Sazuna/UAT_keywords huggingface dataset:
Reconstructing Star Formation Histories of High-redshift Galaxies: A Comparison of Resolved Parametric and Nonparametric Models. We investigate the optimal approach for recovering the star formation histories (SFHs) and spatial distribution of stellar mass in high-redshift galaxies (z ∼ 2–5), focusing on the impact of assumed SFH models on derived galaxy properties. Utilizing pixel-by-pixel spectral energy distribution (SED) fitting of multiband photometry, we explore various parametric SFH models (including exponentially declining (τ), delayed-τ, lognormal, and double power law) alongside spatially resolved nonparametric (NPM) methods. We first analyze the models using simulated galaxies and then apply them to observed galaxies for validation and as proof of concept, with additional comparisons to results from unresolved SED fitting. Our findings demonstrate that pixel-by-pixel analysis with parametric models is particularly robust in recovering the true SFHs of simulated galaxies, with the double-power-law (DPL) model outperforming others, including NPM methods. This model excels in detecting recent starbursts within the last 500 Myr and capturing the stochastic nature of star formation. Conversely, unresolved photometry with simplistic parametric models tends to produce biased estimates of key galaxy properties, particularly underestimating early star formation. NPM methods, resolved or unresolved, typically yield older mass-weighted ages. Biases in early-time star formation rates, likely introduced by prior assumptions, further complicate these models. We conclude that the DPL model, applied in a pixel-by-pixel framework, offers the most reliable recovery of SFHs and produces robust stellar mass maps. Resolved methods simplify modeling dust and metallicity, enhancing parameter interpretability and underscoring the value of flexible parametric models in spatially resolved analyses.

Keywords: Galaxy mass distribution, Star formation, Spectral energy distribution, Galaxy evolution, Galaxy masses, High-redshift galaxies, Galaxies
Ring or No Ring—Revisiting the Multiphase Nuclear Environment in M31. Nuclear rings, prevalent in barred galaxies, are essential to understanding gas transport toward galactic nuclei. However, the peculiar nuclear ring in our neighboring galaxy M31 remains poorly understood. Here we present a comprehensive study of this multiphase gas structure, originally revealed by its dust emission, based on newly acquired CO mappings and archival spectroscopic imaging of atomic hydrogen and warm ionized gas, along with custom numerical simulations. These multiwavelength data offer an unprecedented view of the surface mass density and kinematics of the nuclear ring, challenging the notion of it being a single coherent structure. In particular, the ring shows significant asymmetry in its azimuthal mass distribution, with neutral gas concentrated in the northeast and ionized gas prominent in the southwest. The observed off-centered and lopsided morphology disfavors an interpretation as gas streamers or resonance rings driven solely by a barred potential known to exist in M31. Furthermore, the ring's line-of-sight velocity distribution suggests circular motion in a plane inclined by ∼30° relative to M31's outer disk, implying external torque likely from M32's recent close-in passage. Our hydrodynamical simulations tracking the evolution of nuclear gas in M31 influenced by both a barred potential and an oblique collision with M32 reveal the natural formation of asymmetric spiral arms several hundred Myr after the collision, which could appear ringlike at appropriate viewing angles. Therefore, we suggest that M31's nuclear gas structure, instead of being a persistent rotating ring, comprises recently formed, asymmetric spirals with a substantial tilt.

Keywords: Galaxy interactions, Galaxy structure, Galaxy nuclei, Galaxy evolution, Interstellar medium, Andromeda Galaxy
One Galaxy Sample to Rule Them All: Halo Occupation Distribution Modeling of DES Year 3 Source Galaxies. For the joint analysis of second-order weak-lensing and galaxy clustering statistics, so-called 3 × 2 analyses, the selection and characterization of optimal galaxy samples is a major area of research. One promising choice is to use the same galaxy sample as lenses and sources, which reduces the systematics parameter space that describes the uncertainties related to galaxy samples. Such a "lens-equal-source" analysis significantly improves the self-calibration of photo-z systematics, leading to improved cosmological constraints. With the aim of enabling a lens-equal-source analysis on small scales, we investigate the halo─galaxy connection of DES Year 3 source galaxies. We develop a technique to construct mock source galaxy populations by matching COSMOS/UltraVISTA photometry to UNIVERSEMACHINE galaxies. These mocks predict a source halo occupation distribution (HOD) that exhibits significant redshift evolution, nontrivial central incompleteness, and galaxy assembly bias. We produce multiple realizations of mock source galaxies drawn from the UNIVERSEMACHINE posterior, with added uncertainties in the measured Dark Energy Survey photometry and galaxy shapes. We fit a modified HOD formalism to these realizations to produce priors on the galaxy─halo connection for cosmological analyses. We additionally train an emulator that predicts this HOD to ∼2% accuracy from redshift z = 0.1−1.3 that models the dependence of this HOD on (1) observational uncertainties in galaxy size and photometry and (2) uncertainties in the UNIVERSEMACHINE predictions.

Keywords: Galaxy formation, Large-scale structure of the universe
The JCMT BISTRO Survey: Unveiling the Magnetic Fields around Galactic Center. We acquired 450 and 850 μm dust continuum polarization observations toward the inner region of the Central Molecular Zone (CMZ) as part of the B-Fields In Star-forming Region Observations survey using the POL-2 polarimeter on the James Clerk Maxwell Telescope. These observations encompassed three dense structures: the 20 km s‑1 cloud (20MC), 50 km s‑1 cloud (50MC), and circumnuclear disk (CND). Our aim is to investigate the magnetic field morphology and strength in the inner region of the CMZ using polarized dust continuum and the Davis–Chandrasekhar–Fermi method. The magnetic field morphology is highly ordered in all three dense regions. The plane-of-sky magnetic field strengths are ∼1 mG for the 20MC and the 50MC, and ∼2 mG for the CND. We compare the energy contributions of turbulence, gravity, and thermal motion with that of the magnetic field using the plasma β, mass-to-flux ratio, and Alfvén Mach number. The outcomes reveal the magnetic field stands out as the predominant factor within the inner region of the CMZ. The dominance of the magnetic field may explain the low star-forming rate in the CMZ. We further investigate the dust grain alignment efficiency by exploring the relationship between polarization fraction and total intensity. The results suggest that dust grains are well aligned with the magnetic fields.

Keywords: Galactic center, Star forming regions, Interstellar medium, Submillimeter astronomy, Magnetic fields
Machine and Deep Learning–driven Angular Momentum Inference from BHEX Observations of the n = 1 Photon Ring. The n = 1 photon ring is an important probe of black hole (BH) properties and will be resolved by the Black Hole Explorer (BHEX) for the first time. However, extraction of black hole parameters from observations of the n = 1 subring is not trivial. Developing this capability can be achieved by building a sample of n = 1 subring simulations, as well as by performing feature extraction on this high-volume sample to track changes in the geometry, which presents significant computational challenges. Here, we present a framework for the study of n = 1 photon-ring behavior and BH property measurement from BHEX images. We use KerrBAM to generate a grid of ≳106 images of n = 1 photon rings spanning the entire space of Kerr BH spins and inclinations. Intensity profiles are extracted from images using a novel feature-extraction method developed specifically for BHEX. This novel method is highly optimized and outperforms existing Event Horizon Telescope methods by a factor of ∼3000. Additionally, we propose a novel, minimal set of geometric measurables for characterizing the behavior of the n = 1 subring geometry. We apply these measurables to our simulation grid and test spin recovery on simulated images using (i) gradient boosting, a machine learning algorithm, and (ii) an extension of Deep Horizon, a deep learning framework. We find ≳90% correct recovery of BH properties using the machine/deep learning approaches, and characterize the space of resolution-dependent geometric degeneracies. Finally, we test both approaches on general relativistic magnetohydrodynamic simulations of black hole accretion flows, and report accurate recovery of spin at the expected inclination of M87*.

Keywords: Black hole physics, Convolutional neural networks, High energy astrophysics, Neural networks
Tracing the Evolution of the Cool Gas in CGM and IGM Environments through Mg II Absorption from Redshift z = 0.75 to z = 1.65 Using DESI-Y1 Data. We present a measurement of the mean absorption of cool gas traced by Mg II (λλ2796, 2803) around emission line galaxies (ELGs), spanning spatial scales from 20 kpc to 10 Mpc. The measurement is based on crossmatching the positions ELGs at z = 0.75–1.65 and the metal absorption in the spectra of background quasars with data provided by the Year 1 sample of the Dark Energy Spectroscopic Instrument. The ELGs are divided into two redshift intervals: 0.75 &lt; z &lt; 1.0 and 1.0 &lt; z &lt; 1.65. We find that the composite quasar spectra constructed by stacking the ELG-QSO pairs evolve with redshift, with z &gt; 1 having a systematically higher signal of Mg II absorption. Within 1 Mpc, the covering fraction of the cool gas at z &gt; 1 is higher than that of z &lt; 1. The enhancement becomes less apparent especially if the projected distance rp &gt; 1 Mpc. ELGs with higher stellar mass and star formation rate (SFR) yield higher clustering of Mg II absorbers at z &lt; 1. For z &gt; 1, the covering fractions with different SFRs show little difference. The higher Mg II absorption at higher redshift supports the observations of higher star formation at cosmic noon. Converting the Mg II absorbers to unsaturated Si II, our estimate indicates that the metal abundance of Si II ranges from 0.7 to 1.2 × 10‑6 from z = 0.9 to 1.3. The growth of low-ionization metal abundance strongly suggests a metal-enriched circumgalactic medium and an increased presence of cool gas in the intergalactic medium toward higher redshifts.

Keywords: Quasar absorption line spectroscopy, Metal line absorbers, Intergalactic medium, Galaxy evolution, Circumgalactic medium
Space Weathering Properties of Chang'e-6 Soils and Implication for Regolith Evolution of Young Lunar Maria. Lunar soil samples from young maria (formed &lt;3.0 billion years ago (Ga)) preserve key records of recent space weathering history in the Earth–Moon system. China's Chang'e-6 mission returned the first farside soil samples from a young mare (∼2.8 Ga) at the northeastern South Pole–Aitken basin. We present preliminary results on the space weathering properties of the Chang'e-6 soils. The glassy agglutinate content in the Chang'e-6 soils is approximately 30%, significantly lower than the 50%–70% observed in the mature Apollo soils from older maria (&gt;3.0 Ga) and higher than the ∼21% found in the Chang'e-5 soils from younger mare (∼2.0 Ga). However, our spectroscopic study reveals that the Chang'e-6 soils are well developed, with high maturity, weak absorption, and a red-sloped continuum, similar to the characteristics of the mature soils from the Apollo and Chang'e-5 landing sites. Orbital observations indicate more mature surface than in the returned samples from young mare regions, likely due to the destruction of an optically mature veneer by spacecraft. The optically mature veneer reveals deficiencies in remote sensing and emphasizes the importance of sample return missions. The thinner optically mature veneer and lower abundance of glassy agglutinate in younger maria suggest reduced gardening cycles and changes in impactor properties (such as rate and size) after 3.0 Ga. This is important for understanding how the relative contributions of space weathering agents change over time and the evolution of impactors in the inner solar system.

Keywords: Lunar probes, Lunar maria, Lunar regolith, The Moon, Lunar science, Lunar impacts, Lunar surface, Lunar mineralogy
Improving Photometric Redshifts of Epoch of Reionization Galaxies: A New Empirical Transmission Curve with Neutral Hydrogen Damping Wing Lyα Absorption. We present a new analytical model for the attenuation to Epoch of Reionization (EoR) galaxies by proximate neutral hydrogen gas. Many galaxy spectra in the EoR taken by JWST have shown a flux deficit at wavelengths just redward of the Lyman break, and this has been regarded as resulting from Lyα damping wing absorption by the increasing amount of neutral hydrogen in the line of sight. However, previous attenuation models for the intergalactic medium (IGM) commonly used in photometric redshift template-fitting codes assume that the Lyman break is rather sharp, which leads to systematic overestimation of photometric redshifts at z &gt; 7. In this Letter, we build and empirically calibrate a new attenuation model that takes the increased Lyα damping wing absorption into account. Our model consists of the canonical IGM absorption and an additional absorption component due to dense neutral hydrogen gas clouds proximate to the galaxy, and we derive the redshift evolution of H I column density of the proximate clouds by calibrating the model using CANUCS JWST observations. The resulting total transmission curve resolves the photometric redshift bias at z &gt; 7, an improvement that is robust to the choice of template-fitting code, template set, and photometric catalog used. The new attenuation model can be easily implemented in existing template-fitting codes and significantly improves the photometric redshift performance in the EoR.

Keywords: Reionization, High-redshift galaxies, Circumgalactic medium, Intergalactic medium
Orthogonal Alignment of Galaxy Group Angular Momentum with Cosmic Filament Spines: An Observational Study. We investigated the alignment between the angular momenta of galaxy groups and the spines of their associated cosmic filaments. Our results demonstrate a significant tendency for these two orientations to be perpendicular, indicating that the rotation of a galaxy group does not originate from the spin of cosmic filaments. Instead, it is driven by the orbital angular momentum contributed by member galaxies as they accrete along the direction of the filament spines. Moreover, the strength of this perpendicular alignment signal varies with the richness of the galaxy groups, with the most pronounced alignment observed among the wealthiest groups. This pronounced alignment is largely due to the more coherent spatial distribution of member galaxies in richer groups relative to the filament spines. Our study provides valuable insights into the mechanisms of angular momentum acquisition in galaxy groups from an observational standpoint.

Keywords: Galaxy groups, Galaxies, Large-scale structure of the universe
The Cosmic Evolution Early Release Science Survey (CEERS). We present the Cosmic Evolution Early Release Science (CEERS) Survey, a 77.2 hr Director's Discretionary Early Release Science Program. CEERS demonstrates, tests, and validates efficient extragalactic surveys using coordinated, overlapping parallel observations with the JWST instrument suite, including NIRCam and MIRI imaging, NIRSpec low- (R ∼ 100) and medium- (R ∼ 1000) resolution spectroscopy, and NIRCam slitless grism (R ∼ 1500) spectroscopy. CEERS targets the Hubble Space Telescope–observed region of the Extended Groth Strip field, supported by a rich set of multiwavelength data. CEERS facilitated immediate community science in both of the extragalactic core JWST science drivers "First Light" and "Galaxy Assembly," including: (1) the discovery and characterization of large samples of galaxies at z ≳ 10 from ∼90 arcmin2 of NIRCam imaging, constraining their abundance and physical nature; (2) deep spectra of &gt;1000 galaxies, including dozens of galaxies at 6 &lt; z &lt; 10, enabling redshift measurements and constraints on the physical conditions of star formation and black hole growth via line diagnostics; (3) quantifying the first bulge, bar, and disk structures at z &gt; 3; and (4) characterizing galaxy mid-IR emission with MIRI to study dust-obscured star formation and supermassive black hole growth at z ∼ 1–3. As a legacy product for the community, the CEERS team has provided several data releases, accompanied by detailed notes on the data reduction procedures and notebooks to aid in reproducibility. In addition to an overview of the survey and the quality of the data, we provide science highlights from the first two years with CEERS data.

Keywords: Surveys, Supermassive black holes, Galaxy formation, Galaxy evolution
Exotic Nanophase Iron as a New Agent for Space Weathering on the Moon. Nanophase iron (np-Fe) particles in space-weathered lunar regolith are widely concerning as they can change the spectral, chemical, and physical properties of lunar soils. These np-Fe particles were previously believed to be produced from lunar surface materials by space weathering processes, while the source of np-Fe particles from exotic micrometeorite (flux = ∼5 × 108 t/Ma) has been overlooked. In this study, we report the discovery of np-Fe particles in the micrometeorite impactor residue on a plagioclase crystal from Chang'e-5 lunar soil. Our results show that the source of these np-Fe particles does not originate from lunar materials, but rather are sourced from micrometeorites (i.e., exotic origin). This work provides mineralogical evidence that exotic np-Fe particles can be delivered and preserved by micrometeorite impact melting and reduction on the Moon. The estimated production rate of exotic np-Fe particles is as high as ∼5 × 106 t/Ma on the Moon. We therefore suggest that these exotic np-Fe particles have a nonnegligible influence on the interpretation of the space weathering process in special environments (e.g., permanently shadowed regions) of the Moon and other airless planetary bodies in the solar system.

Keywords: Space weather, Micrometeorites, The Moon
X-class Flare on 2023 December 31 Observed by the Solar Ultraviolet Imaging Telescope on Board Aditya-L1. We present the multiwavelength study of the ejection of a plasma blob from the limb flare SOL2023-12-31T21:36:00 from NOAA 13536 observed by the Solar Ultraviolet Imaging Telescope (SUIT) on board Aditya-L1. We use SUIT observations along with those from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory and Spectrometer/Telescope for Imaging X-rays (STIX) on board Solar Orbiter to infer the kinematics and thermal nature of the ejected blob and its connection to the associated flare. The observations show that the flare was comprised of two eruptions. The blob was ejected during the first eruption and later accelerated to velocities over 1500 km s‑1 measured at a maximum projected height of ∼178 Mm from the Sun's surface. The acceleration of the ejected plasma blob is cotemporal with the bursty appearance of the hard X-ray light curve recorded by STIX. Radio spectrogram observations from STEREO-A/WAVES and RSTN reveal type III bursts at the same time, indicative of magnetic reconnection. DEM analysis using AIA observations suggests the plasma blob is comprised of cooler and denser plasma in comparison to the ambient corona. To the best of our knowledge, this is the first observation of such a plasma blob in the near-ultraviolet providing crucial measurements for eruption thermodynamics.

Keywords: Solar atmosphere, Solar chromosphere, Solar flares, Solar corona
On the Million-degree Signature of Spicules. Spicules have often been proposed as substantial contributors toward the mass and energy balance of the solar corona. While their transition region (TR) counterpart has unequivocally been established over the past decade, the observations concerning the coronal contribution of spicules have often been contested. This is mainly attributed to the lack of adequate coordinated observations, their small spatial scales, highly dynamic nature, and complex multithermal evolution, which are often observed at the limit of our current observational facilities. Therefore, it remains unclear how much heating occurs in association with spicules to coronal temperatures. In this study, we use coordinated high-resolution observations of the solar chromosphere, TR, and corona of a quiet-Sun region and a coronal hole with the Interface Region Imaging Spectrograph (IRIS) and the Atmospheric Imaging Assembly (AIA) to investigate the (lower) coronal (∼1 MK) emission associated with spicules. We perform differential emission measure analysis on the AIA passbands using basis pursuit and a newly developed technique based on Tikhonov regularization to probe the thermal structure of the spicular environment at coronal temperatures. We find that the emission measure (EM) maps at 1 MK reveal the presence of ubiquitous, small-scale jets with a clear spatiotemporal coherence with the spicules observed in the IRIS/TR passband. Detailed spacetime analysis of the chromospheric, TR, and EM maps show unambiguous evidence of rapidly outward-propagating spicules with strong emission (2–3 times higher than the background) at 1 MK. Our findings are consistent with previously reported MHD simulations that show heating to coronal temperatures associated with spicules.

Keywords: Solar atmosphere, The Sun, Solar coronal heating, Solar spicules, Solar physics, Quiet solar corona, Solar corona, Solar chromosphere
Kiloparsec-scale Alignment of a Radio Jet with Cool Gas and Dust in a z ∼ 6 Quasar. We present high-angular-resolution (0 068, ∼400 pc) Atacama Large Millimeter/submillimeter Array (ALMA) imaging of the [C II] line and dust continuum emission of PSO J352.4034─15.3373, a radio-loud quasar at z = 5.83. The observations reveal a remarkably close match between the orientation of the [C II] and thermal dust emission mapped by ALMA and radio synchrotron emission of a radio jet previously mapped by the Very Long Baseline Array. This narrow alignment extends over ∼4 kpc, reminiscent of the well-studied "alignment effect" in lower-redshift radio galaxies. The [C II] kinematics show a linear increase in velocity with galactocentric radii up to ∼200 km s−1 at r = 2 kpc, consistent with bulk motions within the galaxy potential, and not relativistic jet motions. The kinematics and respective morphologies are consistent with a picture in which the relativistic jet injects energy into the interstellar medium (potentially leading to subsequent star formation), giving rise to the observed alignment and significant (≳100 km s−1) [C II] velocity dispersion within the host galaxy on kiloparsec scales. Indeed, the astonishingly close alignment and narrow linearity of the radio jet with the [C II] and dust emission are hard to conceive without some fundamental relationship between the two.

Keywords: Reionization, Interstellar medium, Quasars