Sazuna/UAT_keywords huggingface dataset:
Extrapolation of Three-dimensional Magnetic Field Structure in Flare-productive Active Regions with Different Initial Conditions. Nonlinear force-free field (NLFFF) modeling has been extensively used as a tool to infer three-dimensional (3D) magnetic field structure. In this study, the dependency of the NLFFF calculation with respect to the initial guess of the 3D magnetic field is investigated. While major parts of the previous studies used the potential field as the initial guess in NLFFF modeling, we adopt linear force-free fields with different constant force-free alpha as the initial guesses. This method enables us to investigate the uniqueness of the magnetic field obtained by the NLFFF extrapolation with respect to the initial guess. The dependence of the initial conditions on NLFFF extrapolation is smaller in the strong magnetic field region. Therefore, the magnetic field at lower heights (&lt;10 Mm) tends to be less affected by the initial conditions (correlation coefficient C &gt; 0.9 with different initial conditions); although, the Lorentz force is concentrated at lower heights.

Keywords: Solar active region velocity fields, Solar active regions, Active sun
GASP XXVII: Gas-phase Metallicity Scaling Relations in Disk Galaxies with and without Ram Pressure Stripping. Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we study the gas-phase metallicity scaling relations of a sample of 29 cluster galaxies undergoing ram pressure stripping and of a reference sample of (16 cluster and 16 field) galaxies with no significant signs of gas disturbance. We adopt the PYQZ code to infer the mean gas metallicity at the effective radius and achieve a well-defined mass-metallicity relation (MZR) in the stellar mass range ${10}^{9.25}\leqslant {M}_{\star }\leqslant {10}^{11.5}\,{M}_{\odot }$ with a scatter of 0.12 dex. At any given mass, reference cluster and stripping galaxies have similar metallicities, while the field galaxies with M⋆ &lt; 1010.25 M☉ show on average lower gas metallicity than galaxies in clusters. Our results indicate that at the effective radius, the chemical properties of the stripping galaxies are independent of the ram pressure stripping mechanism. Nonetheless, at the lowest masses, we detect four stripping galaxies well above the common MZR that suggest a more complex scenario. Overall, we find signs of an anticorrelation between the metallicity and both the star formation rate and the galaxy size, in agreement with previous studies. No significant trends are instead found with the halo mass, clustercentric distance, and local galaxy density in clusters. In conclusion, we advise a more detailed analysis of the spatially resolved gas metallicity maps of the galaxies, able to highlight effects of gas redistribution inside the disk due to ram pressure stripping.

Keywords: Galaxy clusters, Galaxy chemical evolution, Field galaxies, Metallicity, Galaxies
Diffusive Shock Acceleration in N Dimensions. Collisionless shocks are often studied in two spatial dimensions (2D) to gain insights into the 3D case. We analyze diffusive shock acceleration for an arbitrary number $N\in {\mathbb{N}}$ of dimensions. For a nonrelativistic shock of compression ratio ${ \mathcal R }$ , the spectral index of the accelerated particles is ${s}_{{\rm{E}}}=1+N/({ \mathcal R }-1);$ this curiously yields, for any N, the familiar ${s}_{{\rm{E}}}=2$ (I.e., equal energy per logarithmic particle energy bin) for a strong shock in a monatomic gas. A precise relation between ${s}_{{\rm{E}}}$ and the anisotropy along an arbitrary relativistic shock is derived and is used to obtain an analytic expression for ${s}_{{\rm{E}}}$ in the case of isotropic angular diffusion, affirming an analogous result in 3D. In particular, this approach yields ${s}_{{\rm{E}}}=(1+\sqrt{13})/2\simeq 2.30$ in the ultrarelativistic shock limit for N = 2, and ${s}_{{\rm{E}}}(N\to \infty )=2$ for any strong shock. The angular eigenfunctions of the isotropic-diffusion transport equation reduce in 2D to elliptic cosine functions, providing a rigorous solution to the problem; the first function upstream already yields a remarkably accurate approximation. We show how these and additional results can be used to promote the study of shocks in 3D.

Keywords: Shocks, Magnetic fields, High energy astrophysics, Cosmic rays
Counting on Short Gamma-Ray Bursts: Gravitational-wave Constraints of Jet Geometry. The detections of GW170817 and GRB 170817A revealed that at least some short gamma-ray bursts (sGRB) are associated with the merger of neutron-star compact binaries. The gamma-rays are thought to result from the formation of collimated jets, but the details of this process continue to elude us. One important feature of gamma-ray bursts is the emission profile of the jet as a function of viewing angle. We present two related methods to measure the effective angular width, ${\theta }_{B}$ , of sGRB jets using gravitational-wave (GW) and gamma-ray data, assuming all sGRBs have the same angular dependence for their luminosities. The first is a counting experiment that requires minimal knowledge about each event, beyond whether or not they were detected in gamma-rays. The second method uses GW and electromagnetic data to estimate parameters of the source. We additionally outline a model-independent method to infer the full jet structure of sGRBs using a nonparametric approach. Applying our methods to GW170817 and GW190425, we find weak constraints on the sGRB luminosity profile. We project that with 5 and 100 binary neutron star detections, the counting method would constrain the relative uncertainty in ${\theta }_{B}$ to within $51 \% $ and $12 \% $ , respectively. Incorporating GW parameter estimation provides only marginal improvements. We conclude that the majority of the information about jet structure comes from the relative sensitivities of GW and gamma-ray detectors as encoded in simple counting experiments.

Keywords: Neutron stars, Gamma-ray bursts, Gravitational waves
Measuring Turbulent Motion in Planet-forming Disks with ALMA: A Detection around DM Tau and Nondetections around MWC 480 and V4046 Sgr. Turbulence is a crucial factor in many models of planet formation, but it has only been directly constrained among a small number of planet-forming disks. Building on the upper limits on turbulence placed in disks around HD 163296 and TW Hya, we present ALMA CO J = 2-1 line observations at ∼0"3 (20-50 au) resolution and 80 ms-1 channel spacing of the disks around DM Tau, MWC 480, and V4046 Sgr. Using parametric models of disk structure, we robustly detect nonthermal gas motions around DM Tau of between 0.25cs and 0.33cs, with the range dominated by systematic effects, making this one of the only systems with directly measured nonzero turbulence. Using the same methodology, we place stringent upper limits on the nonthermal gas motion around MWC 480 (&lt;0.08cs) and V4046 Sgr (&lt;0.12cs). The preponderance of upper limits in this small sample and the modest turbulence levels consistent with dust studies suggest that weak turbulence (α ≲ 10-3) may be a common, albeit not universal, feature of planet-forming disks. We explore the particular physical conditions around DM Tau that could lead this system to be more turbulent than the others.

Keywords: Protoplanetary disks, Planet formation
On the Small Contribution of Supermicron Dust Particles to Light Scattering by Comets. We quantitatively investigate the contribution of large dust particles to the polarimetric response in comets using the light-scattering properties of model agglomerated debris particles. We demonstrate that large, supermicron-sized particles have a decreasing role on the degree of linear polarization at phase angle α ≤ 80°, and the effect of particles greater than 10 μm is minimal. At larger phase angles, they may only slightly increase the measured percent of polarization by up to 1%. Omitting the effects of these particles in modeling the observations only slightly affects the retrievals of the microphysical properties of dust in comets and could lead to a small underestimation of the index in a power-law size distribution and population of weakly absorbing dust particles.

Keywords: Theoretical models, Spectropolarimetry, Comae, Comets, Polarimetry, Coma dust
Individual Estimates of the Virial Factor in 10 Quasars: Implications on the Kinematics of the Broad-line Region. Assuming a gravitational origin for the Fe IIIλλ2039-2113 redshift and using microlensing based estimates of the size of the region emitting this feature, we obtain individual measurements of the virial factor, f, in 10 quasars. The average values for the Balmer lines, $\langle {f}_{{\rm{H}}\beta }\rangle =0.43\pm 0.20$ and $\langle {f}_{{\rm{H}}\alpha }\rangle =0.50\pm 0.24$ , are in good agreement with the results of previous studies for objects with lines of comparable widths. In the case of Mg II, consistent results, ${f}_{\mathrm{Mg}{\rm{II}}}\sim 0.44$ , can be also obtained accepting a reasonable scaling for the size of the emitting region. The modeling of the cumulative histograms of individual measurements, CDF(f), indicates a relatively high value for the ratio between isotropic and cylindrical motions, $a\sim 0.4\mbox{--}0.7$ . On the contrary, we find very large values of the virial factor associated to the Fe IIIλλ2039-2113 blend, ${f}_{\mathrm{Fe}{\rm{III}}}=14.3\pm 2.4$ , which can be explained if this feature arises from a flattened nearly face-on structure, similar to the accretion disk.

Keywords: Supermassive black holes, Active galaxies, Quasars
Galaxy Morphology Network: A Convolutional Neural Network Used to Study Morphology and Quenching in ∼100,000 SDSS and ∼20,000 CANDELS Galaxies. We examine morphology-separated color-mass diagrams to study the quenching of star formation in ∼100,000 (z ∼ 0) Sloan Digital Sky Survey (SDSS) and ∼20,000 (z ∼ 1) Cosmic Assembly Near-Infrared Deep Extragalactic Legacy Survey (CANDELS) galaxies. To classify galaxies morphologically, we developed Galaxy Morphology Network (GAMORNET), a convolutional neural network that classifies galaxies according to their bulge-to-total light ratio. GAMORNET does not need a large training set of real data and can be applied to data sets with a range of signal-to-noise ratios and spatial resolutions. GAMORNET's source code as well as the trained models are made public as part of this work. We first trained GAMORNET on simulations of galaxies with a bulge and a disk component and then transfer learned using ∼25% of each data set to achieve misclassification rates of ≲5%. The misclassified sample of galaxies is dominated by small galaxies with low signal-to-noise ratios. Using the GAMORNET classifications, we find that bulge- and disk-dominated galaxies have distinct color-mass diagrams, in agreement with previous studies. For both SDSS and CANDELS galaxies, disk-dominated galaxies peak in the blue cloud, across a broad range of masses, consistent with the slow exhaustion of star-forming gas with no rapid quenching. A small population of red disks is found at high mass (∼14% of disks at z ∼ 0 and 2% of disks at z ∼ 1). In contrast, bulge-dominated galaxies are mostly red, with much smaller numbers down toward the blue cloud, suggesting rapid quenching and fast evolution across the green valley. This inferred difference in quenching mechanism is in agreement with previous studies that used other morphology classification techniques on much smaller samples at z ∼ 0 and z ∼ 1.

Keywords: Neural networks, Convolutional neural networks, Astronomy data analysis, Galaxy classification systems, Galaxy evolution, Galaxy quenching, Galaxies
Fitting the Nonlinear Matter Bispectrum by the Halofit Approach. We provide a new fitting formula of the matter bispectrum in the nonlinear regime calibrated by high-resolution cosmological N-body simulations of 41 cold dark matter (wCDM, w = constant) models around the Planck 2015 best-fit parameters. As the parameterization in our fitting function is similar to that in Halofit, our fitting is named BiHalofit. The simulation volume is sufficiently large ( $\gt 10\,{\mathrm{Gpc}}^{3}$ ) to cover almost all measurable triangle bispectrum configurations in the universe. The function is also calibrated using one-loop perturbation theory at large scales ( $k\lt 0.3\,h\,{\mathrm{Mpc}}^{-1}$ ). Our formula reproduced the matter bispectrum to within 10% (15%) accuracy in the Planck 2015 model at wavenumber $k\lt 3\,(10)\,h\,{\mathrm{Mpc}}^{-1}$ and redshifts z = 0-3. The other 40 wCDM models obtained poorer fits, with accuracy approximating 20% at $k\lt 3\,h\,{\mathrm{Mpc}}^{-1}$ and $z=0\mbox{--}1.5$ (the deviation includes the 10%-level sample variance of the simulations). We also provide a fitting formula that corrects the baryonic effects such as radiative cooling and active galactic nucleus feedback, using the latest hydrodynamical simulation IllustrisTNG. We demonstrate that our new formula more accurately predicts the weak-lensing bispectrum than the existing fitting formulae. This formula will assist current and future weak-lensing surveys and cosmic microwave background lensing experiments. Numerical codes of the formula are available, written in Python (https://toshiyan.github.io/clpdoc/html/basic/basic.html#module-basic.bispec), C, and Fortran (http://cosmo.phys.hirosaki-u.ac.jp/takahasi/codes_e.htm).

Keywords: Weak gravitational lensing, Large-scale structure of the universe, Cosmic microwave background radiation, Cosmological parameters from large-scale structure, N-body simulations
On the Relation between the Hard X-Ray Photon Index and Accretion Rate for Super-Eddington Accreting Quasars. We investigate whether the correlation between the hard X-ray photon index ( ${\rm{\Gamma }}$ ) and accretion rate for super-Eddington accreting quasars is different from that for sub-Eddington accreting quasars. We construct a sample of 113 bright quasars from the Sloan Digital Sky Survey Data Release 14 quasar catalog, with 38 quasars as the super-Eddington subsample and 75 quasars as the sub-Eddington subsample. We derive black hole masses using a simple-epoch virial mass formula based on the ${\rm{H}}\beta $ lines, and we use the standard thin disk model to derive the dimensionless accretion rates ( $\dot{{\mathscr{M}}}$ ) for our sample. The X-ray data for these quasars are collected from the Chandra and XMM-Newton archives. We fit the hard X-ray spectra using a single power-law model to obtain ${\rm{\Gamma }}$ values. We find a statistically significant ( ${R}_{{\rm{S}}}=0.43$ , $p=7.75\times {10}^{-3}$ ) correlation between ${\rm{\Gamma }}$ and $\dot{{\mathscr{M}}}$ for the super-Eddington subsample. The ${\rm{\Gamma }}$ - $\dot{{\mathscr{M}}}$ correlation for the sub-Eddington subsample is also significant, but weaker ( ${R}_{{\rm{S}}}=0.30$ , $p=9.98\times {10}^{-3}$ ). Linear regression analysis shows that ${\rm{\Gamma }}=(0.34\pm 0.11)\mathrm{log}\dot{{\mathscr{M}}}+(1.71\pm 0.17)$ and ${\rm{\Gamma }}=(0.09\pm 0.04)\mathrm{log}\dot{{\mathscr{M}}}+(1.93\pm 0.04)$ for the super- and sub-Eddington subsamples, respectively. The ${\rm{\Gamma }}$ - $\dot{{\mathscr{M}}}$ correlations of the two subsamples are different, suggesting different disk-corona connections in these two types of systems. We propose one qualitative explanation of the steeper ${\rm{\Gamma }}$ - $\dot{{\mathscr{M}}}$ correlation in the super-Eddington regime that involves larger seed photon fluxes received by the compact coronae from the thick disks in super-Eddington accreting quasars.

Keywords: Accretion, Supermassive black holes, X-ray quasars
Galaxy Merger Rates up to z ∼ 3 Using a Bayesian Deep Learning Model: A Major-merger Classifier Using IllustrisTNG Simulation Data. Merging is potentially the dominant process in galaxy formation, yet there is still debate about its history over cosmic time. To address this, we classify major mergers and measure galaxy merger rates up to z ∼ 3 in all five CANDELS fields (UDS, EGS, GOODS-S, GOODS-N, COSMOS) using deep learning convolutional neural networks trained with simulated galaxies from the IllustrisTNG cosmological simulation. The deep learning architecture used is objectively selected by a Bayesian optimization process over the range of possible hyperparameters. We show that our model can achieve 90% accuracy when classifying mergers from the simulation and has the additional feature of separating mergers before the infall of stellar masses from post-mergers. We compare our machine-learning classifications on CANDELS galaxies and compare with visual merger classifications from Kartaltepe et al., and show that they are broadly consistent. We finish by demonstrating that our model is capable of measuring galaxy merger rates, ${ \mathcal R }$ , that are consistent with results found for CANDELS galaxies using close pairs statistics, with ${ \mathcal R }{(z)=0.02\pm 0.004\times (1+z)}^{2.76\pm 0.21}$ . This is the first general agreement between major mergers measured using pairs and structure at z &lt; 3.

Keywords: Convolutional neural networks, Galaxy mergers
The Ionizing Photon Production Efficiency (ξ<SUB>ion</SUB>) of Lensed Dwarf Galaxies at z ∼ 2. We measure the ionizing photon production efficiency (ξion) of low-mass galaxies (107.8-109.8 M⊙) at 1.4 &lt; z &lt; 2.7 to better understand the contribution of dwarf galaxies to the ionizing background and reionization. We target galaxies that are magnified by strong-lensing galaxy clusters and use Keck/MOSFIRE to measure nebular emission-line fluxes and Hubble Space Telescope to measure the rest-UV and rest-optical photometry. We present two methods of stacking. First, we take the average of the log of Hα-to-UV luminosity ratios (LHα/LUV) of galaxies to determine the standard log(ξion). Second, we take the logarithm of the total LHα over the total LUV. We prefer the latter, as it provides the total ionizing UV luminosity density of galaxies when multiplied by the nonionizing UV luminosity density. log(ξion) calculated from the second method is ∼0.2 dex higher than the first method. We do not find any strong dependence between log(ξion) and stellar mass, far-UV magnitude (MUV), or UV spectral slope (β). We report a value of log(ξion) ∼ 25.47 ± 0.09 for our UV-complete sample ( $-22\lt {M}_{\mathrm{UV}}\lt -17.3$ ) and ∼25.37 ± 0.11 for our mass-complete sample (7.8 &lt; log(M*) &lt; 9.8). These values are consistent with measurements of more massive, more luminous galaxies in other high-redshift studies that use the same stacking technique. Our log(ξion) is 0.2-0.3 dex higher than low-redshift galaxies of similar mass, indicating an evolution in the stellar properties, possibly due to metallicity or age. We also find a correlation between log(ξion) and the equivalent widths of Hα and [O III] λ5007 fluxes, confirming that these equivalent widths can be used to estimate ξion. * Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with programs 12201, 12931, 13389, and 14209.

Keywords: Dwarf galaxies, High-redshift galaxies, Galaxy evolution
A General Formulation for Computing Spherical Helioseismic Sensitivity Kernels while Incorporating Systematical Effects. As helioseismology matures and turns into a precision science, modeling finite-frequency, geometric, and systematical effects is becoming increasingly important. Here we introduce a general formulation for treating perturbations of arbitrary tensor rank in spherical geometry using fundamental ideas of quantum mechanics and their extensions in geophysics. We include line-of-sight projections and center-to-limb differences in line formation heights in our analysis. We demonstrate the technique by computing a travel-time sensitivity kernel for sound-speed perturbations. The analysis produces the spherical harmonic coefficients of the sensitivity kernels, which leads to better-posed and computationally efficient inverse problems.

Keywords: Computational astronomy, Helioseismology, Helioseismic pulsations, Analytical mathematics, Perturbation methods
SN 2013aa and SN 2017cbv: Two Sibling Type Ia Supernovae in the Spiral Galaxy NGC 5643. We present photometric and spectroscopic observations of SN 2013aa and SN 2017cbv, two nearly identical type Ia supernovae (SNe Ia) in the host galaxy NGC 5643. The optical photometry has been obtained using the same telescope and instruments used by the Carnegie Supernova Project. This eliminates most instrumental systematics and provides light curves in a stable and well-understood photometric system. Having the same host galaxy also eliminates systematics due to distance and peculiar velocity, providing an opportunity to directly test the relative precision of SNe Ia as standard candles. The two SNe have nearly identical decline rates, negligible reddenings, and remarkably similar spectra, and, at a distance of ∼20 Mpc, they are ideal potential calibrators for the absolute distance using primary indicators such as Cepheid variables. We discuss to what extent these two SNe can be considered twins and compare them with other supernova "siblings" in the literature and their likely progenitor scenarios. Using 12 galaxies that hosted two or more SNe Ia, we find that when using SNe Ia, and after accounting for all sources of observational error, one gets consistency in distance to 3%.

Keywords: Galaxy distances, Type Ia supernovae, Interstellar dust extinction, Distance indicators
ALMA ACA and Nobeyama Observations of Two Orion Cores in Deuterated Molecular Lines. We mapped two molecular cloud cores in the Orion A cloud with the 7 m Array of the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeterArray (ALMA) and with the Nobeyama 45 m radio telescope. These cores have bright N2D+ emission in single-pointing observations with the Nobeyama 45 m radio telescope, have a relatively high deuterium fraction, and are thought to be close to the onset of star formation. One is a star-forming core, and the other is starless. These cores are located along filaments observed in N2H+ and show narrow line widths of 0.41 km s-1 and 0.45 km s-1 in N2D+, respectively, with the Nobeyama 45 m telescope. Both cores were detected with the ALMA ACA 7 m Array in the continuum and molecular lines at Band 6. The starless core G211 shows a clumpy structure with several sub-cores, which in turn show chemical differences. Also, the sub-cores in G211 have internal motions that are almost purely thermal. The starless sub-core G211D, in particular, shows a hint of the inverse P Cygni profile, suggesting infall motion. The star-forming core G210 shows an interesting spatial feature of two N2D+ peaks of similar intensity and radial velocity located symmetrically with respect to the single dust continuum peak. One interpretation is that the two N2D+ peaks represent an edge-on pseudo-disk. The CO outflow lobes, however, are not directed perpendicular to the line connecting both N2D+ peaks.

Keywords: Star forming regions, Molecular clouds, Astrochemistry, Giant molecular clouds, Interstellar medium, Collapsing clouds