Sazuna/UAT_keywords huggingface dataset:
Dynamics Evolution of a Solar Active-region Filament from a Quasi-static State to Eruption: Rolling Motion, Untwisting Motion, Material Transfer, and Chirality. To better understand the magnetic structure and eruptive process of solar filaments, a solar active-region filament (labeled F2) eruption associated with a B-class flare was investigated by using high-resolution Hα data from the 1 m New Vacuum Solar Telescope (NVST), combined with EUV observations of the Solar Dynamics Observatory (SDO). The filament F2 was disturbed by another filament (labeled F1) eruption that experienced a whip-like motion. Before the filament F2 eruption, the Dopplergrams show that the southern and the northern parts of the filament F2 body exhibit blueshift and redshift along the filament spine, simultaneously. This implies that the filament F2 was rolling from one side to the other. During the filament F2 eruption, the Doppler shifts of the filament body are opposite of those before its eruption. This demonstrates that the filament body exhibits an untwisting motion, which can also be identified by tracing the movement of the eruptive filament threads. Moreover, it is found that the material of the filament F2 was transferred to the surrounding magnetic field loops, which is caused by magnetic reconnection between the filament F2 and the surrounding magnetic loops. According to the right-bearing threads of the filament F2 before its eruption, it can be deduced that the filament F2 is initially supported by a sheared arcade. The following observations reveal that the twisted magnetic structure of filament F2 formed in the eruption phase.

Keywords: Solar atmosphere, Solar flares, Sunspots, Solar filaments, Solar filament eruptions, Active solar chromosphere, Solar chromosphere, Magnetic fields
Massive Black Hole Merger Rates: The Effect of Kiloparsec Separation Wandering and Supernova Feedback. We revisit the predictions for the merger rate of massive black hole binaries detectable by the Laser Interferometer Space Antenna (LISA) and their background signal for pulsar-timing arrays. We focus on the effect of the delays between the merger of galaxies and the final coalescence of black hole binaries, and on supernova feedback on the black hole growth. By utilizing a semianalytic galaxy formation model, not only do we account for the driving of the evolution of binaries at separations ≲1 pc (gas-driven migration, stellar hardening, and triple/quadruple massive black hole systems), but we also improve on previous studies by accounting for the time spent by black hole pairs from kiloparsec down to parsec separation. We also include the effect of supernova feedback, which may eject gas from the nuclear region of low-mass galaxies, thus hampering the growth of black holes via accretion and suppressing their orbital migration in circumbinary disks. Despite including these novel physical effects, we predict that the LISA detection rate should still be $\gtrsim 2{{\rm{yr}}}^{-1}$ , irrespective of the model for the black hole seeds at high redshifts. Scenarios where black holes form from $\sim 100{M}_{\odot }$ seeds are more significantly impacted by supernova feedback. We also find that for detectable events, the merging black holes typically have mass ratios between ∼0.1 and 1. Predictions for the stochastic background in the band of pulsar-timing array experiments are instead rather robust and show only a mild dependence on the model.

Keywords: Supermassive black holes, Galaxy formation, Gravitational waves, Astrophysical black holes
Contribution of Dark Matter Annihilation to Gamma-Ray Burst Afterglows near Massive Galaxy Centers. Gamma-ray bursts (GRBs) are believed to be powered by ultrarelativistic jets. If these jets encounter and accelerate excess electrons and positrons produced by particle dark matter (DM) annihilation, the observed electromagnetic radiation would be enhanced. In this paper, we study GRB afterglow emission with the presence of abundant DM under the weakly interacting massive particle annihilation conditions. We calculate the light curves and spectra of the GRB afterglows with different parameters, i.e., DM density, particle DM mass, annihilation channel, and electron density of the interstellar medium. We find that the effect of DM may become noticeable in the afterglow spectra if the circumburst has a low electron number density ( $n\lesssim 0.1\,{\mathrm{cm}}^{-3}$ ) and if the DM has a high number density ( ${\rho }_{\chi }\gtrsim {10}^{3}\,\mathrm{GeV}\,{\mathrm{cm}}^{-3}$ ). According to the standard galaxy DM density profile, GRB afterglows with DM contribution might occur at distances of several to tens of parsecs from the centers of massive galaxies.

Keywords: Galaxy dark matter halos, Gamma-ray bursts, Relativistic jets, Shocks, Dark matter
Characterizing [C II] Line Emission in Massive Star-forming Clumps. Because the 157.74 μm [C II] line is the dominant coolant of star-forming regions, it is often used to infer the global star formation rates of galaxies. By characterizing the [C II] and far-infrared emission from nearby Galactic star-forming molecular clumps, it is possible to determine whether extragalactic [C II] emission arises from a large ensemble of such clumps, and whether [C II] is indeed a robust indicator of global star formation. We describe [C II] and far-infrared observations using the FIFI-LS instrument on the Stratospheric Observatory For Infrared Astronomy (SOFIA) airborne observatory toward four dense, high-mass, Milky Way clumps. Despite similar far-infrared luminosities, the [C II] to far-infrared luminosity ratio, ${L}_{[{\rm{C}}{\rm\small{II}}]}$ /LFIR, varies by a factor of at least 140 among these four clumps. In particular, for AGAL313.576+0.324, no [C II] line emission is detected despite a FIR luminosity of 24,000 ${L}_{\odot }$ . AGAL313.576+0.324 lies a factor of more than 100 below the empirical correlation curve between ${L}_{[{\rm{C}}{\rm\small{II}}]}$ /LFIR and ${S}_{\nu }(63\,\mu {\rm{m}})/{S}_{\nu }(158\,\mu {\rm{m}})$ found for galaxies. AGAL313.576+0.324 may be in an early evolutionary "protostellar" phase with insufficient ultraviolet flux to ionize carbon, or in a deeply embedded "'hypercompact" ${\rm{H}}\,{\rm\small{II}}$ region phase where dust attenuation of UV flux limits the region of ionized carbon to undetectably small volumes. Alternatively, its apparent lack of [C II] emission may arise from deep absorption of the [C II] line against the 158 μm continuum, or self-absorption of brighter line emission by foreground material, which might cancel or diminish any emission within the FIFI-LS instrument's broad spectral resolution element ( ${\rm{\Delta }}V\sim 250$ km s-1).

Keywords: Star forming regions, H II regions, Molecular clouds
Effects of Modified Theories of Gravity on Neutrino Pair Annihilation Energy Deposition near Neutron Stars. We study the neutrino pair annihilation into electron-positron pairs ( $\nu +\bar{\nu }\to {e}^{-}+{e}^{+}$ ) near the surface of a neutron star. The analysis is performed in the framework of extended theories of gravity. The latter induce a modification of the minimum photon sphere radius (Rph) and the maximum energy deposition rate near Rph, as compared to those of general relativity. These results might lead to an efficient mechanism for generating GRBs.

Keywords: Neutron stars, Supernova neutrinos, Gamma-ray bursts, Black holes, High energy astrophysics, Non-standard theories of gravity, Cosmological neutrinos, Particle astrophysics
Soft X-Ray Observations of Quiescent Solar Active Regions Using the Novel Dual-zone Aperture X-Ray Solar Spectrometer. The Dual-zone Aperture X-ray Solar Spectrometer (DAXSS) was flown on 2018 June 18 on the NASA 36.336 sounding rocket flight and obtained the highest resolution to date for solar soft X-ray (SXR) spectra over a broad energy range. This observation was during a time with quiescent (nonflaring) small active regions on the solar disk and when the 10.7 cm radio flux (F10.7) was 75 solar flux units (1 sfu = 10-22 W m-2 Hz-1). The DAXSS instrument consists of a LASP-developed dual-zone aperture and a commercial X-ray spectrometer from Amptek that measures solar full-disk irradiance from 0.5 to 20 keV with a resolving power of 20 near 1 keV. This paper discusses the novel design of the spectrometer and the instrument characterization techniques. Additionally, the solar measurements obtained from the 2018 sounding rocket flight are analyzed using CHIANTI spectral models to fit the temperatures, emission measures, and relative elemental abundances of the solar corona plasma. The abundance of iron was found to be 35% higher than expected in the quiescent Sun's corona suggesting either that our spectral models require additional sophistication or that the underlying atomic database may require updates. Future long-term systematic observations of this spectral range are needed to provide further insight into the sources of coronal heating through modeling the changes of relative elemental abundances during developments of active regions and solar flaring events.

Keywords: Plasma physics, Quiet sun, Solar spectral irradiance, Solar x-ray emission, Spectrometers, Quiet solar corona
Clumpy Wind Accretion in Cygnus X-1. Cygnus X-1 is one of the brightest X-ray sources observed and shows the X-ray intensity variations on timescales from milliseconds to months in both the soft and hard X-rays. The accretion onto the black hole is believed to be wind fed due to focused stellar wind from the binary companion HDE-226868. We aim to understand the physical mechanism responsible for the short timescale X-ray variability (&lt;100 s) of the source in its hard/low state. We compute the 2D relativistic hydrodynamic simulation of the low angular momentum accretion flow with a time-dependent outer boundary condition that reflects the focused, clumpy wind from the supergiant in this X-ray binary system. We follow the dynamical evolution of our model for about 100 s and present the results showing an oscillatory shock, being a potential explanation of variability observed in hard X-rays. The simulated model with shock solutions is in good agreement with the observed power density spectra of the source.

Keywords: Accretion, Black hole physics, Hydrodynamical simulations, Gravitation, High mass x-ray binary stars, Stellar winds, X-ray transient sources, General relativity
Examining the Relationship Between Convective Core Overshoot and Stellar Properties Using Asteroseismology. Core overshoot is a large source of uncertainty in constructing stellar models. Whether the amount of overshoot is constant or mass dependent is not completely known, even though models sometimes assume a mass-based trend. In this work we use asteroseismic data from stars observed by Kepler to investigate the relationship between various stellar properties and the amount of overshoot needed to properly model a given star. We find a strong positive trend between stellar mass and overshoot amount for stars between 1.1 and 1.5 ${\text{}}{M}_{\odot }$ , with a slope of 0.89. Additionally, we investigate how inferred stellar properties change as a function of overshoot. Our model grids show that the inferred stellar mass and radius can vary by as much as 14% and 6%, respectively, depending on the extent of overshoot. This mass spread results in a commensurate spread in the ages.

Keywords: Stellar interiors, Stellar convective zones, Asteroseismology, Stellar oscillations
Dual AGN Candidates with Double-peaked [O III] Lines Matching that of Confirmed Dual AGNs. We have performed a spectral decomposition to search for dual active galactic nuclei (DAGNs) in the Sloan Digital Sky Survey (SDSS) quasars with z &lt; 0.25. Potential DAGN candidates are searched by referencing velocity offsets and spectral shapes of double-peaked [O III] lines of known DAGNs. Out of 1271 SDSS quasars, we have identified 77 DAGN candidates. Optical and mid-infrared (MIR) diagnostic diagrams are used to investigate the ionizing source in the DAGN candidates. The optical diagnostic analysis suggests 93% of them are powered by AGNs, and MIR diagnostic analysis suggests 97% are powered by AGNs. About one-third of the SDSS images of the DAGN candidates show signs of tidal interaction, but we are unable to identify double nuclei in most of them due to the low spatial resolution of the archival imaging data available for most of the sample. The radio-loud fraction of the DAGN candidates (∼10%) is similar to that of typical AGNs.

Keywords: Galaxy evolution, Active galactic nuclei, Black holes
Near-infrared Opacity of Late M Dwarfs and Hot Jupiters: The E<SUP>3</SUP>Π-X<SUP>3</SUP>Δ Transition of TiO. The TiO E3Π-X3Δ transition is an important opacity source in the near-infrared spectra of late M dwarfs. The 0-0 band of the 48Ti16O E3Π-X3Δ electronic transition has been reanalyzed using a recently published set of high-resolution, high temperature absorption cross sections. The analysis has been extended to higher J values and an improved set of spectroscopic constants were determined. Calculated high-precision line lists for the 0-0 and 0-1 bands are provided with line strengths based on a previously measured experimental lifetime.

Keywords: Spectral line lists, Laboratory astrophysics
JWST Transit Spectra. II. Constraining Aerosol Species, Particle-size Distributions, Temperature, and Metallicity for Cloudy Exoplanets. The James Webb Space Telescope (JWST) will provide moderate-resolution transit spectra with continuous wavelength coverage from the optical to the mid-infrared for the first time. In this paper, we illustrate how different aerosol species, size distributions, and spatial distributions encode information in the JWST transit spectra of warm exoplanets. We use the transit spectral modeling code METIS, along with Mie theory and several flexible treatments of aerosol size and spatial distributions to perform parameter sensitivity studies, calculate transit contribution functions, compute Jacobians, and retrieve parameters from simulated data. The broader wavelength coverage of the JWST can encompass enough non-gray aerosol behavior to recover information about the species and size distribution of particles under many feasible aerosol scenarios. Within the JWST wavelength range, the optical and mid-infrared typically provide information about 0.1-1 μm sized aerosols, while the near-infrared to mid-infrared wavelengths usually provide information about gaseous absorption. Strong gaseous absorption features in the infrared can remain visible, even when clouds and hazes are flattening the optical and near-infrared portion of the spectrum that is currently observable. For some combinations of aerosol properties, temperature, and surface gravity, one can make a precise measure of metallicity despite the presence of aerosols, but more often the retrieved metallicity of a cloudy or hazy atmosphere has significantly lower precision than for a clear atmosphere with otherwise similar properties. Future efforts to securely link aerosol properties to atmospheric metallicity and temperature in a physically motivated manner will ultimately enable a robust physical understanding of the processes at play in cloudy, hazy exoplanet atmospheres.

Keywords: Exoplanet atmospheric composition , Exoplanet atmospheres, Exoplanets
Measurements of the z ∼ 6 Intergalactic Medium Optical Depth and Transmission Spikes Using a New z &gt; 6.3 Quasar Sample. We report new measurements of the intergalactic medium (IGM) Lyα and Lyβ effective optical depth at 5.3 &lt; z &lt; 6.5, using a new sample of quasar sight lines including 32 quasars at 6.308 ≤ z ≤ 7.00. These quasars provide a large statistical sample to measure the IGM evolution during the transition phase of the reionization epoch. We construct a data set of deep optical spectra of these quasars using VLT, Keck, Gemini, LBT, and MMT. We measure the Lyα effective optical depth at 5.36 &lt; z &lt; 6.57 using the Lyα forests of both individual spectra and the stacked spectrum. The large scatter of individual measurements is consistent with previous work, suggesting an inhomogeneous reionization process. Combining our new measurements and previous results, we obtain a best fit for the Lyα effective optical depth evolution at z &gt; 5.3, $\tau \propto {\left(1+z\right)}^{8.6\pm 1.0}$ . We then estimate the observed Lyβ effective optical depth using Lyβ forests and convert them to Lyα optical depth for comparison, which provides additional constraints on the evolution of the IGM optical depth. The Lyβ-based measurements are generally in agreement with the best-fit evolution obtained from Lyα forests. Using this new sample, we identify 389 Lyα and 50 Lyβ transmission spikes at 5.5 &lt; z &lt; 6.3. The upper limits of Lyα optical depth estimated using transmission spikes are well consistent with our best-fit evolution. The evolution in number density of these high-redshift transmission spikes suggests a rapid transition phase at the end of the reionization. Comparison of our optical depth measurements with hydrodynamical simulations indicates an IGM neutral hydrogen fraction $\langle {f}_{{\rm{H}}{\rm\small{I}}}\rangle \gtrsim {10}^{-4}$ at z = 6.

Keywords: Early universe, Quasar absorption line spectroscopy, Intergalactic medium, Extragalactic astronomy, Reionization
X-Ray Constraints on the Spectral Energy Distribution of the z = 5.18 Blazar SDSS J013127.34-032100.1. We report on X-ray measurements constraining the spectral energy distribution (SED) of the high-redshift z = 5.18 blazar SDSS J013127.34-032100.1 with new XMM-Newton and NuSTAR exposures. The blazar's X-ray spectrum is well fit by a power law with Γ = 1.9 and ${N}_{{\rm{H}}}=1.1\times {10}^{21}\,{\mathrm{cm}}^{-2}$ , or a broken power law with ${{\rm{\Gamma }}}_{l}=0.7$ , ${{\rm{\Gamma }}}_{h}=1.8$ , and a break energy ${E}_{b}=0.7\,\mathrm{keV}$ for an expected absorbing column density of ${N}_{{\rm{H}}}=3.6\times {10}^{20}\ {\mathrm{cm}}^{-2}$ , supported by spectral fitting of a nearby bright source. No additional spectral break is found at higher X-ray energies (1-30 keV). We supplement the X-ray data with lower-energy radio-to-optical measurements and Fermi-LAT gamma-ray upper limits, construct broadband SEDs of the source, and model the SEDs using a synchro-Compton scenario. This modeling constrains the bulk Doppler factor of the jets to ≥7 and ≥6 (90%) for the low- and high-NH SEDs, respectively. The corresponding beaming implies ≥130 (low NH) or $\geqslant 100$ (high NH) high-spin supermassive black holes similar to J0131 exist at similar redshifts.

Keywords: Early universe, Supermassive black holes, High energy astrophysics, Quasars, Blazars, Active galactic nuclei, Spectral energy distribution
Mg II Absorbers in High-resolution Quasar Spectra. I. Voigt Profile Models. We present the Voigt profile (VP) models, column densities, Doppler b parameters, kinematics, and distribution of components for 422 Mg II absorbers found in a survey of 249 HIRES and UVES quasar spectra. The equivalent width range of the sample is 0.006 ≤ Wr(2796) ≤ 6.23 Å and the redshift range is 0.19 ≤ z ≤ 2.55, with a mean of $\langle z\rangle =1.18$ . Based on historical precedent, we classified 180 absorbers as weak systems (Wr(2796) &lt; 0.3 Å) and 242 as strong systems (Wr(2796) ≥ 0.3 Å). Assuming a minimum number of significant components per system, the VP fitting, yielded a total of 2989 components, with an average of 2.7 and 10.3 components found for the weak and strong Mg II subsamples, respectively. The VP component line density for the full sample is 8.62 ± 0.23 clouds Å-1. The distribution of VP component column density over the range 12.4 ≤ log N(Mg II) ≤ 17.0 cm-2 is well modeled with a power-law slope of -1.45 ± 0.01. The median Doppler b parameters are 4.5 ± 3.5 km s-1, 6.0 ± 4.5 km s-1, and 5.7 ± 4.4 km s-1 for the weak, strong, and full samples. We modeled the probability of component velocity splitting (the two-point velocity correlation function) of our full sample using a three-component composite Gaussian function. Our resulting velocity dispersions are σ1 = 25.4 km s-1, σ2 = 68.7 km s-1, and σ3 = 207.1 km s-1. These data provide an excellent database for studying the cosmic evolution of Mg II absorber kinematic evolution.

Keywords: Galaxy kinematics, Quasar absorption line spectroscopy, Circumgalactic medium
Screening Effects on Electron Capture Rates and Type Ia Supernova Nucleosynthesis. Type Ia supernovae (SNe Ia) are believed to be a thermonuclear explosion of a white dwarf, but the mass of their progenitors is still an open problem. In near-Chandrasekhar-mass (near-MCh) models of SNe Ia, the central density reaches ≳109 g cm-3. The electron chemical potential becomes higher than the Q-values of electron capture (EC) transitions between fp-shell nuclei, so a portion of the available electrons is captured by iron group elements and thus neutron-rich isotopes are formed. Since EC reaction rates are sensitive to the density, the degree of neutronization is a key to distinguish near- and sub-MCh models. In order to compare observations and theoretical models, an accurate treatment of EC reactions is necessary. In previous theoretical works, however, effects of electron screening on ECs are ignored. Screening lowers EC rates and thus leads to a higher electron fraction. We implement electron screening on ECs to calculate explosive SN Ia nucleosynthesis in a near-MCh single degenerate model. It is found that some of neutron-rich nuclear abundances, namely, those of 46,48Ca, 50Ti, 54Cr, 58Fe, 64Ni, and 67,70Zn, decrease when screening effects on ECs are considered. Of these, 50Ti, 54Cr, and 58Fe are particularly interesting because a significant portion of the solar abundance of these nuclei is presumed to originate from SNe Ia. We conclude that implementing the screening effect on ECs in modern SN Ia models is desirable to precisely calculate abundances of neutron-rich nuclides.

Keywords: Type Ia supernovae, Explosive nucleosynthesis
An Obscured, Seyfert 2-like State of the Stellar-mass Black Hole GRS 1915+105 Caused by Failed Disk Winds. We report on Chandra grating spectra of the stellar-mass black hole GRS 1915+105 obtained during a novel, highly obscured state. As the source entered this state, a dense, massive accretion disk wind was detected through strong absorption lines. Photoionization modeling indicates that it must originate close to the central engine, orders of magnitude from the outer accretion disk. Strong, nearly sinusoidal flux variability in this phase yielded a key insight: the wind is blueshifted when its column density is relatively low, but redshifted as it approaches the Compton-thick threshold. At no point does the wind appear to achieve the local escape velocity; in this sense, it is a "failed wind." Later observations suggest that the disk ultimately fails to keep even the central engine clear of gas, leading to heavily obscured and Compton-thick states characterized by very strong Fe K emission lines. Indeed, these later spectra are successfully described using models developed for obscured active galactic nuclei (AGNs). We discuss our results in terms of the remarkable similarity of GRS 1915+105 deep in its "obscured state" to Seyfert 2 and Compton-thick AGNs, and we explore how our understanding of accretion and obscuration in massive black holes is impacted by our observations.

Keywords: X-ray active galactic nuclei, Active galactic nuclei, Black holes, Compact objects