Sazuna/UAT_keywords huggingface dataset:
Solar Energetic Particle Acceleration at a Spherical Shock with the Shock Normal Angle {\theta }_{{B}_{n}} Evolving in Space and Time. We present a 2D kinematic model to study the acceleration of solar energetic particles (SEPs) at a shock driven by a coronal mass ejection. The shock is assumed to be spherical about an origin that is offset from the center of the Sun. This leads to a spatial and temporal evolution of the angle between the magnetic field and the shock-normal direction (θ  Bn ) as it propagates through the Parker spiral magnetic field from the lower corona to 1 au. We find that the high-energy SEP intensity varies significantly along the shock front due to the evolution of θ  Bn . Generally, the west flank of the shock preferentially accelerates particles to high energies compared to the east flank and shock nose. This can be understood in terms of the rate of acceleration, which is higher at the west flank. Double power-law energy spectra are reproduced in our model as a consequence of the local acceleration and transport effects. These results will help us to better understand the evolution of SEP acceleration and provide new insights into large SEP events observed by multiple spacecraft, especially those close to the Sun, such as Parker Solar Probe and Solar Orbiter.

Keywords: Solar energetic particles, Solar coronal mass ejection shocks, Interplanetary shocks
Quasiperiodic Erupters: A Stellar Mass-transfer Model for the Radiation. Quasiperiodic erupters are a remarkable class of objects exhibiting very-large-amplitude quasiperiodic X-ray flares. Although numerous dynamical models have been proposed to explain them, relatively little attention has been given to using the properties of their radiation to constrain their dynamics. Here we show that the observed luminosity, spectrum, repetition period, duty cycle, and fluctuations in the latter two quantities point toward a model in which a main-sequence star on a moderately eccentric orbit around a supermassive black hole periodically transfers mass to the Roche lobe of the black hole; orbital dynamics lead to mildly relativistic shocks near the black hole; and thermal X-rays at the observed temperature are emitted by the gas as it flows away from the shock. Strong X-ray irradiation of the star by the flare itself augments the mass transfer, creates fluctuations in flare timing, and stirs turbulence in the stellar atmosphere that amplifies the magnetic field to a level at which magnetic stresses can accelerate infall of the transferred mass toward the black hole.

Keywords: Supermassive black holes, X-ray transient sources, Roche lobe overflow
Black Hole Encircled by a Thin Disk: Fully Relativistic Solution. We give a full metric describing the gravitational field of a static and axisymmetric thin disk without radial pressure encircling a Schwarzschild black hole. The disk density profiles are astrophysically realistic, stretching from the horizon to radial infinity, yet falling off quickly at both these locations. The metric functions are expressed as finite series of Legendre polynomials. The main advantages of the solution are that (i) the disks have no edges, so their fields are regular everywhere (outside the horizon), and (ii) all nontrivial metric functions are provided analytically and in closed forms. We examine and illustrate basic properties of the black hole-disk spacetimes. * Dedicated to our teacher, colleague, and friend, Professor Oldřich Semerák, on the occasion of his 60th orbit around the Sun. Oldřich's well-known lectures-famous not only among us (former) students of "math-phys" in Prague-were the first impulse that led us to devote our studies to general relativity.

Keywords: Black holes, Relativistic disks
ArtPop: A Stellar Population and Image Simulation Python Package. We present Artificial Stellar Populations (ArtPop), an open-source Python package for synthesizing stellar populations and generating artificial images of stellar systems, populated star by star. The code is designed to be intuitive to use and as modular as possible, making it possible to use each of its functionalities independently or together. ArtPop has a wide range of scientific and pedagogical use cases, including the measurement of detection efficiencies in current and future imaging surveys, the calculation of integrated stellar population parameters, quantitative comparisons of isochrone models, and the development and validation of astronomical image-processing algorithms. In this paper, we give an overview of the ArtPop package, provide simple coding examples to demonstrate its implementation, and present results from some potential applications of the code. We provide links to the source code that created each example and figure throughout the paper. ArtPop is under active development, and we welcome bug reports, feature requests, and code contributions from the community. https://artpop.readthedocs.io/en/latest/ https://github.com/ArtificialStellarPopulations/ArtPop/ https://artpop.readthedocs.io/en/latest/tutorials/quickstart.html https://github.com/ArtificialStellarPopulations/artpop-paper-figures/blob/main/scripts/

Keywords: Open source software, Astronomy software, Stellar populations, Dwarf galaxies, Star clusters
Standard GRB Spectral Models "Misused"?. The standard model characterizing the gamma-ray burst (GRB) spectrum invokes a four-parameter empirical function, the so-called the BAND model. An alternative model named cutoff power law (COMP) implements a power law with an exponential cutoff. These functions achieve almost equally good fits on observed spectra, and are adopted in nearly all of the GRB literature. Here, we reanalyze the sample defined in Li et al. (39 bursts including 944 spectra). We classify the spectra by two methods: (1) checking their corner-corner plots of the posteriors to determine well-constrained β (BAND-better) and unconstrained β (COMP-better) categories; and (2) defining the four groups by difference of the deviance information criterion (DIC). We find inconsistent peaks of the parameter distributions between the BAND-better spectra (α = -0.64 ± 0.28 and ${\mathrm{log}}_{10}({{E}}_{{\rm{p}}})={\mathrm{log}}_{10}(191)\pm 0.41$ ) and the COMP-better spectra (α = -0.96 ± 0.33 and ${\mathrm{log}}_{10}({{E}}_{{\rm{p}}})={\mathrm{log}}_{10}(249)\pm 0.40$ ). With the statistically preferred model and vice versa the misused model defined based on DIC statistics, we also find that the fitted parameters obtained by the misused model (COMP) significantly deviate from those obtained by the statistically preferred model (BAND). This means that if a spectrum is statistically preferred, described as the BAND, applying COMP to derive the spectral parameters will prominently deviate from their intrinsic shape, therefore affecting the physical interpretation. Our analysis indicates that the better or statistically preferred model should be duly examined during GRB spectral analysis. In addition, the β distribution exhibits a bimodal structure containing the BAND-better and COMP-better spectra, respectively, implying that BAND and COMP both may have physical origin.

Keywords: Gamma-ray bursts, Relativistic jets, Astronomy data analysis
The Double White Dwarf Merger Progenitors of SDSS J2211+1136 and ZTF J1901+1458. Double white dwarf (DWD) mergers are possibly the leading formation channel of massive, rapidly rotating, high-field magnetic white dwarfs (HFMWDs). However, a direct link connecting a DWD merger to any observed HFMWD is still missing. We here show that the HFMWDs SDSS J221141.80+113604.4 (hereafter J2211+1136) and ZTF J190132.9+145808.7 (hereafter J1901+1458) might be DWD merger products. J2211+1136 is a 1.27 M ⊙ white dwarf (WD) with a rotation period of 70.32 s and a surface magnetic field of 15 MG. J1901+1458 is a 1.327-1.365 M ⊙ WD with a rotation period of 416.20 s, and a surface magnetic field in the range 600-900 MG. With the assumption of single-star evolution and the currently measured WD masses and surface temperatures, the cooling ages of J2211+1136 and J1901+1458 are, respectively, 2.61-2.85 Gyr and 10-100 Myr. We hypothesize that these WDs are DWD merger products and compute the evolution of the postmerged configuration formed by a central WD surrounded by a disk. We show that the postmerger system evolves through three phases depending on whether accretion, mass ejection (propeller), or magnetic braking dominates the torque onto the central WD. We calculate the time the WD spends in each of these phases and obtain the accretion rate and disk mass for which the WD rotational age, i.e., the total time elapsed since the merger to the instant where the WD central remnant reaches the current measured rotation period, agrees with the estimated WD cooling age. We infer the mass values of the primary and secondary WD components of the DWD merger that lead to a postmerger evolution consistent with the observations.

Keywords: Stellar mergers, White dwarf stars, Compact binary stars, Compact objects, Stellar rotation, Stellar remnants
Transition Energies and Line Oscillator Strengths of the C <SUP>2</SUP>Π(0)-X <SUP>2</SUP>Π(0-6) Absorption Bands of Nitric Oxide. A Theoretical Study. Theoretical absorption oscillator strengths and wavelengths for rotational transitions of the C 2Π(v' = 0)-X 2Π(v″) bands with v″ = 0-6 of nitric oxide are reported. The Molecular Quantum Defect Orbital method has been used in the calculations and the known interaction between the C 2Π(v = 0) Rydberg and the B 2Π (v = 7) valence states has been dealt with through an appropriate rovibronic energy matrix. We hope that the reported data may be useful in the analysis of the observed ultraviolet nightglow emission from nitric oxide in the upper atmospheres of Earth, Venus, and Mars.

Keywords: Molecular spectroscopy, Line positions, Line intensities
Flux Eruption Events Drive Angular Momentum Transport in Magnetically Arrested Accretion Flows. We evolve two high-resolution general relativistic magnetohydrodynamic simulations of advection-dominated accretion flows around nonspinning black holes (BHs), each over a duration ~3 × 105 GM BH/c 3. One model captures the evolution of a weakly magnetized (SANE) disk and the other that of a magnetically arrested disk (MAD). Magnetic flux eruptions in the MAD model push out gas from the disk and launch strong winds with outflow efficiencies at times reaching 10% of the incoming accretion power. Despite the substantial power in these winds, average mass outflow rates remain low out to a radius ~100GM BH/c 2, only reaching ~60%-80% of the horizon accretion rate. The average outward angular momentum transport is primarily radial in both modes of accretion, but with a clear distinction: magnetic flux eruption-driven disk winds cause a strong vertical flow of angular momentum in the MAD model, while for the SANE model, the magnetorotational instability (MRI) moves angular momentum mostly equatorially through the disk. Further, we find that the MAD state is highly transitory and nonaxisymmetric, with the accretion mode often changing to a SANE-like state following an eruption before reattaining magnetic flux saturation with time. The Reynolds stress changes directions during such transitions, with the MAD (SANE) state showing an inward (outward) stress, possibly pointing to intermittent MRI-driven accretion in MADs. Pinning down the nature of flux eruptions using next-generation telescopes will be crucial in understanding the flow of mass, magnetic flux, and angular momentum in sub-Eddington accreting BHs like M87* and Sagittarius A*.

Keywords: Accretion, Magnetohydrodynamics, General relativity, Astrophysical black holes, Magnetohydrodynamical simulations
Benchmark n ℓ-resolved Cross Sections of Single and Double Charge Exchange Processes in 1.67-20 keV u<SUP>-1</SUP> C<SUP>4+</SUP> Collisions with He. State-resolved charge exchange (CX) cross sections are of the utmost importance for modeling related photon emissions existing in a broad range of astrophysical environments. With the cold-target recoil-ion momentum spectroscopy, we determined with high accuracy the state-resolved single and double CX cross sections at the quantum orbital angular momentum level for solar wind ion C4+ collisions with He in an energy range of 1.67-20 keV u-1, which allow one to benchmark the CX calculations in great detail, and to test the applicability of the analytical n- and ℓ-distribution models widely adopted by the astrophysical community. We found that the present measurements are well reproduced by the most recent state-of-the-art atomic-orbital close-coupling calculations. However, the CX models failed to give a consistent description on the measured ℓ distributions. The present work reveals that the velocity and collision partner species dependence effects as well as electronic correlations for multielectron processes should be included in an improved model. Alternatively, in future modeling to interpret high-resolution astrophysical observations the more elaborate quantum-mechanical calculations may be resorted to with confidence.

Keywords: Collision physics, Charge exchange recombination, Atomic data benchmarking, Atomic physics
Survey of Ices toward Massive Young Stellar Objects. I. OCS, CO, OCN<SUP>-</SUP>, and CH<SUB>3</SUB>OH. An important tracer of the origin and evolution of cometary ices is the comparison with ices found in dense clouds and toward young stellar objects (YSOs). We present a survey of ices in the 2-5 μm spectra of 23 massive YSOs, taken with the NASA InfraRed Telescope Facility SpeX spectrometer. The 4.90 μm absorption band of OCS ice is detected in 20 sight lines, more than 5 times the previously known detections. The absorption profile shows little variation and is consistent with OCS embedded in CH3OH-rich ices, and proton-irradiated H2S or SO2-containing ices. The OCS column densities correlate well with those of CH3OH and OCN-, but not with H2O and apolar CO ice. This association of OCS with CH3OH and OCN- firmly establishes their formation location deep inside dense clouds or protostellar envelopes. The median composition of this ice phase toward massive YSOs, as a percentage of H2O, is CO:CH3OH:OCN-:OCS = 24:20:1.53:0.15. CS, due to its low abundance, is likely not the main precursor to OCS. Sulfurization of CO is likely needed, although the source of this sulfur is not well constrained. Compared to massive YSOs, low-mass YSOs and dense clouds have similar or somewhat lower CO and CH3OH ice abundances, but less OCN- and more apolar CO, while OCS awaits detection. Comets tend to be underabundant in carbon-bearing species, but this does not appear to be the case for OCS, perhaps signalling OCS production in protoplanetary disks.

Keywords: Chemical abundances, Astrochemistry
Modeling the Extragalactic Background Light and the Cosmic Star Formation History. We present an updated model for the extragalactic background light (EBL) from stars and dust, over wavelengths ≈0.1-1000 μm. This model uses accurate theoretical stellar spectra, and tracks the evolution of star formation, stellar mass density, metallicity, and interstellar dust extinction and emission in the universe with redshift. Dust emission components are treated self-consistently, with stellar light absorbed by dust reradiated in the infrared as three blackbody components. We fit our model, with free parameters associated with star formation rate and dust extinction and emission, to a wide variety of data: luminosity density, stellar mass density, and dust extinction data from galaxy surveys; and γ-ray absorption optical depth data from γ-ray telescopes. Our results strongly constraint the star formation rate density and dust photon escape fraction of the universe out to redshift z = 10, about 90% of the history of the universe. We find our model result is, in some cases, below lower limits on the z = 0 EBL intensity, and below some low-z γ-ray absorption measurements.

Keywords: Diffuse radiation, Gamma-ray sources, Blazars, Gamma-ray astronomy, Gamma-rays
A Scintillation Arc Survey of 22 Pulsars with Low to Moderate Dispersion Measures. Context. By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium (ISM). Here, we present observations that probe the ionized ISM on scales of ~0.001-30 au. Aims. We have surveyed pulsars for scintillation arcs in a relatively unbiased sample with DM &lt; 100 pc cm-3. We present multifrequency observations of 22 low to moderate DM pulsars. Many of the 54 observations were also observed at another frequency within a few days. Methods. For all observations, we present dynamic spectra, autocorrelation functions, and secondary spectra. We analyze these data products to obtain scintillation bandwidths, pulse broadening times, and arc curvatures. Results. We detect definite or probable scintillation arcs in 19 of the 22 pulsars and 34 of the 54 observations, showing that scintillation arcs are a prevalent phenomenon. The arcs are better defined in low DM pulsars. We show that well-defined arcs do not directly imply anisotropy of scattering. Only the presence of reverse arclets and a deep valley along the delay axis, which occurs in about 20% of the pulsars in the sample, indicates substantial anisotropy of scattering. Conclusions. The survey demonstrates substantial patchiness of the ionized ISM on both astronomical-unit-size scales transverse to the LoS and on ~100 pc scales along it. We see little evidence for distributed scattering along most lines of sight in the survey.

Keywords: Radio spectroscopy, Stellar wind bubbles, Warm ionized medium, Interstellar medium, Interstellar scattering, Radio astronomy, Radio pulsars
NuSTAR Spectral Analysis beyond 79 keV with Stray Light. Due to the structure of the NuSTAR telescope, photons at a large off axis (&gt;1°) can reach the detectors directly (stray light), without passing through the instrument optics. At these off-axis angles NuSTAR essentially turns into a collimated instrument and the spectrum can extend to energies above the Pt K edge (79 keV) of the multilayers, which limits the effective area bandpass of the optics. We present the first scientific spectral analysis beyond 79 keV using a Cygnus X-1 observation in StrayCats: the catalog of stray light observations. This serendipitous stray light observation occurred simultaneously with an INTEGRAL observation. When the spectra are modeled together in the 30-120 keV energy band, we find that the NuSTAR stray light flux is well calibrated and constrained to be consistent with the INTEGRAL flux at the 90% confidence level. Furthermore, we explain how to treat the background of the stray light spectral analysis, which is especially important at high energies.

Keywords: Black hole physics, Calibration, High energy astrophysics
The Merger Rate of Primordial Black Hole-Neutron Star Binaries in Ellipsoidal-collapse Dark Matter Halo Models. In this work, we calculate the merger rate of primordial black hole-neutron star (PBH-NS) binaries within the framework of ellipsoidal-collapse dark matter models and compare it with that obtained from spherical-collapse dark matter halo models. Our results exhibit that ellipsoidal-collapse dark matter halo models can potentially amplify the merger rate of PBH-NS binaries in such a way that it is very close to the range estimated by the LIGO-Virgo observations. In contrast, spherical-collapse dark matter halo models cannot justify PBH-NS merger events as consistent results with the latest gravitational wave data reported by the LIGO-Virgo collaborations. In addition, we calculate the merger rate of PBH-NS binaries as a function of PBH mass and fraction within the context of ellipsoidal-collapse dark matter halo models. The results indicate that PBH-NS merger events with masses of M PBH ≤ 5M ⊙, M NS ≃ 1.4M ⊙ will be consistent with the LIGO-Virgo observations if f PBH ≃ 1.

Keywords: Neutron stars, Gravitational collapse, Compact objects, Dark matter, Primordial black holes
The Variation of the Solar Wind Correlation Scale and Taylor Scale Upstream of Mars Observed by MAVEN. The correlation scale and Taylor scale, which characterize the turbulence and dissipation levels, of the solar wind upstream of Mars are determined using the Mars atmosphere and volatile evolution magnetic field data from 2015 to 2020, which covers half of a solar cycle from the solar maximum to the solar minimum. Our analysis suggests that the correlation scale varies between 10 and 20 hr and the Taylor scale between 0.3 and 1 s. Applying the frozen-in flow approximation, we convert the two temporal scales to the two spatial scales, which are about (1.5-3.0) × 107 km and 150-500 km, respectively. We further compare the correlation scale and Taylor scale to the sunspot number (SSN) to study the impacts of solar activity. The highest correlation coefficient between the correlation scale and the SSN is 0.78, where the two data sets are shifted by 16 months with the correlation scale behind the SSN. For the Taylor scale, the highest correlation coefficient is 0.52 with the time lag of 17 months. We also analyze the effective magnetic Reynolds number that is the square of the ratio of the two scales. It is more than 3 × 109, suggesting the good assumption of the frozen-in flow. However, its correlation with the SSN is weak.

Keywords: Interplanetary turbulence, Mars, Solar wind, Interplanetary magnetic fields, Solar activity
Self-similar Solution of Rotating Eruptive Outflows on Its Equatorial Plane. We construct axisymmetric self-similar solutions of transonic outflows emanating from a point source including the effect of the rotation. The solutions are constructed exclusively on the equatorial plane. The features of solutions are determined by three parameters: the adiabatic index γ, the dimensionless coordinate of the transonic point, and the dimensionless azimuthal velocity at the transonic point. We classify the solutions into five groups according to asymptotic behaviors. We find that the behaviors of the self-similar solutions change at γ = 11/9. In addition, some solutions show double-power-law density profiles, which are usually seen in ejecta from a binary merger or nova-like explosion. Thus, our self-similar solutions can be applied not only to the outflow blowing from the central spinning objects but also to the ejecta erupted from the binary merger or nova-like explosion.

Keywords: Stellar winds, Solar wind