Sazuna/UAT_keywords huggingface dataset:
CHILES. VIII. Probing the Evolution of Average H I Content in Star-forming Galaxies over the Past 5 Gyr. Utilizing the COSMOS H I Large Extragalactic Survey (CHILES) data set, we investigate the evolution of the average atomic neutral hydrogen (H I) properties of galaxies over the continuous redshift range 0.09 &lt; z &lt; 0.47. First, we introduce a simple multistep, multiscale imaging and continuum subtraction process that we apply to each observing session. These sessions are then averaged onto a common uv-grid and run through a Fourier filtering artifact mitigation technique. We then demonstrate how this process results in science quality data products by comparing to the expected noise and image-cube kurtosis. This work offers the first-look description and scientific analysis after the processing of the entire CHILES database. These data are used to measure the average H I mass in four redshift bins, out to a redshift 0.47, by separately stacking blue cloud (near-UV, NUV-r = ‑1 to 3) and red sequence (NUV-r = 3–6) galaxies. We find little-to-no change in gas fraction for the total ensemble of blue galaxies and make no detection for red galaxies. Additionally, we split up our sample of blue galaxies into an intermediate stellar mass bin (M* = 109‑10M⊙) and a high stellar mass bin (M* = 1010‑12.5M⊙). We find that in the high-mass bin galaxies are becoming increasingly H I poor with decreasing redshift, while the intermediate-mass galaxies maintain a constant H I gas mass. We place these results in the context of the star-forming main sequence of galaxies and hypothesize about the different mechanisms responsible for their different evolutionary tracks.

Keywords: Radio interferometry, Late-type galaxies, Interstellar atomic gas
Model-independent Determination of the Tidal Deformability of a 1.4 M<SUB>⊙</SUB> Neutron Star from Gravitational-wave Measurements. Tidal deformability of a 1.4 M⊙ neutron star provides a pivotal window into the physics of dense nuclear matter, bridging gravitational-wave (GW), electromagnetic observations and nuclear physics. In this work, we present a novel, data-driven approach to constrain Λ1.4 without invoking specific equation-of-state (EOS) models. By interpolating directly over the mass─tidal-deformability posteriors from GW170817, we obtain an EOS-independent constraint of  Λ1.4=222.89−98.85+420.33.  We further combine these GW-based results with the X-ray EOS-independent constraint from C. Huang, deriving a multimessenger limit of  Λ1.4=265.18−104.38+237.88,  which remains largely EOS agnostic. This framework demonstrates that higher-order terms neglected in linear expansion methods do not significantly affect Λ1.4 estimates under current observational uncertainties. As GW detectors improve in sensitivity and more binary neutron-star mergers are discovered, our purely data-driven strategy can serve as a robust standard baseline for extracting neutron-star interior properties without relying on unverified EOS models.

Keywords: Neutron stars, Bayesian statistics, Gravitational waves
Magnetic Accretion Flow Explains the Hysteresis Q-diagram Seen in Outbursts of Black Hole Low-mass X-Ray Binaries. Black hole low-mass X-ray binaries undergo quiescence-outburst cycles. During the outbursts, they typically go through a q-shaped pattern in the hardness-intensity diagram (HID), known as the hysteresis q-diagram, while the physical nature is still unknown. We argue that the hysteresis q-diagram can be well explained with a recently proposed magnetized accretion disk model. The model takes into account the saturated magnetic pressure and predicts that the standard Shakura–Sunyaev disk (SSD) has an inner truncation at relatively low accretion rates, filled with an optically thin, hot accretion flow that resembles the advection-dominated accretion flow (ADAF) inside. Given a perturbation of accretion rate, the variation of the truncation radius can be derived as a result of thermal equilibrium by comparing the heating and cooling rates. We show that the truncation radius displays a hysteresis effect in response to the variation of mass accretion rate. As a result, the spectral hardness due to competition of the soft SSD and hard ADAF components is also hysteresis along with the rise and decay of the mass accretion rate or source intensity, leading to a q-shaped diagram in the HID.

Keywords: Stellar accretion disks, Theoretical models, Black holes, High energy astrophysics
Measuring the Redshift-space Distortions by Cross-correlating the Density Fields Before and After Reconstruction. In this work, we develop a theoretical model for the cross-power spectrum of the matter density field before and after standard baryonic acoustic oscillation reconstruction. Using this model, we extract the redshift-space distortion parameter from the cross-power spectrum. The model is validated against a suite of high-resolution N-body simulations, demonstrating its accuracy and robustness for cosmological analyses.

Keywords: Cosmological models, Baryon acoustic oscillations, Redshift surveys, Cosmological perturbation theory
Simulations of Coronal Mass Ejections on a Young Solar-type Star and Their Detectability Through Coronal Spectral Observations. There is a growing interest in searching for coronal mass ejections (CMEs) in other stellar systems, because they are thought to be one of the important factors shaping planetary atmospheres. We investigated the possible spectral signatures related to stellar CMEs using magnetohydrodynamic (MHD) simulations and spectral synthesis techniques. Blue-wing enhancements of the synthetic coronal line profiles caused by the line-of-sight motion of plasma were observed during the simulated CME events. We included instrumental conditions in the spectral synthesis and tested the detectability of the asymmetries under different instrumental broadening conditions. The results show that blue-wing asymmetries are visible in some extreme-ultraviolet lines with spectral resolutions higher than around 2000, and the line-of-sight velocities of CMEs obtained from asymmetry analysis techniques are comparable to the CME velocities derived from three-dimensional model outputs. However, when the spectral resolution drops below 2000, the asymmetries in the blue wings become barely visible, but blueshifts in the line centroids with velocities around ‑100 to ‑200 km s‑1 are observed. We suggest a method of using MHD simulations to synthesize line profiles and analyze their asymmetries that may help to guide future instrument design, in terms of detecting stellar CMEs through Doppler shifts or the asymmetries of coronal spectral lines.

Keywords: Magnetohydrodynamical simulations, Extreme ultraviolet astronomy, Stellar coronal mass ejections
Spinning Spectral Sirens: Robust Cosmological Measurement Using Mass–Spin Correlations in the Binary Black Hole Population. Gravitational waves from compact binary mergers provide a direct measurement of luminosity distance, which, in combination with redshift information, serves as a cosmological probe. In order to statistically infer merger redshifts, the "spectral standard siren" method relies on features, such as peaks, dips, or breaks, in the compact object mass spectrum, which get redshifted in the detector frame relative to the source frame. However, if the source-frame location of these features evolves over cosmic time, the spectral siren measurement may be biased. Some features, such as the edges of the pair-instability supernova mass gap, may be more stable than others. We point out that binary black hole (BBH) spins, which are not redshifted in the detector frame, provide a natural way to identify robust mass scales for spectral siren cosmology. For example, there is recent evidence for a mass scale in the BBH population that separates slowly spinning from more rapidly spinning BBH mergers, consistent with the lower edge of the pair-instability gap. Applying our method to data from LIGO-Virgo-KAGRA's third transient catalog, we demonstrate how to isolate this mass scale and produce a robust "spinning spectral siren" measurement of the Hubble constant  H0=85‑67+99kms‑1Mpc‑1 , or  H0=80‑46+60kms‑1Mpc‑1  when combined with other mass features, such as the ∼35 M⊙ peak. We consider the possibility that the source-frame location of the ∼35 M⊙ peak evolves with redshift and show that information from black hole spin can be used to mitigate the associated bias for self-calibrating spectral sirens.

Keywords: Gravitational wave astronomy, Cosmology
Rising from the Ashes. II. The Bar-driven Abundance Bimodality of the Milky Way. The Milky Way hosts at least two modes in its present-day distribution of Fe and α-elements. The exact cause of this bimodality is disputed, but one class of explanations involves the merger between the Milky Way and a relatively massive satellite (Gaia-Sausage-Enceladus) at z ∼ 2. However, reproducing this bimodality in simulations is not straightforward, with conflicting results on the prevalence, morphology, and mechanism behind multimodality. We present a case study of a galaxy in the Illustris TNG50 simulation that undergoes sequential phases of starburst, brief quiescence, and then rejuvenation. This scenario results in a pronounced abundance bimodality after a post-processing adjustment of the [α/Fe] of old stars designed to mimic a higher star formation efficiency in dense gas. The high- and low-α sequences are separated in time by the brief quiescent period, which is associated not with a merger but with the formation of a bar followed by active galactic nucleus (AGN) activity. This galaxy indicates a novel scenario in which the α-bimodality in the Milky Way is caused by the formation of the bar via AGN-induced quenching. In addition to a stellar age gap in the Milky Way, we predict that abundance bimodalities should be more common in barred as opposed to unbarred galaxies.

Keywords: Active galactic nuclei, Galactic bar, Milky Way Galaxy, Post-starburst galaxies, Magnetohydrodynamical simulations
The JCMT BISTRO-3 Survey: Variation of Magnetic Field Orientations on Parsec and Subparsec Scales in the Massive Star-forming Region G28.34+0.06. Magnetic fields play a significant role in star-forming processes on core to clump scales. We investigate magnetic field orientations and strengths in the massive star-forming clump P2 within the filamentary infrared dark cloud G28.34+0.06 using dust polarization observations made using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (or BISTRO) survey. We compare the magnetic field orientations at the clump scale of ∼2 pc from these JCMT observations with those at the core scale of ∼0.2 pc from archival Atacama Large Millimeter/submillimeter Array data, finding that the magnetic field orientations on these two different scales are perpendicular to one another. We estimate the distribution of magnetic field strengths, which range from 50 to 430 μG over the clump. The region forming the core shows the highest magnetic field strength. We also obtain the distribution of mass-to-flux ratios across the clump. In the region surrounding the core, the mass-to-flux ratio is larger than 1, which indicates that the magnetic field strength is insufficient to support the region against gravitational collapse. Therefore, the change in the magnetic field orientation from clump to core scales may be the result of gravitational collapse, with the field being pulled inward along with the flow of material under gravity.

Keywords: Magnetic fields, Star formation, Interstellar medium
A Large-scale Search for Photometrically Variable Active Galactic Nuclei in Dwarf Galaxies Using the Young Supernova Experiment. We conduct an analysis of over 60,000 dwarf galaxies ( 7≲logM*/M⊙≲10 ) in search of photometric variability indicative of active galactic nuclei (AGNs). Using data from the Young Supernova Experiment, a time domain survey on the Pan-STARRS telescopes, we construct light curves for each galaxy in up to four bands (griz) where available. We select objects with AGN-like variability by fitting each light curve with a damped random walk (DRW) model. After quality cuts and removing transient contaminants, we identify 1100 variability-selected AGN candidates (representing 2.4% of the available sample). We analyze their spectra to measure various emission lines and calculate black hole (BH) masses, finding general agreement with previously found mass scaling relations and nine potential intermediate-mass BH candidates. Furthermore, we reanalyze the light curves of our candidates to calculate the dampening timescale τDRW associated with the DRW and see a similar correlation between this value and the BH mass. Finally, we estimate the active fraction as a function of stellar mass and see evidence that the active fraction increases with host mass.

Keywords: Light curves, Dwarf galaxies, Active galactic nuclei, Time domain astronomy
Coordinated Space- and Ground-based Monitoring of Accretion Bursts in a Protoplanetary Disk: Establishing Mid-infrared Hydrogen Lines as Accretion Diagnostics for JWST/MIRI. In this paper, we establish and calibrate mid-infrared (MIR) hydrogen recombination lines observed with the James Webb Space Telescope as accretion tracers for pre-main-sequence stars that accrete from circumstellar disks. This work is part of a coordinated, multi-observatory effort that monitored the well-known binary system DQ Tau over three orbital periods, capturing its periodic accretion bursts. In this first paper, we present nine epochs of Mid-Infrared Instrument (MIRI) Medium Resolution Spectrometer (MRS) spectra with near-simultaneous Las Cumbres Observatories (LCO) photometry and Very Large Telescope X-shooter spectroscopy. This program caught exceptional accretion variability, spanning almost 2 orders of magnitude between the peak of the first periastron accretion burst and the following quiescent phases. The MIRI spectra show H I line luminosities that vary in step with the accretion-luminosity time series measured with LCO and X-shooter. The tight correlation with accretion and the large line widths, which MIRI resolves for the first time, support an accretion-flow origin for MIR H I transitions. Combining these three exceptional data sets, we derive accurate relations between MIR line and accretion luminosities for three H I transitions (10─7, 7─6, and 8─7), and improve upon a previous relation based on Spitzer spectra. These new relations equip the community with a direct measurement of the accretion luminosity from MIRI-MRS spectra. A MIRI-derived accretion luminosity is fundamental for time-domain chemistry studies, as well as for studies of accretion in embedded/distant sources that are currently inaccessible in the optical. With these new relations, we provide accretion luminosities for an archival sample of 38 MRS spectra of protoplanetary disks published to date.

Keywords: Pre-main sequence stars, Protoplanetary disks, Stellar accretion, Circumstellar disks, Stellar accretion disks, Exoplanet formation
Unveiling Two Deeply Embedded Young Protostars in the S68N Class 0 Protostellar Core with JWST/NIRSpec. The near-infrared (NIR) emission of the youngest protostars still needs to be characterized to better understand the evolution of their accretion and ejection activity. We analyze James Webb Space Telescope NIRSpec 1.7–5.3 μm observations of two deeply embedded sources in the S68N protostellar core in Serpens. The North Central source exhibits a highly obscured spectrum (AK ∼ 4.8 mag) that is modeled with a pre-main-sequence photosphere and a hot disk component. The photospheric parameters are consistent with a young, low-mass photosphere, as suggested by the low surface gravity, log g of 1.95 ±0.15 cm s‑2. The hot disk suggests that accretion onto the central protostellar embryo is ongoing, although prototypical accretion-tracing emission lines H I are not detected. The South Central source, which is even more embedded (AK ∼ 8 mag; no continuum is detected shortward of 3.6 μm) appears to be driving the large-scale S68N protostellar outflow, and launches a collimated hot molecular jet detected in H2 and CO rovibrational lines. Shock modeling of the H2 (ro)vibrational lines establishes that fast C-type shocks (≥30 km s‑1), with high pre-shock density (≥107 cm‑3), and strong magnetic field (b ∼ 3–10, where  B=b×nH(cm‑3)μG ) best match the data. The bright CO fundamental line forest suggests energetic excitation, with the contribution of non-LTE effects, i.e., irradiation pumping. Detected OH and CH+ rovibrational lines support this hypothesis. These two Class 0 protostars seem to be in very young evolutionary stages and still have to acquire the bulk of their final stellar masses. These results demonstrate that JWST enables unprecedented diagnostics of these first stages of the protostellar evolutionary phase.

Keywords: Jets, Shocks, Molecular spectroscopy, Young stellar objects, Star formation, Stellar accretion, Circumstellar disks, Protostars, Stellar photospheres, Near infrared astronomy
A Multiwavelength Study of the Dynamic Environment Surrounding the FUor V960 Mon. The evolution of young stars and planet-forming environments is intrinsically linked to their nascent surroundings. This is particularly evident for FU Orionis (FUor) objects—a class of young protostars known for dramatic outbursts resulting in significant increases in brightness. We present a case study of V960 Mon, an FUor that has recently been found to show signs of a fragmenting spiral arm, potentially connected to planet formation. Our study explores the large-scale environment (103─104 au) and incorporates Atacama Large Millimeter/submillimeter Array band 3, band 4, and band 6 continuum data, molecular emissions from 12CO, 13CO, C18O, SiO, DCO+, N2D+, and DCN, alongside optical and near-infrared observations from Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) and VLT Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE). We map a region of 20″ across where we find tantalizing emissions that provide a unique view of a young group of protostars, including the discovery of a class-0 protostar to the east of the FUor. The 12CO and SiO tracers suggest that this object is at the base of an outflow, potentially impacting the surrounding medium. The MUSE and SPHERE observations indicate the presence of an elongated feature towards a prominent source to the southeast that may represent interaction between V960 Mon and its surroundings. Moreover, the C18O emission overlaps with the clumps of the detected fragmenting spiral arm. These findings provide the strongest evidence to date for a connection between infalling material, fragmentation, and the intensity outburst of a protostar. Our case study highlights the complex interactions between young stars and their surroundings that drive the evolution of the planet forming environment.

Keywords: Observational astronomy, FU Orionis stars, Young stellar objects, Submillimeter astronomy, Planet formation
A Holistic Exploration of the Potentially Recoverable Redshift Information of Stage IV Galaxy Surveys. Extragalactic science and cosmology with Stage IV galaxy surveys will rely almost exclusively on redshift measurements derived solely from photometry, which are subject to systematic and statistical uncertainties with numerous analysis choices. Single-survey photometric redshift estimates ought to be improved by combining data from multiple surveys, with common wisdom asserting that optical data benefits from additional infrared (IR) but not ultraviolet (UV) coverage. The degree of improvement for either is not well characterized, and attempts necessitate assumptions of a chosen estimator and its prior information. We apply an information-theoretic metric of potentially recoverable redshift information to assess the impact of multi-survey photometry without assuming an estimator or priors in the context of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) in the optical, Roman and Euclid (ROMAN and EUCLID) in the IR, and Cosmological Advanced Survey Telescope for Optical-UV Research (CASTOR) in the UV. Our approach uses mock catalogs to approximate conditional relationships between color and redshift from real samples, but is otherwise independent of estimator and prior information. We conclude that adding UV photometry can benefit redshift determination of certain galaxy populations, but that gain is tempered by their decreased chance of meeting detection criteria at higher wavelengths. We explore the spectral energy distributions of galaxies whose potentially recoverable redshift information is most impacted by additional photometry. The holistic assessment approach we develop here is generic and may be applied to quantify the impact of combining photometric data sets, changing experimental design, optimizing observing strategy, and mitigating systematics.

Keywords: Computational methods, Observational cosmology, Sky surveys, Redshift surveys
The RESOLVE and ECO G3 Initiative: Drivers of H I Content and X-Ray Emission in Galaxy Groups. Adding to the RESOLVE and ECO Gas in Galaxy Groups (G3) initiative, we examine possible drivers of group-integrated H I-to-halo mass ratios (MHI,grp/Mhalo) and group X-ray emission, including group halo mass (Mhalo), virialization as probed by crossing time (tcross), presence of active galactic nuclei (AGN), and group-integrated fractional stellar mass growth rate (FSMGRgrp). G3 groups span Mhalo = 1011‑1014.5 M⊙ with comprehensive H I gas and AGN information, which we combine with X-ray stacking of ROSAT All-Sky data. We detect hot gas emission exceeding AGN and X-ray binary backgrounds confidently for Mhalo = 1012.6‑1014 M⊙ and unambiguously for Mhalo &gt; 1014 M⊙, reflecting an inverse dependence of MHI,grp/Mhalo and hot gas emission on halo mass. At fixed halo mass, MHI,grp/Mhalo transitions to greater spread below tcross ∼ 2 Gyr. Dividing groups across this transition, lower-tcross groups show elevated X-ray emission compared to higher-tcross groups for Mhalo &gt; 1013.3 M⊙, but this trend reverses for Mhalo = 1012.6‑1013.3 M⊙. Additionally, AGN-hosting halos below Mhalo ∼ 1012.1 M⊙ exhibit a broad, ∼0.25 dex deep valley in MHI,grp/Mhalo compared to non-AGN-hosting halos with correspondingly reduced FSMGRgrp. When diluted by non-AGN-hosting halos, this valley becomes shallower and narrower, falling roughly between  Mhalo=1011.5M⊙  and  Mhalo=1012.1M⊙  in the overall MHI,grp/Mhalo vs. Mhalo relation. We may also detect a second, less easily interpreted valley at Mhalo ∼ 1013 M⊙. Neither valley matches theoretical predictions of a deeper valley located at or above  Mhalo=1012.1M⊙ .

Keywords: X-ray astronomy, Galaxy dark matter halos, Active galactic nuclei, Galaxies