that CTTS are in stable spin states. Here, we test expectations for CTTS angular momentum regulation by comparing star and disk rotation. We measure stellar rotation periods and disk corotation radii ($R_{\rm co}$) for 47 CTTS from the HST ULLYSES sample. We compare $R_{\rm co}$ to the magnetospheric truncation radii ($R_{\rm i}$) and show that most CTTS are in the spin-up regime based on model predictions, which may indicate efficient angular momentum loss processes. We find evidence of magnetospheric outflows and episodic accretion, and our observations are consistent with the presence of accretion-powered stellar winds. We confirm predictions that $R_{\rm i}$ is variable over timescales of days, causing some CTTS to cross accretion stability regime boundaries. We characterize light curve morphologies and confirm that our inclined CTTS with $R_{\rm i}\sim R_{\rm co}$ show dipper light curves, consistent with expectations from disk warp models. However, dippers occur at all values of $R_{\rm i}/R_{\rm co}$, suggesting that they do not need to be near the propeller regime. Finally, we show that our measured $R_{\rm i}$ locations are consistent with observed ultra-short-period planet (USP) semi-major axes. If USPs are stable against tidal dissipation, as has been suggested in the literature, then our work provides a plausible USP formation channel. These results show that the star-disk connection produces a large variety of accretion and stellar spin configurations, most of which are likely not in equilibrium.

The Santa cruz Extreme Adaptive optics Lab (SEAL) is a visible/near-infrared wavelength testbed designed to support technology development for high contrast imaging on large, segmented, ground-based telescopes. SEAL saw first light in 2021 as a transmissive, visible-wavelength AO testbed. In this paper, we present four major upgrades to SEAL: (1) the testbed has been rebuilt with custom off-axis parabolic mirrors, enabling operation in both near-infrared and visible wavelengths; (2) the suite of wavefront sensors now includes a Shack-Hartmann, transmissive four-sided pyramid, vector-Zernike, and, in the muirSEAL testbed, a photonic lantern; (3) the testbed includes a vector-vortex coronagraph and will soon include a hybrid astrophotonic coronagraph; (4) in addition to its original Keck-heritage RTC, SEAL now includes two additional control software packages: Catkit, originally developed for the HiCAT testbed at the Space Telescope Science Institute, and the RTC Compute And Control for Adaptive Optics (CACAO), originally designed for Subaru/SCExAO. We discuss the performance of the testbed after the reflective rebuild and on-going technology development work at SEAL.

Turbulent radiative mixing layers (TRMLs), where shear-driven turbulence between dense and diffuse phases produces intermediate-temperature gas with short cooling times, are ubiquitous in the interstellar and circumgalactic media. Drawing an analogy with Reynolds' decomposition, we perform a quasi-steady-state analysis of TRMLs, separating fields into mean and turbulent components. In the quasi-isobaric TRML, upstream gas cools and compresses before streamwise momentum is fully mixed across the shear layer, which exhibits the expected negative turbulent shear stress $R_{xz}$ that steadily spreads into the cold phase. The thermal pressure reaches a minimum within the TRML, compensated by a positive vertical compressive stress $R_{zz}$. The sum of upstream ram and thermal pressures balances the downstream thermal pressure. Radiative losses are offset by enthalpy dissipation, with a negative turbulent heat flux $Q_{z}$ indicating thermal transport within the TRML. The volume-averaged temperature profile is well fit by a tanh function -- an emergent property that, for the first time, enables a predictive theory for TRMLs consistent with numerical experiments, including the universality of their temperature-dependent emissivity distributions.

We present a joint analysis of TESS photometry and radial velocity measurements obtained from the Minerva-Australis facility for two short-period eclipsing binaries, TIC 48227288 and TIC 339607421. TIC 339607421 hosts an M-dwarf companion ($M_B = 0.294 \pm 0.013 \: M_{\odot}$, $R_B = 0.291 \pm 0.006 \: R_{\odot}$) orbiting an F6V star ($M_A=1.09 \pm 0.04 \: M_{\odot}$, $R_A=1.21^{+0.03}_{-0.02} \: R_{\odot}$). While TIC 48227288 contains a late K class companion ($M_B=0.635 \pm 0.037 \: M_{\odot}$, $R_B = 0.605 \pm 0.011 \: R_{\odot}$) orbiting an F3V star ($M_A = 1.36^{+0.06}_{-0.08} \: M_{\odot}$, $R_A = 1.61 \pm 0.03 \: R_{\odot}$). Both companions follow short period, near-circular orbits ($P_B = 2.4-3.0$ d, $e \approx 0.001$). Sky-projected obliquities for each system were derived using a classical analysis of the RV perturbation and the Reloaded Rossiter-McLaughlin (RRM) technique. The classical method indicates minor spin-orbit misalignment for both systems ($\lambda_A = -14.7^{+5.4}_{-5.9}$ deg and $-17.8^{+1.9}_{-2.0}$ deg for TIC 339607421 and TIC 48227288, respectively). The RRM analysis yields smaller obliquities ($\lambda_A = -8.2 \pm 0.2$ deg and $-9.5 \pm 0.2$ deg respectively), but confirms the minor misalignment inferred from the classical analysis. The findings of misaligned, circular orbits are notable even though the misalignments are not large, and suggest potential gaps in current models of binary formation and orbital evolution. As such, further investigation of these and similar systems appears warranted.

We present the discovery of the eclipsing binary MML 48, which is a member of Upper Centaurus Lupus, has an associated age of 16 Myr, and is composed of two young, low-mass stars. We used space- and ground-based observations to characterize the system with both time-series photometry and spectroscopy. Given the extreme mass ratio between the stars, q_EB = 0.209 +- 0.014, we modeled a single-lined spectroscopic and eclipsing binary system. The orbital period, 2.0171068 +- 0.0000004 d, is measured from the highest precision light curves. We derive a primary mass of 1.2 +- 0.07 Msun using stellar models, and with radial velocities we measured a secondary mass of 0.2509 +- 0.0078 Msun. The radii are large, as expected for pre-main-sequence stars, and are measured as 1.574 +- 0.026 +- 0.050 Rsun and 0.587 +- 0.0095 +- 0.050 Rsun, for the primary and secondary stars, respectively. MML 48 joins the short list of known low-mass, pre-main-sequence eclipsing binaries (EBs), being one of only five systems with intermediate ages (15-25 Myr), and the system with the most extreme mass ratio. The primary star is currently at the "fusion bump", undergoing an over-production of energy in the core due to the build-up of 3He before reaching its equilibrium abundance set by the proton-proton (p-p) I chain. MML 48 A is the first young star in an eclipsing system that has been found during its fusion bump. MML 48 is thus an important benchmark for low-mass stellar evolution at a time when the stars are rapidly changing, which allows for a tight constraint on the corresponding isochrone given the uneven mass ratio.

Precision photometric calibration is key to a number of astrophysical research areas such as supernova cosmology and dark energy studies. In the age of large surveys, pushing the limits of photometry is a worthy challenge, with traditional celestial calibrators limited to approximately percent precision. Here we present PANDORA, a novel calibration source that achieves sub-percent photometric precision across the optical spectrum with a selectable dynamic range and high optical efficiency. Building on proven collimated beam projector designs for relative throughput calibration of survey telescopes, PANDORA is capable of delivering photons anywhere in the 350-1100 nm spectral range. It uses selectable neutral density filters and sequential NIST-calibrated photodiode feedback to internally self-calibrate prior to operation, and is illuminated by an Energetiq EQ-99X-FC broadband laser-driven light source. We present here an overview of the system design, operation, and laboratory characterization results. PANDORA will begin science operations this year to support the upcoming LS4 survey on the ESO 1m Schmidt telescope.

Lensed quasars are powerful probes of cosmology, the co-evolution of supermassive black holes and their host galaxies, and the distribution of dark matter. We cross-match 1,724 previously identified candidates from HSC, KiDS, and the DESI Legacy Imaging Surveys (DESI-LS) with DESI DR1, obtaining 937 DESI spectra for 677 unique systems. Combining DESI spectroscopy with observations from the Palomar 200-inch Double Spectrograph (P200/DBSP), we confirm three lensed quasars with source redshifts of 1.71, 1.93, and 3.23 and Einstein radii of 0.96, 0.39, and 1.07 arcsec, respectively. We further identify 11 high-confidence candidates that are well reproduced by a simple singular isothermal ellipsoid (SIE) model, exhibit lens galaxies in the image modeling, and have at least one available spectrum; across these, the Einstein radius spans 0.39 to 2.34 arcsec and the source redshift spans 1.13 to 2.88. In 8 of the 11 cases, the systems already satisfy our lensing criteria except that only one quasar image currently has a spectrum; obtaining a second spectrum for the other image would enable immediate confirmation. As by-products, we report eight new lensed galaxies spanning galaxy- to group-scale lenses. These results provide valuable targets for follow-up studies and underscore the efficiency of wide-field spectroscopic surveys such as DESI in confirming gravitationally lensed quasars and galaxies.

We perform a detailed analysis of radial oscillations to discuss dynamical stability in two-fluid neutron stars composed of ordinary nuclear matter and a gravitationally coupled dark matter component. Using a fully relativistic two-fluid formalism, we solve the eigenvalue problem for a coupled system of equations with small-amplitude radial perturbations and derive the critical line corresponding to stability boundaries. We also compare these stability boundary lines obtained from the radial perturbations with those obtained from a generalized turning-point criterion based on extremization of mass and particle numbers, and find that the two methods agree to within better than $1\%$ across the parameter space explored. We consider both mirror dark matter and self-interacting fermionic dark matter models, and examine how microphysical properties$-$such as nuclear equations of state, dark matter mass, and vector coupling strength$-$reshape the topology of the stability boundary and gravitational mass contours. Our results reveal the emergence of ultra-dense and compact stars, with nuclear central densities exceeding single-fluid instability thresholds by factors of two or more, and the appearance of twin-star configurations with identical masses but distinct radii and internal fluid compositions. These findings have direct implications for the interpretation of neutron star observables and motivate future studies involving phase transitions, density discontinuities, or additional interactions in multi-component stellar systems. In particular, the emergence of exotic stable configurations beyond conventional stability limits underscores the need to reassess standard criteria in light of multi-fluid dynamics, with significant consequences for multimessenger probes of dense matter$-$including gravitational wave signals, mass-radius constraints, and post-merger remnants.

The Habitable Worlds Observatory requires active speckle suppression to directly image Earth-like exoplanets. Focal plane wavefront sensing and control allows us to detect, and subsequently remove, time-varying speckles through measurements of the electric field. Two measurement-based wavefront sensing approaches are pairwise probing (PWP) and the self-coherent camera (SCC). However, the PWP technique is time-consuming, requiring at least 4 images and reducing the speed at which aberrations can be eliminated. In the SCC, a coronagraph mask diffracts light outside of the Lyot stop, where it is filtered with a pinhole. The filtered light creates a reference beam, interfering with speckles that leak through the coronagraph. The classic implementation of the SCC only works over small spectral bandwidths and needs significantly oversized optics which limits its implementation. We propose a new variant, the Spatially-Clipped Self-Coherent Camera (SCSCC). The SCSCC utilizes a pinhole placed closer to the Lyot Stop, reducing the overall beam footprint and boosting the sensor resolution. A knife-edge beam splitter downstream of the Lyot Stop splits the light into two channels: fringed and unfringed. This allows us to sense the wavefront with a single exposure. Time-varying aberrations are effectively frozen in place, making them easy to remove. We present monochromatic simulation results of the SCSCC in a sensing and control loop, demonstrating a normalized intensity of ~ 4 * 10^-10 in a 5-20 lambda/D dark hole. We find that wavefront control paired with the SCSCC achieves ~ 50x deeper contrast than that achieved with PWP in a temporally evolving speckle field. Our results make the SCSCC a valuable wavefront sensor concept for the upcoming Habitable World Observatory mission.

Post-Asymptotic Giant Branch (post-AGB) binary stars are evolved systems that host circumbinary discs formed through mass loss during late-stage binary interaction. Their structural, kinematic, and chemical similarities to planet-forming discs have motivated the idea that these systems may act as sites of "second-generation" planet formation. In this study, we assess whether the gravitational instability mechanism - a proposed pathway for giant planet formation in some protoplanetary discs-can operate in post-AGB discs. Using the Toomre criterion under well-motivated assumptions for disc structure and size, mass, and thermal properties, we assess the conditions for gravitational instability. We first benchmark our analytical framework using several well-studied protoplanetary disc systems before applying the same analysis to observed post-AGB discs. We find that post-AGB discs are generally gravitationally stable at present, due primarily to their low masses. The disks were stable against collapse, even when accounting for potentially higher disk mass in the past. In contrast, several protoplanetary discs analysed in the same way show that they likely experienced gravitationally unstable phases early on. Finally, we revisit the planet formation scenario proposed for the post-common envelope system NN Serpentis first carried out by Schleicher and Dreizler and we show that gravitational instability could be feasible under specific, high disc mass assumptions, however we note that their proposed disc mass is unlikely. Overall, our results provide the first systematic theoretical assessment of gravitational instability in post-AGB discs, demonstrating that this mechanism is unlikely to dominate second-generation planet formation in these systems, and underscoring the need to explore alternative pathways-such as core accretion-in future studies

Quasi-periodic eruptions (QPEs) are a class of X-ray flaring phenomena that occur at the centers of galactic nuclei and are likely to arise from repeated interactions between a star and an accretion disk. This work investigates whether such disk-crossing events can accelerate protons and generate detectable high-energy neutrinos. Based on observed QPE luminosities, recurrence periods, and flare durations, the stellar motion parameters and the disk properties are evaluated. We consider proton acceleration during the breakout phase and evaluate neutrino production, accounting for both $pp$ and $p\gamma$ interactions. Applying the method to ten observed QPE sources, we estimate the neutrino fluence accumulated over a 10-year observation period and compute the corresponding detection numbers for IceCube and IceCube-Gen2. Our analysis indicates that protons can be accelerated up to several tens of TeV, and neutrino production is mostly confined below $\sim 10~\mathrm{TeV}$. The resulting optimized neutrino fluence spans from $ 7.0 \times 10^{-7} $ to $1.5 \times 10^{-4}~\mathrm{GeV~cm^{-2}}$ for these ten QPE sources. We find that the expected neutrino detection number for a single QPE source is low, and the expected neutrino detection number would approach unity only for the most promising QPE source occurring at a distance closer than a few Mpc. Next-generation neutrino telescopes with better detection sensitivities at $\lesssim \rm TeV$ can significantly improve the capture capacity of the cumulative neutrino signal from the QPE population.

Most baryons in present-day galaxy clusters exist as hot gas ($\boldsymbol{\gtrsim10^7\,\rm}\mathrm{K}$), forming the intracluster medium (ICM). Cosmological simulations predict that the mass and temperature of the ICM rapidly decrease with increasing cosmological redshift, as intracluster gas in younger clusters is still accumulating and being heated. The thermal Sunyaev-Zeldovich (tSZ) effect arises when cosmic microwave background (CMB) photons are scattered to higher energies through interactions with energetic electrons in hot ICM, leaving a localized decrement in the CMB at a long wavelength. The depth of this decrement is a measure of the thermal energy and pressure of the gas. To date, the effect has been detected in only three systems at or above $z\sim2$, when the Universe was 4 billion years old, making the time and mechanism of ICM assembly uncertain. Here, we report observations of this effect in the protocluster SPT2349$-$56 with Atacama Large Millimeter/submillimeter Array (ALMA). SPT2349$-$56 contains a large molecular gas reservoir, with at least 30 dusty star-forming galaxies (DSFGs) and three radio-loud active galactic nuclei (AGN) in a 100-kpc region at $z=4.3$, corresponding to 1.4 billion years after the Big Bang. The observed tSZ signal implies a thermal energy of $\mathbf{\sim 10^{61}\,\mathrm{erg}}$, exceeding the possible energy of a virialized ICM by an order of magnitude. Contrary to current theoretical expectations, the strong tSZ decrement in SPT2349$-$56 demonstrates that substantial heating can occur and deposit a large amount of thermal energy within growing galaxy clusters, overheating the nascent ICM in unrelaxed structures, two billion years before the first mature clusters emerged at $\mathbf{z \sim 2}$.

We are developing an X-ray polarimeter using micro-pixel CMOS sensors for solar flare X-ray polarimetry. The system consists of a 2.5-$\mu$m pixel CMOS image sensor with a 12.8$\times$12.8 mm$^2$ imaging area and a readout system based on a Zynq System-on-Chip. While previous studies have validated this concept, no realistic feasibility studies have been conducted for the solar flare X-ray polarization observation. In this work, we performed polarization sensitivity measurements at synchrotron facilities. The results show that our polarimeter is sensitive to the X-ray polarization, exhibiting a modulation factor of 5-15% at an energy range of 6-22 keV. The measurements also determined the thickness of the sensitive layer to be approximately 5 $\mu$m, and the thicknesses of the insensitive layers to be 0.8 $\mu$m (Si), 2.1 $\mu$m (SiO2), and 0.24 $\mu$m (Cu). These measured thicknesses lead to a quantum efficiency of 3-4% at 10 keV. Based on these experimental evaluations, we estimated the sensitivity of the micro-pixel CMOS polarimeter system. We found that, when combined with a telescope with an effective area of $\sim$10 cm$^2$, this system can detect X-ray polarization with a polarization degree of a few percent for M-class flares.

Ultra-high-energy cosmic rays (UHECRs) have long been assumed to entirely consist of iron and/or lighter atomic nuclei, and this assumption has been hard-coded in a great deal of software for UHECR simulations and data analysis. However, in the last few years several authors have started questioning this assumption and entertaining the possibility that UHECRs might at least partly consist of nuclei of elements heavier than iron, especially at the highest energies. Thoroughly testing this hypothesis will require upgrading software so that it can handle such nuclei. In this contribution I will describe the minimal modifications required for the last publicly released version of SimProp, a code for Monte Carlo simulations of the intergalactic propagation of UHECRs, to be able to treat heavier nuclei, and discuss the applicability of approximations first introduced for lighter nuclei.

The detection of primordial black holes (PBHs) would mark a major breakthrough, with far-reaching implications for early universe cosmology, fundamental physics, and the nature of dark matter. Gravitational wave observations have recently emerged as a powerful tool to test the existence and properties of PBHs, as these objects leave distinctive imprints on the gravitational waveform. Notably, there are no known astrophysical processes that can form sub-solar mass black holes, making their discovery a compelling signal of new physics. In addition to PBHs, we consider other exotic compact object (ECO) candidates-such as strange quark stars and boson stars-which can produce similar gravitational signatures and potentially mimic PBHs. In this work, we employ the Fisher matrix formalism to explore a broad parameter space, including binary masses, spins, and a variety of nuclear and quark matter equations of state. Our goal is to assess the ability of next-generation gravitational wave detectors-specifically Cosmic Explorer and the Einstein Telescope-to distinguish PBHs from ECOs, stellar BHs and neutron stars. We compute the maximum luminosity distances at which confident ($\geq 3\sigma$) detections of sub-solar masses or tidal effects are possible, providing quantitative benchmarks for PBH identification or exclusion under various observational scenarios. Our results indicate that next-generation detectors will be capable of probing sub-solar mass PBHs out to cosmological distances of $z \sim 3$. For heavier objects with masses up to $M \lesssim 2 M_\odot$, we show that PBHs can be distinguished from neutron stars via their lack of tidal effects up to redshifts of $z \sim 0.2$.

This paper presents a combined 1D photochemical-thermochemical kinetics model of Jupiter's deeper atmosphere, troposphere and stratosphere. The model covers atmospheric pressure range from $1.1 \times 10^{3}$ bar to $7.4 \times 10^{-11}$ bar and is the first model that incorporates sulfur chemistry when spanning an atmospheric region of this extent. This model incorporates a new version of the STAND reaction network with updated NH4SH chemistry, and updated Antoine equation parameters for NH4SH and H2S. Validation against current models of Jupiter's atmosphere as well as recent observational data shows that our model successfully describes Jupiter's main observed chemical features. Since one of the focuses of the model is the chemistry on nitrogen, it correctly predicts the formation of a mixed NH3-NH4SH cloud layer between 0.1 and 1 bar. It also describes the chemistry of HCN throughout the atmosphere and discovers a region in the stratosphere between $1 \times 10^{-6}$ and $6.76 \times 10^{-8}$ bar, where HCN forms through radical chemistry with maximum mixing ratio 33 ppb at $2.94 \times 10^{-7}$ bar -- a prediction testable by observations. At the same time, our model predicts a quenched N2 mixing ratio 490 ppm up to 10$^{-6}$ bar. The model therefore successfully bridges the gap between existing models of separate regions of Jupiter's atmosphere and makes new testable predictions of several chemical species.

Hadronic cosmic particles (cosmic rays) and gamma rays are constantly absorbed in the Earth's atmosphere and result in air showers of secondary particles. Cherenkov radiation from these atmospheric events is used to measure cosmic gamma rays with ground-based telescopes. We focus here on the dominant hadronic cosmic-ray-initiated background events in the atmosphere, which give rise to gamma-ray like air showers for gamma-ray telescopes. It is shown that only a small subset of hadronic cosmic-ray interactions, those which produce a large energy neutral pion, are responsible for this background. We subsequently address how the predictions of this background vary depending on the hadronic interaction model adopted. The pseudorapidity range of the energetic pions, with respect to the shower axis produced in these background events, is shown to be large. We show that collider experiments, specifically LHCf and RHICf, probe cosmic ray interactions precisely within this pseudorapidity range. Present and future measurements with these instruments are shown to be able to test the ability for current hadronic interaction models to accurately describe these background events.

Until now, the study of unresolved main sequence binary stars in globular clusters has been possible almost exclusively in their central regions with deep Hubble Space Telescope (HST) observations. We present the first detection of unresolved main-sequence binary stars in the outer field of 47 Tucanae using Rubin Observatory's Data Preview 1 (DP1). Our analysis exploits deep $i$ vs. $g-i$ colour-magnitude diagrams beyond the cluster's half-light radius, reaching almost to the tidal radius. The high-quality photometry allowed to identify unresolved binaries with mass ratios $q$ larger than 0.7. The derived binary fraction of $f_\mathrm{bin}(q>0.7) = 0.016 \pm 0.005$ stands in contrast to the significantly lower values in the cluster innermost regions, as measured from HST photometry. This result provides new empirical input for testing physical processes that drive the formation and evolution of binary stars in globular clusters. It also demonstrates Rubin's unique wide-field and high-precision photometric capabilities to address a broader range of outstanding questions in star cluster research. Future full data releases will enable to significantly expand the study of dense stellar systems across the Milky Way.

We present the calibration of stellar and active galactic nucleus (AGN) feedback in the subgrid model for the new COLIBRE hydrodynamical simulations of galaxy formation. COLIBRE directly simulates the multi-phase interstellar medium and the evolution of dust grains, which is coupled to the chemistry. COLIBRE is calibrated at three resolutions: particle masses of $m_{\rm gas} \approx m_{\rm dm} \sim 10^7$ (m7), $10^6$ (m6), and $10^5~\mathrm{M_\odot}$ (m5). To calibrate the COLIBRE feedback at m7 resolution, we run Latin hypercubes of $\approx 200$ simulations that vary up to four subgrid parameters in cosmological volumes of ($50~\mathrm{cMpc}$)$^{3}$. We train Gaussian process emulators on these simulations to predict the $z=0$ galaxy stellar mass function (GSMF) and size - stellar mass relation (SSMR) as functions of the model parameters, which we then fit to observations. The trained emulators not only provide the best-fitting parameter values but also enable us to investigate how different aspects of the prescriptions for supernova and AGN feedback affect the predictions. In particular, we demonstrate that while the observed $z=0$ GSMF and SSMR can be matched individually with a relatively simple supernova feedback model, simultaneously reproducing both necessitates a more sophisticated prescription. We show that the calibrated m7 COLIBRE model not only reproduces the calibration target observables, but also matches various other galaxy properties to which the model was not calibrated. Finally, we apply the calibrated m7 model to the m6 and m5 resolutions and, after slight manual adjustments of the subgrid parameters, achieve a similar level of agreement with the observed $z=0$ GSMF and SSMR.

The Zwicky Transient Facility (ZTF) is conducting a wide-field survey of the northern sky in three optical bands and the collaboration cosmology working group has released 3628 spectroscopically confirmed Type Ia supernovae (SNe Ia) discovered during its first 2.5 years of operation. This "ZTF SN Ia DR2" sample is the largest SN Ia dataset to date. Fully exploiting this dataset to improve understanding of the properties of dark energy requires a photometric accuracy of O(0.1%). This can be achieved using Scene Modeling Photometry (SMP), which is optimal to extract a transient signal (SN) from a complex background (its host), while ensuring a common flux estimator with nearby stars used as calibration reference. In this paper, we present the status of the SMP development and use it to assess the precision and accuracy of the ZTF SN Ia DR2 force photometry light curves. We reach a repeatability of the star observations better than 1%. However, we have identified a new sensor effect, dubbed "pocket-effect", which distorts the Point Spread Function (PSF) in a flux-dependent manner leading to non-linearities in the photometry of a few percent. Correcting for this effect requires time- and sensor-dependent corrections to be applied at the pixel level, which is currently under development. This effects affects all light curve releases to date -- both from forced photometry and scene modelling preventing ZTF SN Ia DR2 to be used for accurate cosmological inference. Comparing the SMP and forced photometry measurements, we find that stretch and color estimated from both processings are consistent, aside from a 10 mmag shift in color. This assess the robustness of results presented as part of the the ZTF SN Ia DR2 release. The absolute calibration however shifts by 90 mmag. A reprocessing of the full ZTF SN Ia DR2 dataset using the SMP method is currently in progress.

This research addresses the growing challenge of artificial satellite trail interference in ground-based astronomical observations by developing an efficient deep learning identification method. With the proliferation of satellite constellations in low Earth orbit, accurate detection of satellite trails has become crucial for preserving astronomical data quality. Using multi-band photometric survey observational data from the $Multi-channel$ $Photometric$ $Survey$ $Telescope$ (Mephisto) of Yunnan University , we constructed a specialized dataset of astronomical images containing satellite trails. We propose a novel ASA-U-Net model that integrates atrous spatial pyramid pooling with channel attention mechanisms into the U-Net architecture to effectively capture sparse satellite trail features that traditional semantic segmentation models often miss during downsampling. The model was implemented and validated on actual telescope data, demonstrating superior performance in end-to-end detection and marking of satellite trails compared to traditional methods. This approach significantly improves data processing precision without requiring manual parameter adjustments, making it suitable for processing massive nightly survey data and enhancing the quality of astronomical data products.

Suppression effects of giant radio lobes from supermassive black holes on gas accretion onto galaxies in the surrounding regions are quantified using cosmological magneto-hydrodynamic simulations. With an appropriate amount of radio jet energy injected into the intergalactic medium following the formation peak of supermassive black holes at redshift two, we find that galaxies in the greater neighborhood of the jet-launching massive galaxies subsequently experience a significant reduction in the amount of accreted gas. The distribution of the resulting magnetic field in the intergalactic medium is highly inhomogeneous, due to the highly biased nature of the most massive supermassive black holes. In regions with magnetic field strength $B>10^{-2}\mu$G, the baryon fraction is on average reduced by 17%, 14%, and 12%, respectively, for halos of mass in the range of $[10^{11}-10^{12})\msun$, $[10^{12}-10^{13})\msun$, and $[10^{13}-10^{14})\msun$. A proper inclusion of this new, external, global, preventive feedback mechanism from AGN in the next generation of cosmological simulation may be necessary.

The remnant of the historical supernova SN 1181 is under discussion: While the previously suggested G130.7+3.1 (3C58) appears too old (3000-5000 yr), the unusual star IRAS 00500+6713 with a surrounding nebula (Pa-30) has an expansion age not inconsistent with a SN Iax explosion in AD 1181 under the assumption that neither acceleration nor deceleration occurred. Previously, only reports from China and Japan were known, pointing to an event near the northern circumpolar region. Any further reports from other cultures can therefore be highly relevant. We present here an Arabic poem in praise of Saladin by the contemporaneous author Ibn Sanā' al-Mulk (Cairo, Egypt). We re-date its composition to between Dec 1181 and May 1182. It contains a new bright star, which can be identified as SN 1181. The poem also provides new and independent information on the object type (called `najm' for `star'), location on sky (in or near the Arabic constellation al-Kaff al-Khabīb, lit. the henna-dyed hand (five bright stars in Cassiopeia), and brightness (brighter than alpha Cas, 2.25 mag). In addition, we present another Arabic text on SN 1006, also from Cairo, by the historian al-Maqrīzī, probably based on the contemporaneous al-Musabbihī

We present a renormalization-free framework for modeling galaxy bias based on Unified Lagrangian Perturbation Theory (ULPT). In this approach, the biased density fluctuation is built solely from Galileon-type operators associated with the intrinsic nonlinear growth of dark matter. This ensures the bias expansion is well defined at the field level, automatically satisfies statistical conditions of vanishing ensemble and volume averages, and removes the need for ad hoc renormalization. We derive analytic one-loop expressions for the galaxy-galaxy and galaxy-matter power spectra and implement an efficient numerical algorithm using \texttt{FFTLog} and \texttt{FAST-PT}, enabling rapid and accurate evaluation. The model requires only a minimal set of bias parameters: three parameters are sufficient to describe correlation functions in configuration space, while four parameters are needed for power spectra in Fourier space. To test accuracy, we jointly fit halo auto- and cross-spectra from the \textit{Dark Emulator}, covering nine redshift-mass combinations with 100 cosmologies each. A single set of bias parameters reproduces both spectra within $\sim1\%$ up to $k \simeq 0.3\,h\,\mathrm{Mpc}^{-1}$ for typical linear bias $b_1 \sim 0.8$-2, and to $k \simeq 0.2\,h\,\mathrm{Mpc}^{-1}$ for $b_1 \sim 3$. The same parameters also match two-point correlation functions down to $r \simeq 15\,h^{-1}\mathrm{Mpc}$. Moreover, ULPT predicts the relation $b_{K^2}^{\mathrm{E}} = -\tfrac{3}{4} b_2^{\mathrm{E}}$, validated against $N$-body results. These results demonstrate that ULPT provides a physically consistent and efficient model for nonlinear galaxy bias, with applications to redshift-space distortions, bispectra, and reconstruction. The numerical implementation is released as the open-source Python package this https URL.

Stellar theory predicts a forbidden range of black-hole masses between ${\sim}50$--$130\,M_\odot$ due to pair-instability supernovae, but evidence for such a gap in the mass distribution from gravitational-wave astronomy has proved elusive. Early hints of a cutoff in black-hole masses at ${\sim} 45\,M_\odot$ disappeared with the subsequent discovery of more massive binary black holes. Here, we report evidence of the pair-instability gap in LIGO--Virgo--KAGRA's fourth gravitational wave transient catalog (GWTC-4), with a lower boundary of $45_{-4}^{+5} M_\odot$ (90\% credibility). While the gap is not present in the distribution of \textit{primary} masses $m_1$ (the bigger of the two black holes in a binary system), it appears unambiguously in the distribution of \textit{secondary} masses $m_2$, where $m_2 \leq m_1$. The location of the gap lines up well with a previously identified transition in the binary black-hole spin distribution; binaries with primary components in the gap tend to spin more rapidly than those below the gap. We interpret these findings as evidence for a subpopulation of hierarchical mergers: binaries where the primary component is the product of a previous black-hole merger and thus populates the gap. Our measurement of the location of the pair-instability gap constrains the $S$-factor for $^{12}\rm{C}(\alpha,\gamma)^{16}\rm{O}$ at 300keV to $256_{-104}^{+197}$ keV barns.

The continuous flux of Galactic cosmic rays that bombard Earth's atmosphere creates ionizing radiation that can damage the DNA of living organisms. While this radiation on Earth is relatively constant in the short term, large and long-scale fluctuations are expected with a period of $\sim 63.5$ million years. As the Solar System moves above or below the Galactic plane during its oscillatory motion about the Galactic center, the Galactic magnetic shielding weakens, allowing more cosmic rays to reach Earth and trigger mutations in organisms. We identify a significant correlation (weighted global p-value: $1.25\times 10^{-4}$, or $3.72\sigma$) between the Solar System's Galactic oscillations and the origination of marine zoo- and phyto-microplankton genera over the Phanerozoic. When we restrict the analysis to time intervals during which all four groups coexisted, a post-trial significance of $4.52\sigma$ emerges. Our findings suggest that changes in biodiversity have been significantly influenced by long-term Galactic forcing.

This work investigates the use of stellar occultation measurements to enhance the orbit determination performance of the Lunar Meteoroid Impact Observer (LUMIO) mission, operating from a quasi-Halo orbit around the Earth-Moon L2 point. During science phases, when radiometric tracking is sparse and low illumination limits conventional optical navigation methods, occultation events, defined as precise timings of stellar appearances/disappearances behind the Moon's limb, offer a suitable alternative. A simulation tool based on JPL's MONTE library was developed to identify valid occultation events, applying geometric and illumination constraints to exclude non-observable cases. These events were integrated into a batch least-squares orbit determination filter alongside conventional radiometric data. The covariance analysis shows that occultation observables reduce the transverse and normal position uncertainties of LUMIO by up to a factor of two, especially during tracking gaps or occultation-rich arcs. This uncertainty reduction is expected to facilitate station-keeping operations and constrain the surface localization of Lunar Impact Flashes (LIFs), enhancing the mission's scientific return. Sensitivity analyses confirm that the orbit determination performance is primarily driven by the timing accuracy of occultation events, with limited dependence on lunar shape uncertainty below 100 m. These findings confirm the potential of occultation-based navigation to enhance spacecraft autonomy and robustness in low-visibility environments, making it a valuable complement to radiometric techniques for future lunar and deep-space missions.

Gravitational waves (GWs) with electromagnetic counterparts (EMc) offer a novel approach to measure the Hubble constant ($H_0$), known as bright sirens, enabling $H_0$ measurements by combining GW-derived distances with EM-derived redshifts. Host galaxy identification is essential for redshift determination but remains challenging due to poor GW sky localization and uncertainties in EMc models. To overcome these limitations, we exploit the ultra-high-precision localization ($\Delta \Omega_s \sim 10^{-4} \, \text{deg}^2$) with a space-based GW detector network (LISA-Taiji-TianQin), which permits unique host identification solely from GW signals. We integrate five massive black hole binary (MBHB) population models and two galaxy number density models to compute the redshift horizon for host galaxy identification and evaluate $H_0$ constraints. We find that (1) The network enhances localization by several orders of magnitude compared to single detectors; (2) The identification horizon reaches $z\sim 1.2$ for specific MBHBs in the most accurate localization case; (3) The population model choice critically impacts the outcomes: the most refined population models yield to independent EMc identification rate of 0.6-1 $\text{yr}^{-1}$ with $H_0$ constraints $< 1\%$ fractional uncertainty, the less refined models lead to the rate $<0.1\text{yr}^{-1}$ and $1-2\%$ uncertainty on $H_0$.

The age of the Local Bubble (LB) can be used to constrain the timescales, on which the interstellar medium in the solar neighborhood is evolving. Previous estimates have put the age of the LB at $\gtrsim 14\,\text{Myr}$, and suggested that its expansion was powered by $\sim 15-20$ SNe, yet in a companion paper we have seen hints that this age might be too high. Following up on these hints, we aim to place new constraints on the age of the LB. We reconstruct the geometry and momentum of the LB using publicly available 3D dust maps to compare its geometry to that of the high-quality sample of simulated supernova remnants in the SISSI project. We find that, in contrast to previous estimates, $\gtrsim 20$ SNe over $\sim 4\,\text{Myr}$ are required to explain both the momentum and the size of the LB. The julia source-code for our analysis is made available at this https URL. Previous estimates of the age of the LB have seemingly overestimated its age and underestimated the number of SNe powering its expansion. Our results are in tension with the assumption that the LB is powered solely by SNe associated with the nearby Scorpius-Centraurus OB association, which appears to have stopped forming stars at about the same time as the LB began to expand. In light of this new evidence, our results cast serious doubts on the claim that star formation in the solar neighborhood was driven by the expansion of the LB, and might have instead quenched it.

Cosmic chronometers offer a model-independent way to trace the expansion history of the Universe via the dating of passively evolving objects. This enables testing the validity of cosmological models without concrete assumptions of their energy content. The main goal of this work is to derive model-independent constraints on the Hubble parameter up to $z \sim 0.4$ using stellar ages from the fitting of Lick index absorption lines in passively evolving galaxies. Contrary to recent related works that rely on finite differences to obtain a discrete measurement of the expansion of the Universe at an average redshift, our goal is to perform a cosmographic fit of $H(z)$ in terms of the Hubble constant ($H_0$) and the deceleration ($q_0$) and jerk ($j_0$) parameters. We carefully select spectra of massive and passively evolving galaxies from the SDSS Legacy Survey. After applying a stacking procedure to ensure a high signal-to-noise ratio, the strength of Lick indices is fit using two stellar population models (TMJ and Knowles) to derive stellar population parameters. A cosmographic fit to the stellar ages is performed, which in turn enables the sampling of the Hubble parameter within the considered redshift range. The baseline result comes from using the TMJ-modelled ages, and it yields a value of $H_0 = 70.0^{+4.1}_{-7.6} \text{ km s}^{-1} \text{ Mpc}^{-1}$ for the Hubble constant, where uncertainties refer only to the statistical treatment of the data. The sampling of the Hubble parameter at $0.05 < z < 0.35$ is competitive with discreet model-independent measurements from the literature. We finally draw attention to an unexpected oscillating pattern in a number of critical indices with respect to redshift, which translates into a similar behaviour in the $t-z$ relations. These features have never been discussed before, although they are present in previous measurements.

The subject of boosted fluxes of dark matter or cosmic relic neutrinos via scattering on cosmic rays has received considerable attention recently. This article investigates the boosted neutrino flux from scattering of cosmic rays and the so-far undetected diffuse supernova neutrino background, taking into account both galactic and extragalactic cosmic rays. The calculated flux is many orders of magnitude smaller than either the galactic diffuse neutrino emission, the extragalactic astrophysical flux measured by IceCube, or the cosmogenic neutrino flux expected at the highest energies.

The reported anomalous global 21-cm signal $(T_{21})$ from the cosmic dawn era by Experiment to Detect the Global Epoch of Reionisation Signature (EDGES) could hint towards new physics beyond the standard model. The resonant conversion of the axion-like particles (ALPs) into photons in the presence of primordial magnetic fields (PMFs) could be a viable solution. However, the strength of the PMFs can change over the time as they can decay by ambipolar diffusion and turbulent decay. Consequently, PMFs can dissipate their energy into the intergalactic medium (IGM), which can alter the global 21-cm signal. We simultaneously consider both magnetic heating of IGM and resonant conversion of ALPs to derive physically motivated upper bounds on the coupling strength $(g_{a\gamma})$ and magnetic field strength $(B_n)$. Our findings report that, for $B_n= 0.1\,\rm nG$, $g_{a\gamma}B_n\lesssim (3.6\times 10^{-4}-3\times 10^{-3})$ is required to recover standard $T_{21}=-156\,\rm mK$, while a deeper absorption of $-500$ mK pushes the upper bound to $g_{a\gamma}B_n\lesssim (6.5\times 10^{-4}-5.7\times 10^{-3})$.

The cosmic web is one of the most complex systems in nature, consisting of galaxies and clusters of galaxies joined by filaments and walls, leaving large empty regions called cosmic voids. The most common method of describing the web is a correlation function and its derivative, the fractal function. In this paper, I provide a review of the fractal properties of the cosmic web from the observational point of view within the Newtonian concordance $\Lambda$CDM Universe framework. I give a brief history of fractal studies of the Universe. I then describe the derivation of the fractal function from angular and spatial distributions of galaxies and their relations. Correlation functions are not sensitive to the shape of the galaxy distribution. To improve our quantitative understanding of properties of the web, statistics must be used which are sensitive to the pattern of the web.

In recent years periodic amplitude modulation has emerged as a unique emission feature in the single pulse sequence of pulsars alongside periodic nulling and subpulse drifting. Despite ample evidence for the uniqueness of this phenomenon, the periodic modulation in several pulsars are often confused with subpulse drifting, primarily due to lack of clear characterisation of the emission features from a representative sample of pulsars. In this work we present a detailed analysis of the single pulse behaviour from seventeen pulsars exhibiting periodic amplitude modulation, six of them being new detections. The pulsar switches between different intensity states as a result of periodic amplitude modulation and we propose a novel statistical scheme to identify these emission states. The periodic modulation can be divided into three broad categories, phase stationary modulation, modulations with phase shift and intermittent periodic modulations. The phase stationary behaviour is seen when the emission intensity across a major part of the pulse window changes periodically. The phase shifts are associated with intensity changes at specific locations within the emission window in a periodic manner; while in some pulsars the periodic modulations become more prominent only at specific intervals resulting in intermittent behaviour.

Planet--disc interactions, despite being fundamentally three-dimensional, are often studied in the two-dimensional `thin-disk' approximation. The overall morphology of planet--disc interactions has ben shown to be similar in both 2D and 3D simulations, however, the ability of a 2D simulation to quantitatively match 3D results depends strongly on how the potential of the planet is handled. Typically, the 2D planetary potential is smoothed out using some `smoothing length', a free parameter, for which different values have been proposed, depending on the particular aspect of the interaction focused on. In this paper, we re-derive 2D Navier--Stokes in detail for planet--disc interactions to find better ways to represent the 2D gravitational force. We perform a large suite of 2D and 3D simulations to test these force prescriptions. We identify the parts of the interaction that are fundamentally 3D, and test how well our new force prescriptions, as well as traditional smoothed potentials, are able to match 3D simulations. Overall, we find that the optimal way to represent the planetary potential is the `Bessel-type potential', but that even in this case 2D simulations are unable to reproduce the correct scaling of the total torque with background gradients, and are at best able match the one-sided Lindblad torque and gap widths to level of 10 per cent. We find that analysis of observed gap structures based on standard 2D simulations may systematically underestimate planetary masses by a factor of two, and discuss the impacts of 3D effects on observations of velocity kinks.

TOI-3884 b is a sub-Saturn transiting a fully convective M-dwarf. Observations indicate that the transit shape is chromatic and asymmetric as a result of persistent starspot crossings. This, along with the lack of photometric variability of the host star, indicates that the rotational axis of the star is tilted along our line of sight and the planet-occulted starspot is located close to the stellar pole. We acquired photometric transits over a period of three years with the Swiss 1.2-meter Euler telescope to track changes in the starspot configuration and detect any signs of decay or growth. The shape of the transit changes over time, and so far no two observations match perfectly. We conclude that the observed variability is likely not caused by changes in the temperature and size of the spot, but due to a slight (5.64 $\pm$ 0.64$^{\circ}$) misalignment between the spot center and the stellar pole, i.e., a small spin-spot angle ($\Theta$). In addition, we were able to obtain precise measurements of the sky-projected spin-orbit angle ($\lambda$) of 37.3 $\pm$ 1.5\degree, and the true spin-orbit angle ($\psi$) of 54.3 $\pm$ 1.4\degree. The precise alignment measurements along with future atmospheric characterisation with the James Webb Space Telescope will be vital for understanding the formation and evolution of close-in, massive planets around fully convective stars.

The POEMMA-Balloon with Radio (PBR) is an Ultra Long Duration Balloon payload scheduled for launch in Spring 2027 from Wanaka, New Zealand. It will circle over the Southern Ocean for a mission duration as long as 50 days, serving as a precursor to the dual satellite mission, Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The PBR mission represents a significant step towards establishing a space-based multi-messenger observatory. Observations from space will enhance the statistics of the highest-energy cosmic rays and complement ground-based observatories by enabling simultaneous observations of both hemispheres with a single instrument. Additionally, POEMMA will facilitate the measurement of Very-High-Energy Neutrinos (VHENs) following multi-messenger alerts of astrophysical transient events, such as gamma-ray bursts. PBR is an adaptation of the POEMMA mission, featuring three primary science goals: 1. Observe Ultra-High-Energy Cosmic Rays (UHECRs) via the fluorescence technique from suborbital space. 2. Observe horizontal high-altitude air showers (HAHAs) with energies exceeding the cosmic ray knee (E > 3 PeV) using optical and radio detection for the first time. 3. Follow astrophysical event alerts in the search for VHENs. This contribution provides an overview of the PBR payload and discusses the expected performance of its various detectors.

Solar tornadoes are believed to influence plasma dynamics and create conditions for heating, yet a direct quantitative link is lacking. Here, for the first time, we directly measure vortex-driven dynamics using information-theoretic diagnostics in a Bifrost simulation. By combining Shannon Entropy (SE) and Normalized Mutual Information (NMI), we track how vortices restructure plasma-magnetic interactions and channel energy into heat. The vortex flow originates in the upper photosphere and extends into the chromosphere and upper atmosphere. Relative to a control region dominated by shear flows and transient swirls, the coherent vortex shows stronger statistical interdependence between vorticity and other MHD variables. SE shows that vertical magnetic field entropy increases at the vortex onset as magnetic flux is redistributed, then decreases as the field becomes ordered. Magnetic shear and magnetic energy entropy peak during vortex development, reflecting current and energy build-up. In the upper atmosphere, low entropy in temperature and pressure alongside high entropy in density indicates ordered thermal and pressure fields but irregular mass distribution, a departure from ideal-gas behavior confirmed by weakened temperature-density coupling. NMI shows that temperature couples to different heating drivers with height: compression and vorticity (viscous heating, since vorticity traces velocity gradients) in the lower atmosphere, and vorticity plus magnetic shear in the upper atmosphere (viscous and current-driven heating). Although the simulation does not include explicit physical dissipation, hyperdiffusivity acts on sharp gradients and mimics these processes. Our results demonstrate that vortices drive multiscale coupling between flows and fields, locally shaping solar atmospheric dynamics and heating

Current observations taken by James Webb Space Telescope (JWST) allow us to observe the absorption features of icy mantles that cover interstellar dust grains, which are mainly composed of $\mathrm{H_2O}$, $\mathrm{CO}$, and $\mathrm{CO_2}$, along with other minor species. Thanks to its sensitivity and spectral resolution, JWST has the potential to observe ice features towards hundreds of sources at different stages along the process of star formation. However, identifying the spectral features of the different species and quantifying the ice composition is not trivial and requires complex spectroscopic analysis. We present Automatic Ice Composition Estimator (AICE), a new tool based on artificial neural networks. Based on the infrared (IR) ice absorption spectrum between 2.5 and 10 microns, AICE predicts the ice fractional composition in terms of $\mathrm{H_2O}$, $\mathrm{CO}$, $\mathrm{CO_2}$, $\mathrm{CH_3OH}$, $\mathrm{NH_3}$, and $\mathrm{CH_4}$. To train the model, we used hundreds of laboratory experiments of ice mixtures from different databases, which were reprocessed with baseline subtraction and normalisation. Once trained, AICE takes less than one second on a conventional computer to predict the ice composition associated with the observed IR absorption spectrum, with typical errors of $\sim$3 $\%$ in the species fraction. We tested its performance on two spectra reported towards the NIR38 and J110621 background stars observed within the JWST Ice Age program, demonstrating a good agreement with previous estimations of the ice composition. The fast and accurate performance of AICE enables the systematic analysis of hundreds of different ice spectra with a modest time investment. In addition, this model can be enhanced and re-trained with more laboratory data, improving the precision of the predictions and expanding the list of predicted species.

We analyze data from 142 of the 218 gravitational-wave (GW) sources in the fourth LIGO-Virgo-KAGRA Collaboration (LVK) Gravitational-Wave Transient Catalog (GWTC-4.0) to estimate the Hubble constant $H_0$ jointly with the population properties of merging compact binaries. We measure the luminosity distance and redshifted masses of GW sources directly; in contrast, we infer GW source redshifts statistically through i) location of features in the compact object mass spectrum and merger rate evolution, and ii) identifying potential host galaxies in the GW localization volume. Probing the relationship between source luminosity distances and redshifts obtained in this way yields constraints on cosmological parameters. We also constrain parameterized deviations from general relativity which affect GW propagation, specifically those modifying the dependence of a GW signal on the source luminosity distance. Assuming our fiducial model for the source-frame mass distribution and using GW candidates detected up to the end of the fourth observing run (O4a), together with the GLADE+ all-sky galaxy catalog, we estimate $H_0 = 76.6^{+13.0}_{-9.5} (76.6^{+25.2}_{-14.0})$ km s$^{-1}$ Mpc$^{-1}$. This value is reported as a median with 68.3% (90%) symmetric credible interval, and includes combination with the $H_0$ measurement from GW170817 and its electromagnetic counterpart. Using a parametrization of modified GW propagation in terms of the magnitude parameter $\Xi_0$, we estimate $\Xi_0 = 1.2^{+0.8}_{-0.4} (1.2^{+2.4}_{-0.5})$, where $\Xi_0 = 1$ recovers the behavior of general relativity.

We report the discovery of a massive and potentially largest Ly$\alpha$ Nebula, RaJav, at z=2.25, associated with a quasar pair: the bright SDSS~J162029.07+433451.1 (hereafter J1620+4334) and the faint newly discovered quasar JPAS-9600-10844, at 2.265 $\pm$ 0.021 using the early data release (17 deg$^{2}$) of the J-PAS. The quasar JPAS-9600-10844 embedded in the nebula is located at ~ 60.2 kpc (7.3'') from J1620+4334, and shows a compact structure with broad emission lines (> 3000 km/s), typical of active galactic nuclei. At a 2$\sigma$ surface brightness (SB) contour of $\sim 1.86 \times 10^{-16}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$, the nebula extends > 100 kpcs and has a total Ly$\alpha$ luminosity of $\sim 7.7 \pm 0.6 \times 10^{44}$ erg s$^{-1}$ signify the presence of a giant Enormous Ly$\alpha$ Nebula (ELAN). The nebula traces an over density of quasars at redshift of 2.2-2.3 consistent with the progenitor of a massive galaxy cluster. The extended CIV emission indicates that the circum-galactic medium (CGM) is metal-enriched and not primordial. The current J-PAS observations suggest photoionization and shocks due to outflows as possible ionization mechanisms. The faint extended FUV and NUV continuum emission likely points to ongoing star formation around the two quasars, suggesting a complex interaction in their environments. These findings provide new insights into the environment of quasars and their role in shaping the dynamics and evolution of the CGM at cosmic noon. Further spectroscopic observations will be required to fully characterize the object's nature and its kinematic properties. This study demonstrates the unique capability of J-PAS to detect massive and rare Ly$\alpha$ nebulae, providing new insights into their properties, environments, and connections to large-scale structures in the cosmic web such as filaments and overdensities in a large cosmological volume.

The one-dimensional flux power spectrum (P1D) of the Lyman-$\alpha$ forest probes small-scale structure in the intergalactic medium (IGM) and is therefore sensitive to a variety of cosmological and astrophysical parameters. These include the amplitude and shape of the matter power spectrum, the thermal history of the IGM, the sum of neutrino masses, and potential small-scale fluctuations due to the nature of dark matter. However, P1D is also highly sensitive to observational and instrumental systematics, making accurate synthetic spectra essential for validating analyses and quantifying these effects, especially in high-volume surveys like the Dark Energy Spectroscopic Instrument (DESI). We present an efficient lognormal mock framework for generating one-dimensional Lyman-$\alpha$ forest spectra tailored for P1D analysis. Our method captures the redshift evolution of the mean transmitted flux and the scale-dependent shape and amplitude of the one-dimensional flux power spectrum by tuning Gaussian field correlations and transformation parameters. Across the DESI Early Data Release (EDR) redshift range ($2.0 \leq z \leq 3.8$), and a wide range of scales ($10^{-4}$ s km$^{-1} \leq k \leq 1.0$ s km$^{-1}$), our mocks recover the mean flux evolution with redshift to sub-percent accuracy, and the P1D at the percent level. Additionally, we discuss potential extensions of this framework, such as the incorporation of astrophysical contaminants, continuum uncertainties, and instrumental effects. Such improvements would expand its utility in ongoing and upcoming surveys and enable a broader range of validation efforts and systematics studies for P1D inference and precision cosmology.

Galaxy clusters, the Universe's largest halo structures, are filled with 10-100 million degree X-ray-emitting gas. Their evolution is shaped by energetic processes such as feedback from supermassive black holes (SMBHs) and mergers with other cosmic structures. The imprints of these processes on gas kinematic properties remain largely unknown, restricting our understanding of gas thermodynamics and energy conversion within clusters. High-resolution spectral mapping across a broad spatial-scale range provides a promising solution to this challenge, enabled by the recent launch of the XRISM X-ray Observatory. Here, we present the kinematic measurements of the X-ray-brightest Perseus cluster with XRISM, radially covering the extent of its cool core. We find direct evidence for the presence of at least two dominant drivers of gas motions operating on distinct physical scales: a small-scale driver in the inner ~60 kpc, likely associated with the SMBH feedback; and a large-scale driver in the outer core, powered by mergers. The inner driver sustains a heating rate at least an order of magnitude higher than the outer one. This finding suggests that, during the active phase, the SMBH feedback generates turbulence, which, if fully dissipated into heat, could play a significant role in offsetting radiative cooling losses in the Perseus core. Our study underscores the necessity of kinematic mapping observations of extended sources for robust conclusions on the properties of the velocity field and their role in the assembly and evolution of massive halos. It further offers a kinematic diagnostic for theoretical models of SMBH feedback.

Despite the pervasive nature of interstellar dust and its impact on nearly all observations, most dust corrections employ line-of-sight averages over large angular scales. This neglects real variations on small angular and distance scales from discrete components of the ISM. We use $V$ band polarimetry, public dust maps, and Gaia DR3 distances of 25 stars along a 50' radius sight line towards the O9.5IV star $\zeta$ Ophiuchi ($d \approx $ 182 pc) to examine both dust and magnetic structures over the range $d = $ 36--1176 pc and angular scales of $< 1$\degr. Polarization and reddening data indicate two discrete dust populations having different magnetic field orientations along the sight line, one at $d \simeq$ 86--127 pc and another at $d\simeq$ 252--287 pc. After removal of the foreground, the more distant component exhibits alignment in polarization angle with 12 $\mu$m PAH striations seen in the field. This more distant dust population exhibits evidence of extreme starlight polarization efficiency with an average of 14.1% mag$^{-1}$, greater than the canonical Serkowski limit of 9% mag$^{-1}$. The spatial coincidence with the PAH striations indicates the PAH-emitting grains and those responsible for the high polarization efficiency may be components of the same dust population. We find no evidence that $\zeta$ Oph's radiative influence affects the polarizing or reddening properties of the surrounding dust. Our study demonstrates that accurate distance-based foreground subtraction is vital to properly understanding superimposed dust and the magnetic field components in the ISM.

Gravitational waves in general relativity are non-dispersive, yet a host of modified theories predict dispersion effects during propagation. In this work, we consider the impact of dispersion effects on gravitational-wave bursts from highly eccentric binary black holes. We consider the dispersion effects within the low-energy, effective field theory limit, and model the dispersion relation via standard parameterized deformations. Such modified dispersion relations produce two modifications to the burst waveform: a modification to the time of arrival of the bursts in the detector, which appears as a 2.5PN correction to the difference in burst arrival times, and a modification to the arrival time of individual orbital harmonics within the bursts themselves, resulting in a Bessel-type amplitude modulation of the waveform. Using the Fisher information matrix, we study projected constraints one might obtain with future observations of repeating burst signals with LIGO. We find that the projected constraints vary significantly depending on the theoretical mechanism producing the modified dispersion. For massive gravitons and multifractional spacetimes that break Lorentz invariance, bounds on the coupling parameters are generally weaker than current bounds. For other Lorentz invariance breaking models such as Hořava-Lifschitz gravity, as well as scenarios with extra dimensions, the bounds in optimal cases can be 1-6 orders of magnitude stronger than current bounds.

Hawking radiation elucidates black holes as quantum thermodynamic systems, thereby establishing a conceptual bridge between general relativity and quantum mechanics through particle emission phenomena. While conventional theoretical frameworks predominantly focus on classical spacetime configurations, recent advancements in Extended Phase Space thermodynamics have redefined cosmological parameters (such as the $\Lambda$-term) as dynamic variables. Notably, the thermodynamics of Anti-de Sitter (AdS) black holes has been successfully extended to incorporate thermodynamic pressure $P$. Within this extended phase space framework, although numerous intriguing physical phenomena have been identified, the tunneling mechanism of particles incorporating pressure and volume remains unexplored. This study investigates Hawking radiation through particle tunneling in Schwarzschild Anti-de Sitter black holes within the extended phase space, where the thermodynamic pressure $P$ is introduced via a dynamic cosmological constant $\Lambda$. By employing semi-classical tunneling calculations with self-gravitation corrections, we demonstrate that emission probabilities exhibit a direct correlation with variations in Bekenstein-Hawking entropy. Significantly, the radiation spectrum deviates from pure thermality, aligning with unitary quantum evolution while maintaining consistency with standard phase space results. Moreover, through thermodynamic analysis, we have verified that the emission rate of particles is related to the difference in Bekenstein-Hawking entropy of the emitted particles before and after they tunnel through the potential barrier. These findings establish particle tunneling as a unified probe of quantum gravitational effects in black hole thermodynamics.

The TianQin(TQ) program is to deploy three satellites that can form an equilateral triangle in about 100,000 km Earth orbit to capture gravitational wave signals in the low-frequency band. In order to ensure accurate capture, noise needs to be analyzed and compensated. In this paper, we model and analyze the acceleration noise generated by the test mass affected by the magnetic field in space. In this paper, we use the Tsyganenko model as the background magnetic field of the TQ orbit, calculate the magnetic field and magnetic field gradient of the satellite orbit from 1997 to 2023, analyze the acceleration noise due to the coupling of the residual magnetic moment, the induced magnetic moment with the magnetic field in space and the acceleration noise due to the Lorentz force, and calculate the acceleration integrated noise of the influence of the magnetic field on the test mass from the power spectral densities of the modeled magnetic field and the magnetic field gradient. The acceleration integrated noise of the magnetic field influence on the test mass is calculated from the power spectral density of the magnetic field and the magnetic field gradient obtained by the model. Through the simulation study, the acceleration of the test mass induced by the magnetic field in the space of the TQ orbit reaches the magnitude of $10^{-16}ms^{-1}Hz^{-1/2}$, which is an important source of the influencing noise. The acceleration noise induced by the magnetic field and the Lorentz force is relatively higher than that induced by the magnetic field gradient.

We show that mono-energetic axions are produced in abundance through nuclear de-excitations in nearby galaxies such as M87, which is the central galaxy of the Virgo cluster, and the starburst galaxy M82. If the axion couples to both nucleons and photons and is ultralight, then monochromatic hard X-ray signatures are induced by the subsequent axion-to-photon conversion in the magnetic fields permeating these systems. We search for evidence of such signals using NuSTAR data, focusing specifically on the $^{57}$Fe de-excitation line at 14.4 keV, and we catalog other potentially relevant nuclear lines. We find no evidence for axions from M87 or M82 and set leading constraints on the combined axion-nucleon and axion-photon coupling at the level of $|g_{ann} \times g_{a\gamma \gamma}| \lesssim 1.1 \times 10^{-22}$ GeV$^{-1}$ in the limit $m_a \lesssim 10^{-10}$ eV, at 95% confidence.

In this paper we initiate a broad study of some central properties of the string axiverse arising from Calabi-Yau compactifications of the perturbative heterotic $E_8\times E_8$ theory. Along this road toward a heterotic axiverse, we characterize the generic structure of the axion mass spectrum and the effective couplings of the non-QCD heterotic axions to Abelian and non-Abelian gauge fields and discuss their implications for cosmology, particle phenomenology, and the QCD axion quality problem. We also provide arguments that the heterotic axion masses are bounded from below much more strongly than, for example, the spectrum in type IIB compactifications.

We investigate the B-L gauge extension of the Standard Model that the Dirac seesaw mechanism with thermal Leptogenesis can be tested using the stochastic gravitational background (SGWB) emanating from a network of cosmic strings when B-L symmetry is broken. With right-handed neutrino mass lighter than the typical scale of grand unification, the B-L symmetry protecting the right-handed neutrinos leads to constraints on the Yukawa couplings for both Dirac and Majorana scenarios. Estimating the predicted gravitational wave background we find that future space-borne missions could probe the range concerning thermal Dirac Leptogenesis. In a comparative analysis between such probes of gravitational wave sourced from cosmic strings in Dirac and Majorana Leptogenesis in the B-L extension, based on the energy scales of the Leptogenesis, for instance, GW detectors will be able to probe the scale of Dirac Leptogenesis upto $ 10^{9}$ GeV, while for Majorana Leptogenesis it would be upto $ 10^{12}$ GeV.

Critical gravitational collapse offers a unique window into regimes of arbitrarily high curvature, culminating in a naked singularity arising from smooth initial data -- thus providing a dynamical counterexample to weak cosmic censorship. Near the critical regime, quantum effects from the collapsing matter are expected to intervene before full quantum gravity resolves the singularity. Despite its fundamental significance, a self-consistent treatment has so far remained elusive. In this work, we perform a one-loop semiclassical analysis using the robust anomaly-based method in the canonical setup of Einstein gravity minimally coupled to a free, massless scalar field. Focusing on explicitly solvable critical solutions in both 2+1 and 3+1 dimensions, we analytically solve the semiclassical Einstein equations and provide definitive answers to several long-standing questions. We find that regularity uniquely selects a Boulware-like quantum state, encoding genuine vacuum polarization effects from the collapsing matter. Remarkably, the resulting quantum corrections manifest as a growing mode. Horizon-tracing analyses, incorporating both classical and quantum modes, reveal the emergence of a finite mass gap, signaling a phase transition from classical Type II to quantum-modified Type I behavior, thereby providing a quantum enforcement of the weak cosmic censorship. The most nontrivial aspect of our analysis involves dealing with non-conformal matter fields in explicitly time-dependent critical spacetimes. Along the way, we uncover intriguing and previously underexplored features of quantum field theory in curved spacetime.

Classical critical collapse yields naked singularities from smooth initial data, challenging cosmic censorship and shaping the spectrum of primordial black holes. We show that one-loop vacuum polarization near the threshold alters this outcome. In analytically tractable Einstein-scalar critical spacetimes, regularity uniquely selects a Boulware-like state whose stress tensor supplies a universal quantum growing mode. Its backreaction competes with the classical unstable mode, producing a shift of the critical point and a finite mass gap at the new threshold, thereby enforcing horizon formation even under arbitrary fine-tuning. In primordial collapse, the threshold shift enters exponentially into the formation fraction, while the gap truncates the low-mass tail -- effects that may reshape the predicted mass spectrum. These results provide the first consistent quantum treatment of critical collapse, offering definitive predictions for several long-standing problems.

We present constraints on low mass dark matter-electron scattering and absorption interactions using a SuperCDMS high-voltage eV-resolution (HVeV) detector. Data were taken underground in the NEXUS facility located at Fermilab with an overburden of 225 meters of water equivalent. The experiment benefits from the minimizing of luminescence from the printed circuit boards in the detector holder used in all previous HVeV studies. A blind analysis of $6.1\,\mathrm{g\cdot days}$ of exposure produces exclusion limits for dark matter-electron scattering cross-sections for masses as low as $1\,\mathrm{MeV}/c^2$, as well as on the photon-dark photon mixing parameter and the coupling constant between axion-like particles and electrons for particles with masses $>1.2\,\mathrm{eV}/c^2$ probed via absorption processes.

The study of exoplanetary atmospheres traditionally relies on forward models to analytically compute the spectrum of an exoplanet by fine-tuning numerous chemical and physical parameters. However, the high-dimensionality of parameter space often results in a significant computational overhead. In this work, we introduce a novel approach to atmospheric retrieval leveraging on quantum extreme learning machines (QELMs). QELMs are quantum machine learning techniques that employ quantum systems as a black box for processing input data. In this work, we propose a framework for extracting exoplanetary atmospheric features using QELMs, employing an intrinsically fault-tolerant strategy suitable for near-term quantum devices, and we demonstrate such fault tolerance with a direct implementation on IBM Fez. The QELM architecture we present shows the potential of quantum computing in the analysis of astrophysical datasets and may, in the near-term future, unlock new computational tools to implement fast, efficient, and more accurate models in the study of exoplanetary atmospheres.

We analyze the effect of the magnetic field on the proton and neutron density distributions of the nuclei 2H, 3H, 3He, which are calculated ab initio, and the 6Li nucleus in the alpha-cluster model. It is found that the asymptotic exponential damp of the probability density at long distance is modified, and that the linear component of the exponent with respect to the magnetic field yields the leading contribution, while those of the second derivative and the confining magnetic force are subleading. Due to the linear dependence of the exponent, fluctuating magnetic fields always enhance the tunneling rate, i.e. the cross section of low energy nuclear reactions which occur at large separation across the Coulomb barrier. While this mechanism cannot suppress the production of 7Be in the early Universe, it has the potential to resolve the lithium problem either by increasing the reaction rate of 7Be + p -> 8B at the bigbang nucleosynthesis era if the magnetic field at this time was sufficiently strong, or by correcting the systematically enlarged 4He + 3He -> 7Be cross section by the unwanted magnetic field generated in the nuclear experimental setup, which was so far used as the input of the simulation of bigbang nucleosynthesis.

We investigate wormhole solutions within the framework of the semi-classical Einstein equations in the presence of the conformal anomaly (or trace anomaly). These solutions are sourced by a stress-energy tensor (SET) derived from the trace anomaly, and depend on two positive coefficients, $\alpha$ and $\lambda$, determined by the matter content of the theory and on the degrees of freedom of the involved quantum fields. For a Type B anomaly ($\alpha=0$), we obtain wormhole geometries assuming a constant redshift function and show that the SET components increase with the parameter $\lambda$. In the case of a Type A anomaly ($\lambda=0$), we generalize previously known solutions, yielding a family of geometries that includes Lorentzian wormholes, naked singularities, and the Schwarzschild black hole. Using isotropic coordinates, we identify parameter choices that produce traversable wormhole solutions. Extending to the full trace-anomaly contribution, we solve the differential equation near the throat to obtain the redshift function and demonstrate that both the Ricci and Kretschmann scalars remain finite at the throat. We further analyze the trajectories of null and timelike particles, showing that the height and width of the effective potential for null geodesics increase monotonically with $\alpha$, while the innermost stable circular orbit (ISCO) radius also grows with larger $\alpha$. These results illustrate the rich interplay between trace anomaly effects and the structure and dynamics of wormhole spacetimes.

We calculate the high-frequency limit of the Halilsoy and Chandrasekhar standing gravitational wave solutions. We show that the backreaction effect is the same for these classes of solutions and we analyze the causal structure of the effective spacetime. In addition, we rederive both classes of solutions without referring to the Ernst equation and generation techniques.

We calculate the absorption mean free paths of electron and muon neutrinos in two-flavor color-superconducting (2SC) quark matter in the density and temperature range that is relevant to binary neutron star mergers. We model the strong interaction between quarks using a Nambu--Jona-Lasinio model, performing calculations self-consistently in the mean-field approximation. Since the 2SC gap is large we restrict our analysis to the contribution of unpaired quarks. We find that at low temperatures absorption by a down quark $\nu+d \to u+e^-/\mu^-$ is kinematically not allowed, so absorption by a strange quark $\nu+s \to u+e^-/\mu^-$ dominates the mean free path. As temperature or neutrino energy rises, the $d$ quark absorption channel becomes active, and the mean free path shrinks. We find that in equilibrated 2SC matter with an electron lepton fraction $Y_{L_e}=0.1$, the neutrinos form a degenerate gas with a mean free path of meters or less, independent of the temperature.

We present a GPU-accelerated implementation of the gravitational-wave Bayesian inference pipeline for parameter estimation and model comparison. Specifically, we implement the `acceptance-walk' sampling method, a cornerstone algorithm for gravitational-wave inference within the bilby and dynesty framework. By integrating this trusted kernel with the vectorized blackjax-ns framework, we achieve typical speedups of 20-40x for aligned spin binary black hole analyses, while recovering posteriors and evidences that are statistically identical to the original CPU implementation. This faithful re-implementation of a community-standard algorithm establishes a foundational benchmark for gravitational-wave inference. It quantifies the performance gains attributable solely to the architectural shift to GPUs, creating a vital reference against which future parallel sampling algorithms can be rigorously assessed. This allows for a clear distinction between algorithmic innovation and the inherent speedup from hardware. Our work provides a validated community tool for performing GPU-accelerated nested sampling in gravitational-wave data analyses.

The detection and characterization of lunar water are critical for enabling sustainable human and robotic exploration of the Moon. Orbital neutron spectrometers, such as instruments on Lunar Prospector and the Lunar Reconnaissance Orbiter, have revealed hydrogen-rich regions near the poles but are limited by coarse spatial resolution and low counting efficiency. We present a compact, lightweight, and low-power epithermal neutron detector based on boron-coated silicon imagers, designed to probe subsurface hydrogen at decimeter scales from mobile platforms such as lunar rovers. This instrument leverages the high neutron capture cross-section of $^{10}$B to convert epithermal neutrons into detectable $\alpha$ and $^{7}$Li ions in a fully-depleted silicon imager, providing a unique event topology to identify neutrons while suppressing backgrounds. Monte Carlo simulations demonstrate that a 3 $\mu$m boron layer achieves optimal neutron detection efficiency, further enhanced with polyethylene moderation to improve sensitivity to the 0.4 eV-500 keV epithermal energy range. For a 10 cm$^2$ active area, the detector achieves sensitivity to H$_2$O weight fractions as low as 0.01 wt % in a 15 minute measurement. This scalable, portable, low-mass design is well-suited for integration into upcoming Artemis and commercial lunar rovers, providing a transformative capability for in-situ resource prospecting and ground-truth validation of orbital measurements.