Sazuna/UAT_keywords huggingface dataset:
The Physical Properties of Fermi-4LAC Flat Spectrum Radio Quasars. In this work, we collect quasi-simultaneous infrared, optical, X-ray and γ-ray data of 60 Fermi fourth LAT AGN catalog (4LAC) flat spectrum radio quasars (FSRQs). In the framework of the conventional one-zone leptonic model, we investigate the physical properties of Fermi-4LAC FSRQs' jets by modeling their quasi-simultaneous spectral energy distributions (SEDs). Our main results are summarized as follows. (1) There is a linear correlation between synchrotron peak frequency and curvature of the electron energy distribution. As suggested by previous works, the slope of the best linear fitting equation of this correlation is consistent with statistic acceleration that needs a fluctuation of fractional acceleration gain. (2) The γ-ray dissipation regions are located at the range from 0.1 to 10 pc away from the supermassive black hole, and located outside the broad-line region and within the dusty torus. (3) A size relation Pe (the kinetic power carried in relativistic electrons) ∼PB (Poynting flux) ≤Pr (the radiative power) &lt;Pp (the kinetic power in cold protons) is found in our modeling. Among them, Pe ∼ PB suggests that SEDs of almost all FSRQs with parameters are close to equipartition between the magnetic field and the relativistic electrons. The Pe &lt; Pr suggest that the most energy of the relativistic electrons are dissipated by EC radiation for FSRQs. (4) There is an anticorrelation between the peak energy of SEDs (γpeak) and the jet power (Pjet), which is consistent with the blazar sequence.

Keywords: Blazars, Relativistic jets, Non-thermal radiation sources, Spectral energy distribution
The Extended Gaia-PS1-SDSS (GPS1+) Proper Motion Catalog. The Gaia + PanSTARRS1 (PS1) + Sloan Digital Sky Survey (SDSS) + Two Micron All-Sky Survey (2MASS) (GPS1) catalog was released in 2017. It delivered precise proper motions for around 350 million sources down to a magnitude of $r\sim 20$ mag. In this study, we present GPS1+, the extension GPS1 catalog down to $r\sim 22.5$ mag, based on Gaia data release 2 (DR2), PS1, SDSS, and 2MASS astrometry. GPS1+ totally provides proper motions for ∼400 million sources with a characteristic systematic error of less than 0.1 mas yr-1. This catalog is divided into two subsamples, i.e., the primary and secondary parts. The primary ∼264 million sources have either or both Gaia and SDSS astrometry, with a typical precision of 2.0-5.0 mas yr-1. In this part, ∼160 million sources have Gaia proper motions, and we provide another new proper motion for each of them by building a Bayesian model. Relative to Gaia's values, the precision is improved by ∼0.1 dex on average; ∼50 million sources are the objects whose proper motions are missing in Gaia DR2, and we provide their proper motions with a precision of ∼4.5 mas yr-1. The remaining ∼54 million faint sources are beyond Gaia detecting capability, and we provide their proper motions for the first time with a precision of 7.0 mas yr-1. However, the secondary ∼136 million sources only have PS1 astrometry, where the average precision is worse than 15.0 mas yr-1. The large uncertainty probably limits it to qualitative applications. All the proper motions have been validated using QSOs and the existing Gaia proper motions. The catalog will be available via the TAP Service in the German Astrophysical Virtual Observatory.

Keywords: Galaxy dynamics, Galaxy kinematics, Astrometry, Proper motions, Catalogs
Unraveling the Complex Behavior of Mrk 421 with Simultaneous X-Ray and VHE Observations during an Extreme Flaring Activity in 2013 April. We report on a multiband variability and correlation study of the TeV blazar Mrk 421 during an exceptional flaring activity observed from 2013 April 11 to 19. The study uses, among others, data from GLAST-AGILE Support Program (GASP) of the Whole Earth Blazar Telescope (WEBT), Swift, Nuclear Spectroscopic Telescope Array (NuSTAR), Fermi Large Area Telescope, Very Energetic Radiation Imaging Telescope Array System (VERITAS), and Major Atmospheric Gamma Imaging Cherenkov (MAGIC). The large blazar activity and the 43 hr of simultaneous NuSTAR and MAGIC/VERITAS observations permitted variability studies on 15 minute time bins over three X-ray bands (3-7 keV, 7-30 keV, and 30-80 keV) and three very-high-energy (VHE; &gt;0.1 TeV) gamma-ray bands (0.2-0.4 TeV, 0.4-0.8 TeV, and &gt;0.8 TeV). We detected substantial flux variations on multi-hour and sub-hour timescales in all of the X-ray and VHE gamma-ray bands. The characteristics of the sub-hour flux variations are essentially energy independent, while the multi-hour flux variations can have a strong dependence on the energy of the X-rays and the VHE gamma-rays. The three VHE bands and the three X-ray bands are positively correlated with no time lag, but the strength and characteristics of the correlation change substantially over time and across energy bands. Our findings favor multi-zone scenarios for explaining the achromatic/chromatic variability of the fast/slow components of the light curves, as well as the changes in the flux-flux correlation on day-long timescales. We interpret these results within a magnetic reconnection scenario, where the multi-hour flux variations are dominated by the combined emission from various plasmoids of different sizes and velocities, while the sub-hour flux variations are dominated by the emission from a single small plasmoid moving across the magnetic reconnection layer. * Contact MAGIC Collaboration (contact.magic@mpp.mpg.de) for queries. Corresponding authors are D. Paneque, A. Babic, J. Finke, T. Hassan, and M. Petropoulou.

Keywords: Observational astronomy, BL Lacertae objects, High energy astrophysics, Markarian galaxies, Blazars, Gamma-ray detectors, Active galaxies, Relativistic jets, Gamma-rays
THOR 2.0: Major Improvements to the Open-source General Circulation Model. THOR is the first open-source general circulation model (GCM) developed from scratch to study the atmospheres and climates of exoplanets, free from Earth- or solar-system-centric tunings. It solves the general nonhydrostatic Euler equations (instead of the primitive equations) on a sphere using the icosahedral grid. In the current study, we report major upgrades to THOR, building on the work of Mendonça et al. First, while the horizontally explicit and vertically implicit integration scheme is the same as that described in Mendonça et al., we provide a clearer description of the scheme and improve its implementation in the code. The differences in implementation between the hydrostatic shallow, quasi-hydrostatic deep, and nonhydrostatic deep treatments are fully detailed. Second, standard physics modules are added: two-stream, double-gray radiative transfer and dry convective adjustment. Third, THOR is tested on additional benchmarks: tidally locked Earth, deep hot Jupiter, acoustic wave, and gravity wave. Fourth, we report that differences between the hydrostatic and nonhydrostatic simulations are negligible in the Earth case but pronounced in the hot Jupiter case. Finally, the effects of the so-called "sponge layer," a form of drag implemented in most GCMs to provide numerical stability, are examined. Overall, these upgrades have improved the flexibility, user-friendliness, and stability of THOR.

Keywords: Extrasolar rocky planets, Open source software, Exoplanets, Astronomy software, Hot Jupiters, Atmospheric circulation, GPU computing, Exoplanet atmospheres
X-Ray Binary Luminosity Function Scaling Relations in Elliptical Galaxies: Evidence for Globular Cluster Seeding of Low-mass X-Ray Binaries in Galactic Fields. We investigate X-ray binary (XRB) luminosity function (XLF) scaling relations for Chandra-detected populations of low-mass XRBs (LMXBs) within the footprints of 24 early-type galaxies. Our sample includes Chandra and Hubble Space Telescope observed galaxies at $D\lesssim 25$ Mpc that have estimates of the globular cluster (GC) specific frequency (SN) reported in the literature. As such, we are able to directly classify X-ray-detected sources as being coincident with unrelated background/foreground objects, GCs, or sources that are within the fields of the galaxy targets. We model the GC and field LMXB population XLFs for all galaxies separately and then construct global models characterizing how the LMXB XLFs vary with galaxy stellar mass and SN. We find that our field LMXB XLF models require a component that scales with SN and has a shape consistent with that found for the GC LMXB XLF. We take this to indicate that GCs are "seeding" the galactic field LMXB population, through the ejection of GC LMXBs and/or the diffusion of the GCs in the galactic fields themselves. However, we also find that an important LMXB XLF component is required for all galaxies that scales with stellar mass, implying that a substantial population of LMXBs are formed "in situ," which dominates the LMXB population emission for galaxies with SN ≲ 2. For the first time, we provide a framework quantifying how directly associated GC LMXBs, GC-seeded LMXBs, and in situ LMXBs contribute to LMXB XLFs in the broader early-type galaxy population.

Keywords: Globular star clusters, X-ray binary stars, X-ray point sources, Low-mass x-ray binary stars, Elliptical galaxies, Early-type galaxies
The AREPO Public Code Release. We introduce the public version of the cosmological magnetohydrodynamical moving-mesh simulation code AREPO. This version contains a finite-volume magnetohydrodynamics algorithm on an unstructured, dynamic Voronoi tessellation coupled to a tree-particle-mesh algorithm for the Poisson equation either on a Newtonian or cosmologically expanding spacetime. Time integration is performed adopting local time step constraints for each cell individually, solving the fluxes only across active interfaces, and calculating gravitational forces only between active particles, using an operator-splitting approach. This allows simulations with high dynamic range to be performed efficiently. AREPO is a massively distributed-memory parallel code, using the message passing interface (MPI) communication standard and employing a dynamical workload and memory balancing scheme to allow for optimal use of multi-node parallel computers. The employed parallelization algorithms of AREPO are deterministic and produce binary-identical results when rerun on the same machine and with the same number of MPI ranks. A simple primordial cooling and star formation model is included as an example of sub-resolution models commonly used in simulations of galaxy formation. AREPO also contains a suite of computationally inexpensive test problems, ranging from idealized tests for automated code verification to scaled-down versions of cosmological galaxy formation simulations, and is extensively documented in order to assist adoption of the code by new scientific users.

Keywords: Hydrodynamical simulations, Computational astronomy, Magnetohydrodynamics, Galaxy formation, Large-scale structure of the universe, Gravitation, Computational methods, Astrophysical fluid dynamics
A Sample of Edge-on H I-rich Low Surface Brightness Galaxy Candidates in the 40% ALFALFA Catalog. Low surface brightness galaxies (LSBGs) are defined as galaxies that are fainter than dark night sky and are important for studying our universe. Particularly, edge-on galaxies are useful for the study of rotational velocity and dynamical properties of galaxies. Hence here we focus on searching for edge-on LSBGs. In order to find these edge-on dim galaxies, a series of effects caused by inclination, including the surface brightness profile, internal extinction, and scale length, have been corrected. In this work, we present a catalog of 281 edge-on LSBG candidates, which are selected from the crossmatch between Sloan Digital Sky Survey Data Release 7 and the 40% ALFALFA catalog. We also present the properties of these edge-on LSBG candidates including the absolute magnitude, central surface brightness, B - V color, scale length, and relative thickness. Our result suggests that the correction of inclination effects is very important for obtaining a complete sample of LSBGs.

Keywords: Galaxies, Catalogs, Low surface brightness galaxies
A Systematic Search for the Reddest Far-infrared and Submillimeter Galaxies: Revealing Dust-embedded Starbursts at High Redshifts. We present the results of our systematic search for the reddest far-infrared (FIR) and submillimeter (sub-mm) galaxies using the data from the Herschel Multi-tiered Extragalactic Survey (HerMES) and the SCUBA2 Cosmological Legacy Survey (S2CLS). The red FIR galaxies are "500 μm risers," whose spectral energy distributions increase with wavelength across the three FIR passbands of the Spectral and Photometric Imaging REceiver (SPIRE) of Herschel. Within 106.5 deg2 of the HerMES fields, we have selected 629 500 μm risers. The red sub-mm galaxies are "SPIRE drop-outs," which are prominent detections in the S2CLS 850 μm data but are extremely weak or invisible in the SPIRE bands. Within the 2.98 deg2 common area of HerMES and S2CLS, we have selected 95 such objects. These very red sources could be dusty starbursts at high redshifts (z ≳ 4-6) because the peak of their cold-dust emission heated by star formation is shifted to the reddest FIR/sub-mm bands. The surface density of 500 μm risers is ∼8.2 deg-2 at the ≥20 mJy level in 500 μm, while that of SPIRE drop-outs is ∼19.3 deg-2 at the ≥5 mJy level in 850 μm. Both types of objects could span a wide range of redshifts, however. Using deep radio data in these fields to further select the ones likely at the highest redshifts, we find that the surface density of z &gt; 6 candidates is 5.5 deg-2 among 500 μm risers and is 0.8-13.6 deg-2 among SPIRE drop-outs. If this is correct, the dust-embedded star formation processes in such objects could contribute comparably as Lyman-break galaxies to the global SFR density at z &gt; 6.

Keywords: Starburst galaxies, Ultraluminous infrared galaxies, Blazars, Galaxy evolution, Submillimeter astronomy, High-redshift galaxies, Radio sources
A Monte Carlo Implementation of Galactic Free-Free Emission for the EoR Foreground Models. The overwhelming foreground causes severe contamination on the detection of 21 cm signal during the Epoch of Reionization (EoR). Among various foreground components, the Galactic free-free emission is less studied, so that its impact on the EoR observation remains unclear. To better constrain this emission, we perform Monte Carlo simulation of Hα emission, which comprises direct and scattered Hα radiation from H II regions and warm ionized medium (WIM). The positions and radii of H II regions are quoted from the Wide-Field Infrared Survey Explorer H II catalog, and the WIM is described by an axisymmetric model. The scattering is off dust and free electrons that are realized by applying an exponential fitting to the HI4PI H I map and an exponential disk model, respectively. The simulated Hα intensity, the Simfast21 software, and the latest SKA1-Low layout configuration are employed to simulate the SKA "observed" images of Galactic free-free emission and the EoR signal. By analyzing the one-dimensional power spectra, we find that the Galactic free-free emission can be about 105.4-102.1, 105.0-101.7, and 104.3-101.1 times more luminous than the EoR signal on scales of $0.1\,{\mathrm{Mpc}}^{-1}\lt k\lt 2\,{\mathrm{Mpc}}^{-1}$ in the 116-124, 146-154, and 186-194 MHz frequency bands, respectively. We further calculate the two-dimensional power spectra inside the EoR window and show that the power leaked by Galactic free-free emission can still be significant, as the power ratios can reach about 110%-8000%, 30%-2400%, and 10%-250% on scales of $0.5\,{\mathrm{Mpc}}^{-1}\lesssim k\lesssim 1\,{\mathrm{Mpc}}^{-1}$ in three frequency bands. Therefore, we indicate that the Galactic free-free emission should be carefully treated in future EoR detections.

Keywords: Early universe, Population III stars, Astronomy data analysis, Radiative transfer, Intergalactic medium, Reionization, H II regions, Interferometry
The 16th Data Release of the Sloan Digital Sky Surveys: First Release from the APOGEE-2 Southern Survey and Full Release of eBOSS Spectra. This paper documents the 16th data release (DR16) from the Sloan Digital Sky Surveys (SDSS), the fourth and penultimate from the fourth phase (SDSS-IV). This is the first release of data from the Southern Hemisphere survey of the Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2); new data from APOGEE-2 North are also included. DR16 is also notable as the final data release for the main cosmological program of the Extended Baryon Oscillation Spectroscopic Survey (eBOSS), and all raw and reduced spectra from that project are released here. DR16 also includes all the data from the Time Domain Spectroscopic Survey and new data from the SPectroscopic IDentification of ERosita Survey programs, both of which were co-observed on eBOSS plates. DR16 has no new data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey (or the MaNGA Stellar Library "MaStar"). We also preview future SDSS-V operations (due to start in 2020), and summarize plans for the final SDSS-IV data release (DR17).

Keywords: Astronomy databases, Stellar properties, Infrared astronomy, Optical telescopes, Galactic abundances, Stellar spectral lines, Redshift surveys
The Athena++ Adaptive Mesh Refinement Framework: Design and Magnetohydrodynamic Solvers. The design and implementation of a new framework for adaptive mesh refinement calculations are described. It is intended primarily for applications in astrophysical fluid dynamics, but its flexible and modular design enables its use for a wide variety of physics. The framework works with both uniform and nonuniform grids in Cartesian and curvilinear coordinate systems. It adopts a dynamic execution model based on a simple design called a "task list" that improves parallel performance by overlapping communication and computation, simplifies the inclusion of a diverse range of physics, and even enables multiphysics models involving different physics in different regions of the calculation. We describe physics modules implemented in this framework for both nonrelativistic and relativistic magnetohydrodynamics (MHD). These modules adopt mature and robust algorithms originally developed for the Athena MHD code and incorporate new extensions: support for curvilinear coordinates, higher-order time integrators, more realistic physics such as a general equation of state, and diffusion terms that can be integrated with super-time-stepping algorithms. The modules show excellent performance and scaling, with well over 80% parallel efficiency on over half a million threads. The source code has been made publicly available.

Keywords: Magnetohydrodynamics, Astronomy software
SPECULATOR: Emulating Stellar Population Synthesis for Fast and Accurate Galaxy Spectra and Photometry. We present SPECULATOR -- a fast, accurate, and flexible framework for emulating stellar population synthesis (SPS) models for predicting galaxy spectra and photometry. For emulating spectra, we use a principal component analysis to construct a set of basis functions and neural networks to learn the basis coefficients as a function of the SPS model parameters. For photometry, we parameterize the magnitudes (for the filters of interest) as a function of SPS parameters by a neural network. The resulting emulators are able to predict spectra and photometry under both simple and complicated SPS model parameterizations to percent-level accuracy, giving a factor of 103-104 speedup over direct SPS computation. They have readily computable derivatives, making them amenable to gradient-based inference and optimization methods. The emulators are also straightforward to call from a GPU, giving an additional order of magnitude speedup. Rapid SPS computations delivered by emulation offers a massive reduction in the computational resources required to infer the physical properties of galaxies from observed spectra or photometry and simulate galaxy populations under SPS models, while maintaining the accuracy required for a range of applications.

Keywords: Galaxy photometry, Galaxies, Neural networks
A Systematic Observational Study on Galactic Interstellar Ratio <SUP>18</SUP>O/<SUP>17</SUP>O. I. C<SUP>18</SUP>O and C<SUP>17</SUP>O J = 1-0 Data Analysis. The interstellar oxygen isotopic ratio of 18O/17O can reflect the relative amount of the secular enrichment by ejecta from high-mass versus intermediate-mass stars. Previous observations found a Galactic gradient of 18O/17O, i.e., low ratios in the Galactic center and large values in the Galactic disk, which supports the inside-out formation scenario of our Galaxy. However, there are not many observed objects and, in particular, there are not many at large galactocentric distances. For this reason, we started a systematic study on Galactic interstellar 18O/17O, through observations of C18O and C17O multi-transition lines toward a large sample of 286 sources (at least one order of magnitude larger than previous ones), from the Galactic center region to the far outer Galaxy (∼22 kpc). In this article, we present our observations of J = 1-0 lines of C18O and C17O, with the 12 m antenna of the Arizona Radio Observatory (ARO 12 m) and the Institut de Radio Astronomie Millimétrique (IRAM) 30 m telescopes. Among our IRAM 30 m sample of 50 targets, we detected successfully both C18O and C17O 1-0 lines for 34 sources. Similarly, our sample of 260 targets for ARO 12 m observations resulted in the detection of both lines for 166 sources. The C18O optical depth effect on our ratio results, evaluated by fitting results of C17O spectra with hyperfine components (assuming ${\tau }_{C18O}=4{\tau }_{C17O}$ ) and our radiative transfer and excitation model nonlocal thermodynamic equilibrium (non-LTE) model calculation for the strongest source, was found to be insignificant. Beam dilution does not seem to be a problem either, which was supported by the fact that there is no systematic variation between the isotopic ratio and the heliocentric distance, and ratios are consistently measured from two telescopes for most of those detected sources. With this study we obtained 18O/17O isotopic ratios for a large sample of molecular clouds with different galactocentric distances. Our results, though there are still very few detections made for sources in the outer Galaxy, confirm the apparent 18O/17O gradient of 18O/17O=(0.10 ± 0.03)RGC+(2.95 ± 0.30), with a Pearson's rank correlation coefficient of R = 0.69. This is supported by the newest Galactic chemical evolution model including the impact of massive stellar rotators and novae. Our future J = 2-1 and J = 3-2 observations of C18O and C17O toward the same sample would be important to determine their physical parameters (opacities, abundances, etc.) and further accurately determine the Galactic radial gradient of the isotopic ratio 18O/17O.

Keywords: Interstellar molecules, Isotopic abundances, Galaxy chemical evolution, Radio source counts, Milky Way evolution