Sazuna/UAT_keywords huggingface dataset:
Electromagnetic Signatures from the Tidal Tail of a Black Hole-Neutron Star Merger. Black hole-neutron star (BH-NS) mergers are a major target for ground-based gravitational wave observatories. A merger can also produce an electromagnetic counterpart (a kilonova) if it ejects neutron-rich matter that assembles into heavy elements through r-process nucleosynthesis. We study the kilonova signatures of the unbound dynamical ejecta of a BH-NS merger. We take as our initial state the results from a numerical relativity simulation and then use a general relativistic hydrodynamics code to study the evolution of the ejecta with parameterized r-process heating models. The unbound dynamical ejecta is initially a flattened, directed tidal tail largely confined to a plane. Heating from the r-process inflates the ejecta into a more spherical shape and smooths its small-scale structure, though the ejecta retains its bulk directed motion. We calculate the electromagnetic signatures using a 3D radiative transfer code and a parameterized opacity model for lanthanide-rich matter. The light curve varies with viewing angle because of two effects: asphericity results in brighter emission for orientations with larger projected areas, while Doppler boosting results in brighter emission for viewing angles more aligned with the direction of bulk motion. For typical r-process heating rates, the peak bolometric luminosity varies by a factor of ~3 with orientation while the peak in the optical bands varies by ~3 magnitudes. The spectrum is blueshifted at viewing angles along the bulk motion, which increases the V-band peak magnitude to ~-14 despite the lanthanide-rich composition.

Keywords: Neutron stars, Hydrodynamical simulations, R-process, Transient sources, Stellar mass black holes, Radiative transfer simulations
WALLABY Pilot Survey: The Diversity of Ram Pressure Stripping of the Galactic H I Gas in the Hydra Cluster. This study uses H I image data from the Widefield ASKAP L-band Legacy All-sky Blind surveY (WALLABY) pilot survey with the Australian Square Kilometre Array Pathfinder (ASKAP) telescope, covering the Hydra cluster out to 2.5r200. We present the projected phase-space distribution of H I-detected galaxies in Hydra, and identify that nearly two-thirds of the galaxies within $1.25{r}_{200}$ may be in the early stages of ram pressure stripping. More than half of these may be only weakly stripped, with the ratio of strippable H I (i.e., where the galactic restoring force is lower than the ram pressure in the disk) mass fraction (over total H I mass) distributed uniformly below 90%. Consequently, the H I mass is expected to decrease by only a few 0.1 dex after the currently strippable portion of H I in these systems has been stripped. A more detailed look at the subset of galaxies that are spatially resolved by WALLABY observations shows that, while it typically takes less than 200 Myr for ram pressure stripping to remove the currently strippable portion of H I, it may take more than 600 Myr to significantly change the total H I mass. Our results provide new clues to understanding the different rates of H I depletion and star formation quenching in cluster galaxies.

Keywords: Disk galaxies, Galaxy environments, Interstellar atomic gas, Galaxy evolution, Galaxies
The CAMELS Project: Cosmology and Astrophysics with Machine-learning Simulations. We present the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) project. CAMELS is a suite of 4233 cosmological simulations of ${\left(25{h}^{-1}\mathrm{Mpc}\right)}^{3}$ volume each: 2184 state-of-the-art (magneto)hydrodynamic simulations run with the AREPO and GIZMO codes, employing the same baryonic subgrid physics as the IllustrisTNG and SIMBA simulations, and 2049 N-body simulations. The goal of the CAMELS project is to provide theory predictions for different observables as a function of cosmology and astrophysics, and it is the largest suite of cosmological (magneto)hydrodynamic simulations designed to train machine-learning algorithms. CAMELS contains thousands of different cosmological and astrophysical models by way of varying Ωm, σ8, and four parameters controlling stellar and active galactic nucleus feedback, following the evolution of more than 100 billion particles and fluid elements over a combined volume of ${(400{h}^{-1}\mathrm{Mpc})}^{3}$ . We describe the simulations in detail and characterize the large range of conditions represented in terms of the matter power spectrum, cosmic star formation rate density, galaxy stellar mass function, halo baryon fractions, and several galaxy scaling relations. We show that the IllustrisTNG and SIMBA suites produce roughly similar distributions of galaxy properties over the full parameter space but significantly different halo baryon fractions and baryonic effects on the matter power spectrum. This emphasizes the need for marginalizing over baryonic effects to extract the maximum amount of information from cosmological surveys. We illustrate the unique potential of CAMELS using several machine-learning applications, including nonlinear interpolation, parameter estimation, symbolic regression, data generation with Generative Adversarial Networks, dimensionality reduction, and anomaly detection.

Keywords: Cosmology, Galaxy formation, Astrostatistics, Cosmological parameters from large-scale structure
Optical Properties of Interstellar Dust around the Orion A Molecular Cloud. We have studied optical properties of interstellar dust around the Orion A molecular cloud to investigate the size distribution and the composition of dust grains. Orion A is one of the most studied molecular clouds in the solar vicinity (d ≃ 400 pc). In this paper, we used optical and near-infrared photometric data. The optical data were obtained by BVRI bands imaging observations. The near-infrared data consisting of JHKS bands were taken from 2MASS point source catalog. We produced some color excess maps around Orion A and measured their ratios such as E(R - I)/E(B - V). In order to investigate dust properties, we compared the observed ratios with results of simulation performed by Naoi et al. who calculated the extinction in the optical to near-infrared wavelengths based on a standard dust model. They assumed a power-law grain-size distribution with an upper cutoff radius and assumed graphite and silicate as dominant components. As a result, we found that the upper cutoff radius around Orion A is ≃0.3 μm, and silicate predominates compared with graphite (with the fraction of silicate grater than 93%). In addition, we further derived the total-to-selective extinction ratio RV from the observed extinction of AV and the color excess E(B - V), and compared it with the model calculations. Dust properties (i.e., the upper cutoff radius and the ratio of graphite/silicate) derived from RV are almost consistent with those derived from the color excess ratios.

Keywords: Interstellar dust, Optical observation, Interstellar dust extinction, Reddening law, Near infrared astronomy, Extinction, Diffuse interstellar clouds
An Accurate P<SUP>3</SUP>M Algorithm for Gravitational Lensing Studies in Simulations. We present a two-dimensional particle-particle-particle-mesh (P3M) algorithm with an optimized Green's function and adaptive softening length for gravitational lensing studies in N-body simulations. The analytical form of the optimized Green's function $\hat{G}({\boldsymbol{k}})$ is given. The softening schemes (S) are studied for both the particle-mesh (PM) and the particle-particle (PP) calculations in order for accurate force calculation and suppression of the particle discreteness effect. Our method is two orders of magnitude more accurate than the simple PM algorithm with the poor man's Green's function (∝ 1/k2) at a scale of a few mesh cells or smaller. The force anisotropy is also much smaller than the conventional PM calculation. We can achieve a force accuracy better than 0.1% at all scales with our algorithm, which makes it an ideal (accurate and fast) algorithm for microlensing studies. When we apply the algorithm to computing weak and strong lensing quantities in N-body simulations, the errors are dominated by the Poisson noise caused by particle discreteness. The Poisson noise can be suppressed by smoothing out the particle distribution, which can be achieved by simply choosing an adaptive softening length in the PP calculation. We have presented a criterion to set the adaptive softening length. Our algorithm is also applicable to cosmological simulations. We provide a PYTHON implementation P3Mlens for this algorithm.

Keywords: Algorithms, Gravitational lensing, N-body simulations
Laboratory Detection of Cyanoacetic Acid: A Jet-cooled Rotational Study. Herein we present a laboratory rotational study of cyanoacetic acid (CH2(CN)C(O)OH), an organic acid as well as a -CN-bearing molecule, which is a candidate molecular system to be detected in the interstellar medium (ISM). Our investigation aims to provide direct experimental frequencies of cyanoacetic acid to guide its eventual astronomical search in low-frequency surveys. Using different jet-cooled rotational spectroscopic techniques in the time domain, we have determined a precise set of the relevant rotational spectroscopic constants, including the 14N nuclear quadrupole coupling constants for the two distinct structures, cis- and gauche-cyanoacetic acid. We believe this work will potentially allow the detection of cyanoacetic acid in the ISM, whose rotational features have remained unknown until now.

Keywords: Interstellar molecules, Molecular spectroscopy, Laboratory astrophysics, Catalogs
Exploring Mutual Information between IRIS Spectral Lines. II. Calculating the Most Probable Response in all Spectral Windows. A three-dimensional picture of the solar atmosphere's thermodynamics can be obtained by jointly analyzing multiple spectral lines that span many formation heights. In Paper I, we found strong correlations between spectral shapes from a variety of different ions during solar flares in comparison to the quiet Sun. We extend these techniques to address the following questions: which regions of the solar atmosphere are most connected during a solar flare, and what are the most likely responses across several spectral windows based on the observation of a single Mg II spectrum? Our models are derived from several million IRIS spectra collected from 21 M- and X-class flares. We applied this framework to archetypal Mg II flare spectra and analyzed the results from a multiline perspective. We find that (1) the line correlations from the photosphere to the transition region are highest in flare ribbons. (2) Blueshifted reversals appear simultaneously in Mg II, C II, and Si IV during the impulsive phase, with Si IV displaying possible optical depth effects. Fe II shows signs of strong emission, indicating deep early heating. (3) The Mg II line appears to typically evolve a blueshifted reversal that later returns to line center and becomes single peaked within 1-3 minutes. The widths of these single-peaked profiles slowly erode with time. During the later flare stages, strong red-wing enhancements indicating coronal rain are evident in Mg II, C II, and Si IV. Our framework is easily adaptable to any multiline data set and enables comprehensive statistical analyses of the atmospheric behavior in different spectral windows.

Keywords: Bayesian information criterion, Solar flares, Solar flare spectra, Neural networks
Measurements of <SUP>160</SUP>Dy (p, γ) at Energies Relevant for the Astrophysical γ Process. Rare information on photodisintegration reactions of nuclei with mass numbers A ≈ 160 at astrophysical conditions impedes our understanding of the origin of p-nuclei. Experimental determination of the key (p, γ) cross sections has been playing an important role in verifying nuclear reaction models and providing rates of relevant (γ, p) reactions in the γ process. In this paper we report the first cross-section measurements of 160Dy(p, γ)161Ho and 161Dy(p, n)161Ho in the beam energy range of 3.4-7.0 MeV, partially covering the Gamow window. Such determinations are possible by using two targets with various isotopic fractions. The cross-section data can put a strong constraint on the nuclear level densities and gamma strength functions for A ≈ 160 in the Hauser-Feshbach statistical model. Furthermore, we find the best parameters for TALYS that reproduce the available A ~ 160 data, 160Dy(p, γ)161Ho and 162Er(p, γ)163Tm, and recommend the constrained 161Ho(γ, p)160Dy reaction rates over a wide temperature range for γ process network calculations. Although the determined 161Ho(γ, p) stellar reaction rates at the temperature of 1 to 2 GK can differ by up to one order of magnitude from the NON-SMOKER predictions, it has a minor effect on the yields of 160Dy and accordingly the p-nuclei, 156,158Dy. A sensitivity study confirms that the cross section of 160Dy(p, γ)161Ho is measured precisely enough to predict yields of p nuclei in the γ process.

Keywords: Nucleosynthesis, P-process
Atomic Carbon in the Central Molecular Zone of the Milky Way: Possible Cosmic-Ray Induced Chemistry or Time-dependent Chemistry Associated with SNR Sagittarius A East. Atomic carbon (C0), being one of the most abundant atomic/molecular species observed in dense molecular gas, is potentially a good tracer of molecular gas mass in many chemical/physical environments, though the variation in C0 abundance outside the Galactic disk region is not yet fully known. This paper presents a wide-field 500 GHz [C I] map of the Galactic central molecular zone (CMZ) obtained with the ASTE 10 m telescope. Principal component analysis and non-LTE multi-transition analysis have shown that [C I] emission predominantly originates from the low-excitation gas component with a temperature of 20-50 K and density of ~103 cm-3, whereas C0 abundance is likely suppressed in the high-excitation gas component. The average N(C0)/N(CO) abundance ratio in the CMZ is 0.3-0.4, which is 2-3 times that in the Galactic disk. The N(C0)/N(CO) ratio increases to 0.7 in the innermost 10 pc region and to ~2 in the circumnuclear disk. We discovered C0-rich regions distributed in a ring shape encircling the supernova remnant (SNR) Sgr A East, indicating that the C0 enrichment in the central 10 pc region is a consequence of a molecular cloud-SNR interaction. In the 15 atoms/molecules included in principal component analysis, CN is the only other species that increases in the [C I]-bright ring. The origin of the [C I]-bright ring is likely a cosmic-ray-dominated region created by low-energy cosmic-ray particles accelerated by Sgr A East or primitive molecular gas collected by the SNR in which the conversion from C0 to CO has not reached equilibrium.

Keywords: Galactic center, Molecular clouds, Photodissociation regions, Astrochemistry, Supernova remnants
Fast Blue Optical Transients Due to Circumstellar Interaction and the Mysterious Supernova SN 2018gep. The discovery of SN 2018gep (ZTF 18abukavn) challenged our understanding of the late-phase evolution of massive stars and their supernovae (SNe). The fast rise in luminosity of this SN (spectroscopically classified as a broad-lined Type Ic SN) indicates that the ejecta interacts with a dense circumstellar medium (CSM), while an additional energy source such as 56Ni decay is required to explain the late-time light curve. These features hint at the explosion of a massive star with pre-SN mass loss. In this work, we examine the physical origins of rapidly evolving astrophysical transients like SN 2018gep. We investigate the wave-driven mass-loss mechanism and how it depends on model parameters such as progenitor mass and deposition energy, searching for stellar progenitor models that can reproduce the observational data. A model with an ejecta mass ~2 M☉, explosion energy ~1052 erg, a CSM of mass ~0.3 M☉ and radius ~1000 R☉, and a 56Ni mass ~0.3 M☉ provides a good fit to the bolometric light curve. We also examine how interaction-powered light curves depend more generally on these parameters and how ejecta velocities can help break degeneracies. We find both wave-driven mass loss and mass ejection via pulsational pair instability can plausibly create the dense CSM in SN 2018gep, but we favor the latter possibility.

Keywords: Stellar pulsations, Light curves, Radiative transfer, Supernovae, Supernova dynamics
Collapsar R-process Yields Can Reproduce [Eu/Fe] Abundance Scatter in Metal-poor Stars. It is unclear if neutron star mergers can explain the observed r-process abundances of metal-poor stars. Collapsars, defined here as rotating massive stars whose collapse results in a rapidly accreting disk around a black hole that can launch jets, are a promising alternative. We find that we can produce a self-consistent model in which a population of collapsars with stochastic europium yields synthesizes all of the r-process material in metal-poor ([Fe/H] &lt; - 2.5) stars. Our model reproduces the observed scatter and evolution of scatter of [Eu/Fe] abundances. We find that if collapsars are the dominant r-process site for metal-poor stars, r-process synthesis may be linked to supernovae that produce long γ-ray bursts. Our results also allow for the possibility that core-collapse supernovae beyond those that launch γ-ray bursts also produce r-process material (e.g., potentially a subset of Type Ic-BL supernovae). Furthermore, we identify collapsar jet properties (isotropic energy, engine luminosity, or engine time) that may trace r-process yield and verify that the amount of r-process yield produced per collapsar in our model ( ~ 0.07M⊙) is consistent with other independent estimates. In the future, achieving 0.05 dex precision on distribution scatter or a reliable selection function would further constrain our probe of r-process production. Our model would also hold for another prompt r-process site with a power-law yield, and work is needed to determine if, for example, fast-merging neutron stars can also explain abundance scatter.

Keywords: Nucleosynthesis, Core-collapse supernovae, Stellar abundances, Stellar jets, R-process
The Common Origin of High-energy Protons in Solar Energetic Particle Events and Sustained Gamma-Ray Emission from the Sun. We report that the number of &gt;500 MeV protons (Ng) inferred from sustained gamma-ray emission (SGRE) from the Sun is significantly correlated with that of protons propagating into space (NSEP) as solar energetic particles (SEPs). Under the shock paradigm for SGRE, shocks driven by coronal mass ejections (CMEs) accelerate high-energy protons sending them toward the Sun to produce SGRE by interacting with the atmospheric particles. Particles also escape into the space away from the Sun to be detected as SEP events. Therefore, the significant NSEP-Ng correlation (correlation coefficient 0.77) is consistent with the common shock origin for the two proton populations. Furthermore, the underlying CMEs have properties akin to those involved in ground level enhancement events indicating the presence of high-energy (up to ~GeV) particles required for SGRE. We show that the observed gamma-ray flux is an underestimate in limb events (central meridian distance &gt;60°) because SGRE sources are partially occulted when the emission is spatially extended. With the assumption that the SEP spectrum at the shock nose is hard and that the 100 MeV particles are accelerated throughout the shock surface (half width in the range 60°-120°) we find that the latitudinal widths of SEP distributions are energy dependent with the smallest width at the highest energies. Not using the energy-dependent width results in an underestimate of NSEP in SGRE events occurring at relatively higher latitudes. Taking these two effects into account removes the apparent lack of NSEP-Ng correlation reported in previous studies.

Keywords: Solar flares, Solar energetic particles, Solar gamma-ray emission, Solar coronal mass ejection shocks, Solar coronal mass ejections
Fresh Insights on the Kinematics of M49's Globular Cluster System with MMT/Hectospec Spectroscopy. We present the first results of an MMT/Hectospec campaign to measure the kinematics of globular clusters (GCs) around M49-the brightest galaxy in the Virgo galaxy cluster, which dominates the Virgo B subcluster. The data include kinematic tracers beyond 95 kpc (~5.2 effective radii) for M49 for the first time, enabling us to achieve three key insights reported here. First, beyond ~20'-30' (~100-150 kpc), the GC kinematics sampled along the minor photometric axis of M49 become increasingly hotter, indicating a transition from GCs related to M49 to those representing the Virgo B intra-cluster medium. Second, there is an anomaly in the line-of-sight radial velocity dispersion (σr,los) profile in an annulus ~10-15' (~50-90 kpc) from M49 in which the kinematics cool by Δσr,los ≈ 150 km s-1 relative to those in- or outward. The kinematic fingerprint of a previous accretion event is hinted at in projected phase-space, and we isolate GCs that both give rise to this feature, and are spatially co-located with two prominent stellar shells in the halo of M49. Third, we find a subsample of GCs with velocities representative of the dwarf galaxy VCC 1249 that is currently interacting with M49. The spatial distribution of these GCs closely resembles the morphology of VCC 1249's isophotes, indicating that several of these GCs are likely in the act of being stripped from the dwarf during its passage through M49's halo. Taken together, these results point toward the opportunity of witnessing ongoing giant halo assembly in the depths of a cluster environment.

Keywords: Globular star clusters, Galaxy clusters, Giant elliptical galaxies, Dwarf galaxies
Pursuing the Origin of the Gamma Rays in RX J1713.7-3946 Quantifying the Hadronic and Leptonic Components. We analyzed the TeV gamma-ray image of a supernova remnant RX J1713.7-3946 (RX J1713) through a comparison with the interstellar medium (ISM) and nonthermal X-rays. The gamma-ray data sets at two energy bands of &gt;2 TeV and &gt;250-300 GeV were obtained with H.E.S.S. and utilized in the analysis. We employed a new methodology, which assumes that the gamma-ray counts can be expressed as a linear combination of two terms: one is proportional to the ISM column density and the other proportional to the X-ray count. We then assume that these represent the hadronic and leptonic components, respectively. By fitting the expression to the data pixels, we find that the gamma-ray counts are well represented by a flat plane in the 3D space formed by the gamma-ray counts, the ISM column density, and the X-ray counts. The results using the latest H.E.S.S. data at 4'8 resolution show that the hadronic and leptonic components constitute (67 ± 8)% and (33 ± 8)% of the total gamma rays, respectively, where the two components have been quantified for the first time. The hadronic component is greater than the leptonic component, which reflects the massive ISM of ~104 M☉ associated with the remnant, lending support for the acceleration of cosmic-ray protons. There is a marginal hint that the gamma rays are suppressed at high gamma-ray counts, which may be ascribed to second-order effects including the shock-cloud interaction and the effect of penetration depth.

Keywords: Gamma-ray sources, Supernova remnants, Cosmic ray sources, X-ray sources, Interstellar medium