Sazuna/UAT_keywords huggingface dataset:
Searching for Short-period Variables in M31: Method and Catalogs. Utilizing high-cadence and continuous g- and r-band data over three nights acquired from the 3.6 m Canada–France–Hawaii Telescope, aiming to find short-duration microlensing events, we conduct a systematic search for variables, transients, and asteroids across a ∼1° field of view of the Andromeda galaxy (M31). We present a catalog of 5859 variable stars, yielding the most extensive compilation of short-period variable sources of M31. We also detected 19 flares, predominantly associated with foreground M dwarfs in the Milky Way. In addition, we discovered 17 previously unknown asteroid candidates, and we subsequently reported them to the Minor Planet Center. Lastly, we report a microlensing event candidate C-ML-1 and present a preliminary analysis.

Keywords: Asteroids, Time domain astronomy, Variable stars, Gravitational microlensing, Andromeda Galaxy, Astronomy data reduction
Self-consistent Combined HST, K-band, and Spitzer Photometric Catalogs of the BUFFALO Survey Fields. This article presents new astronomical source catalogs using data from the BUFFALO Survey. These catalogs contain detailed information for over 100,000 astronomical sources in the six BUFFALO clusters: A370, A2744, AS1063, MACS 0416, MACS 0717, and MACS 1149 spanning a total of 240 arcmin2. The catalogs include positions and forced photometry measurements of these objects in the F275W, F336W, F435W, F606W, F814W, F105W, F125W, F140W, and F160W HST bands, Keck-NIRC2/VLT-HAWKI Ks band, and IRAC Channel 1 and 2 bands. Additionally, we include photometry measurements in the F475W, F625W, and F110W bands for A370. This catalog also includes photometric redshift estimates computed via template fitting using LEPHARE. When comparing to a spectroscopic reference, we obtain an outlier fraction of 8.6% and scatter, normalized median absolute deviation, of 0.059. The catalogs are publicly available for their use by the community (https://archive.stsci.edu/hlsp/buffalo/).

Keywords: Galaxy clusters, High-redshift galaxies, HST photometry
BxC Toolkit: Generating Tailored Turbulent 3D Magnetic Fields. Turbulent states are ubiquitous in plasmas, and the understanding of turbulence is fundamental in modern astrophysics. Numerical simulations, which are the state-of-the-art approach to the study of turbulence, require substantial computing resources. Recently, attention shifted to methods for generating synthetic turbulent magnetic fields, affordably creating fields with parameter-controlled characteristic features of turbulence. In this context, the BxC toolkit was developed and validated against direct numerical simulations (DNSs) of isotropic turbulent magnetic fields. Here, we demonstrate novel extensions of BxC to generate realistic turbulent magnetic fields in a fast, controlled, geometric approach. First, we perform a parameter study to determine quantitative relations between the BxC input parameters and the desired characteristic features of the turbulent power spectrum, such as the extent of the inertial range, its spectral slope, and the injection and dissipation scale. Second, we introduce in the model a set of structured background magnetic fields, B 0, as a natural and more realistic extension to the purely isotropic turbulent fields. Third, we extend the model to include anisotropic turbulence properties in the generated fields. With all these extensions combined, our tool can quickly generate any desired structured magnetic field with controlled, anisotropic turbulent fluctuations, faster by orders of magnitude with respect to DNSs. These can be used, e.g., to provide initial conditions for DNSs or easily generate synthetic data for many astrophysical settings, all at otherwise unaffordable resolutions.

Keywords: Space plasmas, Magnetohydrodynamics, Plasma astrophysics
Candidate Members of the VMP/EMP Disk System of the Galaxy from the SkyMapper and SAGES Surveys. Photometric stellar surveys now cover a large fraction of the sky, probe to fainter magnitudes than large-scale spectroscopic surveys, and are relatively free from the target selection biases often associated with such studies. Photometric-metallicity estimates that include narrow/medium-band filters can achieve comparable accuracy and precision to existing low-resolution spectroscopic surveys such as Sloan Digital Sky Survey/SEGUE and LAMOST. Here we report on an effort to identify likely members of the Galactic disk system among the very metal-poor (VMP; [Fe/H] ≤ ‑2) and extremely metal-poor (EMP; [Fe/H] ≤ ‑3) stars. Our analysis is based on an initial sample of ∼11.5 million stars with full space motions selected from the SkyMapper Southern Survey (SMSS) and Stellar Abundance and Galactic Evolution Survey (SAGES). After applying a number of quality cuts to obtain the best available metallicity and dynamical estimates, we analyze a total of ∼5.86 million stars in the combined SMSS/SAGES sample. We employ two techniques that, depending on the method, identify between 876 and 1476 VMP stars (6.9%‑11.7% of all VMP stars) and between 40 and 59 EMP stars (12.4%‑18.3% of all EMP stars) that appear to be members of the Galactic disk system on highly prograde orbits (v  ϕ  &gt; 150 km s‑1). The total number of candidate VMP/EMP disklike stars is 1496, the majority of which have low orbital eccentricities, ecc ≤ 0.4; many have ecc ≤ 0.2. The large fractions of VMP/EMP stars associated with the Milky Way disk system strongly suggest the presence of an early-forming "primordial" disk.

Keywords: Milky Way formation, Galactic archaeology, Milky Way dynamics, Milky Way disk, Milky Way evolution, Milky Way Galaxy
PHANGS-JWST: Data-processing Pipeline and First Full Public Data Release. The exquisite angular resolution and sensitivity of JWST are opening a new window for our understanding of the Universe. In nearby galaxies, JWST observations are revolutionizing our understanding of the first phases of star formation and the dusty interstellar medium. Nineteen local galaxies spanning a range of properties and morphologies across the star-forming main sequence have been observed as part of the PHANGS-JWST Cycle 1 Treasury program at spatial scales of ∼5–50 pc. Here, we describe pjpipe, an image-processing pipeline developed for the PHANGS-JWST program that wraps around and extends the official JWST pipeline. We release this pipeline to the community as it contains a number of tools generally useful for JWST NIRCam and MIRI observations. Particularly for extended sources, pjpipe products provide significant improvements over mosaics from the MAST archive in terms of removing instrumental noise in NIRCam data, background flux matching, and calibration of relative and absolute astrometry. We show that slightly smoothing F2100W MIRI data to 0.″9 (degrading the resolution by about 30%) reduces the noise by a factor of ≈3. We also present the first public release (DR1.1.0) of the pjpipe processed eight-band 2–21 μm imaging for all 19 galaxies in the PHANGS-JWST Cycle 1 Treasury program. An additional 55 galaxies will soon follow from a new PHANGS-JWST Cycle 2 Treasury program.

Keywords: Interstellar dust, Spiral galaxies, Surveys, Young star clusters, Star formation, Interstellar medium, Astronomy data reduction
PHANGS-HST Catalogs for ∼100,000 Star Clusters and Compact Associations in 38 Galaxies. I. Observed Properties. We present the largest catalog to date of star clusters and compact associations in nearby galaxies. We have performed a V-band-selected census of clusters across the 38 spiral galaxies of the PHANGS–Hubble Space Telescope (HST) Treasury Survey, and measured integrated, aperture-corrected near-ultraviolet-U-B-V-I photometry. This work has resulted in uniform catalogs that contain ∼20,000 clusters and compact associations, which have passed human inspection and morphological classification, and a larger sample of ∼100,000 classified by neural network models. Here, we report on the observed properties of these samples, and demonstrate that tremendous insight can be gained from just the observed properties of clusters, even in the absence of their transformation into physical quantities. In particular, we show the utility of the UBVI color–color diagram, and the three principal features revealed by the PHANGS-HST cluster sample: the young cluster locus, the middle-age plume, and the old globular cluster clump. We present an atlas of maps of the 2D spatial distribution of clusters and compact associations in the context of the molecular clouds from PHANGS–Atacama Large Millimeter/submillimeter Array. We explore new ways of understanding this large data set in a multiscale context by bringing together once-separate techniques for the characterization of clusters (color–color diagrams and spatial distributions) and their parent galaxies (galaxy morphology and location relative to the galaxy main sequence). A companion paper presents the physical properties: ages, masses, and dust reddenings derived using improved spectral energy distribution fitting techniques.

Keywords: Star formation, Galaxy evolution, Star clusters
Lagrangian Perspectives on the Small-scale Structure of Alfvénic Turbulence and Stochastic Models for the Dispersion of Fluid Particles and Magnetic Field Lines in the Solar Wind. Lagrangian perspectives on the small-scale structure of anisotropic Alfvénic turbulence are adopted. We are interested in relating the statistical properties of the Eulerian field increments evaluated along the fluid particle trajectories, in the direction perpendicular to the guiding magnetic field and along the magnetic field lines. We establish the basis for a unified multifractal phenomenology of Eulerian and Lagrangian Alfvénic turbulence. The critical balance condition is generalized to structure functions of an order different than 2. A Lagrangian perspective is not only useful for investigating the small-scale structure of Alfvénic turbulence, it is also tailored to the modeling of large-scale turbulent transport. Therefore, we develop Lagrangian stochastic models for the dispersion of fluid particles and magnetic field lines in the solar wind. The transport models are based on the integrated Ornstein–Uhlenbeck process that is not Markov, yielding smooth stochastic fluid particle trajectories and magnetic field lines. Brownian diffusion is recovered by tending the integral scale parameter to zero while keeping the diffusivity finite.

Keywords: Interplanetary turbulence, Magnetohydrodynamics, Solar wind, Solar energetic particles
1991T-like Supernovae. Understanding the nature of the luminous 1991T-like supernovae (SNe) is of great importance to SN cosmology as they are likely to have been more common in the early Universe. In this paper, we explore the observational properties of 1991T-like SNe to study their relationship to other luminous, slow-declining Type Ia supernovae (SNe Ia). From the spectroscopic and photometric criteria defined in Phillips et al., we identify 17 1991T-like SNe from the literature. Combining these objects with 10 1991T-like SNe from the Carnegie Supernova Project-II, the spectra, light curves, and colors of these events, along with their host galaxy properties, are examined in detail. We conclude that 1991T-like SNe are closely related in essentially all of their UV, optical, and near-infrared properties—as well as their host galaxy parameters—to the slow-declining subset of Branch core-normal SNe and to the intermediate 1999aa-like events, forming a continuum of luminous SNe Ia. The overriding difference between these three subgroups appears to be the extent to which 56Ni mixes into the ejecta, producing the premaximum spectra dominated by Fe III absorption, the broader UV light curves, and the higher luminosities that characterize the 1991T-like events. Nevertheless, the association of 1991T-like SNe with the rare Type Ia circumstellar material SNe would seem to run counter to this hypothesis, in which case 1991T-like events may form a separate subclass of SNe Ia, possibly arising from single-degenerate progenitor systems. *This paper includes data gathered with the 6.5 m Magellan telescopes at Las Campanas Observatory, Chile.

Keywords: Observational cosmology, Type Ia supernovae, Supernovae
jetsimpy: A Highly Efficient Hydrodynamic Code for Gamma-Ray Burst Afterglow. Gamma-ray burst (GRB) afterglows are emissions from ultrarelativistic blast waves produced by a narrow jet interacting with surrounding matter. Since the first multimessenger observation of a neutron star merger, hydrodynamic modeling of GRB afterglows for structured jets with smoothly varying angular energy distributions has gained increased interest. While the evolution of a jet is well described by self-similar solutions in both ultrarelativistic and Newtonian limits, modeling the transitional phase remains challenging. This is due to the nonlinear spreading of a narrow jet to a spherical configuration and the breakdown of self-similar solutions. Analytical models are limited in capturing these nonlinear effects, while relativistic hydrodynamic simulations are computationally expensive, which restricts the exploration of various initial conditions. In this work, we introduce a reduced hydrodynamic model that approximates the blast wave as an infinitely thin two-dimensional surface. Further assuming axial symmetry, this model simplifies the simulation to one dimension and drastically reduces the computational costs. We have compared our modeling to relativistic hydrodynamic simulations and semianalytic methods, and applied it to fit the light curve and flux centroid motion of GRB 170817A. These comparisons demonstrate good agreement and validate our approach. We have developed this method into a numerical tool, jetsimpy, which models the synchrotron GRB afterglow emission from a blast wave with arbitrary angular energy and Lorentz factor distribution. Although the code is built with GRB afterglow in mind, it applies to any relativistic jet. This tool is particularly useful in Markov Chain Monte Carlo studies and is provided to the community.

Keywords: Gamma-ray bursts, Jets, Hydrodynamics
LAMA: LAMOST Medium-Resolution Spectral Analysis Pipeline. The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) has obtained more than 23 million spectra, opening an unprecedented opportunity to study stellar physics, as well as the formation and evolution of our Milky Way. In order to obtain the accurate stellar parameters, we develop a LAMOST Medium-Resolution Spectral Analysis Pipeline (LAMA), which estimates the stellar parameters from the LAMOST medium-resolution spectra, including the effective temperature (T eff), surface gravity ( ), metallicity ([Fe/H]), radial velocity, and rotational velocity ( ). LAMA estimates these parameters utilizing the template-matching method. The comparison between our results and those from the high-resolution ones, including APOGEE, GALAH, and PASTEL, shows no obvious bias, indicating the reliability of our results. The accuracy of T eff and [Fe/H] can reach 75 K and 0.12 dex, respectively, for the LAMOST Medium-Resolution Spectroscopic Survey (MRS) spectra with a signal-to-noise ratio higher than 10. For dwarfs, the uncertainty of is around 0.17 dex, while, for giants, it ranges from 0.18 to 0.30 dex, with the errors decreasing as increases. Using LAMA for the LAMOST-MRS spectra, we estimate the stellar parameters of 497,412 stars. This sample will be very helpful for investigating the formation and evolution of our Galaxy.

Keywords: Surveys, Fundamental parameters of stars, Catalogs, Spectroscopy
Determining Stellar Elemental Abundances from DESI Spectra with the Data-driven Payne. Stellar abundances for a large number of stars provide key information for the study of Galactic formation history. Large spectroscopic surveys such as the Dark Energy Spectroscopic Instrument (DESI) and LAMOST take median-to-low-resolution (R ≲ 5000) spectra in the full optical wavelength range for millions of stars. However, the line-blending effect in these spectra causes great challenges for elemental abundance determination. Here we employ DD-PAYNE, a data-driven method regularized by differential spectra from stellar physical models, to the DESI early data release spectra for stellar abundance determination. Our implementation delivers 15 labels, including effective temperature T eff, surface gravity  , microturbulence velocity v mic, and the abundances for 12 individual elements, namely C, N, O, Mg, Al, Si, Ca, Ti, Cr, Mn, Fe, and Ni. Given a spectral signal-to-noise ratio of 100 per pixel, the internal precisions of the label estimates are about 20 K for T eff, 0.05 dex for  , and 0.05 dex for most elemental abundances. These results agree with the theoretical limits from the Crámer–Rao bound calculation within a factor of 2. The majority of the accreted halo stars contributed by the Gaia–Enceladus–Sausage are discernible from the disk and in situ halo populations in the resultant [Mg/Fe]–[Fe/H] and [Al/Fe]–[Fe/H] abundance spaces. We also provide distance and orbital parameters for the sample stars, which spread over a distance out to ∼100 kpc. The DESI sample has a significantly higher fraction of distant (or metal-poor) stars than the other existing spectroscopic surveys, making it a powerful data set for studying the Galactic outskirts. The catalog is publicly available.

Keywords: Surveys, Stellar abundances, Chemical abundances, Stellar physics, Spectroscopy, Milky Way evolution, Stellar distance
The NuSTAR Serendipitous Survey: The 80 Month Catalog and Source Properties of the High-energy Emitting Active Galactic Nucleus and Quasar Population. We present a catalog of hard X-ray serendipitous sources detected in the first 80 months of observations by the Nuclear Spectroscopic Telescope Array (NuSTAR). The NuSTAR serendipitous survey 80 month (NSS80) catalog has an unprecedented ∼62 Ms of effective exposure time over 894 unique fields (a factor of 3 increase over the 40 month catalog, NSS40), with an areal coverage of ∼36 deg2, larger than all NuSTAR extragalactic surveys. NSS80 provides 1274 hard X-ray sources in the 3‑24 keV band (822 new detections compared to the previous NSS40). Approximately 76% of the NuSTAR sources have lower-energy (&lt;10 keV) X-ray counterparts from Chandra, XMM-Newton, and Swift-XRT. We have undertaken an extensive campaign of ground-based spectroscopic follow-up to obtain new source redshifts and classifications for 427 sources. Combining these with existing archival spectroscopy provides redshifts for 550 NSS80 sources, of which 547 are classified. The sample is primarily composed of active galactic nuclei (AGNs), detected over a large range in redshift (z = 0.012–3.43), but also includes 58 spectroscopically confirmed Galactic sources. In addition, five AGN–galaxy pairs, one dual AGN system, one BL Lac candidate, and a hotspot of 4C 74.26 (radio quasar) have been identified. The median rest-frame 10‑40 keV luminosity and redshift of NSS80 are &lt;L 10‑40 keV&gt; = 1.2 × 1044 erg s‑1 and &lt;z&gt; = 0.56. We investigate the optical properties and construct composite optical spectra to search for subtle signatures not present in the individual spectra, finding an excess of redder BL AGNs compared to optical quasar surveys, predominantly due to the presence of the host galaxy and, at least in part, due to dust obscuration.

Keywords: Quasars, Active galaxies, X-ray active galactic nuclei, X-ray surveys, Catalogs
The Plane Quasar Survey: First Data Release. We present a sample of 305 QSO candidates having ∣b∣ &lt; 30°, the majority with GALEX magnitudes near-UV &lt; 18.75. To generate this sample, we apply UV–IR color selection criteria to photometric data from the Ultraviolet Galactic Plane Survey as part of GALEX-CAUSE, the Million Quasars Catalog, Gaia DR2, and Pan-STARRS DR1. 165 of these 305 candidate UV-bright active galactic nuclei (AGN; 54%) have published spectroscopic redshifts from 45 different surveys, confirming them as AGN. We further obtained low-dispersion, optical, long-slit spectra with the Apache Point Observatory 3.5 m, MDM 2.4 m, and MDM 1.3 m telescopes for 84 of the candidates, and confirm 86% (N = 72) as AGN, generally with z &lt; 0.6. Of these 72 confirmed AGN, 25 are newly discovered low-latitude QSOs without any previous spectroscopy. These sources fill a gap in the Galactic latitude coverage of the available samples of known UV-bright QSO background probes. Along with a description of the confirmed QSO properties, we provide the fully reduced, flux- and wavelength-calibrated spectra of 72 low-latitude QSOs through the Mikulski Archive for Space Telescopes. Future Hubble Space Telescope/Cosmic Origins Spectrograph spectroscopy of these low-Galactic-latitude QSOs has the potential to transform our view of the Milky Way and Local Group circumgalactic medium.

Keywords: Quasar absorption line spectroscopy, Quasars, Active galactic nuclei, Spectroscopy, Circumgalactic medium, Milky Way Galaxy
Subaru Suprime-Cam Wide-field BVI Stellar Photometry of the M33 Galaxy. We have surveyed the complete extent of the disk of M33—a gas-rich low-mass dwarf spiral galaxy in the Local Group. The B-, V-, and I-passband (the Johnson–Cousins system) CCD images (typical seeing ∼0.″8) were obtained with the Subaru Telescope equipped with the Suprime-Cam mosaic camera. The wide-field (∼1.°0 × 1.°5) catalog of 803,095 (15 ≤ V ≤ 25) starlike objects, measured using the point-spread function and aperture photometry techniques, is presented. We determined the distance modulus of M33 using the tip of the red giant branch (I TRGB = 20.64 ± 0.02) as a reference point of (m ‑ M)0 = 24.63 ± 0.02stat ± 0.06syst (843 kpc). We found young (≲100 Myr) stellar populations residing up to the deprojected radius of ∼10 kpc. The scale length of the young main-sequence (MS) star surface-number density in the range of radial distances from 7 to 9 kpc is 0.53 ± 0.03 kpc. The youngest MS stars (≲15 Myr) reside up to the radius of ∼8 kpc. This distribution of stellar populations may suggest an outside-in scenario of recent star formation in the disk of M33.

Keywords: Stellar photometry, Triangulum Galaxy, Spiral galaxies
Pulsar Timing Arrays Require Hierarchical Models. Pulsar timing array (PTA) projects have found evidence of a stochastic background of gravitational waves (GWB) using data from an ensemble of pulsars. In the literature, minimal assumptions are made about the signal and noise processes that affect data from these pulsars, such as pulsar spin noise. These assumptions are encoded as uninformative priors in Bayesian searches, though frequentist approaches make similar assumptions. Uninformative priors are not suitable for (noise) properties of pulsars in an ensemble, and they bias estimates of model parameters such as gravitational-wave signal parameters. Both frequentist and Bayesian searches are affected. In this article, more appropriate priors are proposed in the language of hierarchical Bayesian modeling, where the properties of the ensemble of pulsars are jointly described with the properties of the individual components of the ensemble. Results by PTA projects should be reevaluated using hierarchical models.

Keywords: Bayesian statistics, Pulsar timing method, Millisecond pulsars, Astronomy data analysis, Gravitational waves, Hierarchical models, Radio pulsars