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<jats:title>Abstract</jats:title> <jats:p>We compare the performance of energy-based and entropy-conserving schemes for modeling nonthermal energy components, such as unresolved turbulence and cosmic rays, using idealized fluid dynamics tests and isolated galaxy simulations. While both methods are aimed to model advection and adiabatic compression or expansion of different energy components, the energy-based scheme numerically solves the nonconservative equation for the energy density evolution, while the entropy-conserving scheme uses a conservative equation for modified entropy. Using the standard shock tube and Zel’dovich pancake tests, we show that the energy-based scheme results in a spurious generation of nonthermal energy on shocks, while the entropy-conserving method evolves the energy adiabatically to machine precision. We also show that, in simulations of an isolated <jats:italic>L</jats:italic> <jats:sub>⋆</jats:sub> galaxy, switching between the schemes results in ≈20%–30% changes of the total star formation rate and a significant difference in morphology, particularly near the galaxy center. We also outline and test a simple method that can be used in conjunction with the entropy-conserving scheme to model the injection of nonthermal energies on shocks. Finally, we discuss how the entropy-conserving scheme can be used to capture the kinetic energy dissipated by numerical viscosity into the subgrid turbulent energy <jats:italic>implicitly</jats:italic>, without explicit source terms that require calibration and can be rather uncertain. Our results indicate that the entropy-conserving scheme is the preferred choice for modeling nonthermal energy components, a conclusion that is equally relevant for Eulerian and moving-mesh fluid dynamics codes.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The solar radiation in the cores of the Mg <jats:sc>ii</jats:sc> h and k spectral lines plays a significant role in the illumination of prominences, coronal mass ejections (CMEs), spicules, flare loops, and surges. Moreover, the radiation in these lines strongly correlates with solar magnetic activity and the ultraviolet solar spectral irradiance affecting the photochemistry, especially of oxygen and nitrogen, in the middle atmosphere of the Earth. This work provides a data-driven model of temporal evolution of the solar full-disk Mg <jats:sc>ii</jats:sc> h and k profiles over the solar cycle. The capability of the model to reproduce the Mg <jats:sc>ii</jats:sc> h and k profiles for an arbitrary date is statistically assessed. Based on selected 76 IRIS near-UV full-Sun mosaics covering almost the full solar cycle 24, we find the parameters of double-Gaussian fits of the disk-averaged Mg <jats:sc>ii</jats:sc> h and k profiles and a model of their temporal evolution parameterized by the Bremen composite Mg <jats:sc>ii</jats:sc> index. The model yields intensities within the uncertainties of the observed data in more than 90% of the reconstructed profiles assuming a statistically representative set of Bremen Mg <jats:sc>ii</jats:sc> index values in the range of 0.150–0.165. The relevant full-disk Mg <jats:sc>ii</jats:sc> h and k calibrated profiles with uncertainties and spectral irradiances are provided as an online machine-readable table. The model yields Mg <jats:sc>ii</jats:sc> h and k profiles representing the disk incident radiation for the radiative-transfer modeling of prominences, CMEs, spicules, flare loops, and surges observed at arbitrary time.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>The Interstellar Boundary Explorer (IBEX) is a NASA satellite in Earth orbit, dedicated to observing both interstellar neutral atoms entering the heliosphere and energetic neutral atoms (ENAs) from the interstellar boundaries from roughly 10 eV to 6 keV. This work presents the averaged maps, energy spectra, and temporal variability of heliospheric ENA intensities measured with the IBEX-Lo instrument at 1 au at energies between 10 eV and 2 keV, covering one entire solar cycle from 2009 through 2019. These results expand the range in time and energy for studying the globally distributed ENA flux and the IBEX Ribbon. The observed ENA intensities exceed model predictions, in particular below 500 eV. Moreover, the ENA intensities between 50–200 eV energy show an unexpected rise and fall around the year 2015 in most sky regions.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>Orbital characteristics based on Gaia Early Data Release 3 astrometric parameters are analyzed for ∼8000 metal-poor stars ([Fe/H] ≤ −0.8) compiled from the Radial Velocity Experiment (RAVE) Data Release 6. Selected as metal-poor candidates based on broadband photometry, RAVE collected moderate-resolution (<jats:italic>R</jats:italic> ∼ 7500) spectra in the region of the Ca triplet for these stars. About 20% of the stars in this sample also have medium-resolution (1200 ≲ <jats:italic>R</jats:italic> ≲ 2000) validation spectra obtained over a 4 yr campaign from 2014 to 2017 with a variety of telescopes. We match the candidate stars to photometric metallicity determinations from the Huang et al. recalibration of the SkyMapper Southern Survey Data Release 2. We obtain dynamical clusters of these stars from the orbital energy and cylindrical actions using the <jats:monospace>HDBSCAN</jats:monospace> unsupervised learning algorithm. We identify 179 dynamically tagged groups (DTGs) with between 5 and 35 members; 67 DTGs have at least 10 member stars. Milky Way (MW) substructures such as Gaia–Sausage–Enceladus, the Metal-weak Thick Disk, the Splashed Disk, Thamnos, the Helmi Stream, and LMS-1 (Wukong) are identified. Associations with MW globular clusters are determined for 10 DTGs; no recognized MW dwarf galaxies were associated with any of our DTGs. Previously identified dynamical groups are also associated with our DTGs, with emphasis placed on their structural determination and possible new identifications. We identify chemically peculiar stars as members of several DTGs; we find 22 DTGs that are associated with <jats:italic>r</jats:italic>-process-enhanced stars. Carbon-enhanced metal-poor (CEMP) stars are identified among the targets with available spectroscopy, and we assign these to morphological groups following the approach given by Yoon et al.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We introduce C<jats:sc>o</jats:sc>SHA: a Code for Stellar properties Heuristic Assignment. In order to estimate the stellar properties, C<jats:sc>o</jats:sc>SHA implements a Gradient Tree Boosting algorithm to label each star across the parameter space (<jats:italic>T</jats:italic> <jats:sub>eff</jats:sub>, <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}g$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac67f4ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, [Fe/H], and [<jats:italic>α</jats:italic>/Fe]). We use C<jats:sc>o</jats:sc>SHA to estimate the stellar atmospheric parameters of 22,000 unique stars in the MaNGA Stellar Library (MaStar). To quantify the reliability of our approach, we run internal tests, using both the Göttingen Stellar Library (a theoretical library) and the first data release of MaStar, and external tests, by comparing the resulting distributions in the parameter space with the APOGEE estimates of the same properties. In summary, our parameter estimates span the ranges <jats:italic>T</jats:italic> <jats:sub>eff</jats:sub> = [2900, 12,000] K, <jats:inline-formula> <jats:tex-math> <?CDATA $\mathrm{log}g=[-0.5,5.6]$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> <mml:mo>=</mml:mo> <mml:mo stretchy="false">[</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.5</mml:mn> <mml:mo>,</mml:mo> <mml:mn>5.6</mml:mn> <mml:mo stretchy="false">]</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac67f4ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, [Fe/H] = [−3.74, 0.81], and <jats:italic>α</jats:italic> <jats:italic>M</jats:italic> = [−0.22, 1.17]. We report internal (external) uncertainties of the properties of <jats:inline-formula> <jats:tex-math> <?CDATA ${\sigma }_{{T}_{\mathrm{eff}}}\sim 43(240)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>eff</mml:mi> </mml:mrow> </mml:msub> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>43</mml:mn> <mml:mo stretchy="false">(</mml:mo> <mml:mn>240</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac67f4ieqn3.gif" xlink:type="simple" /> </jats:inline-formula> K, <jats:inline-formula> <jats:tex-math> <?CDATA ${\sigma }_{\mathrm{log}g}\sim 0.2(0.4)$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>σ</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>log</mml:mi> <mml:mi>g</mml:mi> </mml:mrow> </mml:msub> <mml:mo>∼</mml:mo> <mml:mn>0.2</mml:mn> <mml:mo stretchy="false">(</mml:mo> <mml:mn>0.4</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac67f4ieqn4.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:italic>σ</jats:italic> <jats:sub>[Fe/H]</jats:sub> ∼ 0.16(0.24), and <jats:italic>σ</jats:italic> <jats:sub>[<jats:italic>α</jats:italic>/Fe]</jats:sub> ∼ 0.09(0.08). These uncertainties are comparable to those of other methods with similar objectives. Despite the fact that C<jats:sc>o</jats:sc>SHA is not aware of the spatial distributions of these physical properties in the Milky Way, we are able to recover the main trends known in the literature. The catalog of physical properties for MaStar can be accessed online.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present a uniform analysis of the integrated profile of the H <jats:sc>i</jats:sc> emission line of 29,958 nearby (<jats:italic>z</jats:italic> &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 <jats:sc>i</jats:sc> sizes estimated from the H <jats:sc>i</jats:sc> 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 <jats:sc>i</jats:sc> 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 <jats:sc>i</jats:sc> profile asymmetry is detected in ∼20% of the galaxy population. The global H <jats:sc>i</jats:sc> 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.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the implementation of general-relativistic <jats:italic>resistive</jats:italic> magnetohydrodynamics solvers and three divergence-free handling approaches adopted in the <jats:monospace>G</jats:monospace>eneral-relativistic <jats:monospace>mu</jats:monospace>ltigrid <jats:monospace>nu</jats:monospace>merical (<jats:monospace>Gmunu</jats:monospace>) 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.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>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 <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>–<jats:italic>σ</jats:italic> relations for Type 2 AGNs and from virial BH masses for Type 1 AGNs, reliable stellar velocity dispersions <jats:italic>σ</jats:italic> measured from absorption features around 4000 Å are directly compared between the thus far largest samples of 6260 low-redshift (<jats:italic>z</jats:italic> &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 <jats:italic>σ</jats:italic> due to unapparent absorption features overwhelmed by AGN activities, both properties of the mean spectra of Type 1 AGNs with and without a measured <jats:italic>σ</jats:italic> and a positive dependence of <jats:italic>σ</jats:italic> on the [O <jats:sc>iii</jats:sc>] luminosity can lead to a statistically larger <jats:italic>σ</jats:italic> for all Type 1 AGNs compared to the 6260 Type 1 AGNs with measured stellar velocity dispersions. Then, direct <jats:italic>σ</jats:italic> comparisons can lead to a statistically larger <jats:italic>σ</jats:italic> in Type 1 AGNs, with a confidence level higher than 10<jats:italic>σ</jats:italic>, after considering the necessary effects of different redshifts and different central AGN activities. Although Type 1 AGNs have a <jats:italic>σ</jats:italic> 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 <jats:italic>M</jats:italic> <jats:sub>BH</jats:sub>–<jats:italic>σ</jats:italic> relations or to support quite different evolutionary histories between Type 1 and Type 2 AGNs, the statistically larger <jats:italic>σ</jats:italic> in Type 1 AGNs provides a strong challenge to the UM of AGNs.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>We present the first active galactic nuclei (AGN) catalog of the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX) observed between 2017 January and 2020 June. HETDEX is an ongoing spectroscopic survey (3500–5500 Å) with no target preselection based on magnitudes, colors or morphologies, enabling us to select AGN based solely on their spectral features. Both luminous quasars and low-luminosity Seyferts are found in our catalog. AGN candidates are selected with at least two significant AGN emission lines, such as the Ly<jats:italic>α</jats:italic> and C <jats:sc>iv</jats:sc> <jats:italic>λ</jats:italic>1549 line pair, or with a single broad emission line with FWHM &gt; 1000 km s<jats:sup>−1</jats:sup>. Each source is further confirmed by visual inspections. This catalog contains 5322 AGN, covering an effective sky coverage of 30.61 deg<jats:sup>2</jats:sup>. A total of 3733 of these AGN have secure redshifts, and we provide redshift estimates for the remaining 1589 single broad-line AGN with no crossmatched spectral redshifts from the Sloan Digital Sky Survey Data Release 14 of QSOs. The redshift range of the AGN catalog is 0.25 &lt; <jats:italic>z</jats:italic> &lt; 4.32, with a median of <jats:italic>z</jats:italic> = 2.1. The bolometric luminosity range is 10<jats:sup>9</jats:sup>–10<jats:sup>14</jats:sup> <jats:italic>L</jats:italic> <jats:sub>☉</jats:sub> with a median of 10<jats:sup>12</jats:sup> <jats:italic>L</jats:italic> <jats:sub>☉</jats:sub>. The median <jats:italic>r</jats:italic>-band magnitude of our AGN catalog is 21.6 mag, with 34% having <jats:italic>r</jats:italic> &gt; 22.5, and 2.6% reaching the detection limit at <jats:italic>r</jats:italic> ∼ 26 mag of the deepest imaging surveys we searched. We also provide a composite spectrum of the AGN sample covering 700–4400 Å.</jats:p>

<jats:title>Abstract</jats:title> <jats:p>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, <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{opt}}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>opt</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac7c64ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, its optical luminosity, <jats:italic>L</jats:italic> <jats:sub>opt</jats:sub>, and the peak in the optical prompt emission, <jats:italic>L</jats:italic> <jats:sub>peak,opt</jats:sub>, 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 (<jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{\mathrm{opt}}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>opt</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac7c64ieqn2.gif" xlink:type="simple" /> </jats:inline-formula>, <jats:inline-formula> <jats:tex-math> <?CDATA ${T}_{{\rm{X}}}^{* }$?> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>T</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">X</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msubsup> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsac7c64ieqn3.gif" xlink:type="simple" /> </jats:inline-formula>), 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.</jats:p>