Sazuna/UAT_keywords huggingface dataset:
Statistical Analysis of H I Profile Asymmetry and Shape for Nearby Galaxies. We present a uniform analysis of the integrated profile of the H I emission line of 29,958 nearby (z &lt; 0.06) galaxies extracted from the ALFALFA 21 cm survey. We apply the curve-of-growth technique to derive a database of spectral parameters and robust estimates of their associated uncertainties. Besides the central velocity and total flux, the main catalog provides new measures of line width, profile asymmetry, and profile shape. For a subsample of 13,511 galaxies with optical properties available from the Sloan Digital Sky Survey, we compute inclination angle-corrected line widths, rotation velocities empirically calibrated from spatially resolved observations, and dynamical masses based on H I sizes estimated from the H I mass. To facilitate subsequent scientific applications of the database, we also compile a number of ancillary physical properties of the galaxies, including their optical morphology, stellar mass, and various diagnostics of star formation activity. We use the homogeneous catalog of H I parameters to examine the statistical properties of profile asymmetry and shape. Across the full sample, which covers a wide range of stellar masses and environments, statistically significant H I profile asymmetry is detected in ~20% of the galaxy population. The global H I profiles are 35.2% ± 0.3% single-peaked, 26.9% ± 0.3% flat-topped, and 37.9% ± 0.3% double-horned. At a given inclination angle, double-horned profiles are preferentially associated with galaxies of higher stellar mass or optical concentration, while galaxies of lower mass or concentration tend to have single-peaked profiles.

Keywords: Interstellar medium, Disk galaxies, Interstellar atomic gas
An Extension of Gmunu: General-relativistic Resistive Magnetohydrodynamics Based on Staggered-meshed Constrained Transport with Elliptic Cleaning. We present the implementation of general-relativistic resistive magnetohydrodynamics solvers and three divergence-free handling approaches adopted in the General-relativistic multigrid numerical (Gmunu) code. In particular, implicit-explicit Runge-Kutta schemes are used to deal with the stiff terms in the evolution equations for small resistivity. The three divergence-free handling methods are (i) hyperbolic divergence cleaning (also known as the generalized Lagrange multiplier), (ii) staggered-meshed constrained transport schemes, and (iii) elliptic cleaning through a multigrid solver, which is applicable in both cell-centered and face-centered (stagger grid) magnetic fields. The implementation has been tested with a number of numerical benchmarks from special-relativistic to general-relativistic cases. We demonstrate that our code can robustly recover from the ideal magnetohydrodynamics limit to a highly resistive limit. We also illustrate the applications in modeling magnetized neutron stars, and compare how different divergence-free handling methods affect the evolution of the stars. Furthermore, we show that the preservation of the divergence-free condition of the magnetic field when using staggered-meshed constrained transport schemes can be significantly improved by applying elliptic cleaning.

Keywords: Magnetohydrodynamics, Plasma astrophysics, Computational methods, General relativity, Magnetars
Are There Larger Stellar Velocity Dispersions in Low-redshift Type 1 AGNs than in Type 2 AGNs?. The main objective of this article is to check the Unified Model (UM) for the expected similar stellar velocity dispersions between Type 1 and Type 2 active galactic nuclei (AGNs) and then to provide further clues on black hole (BH) mass properties. Unlike previous comparisons of BH masses estimated from M BH-σ relations for Type 2 AGNs and from virial BH masses for Type 1 AGNs, reliable stellar velocity dispersions σ measured from absorption features around 4000 Å are directly compared between the thus far largest samples of 6260 low-redshift (z &lt; 0.3) Type 1 AGNs and almost all Type 2 AGNs in SDSS DR12. Although half of Type 1 AGNs do not have a measured σ due to unapparent absorption features overwhelmed by AGN activities, both properties of the mean spectra of Type 1 AGNs with and without a measured σ and a positive dependence of σ on the [O III] luminosity can lead to a statistically larger σ for all Type 1 AGNs compared to the 6260 Type 1 AGNs with measured stellar velocity dispersions. Then, direct σ comparisons can lead to a statistically larger σ in Type 1 AGNs, with a confidence level higher than 10σ, after considering the necessary effects of different redshifts and different central AGN activities. Although Type 1 AGNs have a σ of only about (9 ± 3)% larger than Type 2 AGNs, the difference cannot be well explained at the current stage. Unless there is strong evidence to support different M BH-σ relations or to support quite different evolutionary histories between Type 1 and Type 2 AGNs, the statistically larger σ in Type 1 AGNs provides a strong challenge to the UM of AGNs.

Keywords: Supermassive black holes, Active galaxies, Active galactic nuclei, Emission line galaxies
The Optical Two- and Three-dimensional Fundamental Plane Correlations for Nearly 180 Gamma-Ray Burst Afterglows with Swift/UVOT, RATIR, and the Subaru Telescope. Gamma-ray bursts (GRBs) are fascinating events due to their panchromatic nature. We study optical plateaus in GRB afterglows via an extended search into archival data. We comprehensively analyze all published GRBs with known redshifts and optical plateaus observed by many ground-based telescopes (e.g., Subaru Telescope, RATIR) around the world and several space-based observatories such as the Neil Gehrels Swift Observatory. We fit 500 optical light curves, showing the existence of the plateau in 179 cases. This sample is 75% larger than the previous one, and it is the largest compilation so far of optical plateaus. We discover the 3D fundamental plane relation at optical wavelengths using this sample. This correlation is between the rest-frame time at the end of the plateau emission, ${T}_{\mathrm{opt}}^{* }$ , its optical luminosity, L opt, and the peak in the optical prompt emission, L peak,opt, thus resembling the three-dimensional (3D) X-ray fundamental plane (the so-called 3D Dainotti relation). We correct our sample for redshift evolution and selection effects, discovering that this correlation is indeed intrinsic to GRB physics. We investigate the rest-frame end-time distributions in X-rays and optical ( ${T}_{\mathrm{opt}}^{* }$ , ${T}_{{\rm{X}}}^{* }$ ), and conclude that the plateau is achromatic only when selection biases are not considered. We also investigate if the 3D optical correlation may be a new discriminant between optical GRB classes and find that there is no significant separation between the classes compared to the Gold sample plane after correcting for evolution.

Keywords: Gamma-ray bursts
Magnetic Activity and Physical Parameters of Exoplanet Host Stars Based on LAMOST DR7, TESS, Kepler, and K2 Surveys. Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) low- and medium-resolution spectroscopic surveys are important for determination of the orbital parameters and chromospheric activity of extrasolar planet systems. We crossmatched the exoplanet catalog confirmed before 2021 March 11 with the LAMOST DR7 survey to study their properties. There are 1026 targets with exoplanets observed in the LAMOST DR7 low-resolution spectroscopic survey and 158 targets in the medium-resolution spectroscopic survey. We have calculated the equivalent width of the Hα line and determined their stellar activity. The Hα and flare intensities are almost constant for the Rossby number Ro ≤ 0.12 in the saturated regime and decrease with increasing Ro in the unsaturated regime. In addition, we searched the flare events of all stars with exoplanets in the Transiting Exoplanet Survey Satellite (TESS), Kepler, and K2 surveys. Among the 733 extrasolar planetary systems observed by TESS, we found 481 flares from 57 stars. For Kepler data, we obtained the light curve of 1699 stars and found 1886 flares from 417 stars. For K2 data, we obtained the light curves of 347 stars and found 467 flares from 89 stars. There were light curves of 361 objects with obvious eclipse observed from the TESS survey. We have fitted their light curves with a high signal-to-noise ratio using the JKTEBOP program, and we reobtained the orbital parameters, such as inclination, radius, and period. In the end, we made a judgment on the habitability of exoplanets of stars with flares.

Keywords: Stellar chromospheres, Exoplanet catalogs, Stellar flares
Evolution of the Heliotail Lobes over a Solar Cycle as Measured by IBEX. Energetic neutral atom (ENA) measurements by IBEX reveal that the heliotail comprises an energy-dependent multilobe structure. We examine the heliotail evolution over 11 yr of IBEX observations covering a full solar cycle (SC). We find the following: (1) The heliotail structure persists over the entire SC, comprising three ENA-enhanced and two ENA-suppressed lobes. (2) Lobe sizes and locations are generally stable but exhibit variations in ENA fluxes driven by the SC. (3) Lobe centers follow a cyclic behavior over multiple SC phases, indicating direct signatures of slow and fast solar wind (SW) interactions in the inner heliosheath (IHS). (4) The tilted plane passing through the port-starboard lobes' centers oscillates in latitude but maintains its tilt from the ecliptic plane, likely a consequence of the interstellar magnetic field draping around the heliosphere. (5) The transition of the central heliotail from a single lobe at ~1.1 keV to two lobes above ~2 keV is SC-dependent and directly reflects the IHS plasma properties, i.e., when ENA fluxes from fast SW from the polar coronal holes change over time. (6) The central lobe exhibits a substructure that is enhanced and offset from the downwind direction, possibly indicating an asymmetric ENA emission or an asymmetry in the parent plasma distribution. These results reveal the general stability of the heliotail structure over time and distinct variations in individual lobes' properties in relation to the SC phases. Furthermore, results show the effects of multiple SC phases in the tail, reflecting different ENA travel times and source histories.

Keywords: Solar cycle, Heliosphere, The Sun, Solar wind, Interstellar medium, Charge exchange ionization
Comparison of Spatial Distributions of Intracluster Light and Dark Matter. In a galaxy cluster, the relative spatial distributions of dark matter, member galaxies, gas, and intracluster light (ICL) may connote their mutual interactions over the cluster's evolution. However, it is a challenging problem to provide a quantitative measure for matching the shapes between two multidimensional scalar distributions. We present a novel methodology, named the weighted overlap coefficient (WOC), to quantify the similarity of two-dimensional spatial distributions. We compare the WOC with a standard method known as the modified Hausdorff distance (MHD) method. We find that our method is robust, and performs well even with the existence of multiple substructures. We apply our methodology to search for a visible component whose spatial distribution resembles that of dark matter. If such a component could be found to trace the dark-matter distribution with high fidelity for more relaxed galaxy clusters, then the similarity of the distributions could also be used as a dynamical stage estimator of the cluster. We apply the method to six galaxy clusters at different dynamical stages, simulated within a GRT simulation, which is an N-body simulation using the galaxy replacement technique. Among the various components (stellar particles, galaxies, ICL), the ICL+brightest cluster galaxy (BCG) component most faithfully traced the dark-matter distribution. Among the sample galaxy clusters, the relaxed clusters show stronger similarity in the spatial distribution of the dark matter and ICL+BCG than the dynamically young clusters, while the results of the MHD method show a weaker trend with the dynamical stages.

Keywords: Galaxy clusters, Astrostatistics tools, Astronomy data analysis, Galaxy stellar halos, Computational methods, Dark matter
An Overview of CHIME, the Canadian Hydrogen Intensity Mapping Experiment. The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a drift scan radio telescope operating across the 400-800 MHz band. CHIME is located at the Dominion Radio Astrophysical Observatory near Penticton, BC, Canada. The instrument is designed to map neutral hydrogen over the redshift range 0.8-2.5 to constrain the expansion history of the universe. This goal drives the design features of the instrument. CHIME consists of four parallel cylindrical reflectors, oriented north-south, each 100 m × 20 m and outfitted with a 256-element dual-polarization linear feed array. CHIME observes a two-degree-wide stripe covering the entire meridian at any given moment, observing three-quarters of the sky every day owing to Earth's rotation. An FX correlator utilizes field-programmable gate arrays and graphics processing units to digitize and correlate the signals, with different correlation products generated for cosmological, fast radio burst, pulsar, very long baseline interferometry, and 21 cm absorber back ends. For the cosmology back end, the ${N}_{\mathrm{feed}}^{2}$ correlation matrix is formed for 1024 frequency channels across the band every 31 ms. A data receiver system applies calibration and flagging and, for our primary cosmological data product, stacks redundant baselines and integrates for 10 s. We present an overview of the instrument, its performance metrics based on the first 3 yr of science data, and we describe the current progress in characterizing CHIME's primary beam response. We also present maps of the sky derived from CHIME data; we are using versions of these maps for a cosmological stacking analysis, as well as for investigation of Galactic foregrounds.

Keywords: Cosmology, H I line emission, Radio telescopes, Astronomical instrumentation, Radio interferometers, Interferometric correlation, Baryon acoustic oscillations, Telescopes, Dark energy
The Intermediate-ionization Lines as Virial Broadening Estimators for Population A Quasars. The identification of a virial broadening estimator in the quasar UV rest frame suitable for black hole mass computation at high redshift has become an important issue. We compare the H I Balmer H β line width to the ones of two intermediate-ionization lines: the Al III λ1860 doublet and the C III] λ1909 line, over a wide interval of redshift and luminosity (0 ≲ z ≲ 3.5; $43\lesssim \mathrm{log}L\lesssim 48.5$ [erg s-1]), for 48 sources belonging to the quasar population characterized by intermediate to high values of the Eddington ratio (Population A). The present analysis indicates that the line widths of Al III λ1860 and H β are highly correlated and can be considered equivalent for most Population A quasars over five orders of magnitude in luminosity; for C III] λ1909, multiplication by a constant correction factor ξ ≍ 1.25 is sufficient to bring the FWHM of C III] in agreement with that of H β. The statistical concordance between low-ionization and intermediate-ionization lines suggests that they predominantly arise from the same virialized part of the broad-line region. However, blueshifts of modest amplitude (few hundred kilometers per second) with respect to the quasar rest frame and an excess (≲1.1) Al III broadening with respect to H β are found in a fraction of our sample. Scaling laws to estimate M BH of high-redshift quasars using the Al III and C III] line widths have rms scatter ≍0.3 dex. The Al III scaling law takes the form $\mathrm{log}{M}_{\mathrm{BH}}\approx 0.58\mathrm{log}{L}_{\mathrm{1700,44}}+2\mathrm{logFWHM}+0.49$ [M ☉]. *Based in part on observations made with ESO Telescopes at the Paranal Observatory under programs 082.B-0572(A) and 083.B-0273(A).

Keywords: Supermassive black holes, Active galactic nuclei, Quasars
The COS Legacy Archive Spectroscopy Survey (CLASSY) Treasury Atlas. Far-ultraviolet (FUV; ~1200-2000 Å) spectra are fundamental to our understanding of star-forming galaxies, providing a unique window on massive stellar populations, chemical evolution, feedback processes, and reionization. The launch of the James Webb Space Telescope will soon usher in a new era, pushing the UV spectroscopic frontier to higher redshifts than ever before; however, its success hinges on a comprehensive understanding of the massive star populations and gas conditions that power the observed UV spectral features. This requires a level of detail that is only possible with a combination of ample wavelength coverage, signal-to-noise, spectral-resolution, and sample diversity that has not yet been achieved by any FUV spectral database. We present the Cosmic Origins Spectrograph Legacy Spectroscopic Survey (CLASSY) treasury and its first high-level science product, the CLASSY atlas. CLASSY builds on the Hubble Space Telescope (HST) archive to construct the first high-quality (S/N1500 Å ≳ 5/resel), high-resolution (R ~ 15,000) FUV spectral database of 45 nearby (0.002 &lt; z &lt; 0.182) star-forming galaxies. The CLASSY atlas, available to the public via the CLASSY website, is the result of optimally extracting and coadding 170 archival+new spectra from 312 orbits of HST observations. The CLASSY sample covers a broad range of properties including stellar mass (6.2 &lt; log M ⋆(M ☉) &lt; 10.1), star formation rate (-2.0 &lt; log SFR (M ☉ yr-1) &lt; +1.6), direct gas-phase metallicity (7.0 &lt; 12+log(O/H) &lt; 8.8), ionization (0.5 &lt; O32 &lt; 38.0), reddening (0.02 &lt; E(B - V) &lt; 0.67), and nebular density (10 &lt; n  e  (cm-3) &lt; 1120). CLASSY is biased to UV-bright star-forming galaxies, resulting in a sample that is consistent with the z ~ 0 mass-metallicity relationship, but is offset to higher star formation rates by roughly 2 dex, similar to z ≳ 2 galaxies. This unique set of properties makes the CLASSY atlas the benchmark training set for star-forming galaxies across cosmic time. ∗ Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

Keywords: Interstellar line absorption, Emission line galaxies, Ultraviolet surveys, Lyman-alpha galaxies, High-redshift galaxies, Galaxies
Finding Quasars behind the Galactic Plane. II. Spectroscopic Identifications of 204 Quasars at ∣b∣ &lt; 20°. Quasars behind the Galactic plane (GPQs) are important astrometric references and valuable probes of Galactic gas, yet the search for GPQs is difficult due to severe extinction and source crowding in the Galactic plane. In this paper, we present a sample of 204 spectroscopically confirmed GPQs at ∣b∣ &lt; 20°, 191 of which are new discoveries. This GPQ sample covers a wide redshift range from 0.069 to 4.487. For the subset of 230 observed GPQ candidates, the lower limit of the purity of quasars is 85.2%, and the lower limit of the fraction of stellar contaminants is 6.1%. Using a multicomponent spectral fitting, we measure the emission line and continuum flux of the GPQs, and estimate their single-epoch virial black hole masses. Due to selection effects raised from Galactic extinction and target magnitude, these GPQs have higher black hole masses and continuum luminosities in comparison to the SDSS DR7 quasar sample. The spectral-fitting results and black hole mass estimates are compiled into a main spectral catalog, and an extended spectral catalog of GPQs. The successful identifications prove the reliability of both our GPQ selection methods and the GPQ candidate catalog, shedding light on the astrometric and astrophysical programs that make use of a large sample of GPQs in the future.

Keywords: Supermassive black holes, Quasars, Galactic and extragalactic astronomy, Active galactic nuclei, Spectroscopy, Catalogs
Photometric Metallicity Prediction of Fundamental-mode RR Lyrae Stars in the Gaia Optical and K <SUB> s </SUB> Infrared Wave Bands by Deep Learning. RR Lyrae stars are useful chemical tracers thanks to the empirical relationship between their heavy-element abundance and the shape of their light curves. However, the consistent and accurate calibration of this relation across multiple photometric wave bands has been lacking. We have devised a new method for the metallicity estimation of fundamental-mode RR Lyrae stars in the Gaia optical G and near-infrared VISTA K  s  wave bands by deep learning. First, an existing metallicity prediction method is applied to large photometric data sets, which are then used to train long short-term memory recurrent neural networks for the regression of the [Fe/H] to the light curves in other wave bands. This approach allows an unbiased transfer of our accurate, spectroscopically calibrated I-band formula to additional bands at the expense of minimal additional noise. We achieve a low mean absolute error of 0.1 dex and high R 2 regression performance of 0.84 and 0.93 for the K  s  and G bands, respectively, measured by cross-validation. The resulting predictive models are deployed on the Gaia DR2 and VVV inner bulge RR Lyrae catalogs. We estimate mean metallicities of -1.35 dex for the inner bulge and -1.7 dex for the halo, which are significantly less than the values obtained by earlier photometric prediction methods. Using our results, we establish a public catalog of photometric metallicities of over 60,000 Galactic RR Lyrae stars and provide an all-sky map of the resulting RR Lyrae metallicity distribution. The software code used for training and deploying our recurrent neural networks is made publicly available in the open-source domain.

Keywords: Light curves, RR Lyrae variable stars, Metallicity, Neural networks
Close Major-merger Pairs at z = 0: Bulge-to-total Ratio and Star Formation Enhancement. We present a study of the bulge-to-total ratio (B/T) of a Ks-band-selected sample of 88 close major-merger pairs of galaxies (H-KPAIR), based on two-dimensional decompositions of SDSS r-band images with GALFIT. We investigate the dependence of the interaction-induced specific star formation rate enhancement (sSFRenh) on the B/T ratio, and the effects of this dependence on the differences between star-forming galaxies (SFGs) in spiral+spiral (S+S) and spiral+elliptical (S+E) pairs. Of all the 132 spiral galaxies in H-KPAIR, the 44 in S+E pairs show higher B/T than those in the 44 S+S pairs, with means of B/T = 0.35 ± 0.05 and B/T = 0.26 ± 0.03, respectively. There is a strong negative dependence of sSFRenh on the B/T ratio, and only paired SFGs with B/T &lt; 0.3 show significant (&gt;5σ) enhancement. Paired SFGs in S+S pairs show a similar trend, and many disky SFGs (B/T &lt; 0.1) in S+S pairs have strong sSFR enhancements (sSFRenh &gt; 0.7 dex). For SFGs in S+E pairs, the sSFR has no clear B/T dependence, nor any significant enhancement in any B/T bin. Disky SFGs in S+S pairs show significant (&gt;4σ) enhancement in molecular gas content ( ${M}_{{{\rm{H}}}_{2}}/{M}_{\mathrm{star}}$ ), while SFGs in S+E pairs have no such enhancement in any B/T bin. No significant enhancement of the total gas content (M gas/M star) is found in any B/T bin for paired galaxies. The star formation efficiency of either the total gas (SFEgas = SFR/M gas) or molecular gas ( ${\mathrm{SFE}}_{{{\rm{H}}}_{2}}=\mathrm{SFR}/{M}_{{{\rm{H}}}_{2}}$ ) does not depend on the B/T ratio. The only significant (&gt; 4σ) SFE enhancement found for paired SFGs is the SFEgas for disky SFGs in S+S pairs.

Keywords: Galaxy structure, Galaxy interactions, Star formation, Galaxy evolution