Sazuna/UAT_keywords huggingface dataset:
Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XII. Reverberation Mapping Results for 15 PG Quasars from a Long-duration High-cadence Campaign. In this work, we present the first results of the long-term high-cadence spectroscopic monitoring of 15 PG quasars with relatively strong Fe ii emission, as a part of a broader reverberation mapping campaign performed using the Calar Alto Observatory's 2.2 m telescope. The V-band, 5100 Å continuum, and Hβ broad emission line light curves are measured for a set of quasars for periods ranging from dozens to more than a hundred epochs between 2017 May and 2020 July. Accurate time lags between the variations of the Hβ broad-line fluxes and the optical continuum strength are obtained for all 15 quasars, ranging from ${17.0}_{-3.2}^{+2.5}$?--&gt; 17.0 - 3.2 + 2.5 to ${95.9}_{-23.9}^{+7.1}$?--&gt; 95.9 - 23.9 + 7.1 days in the rest frame. The virial masses of the central supermassive black holes are derived for all 15 quasars, ranging between ${0.50}_{-0.19}^{+0.18}$?--&gt; 0.50 - 0.19 + 0.18 and ${19.17}_{-2.73}^{+2.98}$?--&gt; 19.17 - 2.73 + 2.98 in units of 107M⊙. For 11 of the objects in our sample, this is the first reverberation analysis to be published. Of the rest, two objects have been the subject of previous reverberation studies, but we determine time lags for these that are only half as long as those found in the earlier investigations, which had only been able to sample much more sparsely. The remaining two objects have previously been monitored with high sampling rates. Our results here are consistent with the earlier findings, in the sense that the time lag and the line width vary inversely, consistent with virialization.

Keywords: Supermassive black holes, Quasars, Reverberation mapping, Seyfert galaxies, Active galactic nuclei, Time domain astronomy
thornado-hydro: A Discontinuous Galerkin Method for Supernova Hydrodynamics with Nuclear Equations of State. This paper describes algorithms for nonrelativistic hydrodynamics in the toolkit for high-order neutrino radiation hydrodynamics (thornado), which is being developed for multiphysics simulations of core-collapse supernovae (CCSNe) and related problems with Runge-Kutta discontinuous Galerkin (RKDG) methods. More specifically, thornado employs a spectral-type nodal collocation approximation, and we have extended limiters—a slope limiter to prevent nonphysical oscillations and a bound-enforcing limiter to prevent nonphysical states—from the standard RKDG framework to be able to accommodate a tabulated nuclear equation of state (EoS). To demonstrate the efficacy of the algorithms with a nuclear EoS, we first present numerical results from basic test problems in idealized settings in one and two spatial dimensions, employing Cartesian, spherical-polar, and cylindrical coordinates. Then, we apply the RKDG method to the problem of adiabatic collapse, shock formation, and shock propagation in spherical symmetry, initiated with a 15 M⊙ progenitor. We find that the extended limiters improve the fidelity and robustness of the RKDG method in idealized settings. The bound-enforcing limiter improves the robustness of the RKDG method in the adiabatic collapse application, while we find that slope limiting in characteristic fields is vulnerable to structures in the EoS—more specifically, in the phase transition from nuclei and nucleons to bulk nuclear matter. The success of these applications marks an important step toward applying RKDG methods to more realistic CCSN simulations with thornado in the future. * This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US Government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).

Keywords: Hydrodynamical simulations, Computational methods, Nuclear astrophysics, Core-collapse supernovae
Data-driven Spectroscopic Estimates of Absolute Magnitude, Distance, and Binarity: Method and Catalog of 16,002 O- and B-type Stars from LAMOST. We present a data-driven method to estimate absolute magnitudes for O- and B-type stars from the LAMOST spectra, which we combine with Gaia DR2 parallaxes to infer distance and binarity. The method applies a neural network model trained on stars with precise Gaia parallax to the spectra and predicts Ks-band absolute magnitudes ${M}_{K{\rm{s}}}$ with a precision of 0.25 mag, which corresponds to a precision of 12% in spectroscopic distance. For distant stars (e.g., &gt;5 kpc), the inclusion of constraints from spectroscopic ${M}_{K{\rm{s}}}$ significantly improves the distance estimates compared to inferences from Gaia parallax alone. Our method accommodates for emission-line stars by first identifying them via principal component analysis reconstructions and then treating them separately for the ${M}_{K{\rm{s}}}$ estimation. We also take into account unresolved binary/multiple stars, which we identify through deviations in the spectroscopic ${M}_{K{\rm{s}}}$ from the geometric ${M}_{K{\rm{s}}}$ inferred from Gaia parallax. This method of binary identification is particularly efficient for unresolved binaries with near equal-mass components and thus provides a useful supplementary way to identify unresolved binary or multiple-star systems. We present a catalog of spectroscopic ${M}_{K{\rm{s}}}$ , extinction, distance, flags for emission lines, and binary classification for 16,002 OB stars from LAMOST DR5. As an illustration, we investigate the ${M}_{K{\rm{s}}}$ of the enigmatic LB-1 system, which Liu et al. had argued consists of a B star and a massive stellar-mass black hole. Our results suggest that LB-1 is a binary system that contains two luminous stars with comparable brightness, and the result is further supported by parallax from the Gaia eDR3.

Keywords: Early-type stars, Astronomy data modeling, Binary stars, Emission line stars, Neural networks, Spectroscopic binary stars, OB stars, Principal component analysis, Absolute magnitude, Stellar distance, Astronomical methods, Catalogs
A VLA Census of the Galactic H II Region Population. The Milky Way contains thousands of H II region candidates identified by their characteristic mid-infrared morphology, but lacking detections of ionized gas tracers such as radio continuum or radio recombination line emission. These targets thus remain unconfirmed as H II regions. With only ∼2500 confirmed H II regions in the Milky Way, Galactic surveys are deficient by several thousand nebulae when compared to external galaxies with similar star formation rates. Using sensitive 9 GHz radio continuum observations with the Karl G. Jansky Very Large Array, we explore a sample of H II region candidates in order to set observational limits on the actual total population of Galactic H II regions. We target all infrared-identified "radio-quiet" sources from the Wide-field Infrared Survey Explorer Catalog of Galactic H II regions between 245° ≥ ℓ ≥ 90° with infrared diameters less than 80''. We detect radio continuum emission from 50% of the targeted H II region candidates, providing strong evidence that most of the radio-quiet candidates are bona fide H II regions. We measure the peak and integrated radio flux densities and compare the inferred Lyman continuum fluxes using models of OB stars. We conclude that stars of approximately spectral type B2 and earlier are able to create H II regions with similar infrared and radio continuum morphologies as the more luminous H II regions created by O stars. From our 50% detection rate of "radio-quiet" sources, we set a lower limit of ∼7000 for the H II region population of the Galaxy. Thus the vast majority of the Milky Way's H II regions remain to be discovered.

Keywords: Very Large Array, Massive stars, Galaxy structure, Star formation, Interstellar medium, H II regions
Modified Path-conservative HLLEM Scheme for Magnetohydrodynamic Solar Wind Simulations. The goal of the present work is to solve the magnetohydrodynamic (MHD) system of extended generalized Lagrange multiplier (EGLM) formulation with Galilean invariance (G-EGLM MHD equations) through a modified path-conservative HLLEM finite-volume method. A second-order least-squares reconstruction with Venkatakrishnan limiter is employed for state variables, and a solenoidality-preserving condition is considered for the magnetic field with the purpose of magnetic divergence cleaning. The two-stage Runge-Kutta time-integration method is utilized to advance the MHD governing equations. Compared with the original path-conservative HLLEM method, the modified method in this paper is shock stable and is able to adjust the diffusion according to the smoothness of the physical flow so as to automatically apply more diffusion near strong shocks and less in smooth regions near rarefaction waves and at contact discontinuities. Meanwhile, it can be robustly defined in the low plasma-β region. After several tests of smooth Alfvén wave, strong Lax, odd-even perturbation, and blast-wave problems, the large-scale structures of the solar corona for Carrington Rotation 2185 are numerically modeled in a six-component grid system of spherical coordinates with input from a Carrington rotation synoptic map provided by the Helioseismic and Magnetic Imager. Numerical results show the model's capability of producing a structured solar wind in agreement with the observations.

Keywords: Solar wind, Solar corona, Magnetohydrodynamical simulations
Giant Radio Quasars: Sample and Basic Properties. We present the largest sample of giant radio quasars (GRQs), which are defined as having a projected linear size greater than 0.7 Mpc. The sample consists of 272 GRQs, of which 174 are new objects discovered through cross-matching the NRAO Very Large Array Sky Survey and the Sloan Digital Sky Survey 14th Data Release Quasar Catalog (DR14Q) and confirmed using Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) radio maps. In our analysis we compare the GRQs with 367 smaller, lobe-dominated radio quasars found using our search method, as well as with quasars from the SDSS DR14Q, investigating the parameters characterizing their radio emission (i.e., total and core radio luminosity, radio core prominence), optical properties (black hole masses, accretion rates, distribution in Eigenvector 1 plane) and infrared colors. For the GRQs and smaller radio quasars we find a strong correlation between [O III] luminosity and radio luminosity at 1.4 GHz, indicating a strong connection between radio emission and conditions in the narrow-line region. We spot no significant differences between GRQs and smaller radio quasars, however we show that most extended radio quasars belong to a quasar population of evolved active galactic nuclei with large black hole masses and low accretion rates. We also show that GRQs have bluer W2-W3 colors compared to SDSS quasars with FIRST detections, indicating differences in the structure of the dusty torus.

Keywords: Active galaxies, Active galactic nuclei, Giant radio galaxies
Eight-year Simultaneous Monitoring Observations of H<SUB>2</SUB>O and SiO Masers toward V627 Cas. Simultaneous monitoring observations of H2O 61,6 - 52,3 and SiO v = 1, 2, J = 1 → 0, v = 1, J = 2 → 1, J = 3 → 2 masers were performed toward the suspected D-type symbiotic star V627 Cas from 2011 October to 2020 March using the Korean Very Long Baseline Interferometry (VLBI) Network (KVN) single-dish telescopes. All spectra of the H2O masers showed highly redshifted emissions with respect to the stellar velocity of -52 km s-1 with high asymmetries. In addition, the spectra of the H2O maser showed three components which varied according to observational dates. On the other hand, the SiO v = 1, 2, J = 1 → 0 and v = 1, J = 2 → 1 masers exhibited a predominantly blueshifted emission in most epochs. The SiO v = 1, J = 3 → 2 maser has arisen around the stellar velocity from 2016 November 19 and shows a predominantly redshifted emission from 2018 June 15. We analyze time variations of the H2O and SiO maser intensities, their intensity ratios, peak and mean velocities, and full width zero power. Based on these analyses, the asymmetries of the H2O and SiO masers' spectra in V627 Cas and the variation characteristics of the maser properties of the different maser lines are discussed. As a possible cause of asymmetries, the influence of a hot component located at the eastern part of the red giant can be suggested based on the KVN VLBI results. The differences in the variation characteristics of the maser properties may originate from the differences in their locations and excitation conditions.

Keywords: Symbiotic binary stars, Silicon monoxide masers, Circumstellar masers, Water masers
The UBV Color Evolution of Classical Novae. IV. Time-stretched (U - B)<SUB>0</SUB>-(M<SUB>B</SUB> - 2.5 log f<SUB>s</SUB>) and (V - I)<SUB>0</SUB>-(M<SUB>I</SUB> - 2.5 log f<SUB>s</SUB>) Color-Magnitude Diagrams of Novae in Outbursts. Light curves and color evolutions of two classical novae can be largely overlapped if we properly squeeze or stretch the timescale of a target nova against that of a template nova by $t^{\prime} =t/{f}_{{\rm{s}}}$ &lt;!-- --&gt; . Then, the brightness of the target nova is related to the brightness of the template nova by ${(M[t])}_{\mathrm{template}}={(M[t/{f}_{{\rm{s}}}]-2.5\mathrm{log}{f}_{{\rm{s}}})}_{\mathrm{target}}$ &lt;!-- --&gt; ,where M[t] is the absolute magnitude and a function of time t, and fs is the ratio of timescales between the target and template novae. In the previous papers of this series, we show that many novae broadly overlap in the time-stretched (B - V)0- $({M}_{V}-2.5\mathrm{log}{f}_{{\rm{s}}})$ &lt;!-- --&gt; color-magnitude diagram. In the present paper, we propose two other (U - B)0- $({M}_{B}-2.5\mathrm{log}{f}_{{\rm{s}}})$ &lt;!-- --&gt; and (V - I)0- $({M}_{I}-2.5\mathrm{log}{f}_{{\rm{s}}})$ &lt;!-- --&gt; diagrams and show that their tracks overlap for 16 and 52 novae, respectively. Here (U - B)0, (B - V)0, and (V - I)0 are the intrinsic U - B, B - V, and V - I colors and not changed by the time stretch, and MB, MV, and MI are the absolute B, V, and I magnitudes. Using these properties, we considerably refine the previous estimates of their distance and reddening. The obtained distances are in reasonable agreement with those of the Gaia Data Release 2 catalog.

Keywords: Fast novae, Recurrent novae, Hertzsprung Russell diagram, Symbiotic binary stars, Classical novae
High-redshift Narrow-line Seyfert 1 Galaxies: A Candidate Sample. The study of narrow-line Seyfert 1 galaxies (NLS1s) is now mostly limited to low redshift (z &lt; 0.8) because their definition requires the presence of the Hβ emission line, which is redshifted out of the spectral coverage of major ground-based spectroscopic surveys at z &gt; 0.8. We studied the correlation between the properties of Hβ and Mg II lines of a large sample of SDSS DR14 quasars to find high-z NLS1 candidates. Based on the strong correlation of FWHM(Mg II) = (0.880 ± 0.005) × FWHM(Hβ) + (0.438 ± 0.018), we present a sample of high-z NLS1 candidates having FWHM of Mg II &lt; 2000 km s-1. The high-z sample contains 2684 NLS1s with redshift z = 0.8-2.5 with a median logarithmic bolometric luminosity of 46.16 ± 0.42 erg s-1, logarithmic black hole mass of 8.01 ± 0.35 M⊙, and logarithmic Eddington ratio of 0.02 ± 0.27. The fraction of radio-detected high-z NLS1s is similar to that of the low-z NLS1s and SDSS DR14 quasars at a similar redshift range, and their radio luminosity is found to be strongly correlated with their black hole mass.

Keywords: Supermassive black holes, Spectroscopy, Quasars
Catalog and Statistical Examinations of Lyα Solar Flares from GOES/EUVS-E Measurements. The Lyman-alpha (Lyα) line of neutral hydrogen at 121.6 nm is by far the brightest emission line in the vacuum ultraviolet spectral range of the Sun. The emission at this line could be a major energy input to the upper layers of the Earth's atmosphere, strongly impacting the geospace environment. The Geostationary Operational Environmental Satellite (GOES) series, starting with GOES-13, began to carry a multichannel Extreme UltraViolet Sensor (EUVS) with one channel (E-channel) targeting the Lyα line. In the present work, we produce a Lyα flare catalog from the GOES-15/EUVS-E data between 2010 April 8 and 2016 June 6 with an automatic flare detection algorithm. This algorithm is designed to search events at various scales and find their real start and end times. Based on the obtained flare list, statistics on the temporal behavior such as the duration, rise, and decay times, and the event asymmetries of Lyα flares is presented. On average (defined by the median of the distributions), the duration, rise and decay times of the flares were estimated to be 20.8 minutes, 5.6 minutes, and 14.2 minutes, respectively. We also discuss the frequency distributions of the peak flux and the fluence of Lyα flares, both of which reveal power-law behaviors with power-law indices of 2.71 ± 0.06 and 2.42 ± 0.06, respectively, implying that more flares are accumulated at small scales and these small-scale events play an important role in explaining the violent solar energy release.

Keywords: Astrostatistics distributions, Algorithms, Solar flares, Solar ultraviolet emission
HELIOS-K 2.0 Opacity Calculator and Open-source Opacity Database for Exoplanetary Atmospheres. Computing and using opacities is a key part of modeling and interpreting data of exoplanetary atmospheres. Since the underlying spectroscopic line lists are constantly expanding and currently include up to ∼1010-1011 transition lines, the opacity calculator codes need to become more powerful. Here we present major upgrades to the HELIOS-K GPU-accelerated opacity calculator and describe the necessary steps to process large line lists within a reasonable amount of time. Besides performance improvements, we include more capabilities and present a toolbox for handling different atomic and molecular data sets, from downloading and preprocessing the data to performing the opacity calculations in a user-friendly way. HELIOS-K supports line lists from ExoMol, HITRAN, HITEMP, NIST, Kurucz, and VALD3. By matching the resolution of 0.1 cm-1 and cutting length of 25 cm-1 used by the ExoCross code for timing performance (251 s excluding data read-in time), HELIOS-K can process the ExoMol BT2 water line list in 12.5 s. Using a resolution of 0.01 cm-1, it takes 45 s, equivalent to about 107 lines s-1. As a wavenumber resolution of 0.01 cm-1 suffices for most exoplanetary atmosphere spectroscopic calculations, we adopt this resolution in calculating opacity functions for several hundred atomic and molecular species and make them freely available on the open-access DACE database. For the opacity calculations of the database, we use a cutting length of 100 cm-1 for molecules and no cutting length for atoms. Our opacities are available for downloading from https://dace.unige.ch/opacityDatabase and may be visualized using https://dace.unige.ch/opacity.

Keywords: Exoplanet atmospheres
The LSST DESC DC2 Simulated Sky Survey. We describe the simulated sky survey underlying the second data challenge (DC2) carried out in preparation for analysis of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) by the LSST Dark Energy Science Collaboration (LSST DESC). Significant connections across multiple science domains will be a hallmark of LSST; the DC2 program represents a unique modeling effort that stresses this interconnectivity in a way that has not been attempted before. This effort encompasses a full end-to-end approach: starting from a large N-body simulation, through setting up LSST-like observations including realistic cadences, through image simulations, and finally processing with Rubin's LSST Science Pipelines. This last step ensures that we generate data products resembling those to be delivered by the Rubin Observatory as closely as is currently possible. The simulated DC2 sky survey covers six optical bands in a wide-fast-deep area of approximately 300 deg2, as well as a deep drilling field of approximately 1 deg2. We simulate 5 yr of the planned 10 yr survey. The DC2 sky survey has multiple purposes. First, the LSST DESC working groups can use the data set to develop a range of DESC analysis pipelines to prepare for the advent of actual data. Second, it serves as a realistic test bed for the image processing software under development for LSST by the Rubin Observatory. In particular, simulated data provide a controlled way to investigate certain image-level systematic effects. Finally, the DC2 sky survey enables the exploration of new scientific ideas in both static and time domain cosmology.

Keywords: Cosmology, Sky surveys, N-body simulations
Building and Calibrating the Binary Star Population Using Kepler Data. Modeling binary star populations is critical to linking the theories of star formation and stellar evolution with observations. In order to test these theories, we need accurate models of observable binary populations. The Kepler Eclipsing Binary Catalog (KEBC), with its estimated &gt;90% completeness, provides an observational anchor on binary population models. In this work we present the results of a new forward model of the binary star population in the Kepler field. The forward model takes a single star population from a model of the Galaxy and pairs the stars into binaries by applying the constraints on the population from the results of observational binary population surveys such as Raghavan et al. and Duchêne &amp; Kraus. A synthetic binary population is constructed from the initial distributions of orbital parameters. We identify the eclipsing binary sample from the generated binary star population and compare this with the observed sample of eclipsing binaries contained in the KEBC. Finally, we update the distributions of the synthetic population and repeat the process until the synthetic eclipsing binary sample agrees with the KEBC. The end result of this process is a model of the underlying binary star population that has been fit to observations. We find that for fixed flat mass ratio and eccentricity input distributions, the binary period distribution is logarithmically flat above ∼3.2 days. With additional constraints on distributions from observations, we can further adjust the synthetic binary population by relaxing other input constraints, such as mass ratio and eccentricity.

Keywords: Stellar populations, Eclipsing binary stars, Binary stars