Sazuna/UAT_keywords huggingface dataset:
Formation and Eruption of Hot Channels during an M6.5 Class Solar Flare. We investigate the formation and eruption of hot channels associated with the M6.5 class flare (SOL 2015-06-22T18:23) that occurred in NOAA AR 12371 on 2015 June 22. Two flare precursors are observed before the flare's main phase. Observations in 94 and 131 Å by SDO/AIA revealed the early morphology of the first hot channel as a group of hot loops, termed the seed hot channel. A few seed hot channels are formed above the polarity inversion line (PIL) and the formation is associated with the parallel motion of the footpoint brightenings along the PIL, which proceeds into the early stage of the flare main phase. During this process, seed hot channels build up and rise slowly, accelerating at the peak of the second precursor. They merge during the process of acceleration, forming a larger hot channel, which then forms an inverted-γ-shape kinking structure. Before the flare peak, the second kinking hot channel with negative crossing appears near the first kinking hot channel that erupted. The eruption of these two hot channels produces two peaks on the main flare's GOES light curve. The propagation of the footpoint brightenings along the PIL indicates that the first kinking hot channel may be formed due to zipper reconnection. The occurrence of merging between seed hot channels observed by AIA is supported by the extrapolated nonlinear force-free field models. The observed writhing motion of the first kinking hot channel may be driven by the Lorentz force.

Keywords: Solar magnetic reconnection, Solar extreme ultraviolet emission, Solar x-ray flares
Calibrating Gamma-Ray Bursts by Using a Gaussian Process with Type Ia Supernovae. In this paper, we calibrate the Amati relation (the E p-E iso correlation) of gamma-ray bursts (GRBs) in a cosmology-independent way. By using a Gaussian process to reconstruct the smoothed luminosity distance from the Pantheon type Ia supernovae sample, we utilize the reconstructed results to calibrate the E p-E iso correlation with the Markov Chain Monte Carlo method and construct a Hubble diagram with the A220 GRB data, in which there are A118 GRB data with the higher qualities appropriate for cosmological purposes. With 98 GRBs at 1.4 &lt; z ≤ 8.2 in the A118 sample and the observed Hubble data, we obtain Ωm = ${0.346}_{-0.069}^{+0.048}$ , h = ${0.677}_{-0.029}^{+0.029}$ for the flat ΛCDM model, and Ωm = ${0.314}_{-0.055}^{+0.072}$ , h = ${0.705}_{-0.069}^{+0.055}$ , w = $-{1.23}_{-0.64}^{+0.33}$ for the flat wCDM model, which are consistent with those from fitting the coefficients of the Amati relation and the cosmological parameters simultaneously.

Keywords: Cosmology, Gamma-ray bursts
(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?. Why the atmosphere of the Sun is orders of magnitudes hotter than its surface is a long standing question in solar physics. Over the years, many studies have looked at the potential role of magnetohydrodynamic (MHD) waves in sustaining these high temperatures. In this study, we use 3D MHD simulations to investigate (driven) transverse waves in a coronal loop. As the boundary-driven transverse waves propagate along the flux tube, the radial density profile leads to resonant absorption (or mode coupling) and phase mixing in the boundaries of the flux tube and the large velocity shears are subject to the Kelvin-Helmholtz instability (KHI). The combination of these effects leads to enhanced energy dissipation and wave heating. Considering both resonant and nonresonant boundary driving as well as different densities for the flux tube, we show that only wave heating associated with a resonant driver in a lower-density loop (with a loop core density ~5 × 10-13 kg m-3) is able to balance radiative losses in the loop shell. Changing the model parameters to consider a denser loop or a driver with a nonresonant frequency, or both, leads to cooling of the coronal loop as the energy losses are greater than the energy injection and dissipation rates.

Keywords: Solar coronal loops, Solar coronal heating, Solar coronal waves
The Solar Disk at High Energies. High energy cosmic rays illuminate the Sun and produce an image that could be observed in up to five different channels: a cosmic-ray shadow (whose energy dependence has been studied by HAWC); a gamma-ray flux (observed at E ≤ 200 GeV by Fermi-LAT); a muon shadow (detected by ANTARES and IceCube); a neutron flux (undetected, as there are no hadronic calorimeters in space); a flux of high energy neutrinos. Since these signals are correlated, the ones already observed can be used to reduce the uncertainty in the still undetected ones. Here we define a simple setup that uses the Fermi-LAT and HAWC observations to imply very definite fluxes of neutrons and neutrinos from the solar disk. In particular, we provide a fit of the neutrino flux at 10 GeV-10 TeV that includes its dependence on the zenith angle and on the period of the solar cycle. This flux represents a neutrino floor in indirect dark matter searches. We show that in some benchmark models the current bounds on the dark matter-nucleon cross section push the solar signal below this neutrino floor.

Keywords: Neutrino telescopes, Gamma-rays, Solar physics, Cosmic rays
One-dimensional Numerical Study on Ignition of the Helium Envelope in Dynamical Accretion during the Double-degenerate Merger. In order for a double-detonation model to be viable for normal type Ia supernovae, the adverse impact of helium-burning ash on early time observables has to be avoided, which requires that the helium envelope mass should be at most 0.02 M ⊙. Most of the previous studies introduced detonation by artificial hot spots, and therefore the robustness of the spontaneous helium detonation remains uncertain. In the present work, we conduct a self-consistent hydrodynamic study on the spontaneous ignition of the helium envelope in the context of the double-degenerate channel, by applying an idealized one-dimensional model and a simplified seven-isotope reaction network. We explore a wide range of the progenitor conditions and demonstrate that the chance of direct initiation of detonation is limited. Especially, the spontaneous detonation requires the primary envelope mass of ≳0.03 M ⊙. Ignition as deflagration is instead far more likely, which is feasible for the lower envelope mass down to ~0.01 M ⊙, which might lead to subsequent detonation once the deflagration-to-detonation transition (DDT) is realized. High-resolution multidimensional simulations are required to further investigate the DDT possibility, as well as accurately derive the threshold between the spontaneous detonation and deflagration ignition regimes. Another interesting finding is the effect of the composition: while mixing with the core material enhances detonation as previously suggested, it rather narrows the chance for deflagration due to the slower rate of the 12C(α,γ)16O reaction at the lower temperature ~108K, with the caveat that we presently neglect the proton-catalyzed reaction sequence of 12C(p,γ)13O(α,p)16O.

Keywords: Hydrodynamical simulations, Type Ia supernovae
Black Hole Images as Tests of General Relativity: Effects of Plasma Physics. The horizon-scale images of black holes obtained with the Event Horizon Telescope have provided new probes of their metrics and tests of general relativity. The images are characterized by a bright, near-circular ring from the gravitationally lensed emission from the hot plasma and a deep central depression cast by the black hole. The metric tests rely on the fact that the bright ring closely traces the boundary of the black hole shadow with a small displacement that has been quantified using simulations. In this paper we develop a self-consistent covariant analytic model of the accretion flow that spans a broad range of plasma conditions and black hole properties to explore the general validity of this result. We show that, for any physical model of the accretion flow, the ring always encompasses the outline of the shadow and is not displaced by it by more than half the ring width. This result is a consequence of conservation laws and basic thermodynamic considerations and does not depend on the microphysics of the plasma or the details of the numerical simulations. We also present a quantitative measurement of the bias between the bright ring and the shadow radius based on the analytical models.

Keywords: Black hole physics, Supermassive black holes, Plasma astrophysics
Is the Hot, Dense Sub-Neptune TOI-824 b an Exposed Neptune Mantle? Spitzer Detection of the Hot Dayside and Reanalysis of the Interior Composition. The Kepler and TESS missions revealed a remarkable abundance of sub-Neptune exoplanets. Despite this abundance, our understanding of the nature and compositional diversity of sub-Neptunes remains limited, to a large part because atmospheric studies via transmission spectroscopy almost exclusively have aimed for low-density sub-Neptunes, and even those were often affected by high-altitude clouds. The recent TESS discovery of the hot, dense TOI-824 b (2.93 R ⊕ and 18.47 M ⊕) opens a new window into sub-Neptune science by enabling the study of a dense sub-Neptune via secondary eclipses. Here, we present the detection of TOI-824 b's hot dayside via Spitzer secondary-eclipse observations in the 3.6 and 4.5 μm channels, combined with a reanalysis of its interior composition. The measured eclipse depths (142 ${}_{-52}^{+57}$ and ${245}_{-77}^{+75}$ ppm) and brightness temperatures (1463 ${}_{-196}^{+183}$ and ${1484}_{-202}^{+180}$ K) indicate a poor heat redistribution (f &lt; 0.49) and a low Bond albedo (A  B  &lt; 0.26). We conclude that TOI-824 b could be an "exposed Neptune mantle": a planet with a Neptune-like water-rich interior that never accreted a hydrogen envelope or that subsequently lost it. The hot dayside temperature is then naturally explained by a high-metallicity envelope reemitting the bulk of the incoming radiation from the dayside. TOI-824 b's density is also consistent with a massive rocky core that accreted up to 1% of hydrogen, but the observed eclipse depths favor our high-metallicity general circulation model (GCM) simulation to a solar-metallicity GCM simulation with a likelihood ratio of 7:1. The new insights into TOI-824 b's nature suggest that the sub-Neptune population may be more diverse than previously thought, with some of the dense hot sub-Neptunes potentially not hosting a hydrogen-rich envelope as generally assumed for sub-Neptunes.

Keywords: Mini Neptunes, Exoplanet atmospheres, Hot Neptunes, Exoplanets
Investigating Anomalous Photochemistry in the Inner Wind of IRC+10216 through Interferometric Observations of HC<SUB>3</SUB>N. In recent years, many questions have arisen regarding the chemistry of photochemical products in the carbon-rich winds of evolved stars. To address them, it is imperative to constrain the distributions of such species through high-angular-resolution interferometric observations covering multiple rotational transitions. We used archival Atacama Large Millimeter/submillimeter Array observations to map rotational lines involving high energy levels of cyanoacetylene (HC3N) toward the inner envelope (radius &lt; 8″/1000 au) of the carbon star IRC+10216. The observed lines include the J = 28 - 27, J = 30 - 29, and J = 38 - 37 transitions of HC3N in its ground vibrational state. In contrast to previous observations of linear carbon chains toward this asymptotic giant branch (AGB) star that show extended, hollow emission at 15″-20″ radii (e.g., C4H, C6H, and HC5N), the maps of the HC3N lines here show compact morphologies comprising various arcs and density enhancements, with significant emission from gas clumps at an angular distance of ~3″ (350 au) from the central AGB star. We compared visibility sampled non-LTE radiative transfer models with the observed brightness distributions, and derive a fractional abundance with respect to H2 of 10-8 for HC3N at the radii probed by these lines. These results are consistent with enhanced photochemistry occurring in warm (~200 K) regions of the circumstellar envelope. After application of a specialized chemical model for IRC+10216, we find evidence that the enhanced HC3N abundances in the inner wind are most likely due to a solar-type binary companion initiating photochemistry in this region.

Keywords: Circumstellar envelopes, Evolved stars, Carbon stars, Chemical abundances, Astrochemistry
Properties of Globular Clusters in Galaxy Clusters: Sensitivity from the Formation and Evolution of Globular Clusters. We investigate the properties of globular clusters (GCs) in a galaxy cluster, using the particle tagging method with a semianalytical approach in a cosmological context. We assume GCs form from dark matter halo mergers and their metallicity is assigned based on the stellar mass of the host dark matter halos and the formation redshift of GCs. Dynamical evolution and disruption of GCs are considered using semianalytical approaches, controlled by several free parameters. In this paper, we investigate how our results are changed by the choice of free parameters. We compare our fiducial results with representative observations, including the mass ratio between the GC system and its host galaxy, the GC occupancy, the number fraction of blue GCs, and the metallicity gradient with the GC mass. Because we can know the positions of GCs with time, comparison with additional observations is possible, e.g., the median radii of the GC system in individual galaxies, the mean projected density profiles of intracluster GCs, and the metallicity and age gradients of GCs with a clustercentric radius. We also find that the specific mass of the GC system in each galaxy is different with a clustercentric radius.

Keywords: Galaxy clusters, Galaxy formation, Computational astronomy, Globular star clusters
Role of Magnetic Fields in Fueling Seyfert Nuclei. Molecular gas is believed to be the fuel for star formation and nuclear activity in Seyfert galaxies. To explore the role of magnetic fields in funneling molecular gas into the nuclear region, measurements of the magnetic fields embedded in molecular gas are needed. By applying the new velocity gradient technique (VGT) to CO isotopolog data from the Atacama Large Millimeter/submillimeter Array and the Plateau de Bure Interferometer Arcsecond Whirlpool Survey, we obtain the first detection of CO-associated magnetic fields in several nearby Seyfert galaxies and their unprecedented high-resolution magnetic field maps. The VGT-measured magnetic fields in molecular gas globally agree with those inferred from existing HAWC+ dust polarization and Very Large Array synchrotron polarization. An overall good alignment between the magnetic fields traced by VGT-CO and by synchrotron polarization may support the correlation between star formation and cosmic-ray generation. We find that the magnetic fields traced by VGT-CO have a significant radial component in the central regions of most Seyferts in our sample, where efficient molecular gas inflows or outflow may occur. In particular, we find local misalignment between the magnetic fields traced by CO and dust polarization within the nuclear ring of NGC 1097, and the former aligns with the central bar's orientation. This misalignment reveals different magnetic field configurations in different gas phases and may provide an observational diagnostic for the ongoing multiphase fueling of Seyfert activity.

Keywords: Galaxy nuclei, Interstellar synchrotron emission, Interstellar medium, Extragalactic magnetic fields
Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past. Post-starburst (PSB) galaxies have recently and rapidly quenched their star formation; thus, they are an important way to understand how galaxies transition from star-forming late types to quiescent early types. The recent discovery of large cold gas reservoirs in PSB galaxies calls into question the theory that galaxies must lose their gas to become quiescent. Optical Integral Field Spectroscopy (IFS) surveys have revealed two classes of PSB galaxies: central PSB (cPSB) galaxies with central quenching regions and ring PSB (rPSB) galaxies with quenching in their outskirts. We analyze a sample of 13 nearby (z &lt; 0.1) PSB galaxies with spatially resolved optical IFS data from the Mapping Nearby Galaxies at Apache Point Observatory survey and matched resolution Atacama Large Millimeter/submillimeter Array observations of 12CO(1-0). Disturbed stellar kinematics in 7/13 of our PSB galaxies and centrally concentrated molecular gas is consistent with a recent merger for most of our sample. In galaxies without merger evidence, alternate processes may funnel gas inward and suppress star formation, which may include outflows, stellar bars, and minor mergers or interactions. The star formation efficiencies of the PSB regions in nearly half our galaxies are suppressed while the gas fractions are consistent with star-forming galaxies. Active galactic nucleus (AGN) feedback may drive this stabilization, and we observe AGN-consistent emission in the centers of 5/13 galaxies. Finally, our cPSB and rPSB galaxies have similar properties except the ionized and molecular gas in cPSB galaxies is more disturbed. Overall, the molecular gas in our PSB galaxies tends to be compact and highly disturbed, resulting in concentrated gas reservoirs unable to form stars efficiently.

Keywords: Molecular gas, Post-starburst galaxies, Galaxy evolution, Galaxy quenching, Galaxies
Radiation-induced D-to-H Exchange in Ices Containing Ethane or Benzene: Reactions and Rate Constants. The rate constants for radiation-induced deuterium to hydrogen (D-to-H) exchange were recently measured for CD4 in H2O and C2D6 in H2O at 20 K. In the current study, rate constants for radiation-induced D-to-H exchange were obtained for C6D6 in H2O at 20, 50, and 100 K. The rate constants for D-to-H exchange for an organic molecule in water were found to be an order of magnitude greater for benzene than ethane. Additionally, D-to-H exchange for benzene was found to be far more favorable than the production of any other radiolysis product, a result that contrasts with our previous findings for methane and ethane. Finally, rate constants were obtained for C2D6 in H2O at 50 K. For all ice mixtures, increasing the temperature of the experiment yielded a larger rate constant. There is a notable difference in the magnitude of the response of the rate constant for D-to-H exchange as a function of temperature for C2D6 versus C6D6 containing ices. The results suggest that radiation will have an asymmetric effect on D-to-H exchange between different types of organic compounds and water ice matrices. These results suggest that the radiation history of an extraterrestrial sample will influence the D/H ratios of its organic compounds.

Keywords: Reaction rates, Astrochemistry
An Elusive Population of Massive Disk Galaxies Hosting Double-lobed Radio-loud Active Galactic Nuclei. It is commonly accepted that radio-loud active galactic nuclei are hosted exclusively by giant elliptical galaxies. We analyze high-resolution optical Hubble Space Telescope images of a sample of radio galaxies with extended double-lobed structures associated with disk-like optical counterparts. After systematically evaluating the probability of chance alignment between the radio lobes and the optical counterparts, we obtain a sample of 18 objects likely to have genuine associations. The host galaxies have unambiguous late-type morphologies, including spiral arms, large-scale dust lanes among the edge-on systems, and exceptionally weak bulges, as judged by the low global concentrations, small global Sérsic indices, and low bulge-to-total light ratios (median B/T = 0.13). With a median Sérsic index of 1.4 and low effective surface brightnesses, the bulges are consistent with being pseudobulges. The majority of the hosts have unusually large stellar masses (median M * = 1.3 × 1011 M ⊙) and red optical colors (median g - r = 0.69 mag), consistent with massive, quiescent galaxies on the red sequence. We suggest that the black hole mass (stellar mass) plays a fundamental role in launching large-scale radio jets, and that the rarity of extended radio lobes in late-type galaxies is the consequence of the steep stellar mass function at the high-mass end. The disk radio galaxies have mostly Fanaroff-Riley type II morphologies yet lower radio power than sources of a similar type traditionally hosted by ellipticals. The radio jets show no preferential alignment with the minor axis of the galactic bulge or disk, apart from a possible mild tendency for alignment among the most disk-dominated systems.

Keywords: AGN host galaxies, Radio jets, Quasars, Active galaxies, Galaxy nuclei, Radio loud quasars, Radio galaxies, Active galactic nuclei, Radio active galactic nuclei, Galaxy masses
A New Reaction Rate of the <SUP>27</SUP>Al(p/α)<SUP>24</SUP>Mg Reaction Based on Indirect Measurements at Astrophysical Energies and Implications for <SUP>27</SUP>Al Yields of Intermediate-mass Stars. The abundance of 26Al carries a special role in astrophysics, since it probes active nucleosynthesis in the Milky Way and constrains the Galactic core-collapse supernovae rate. It is estimated through the detection of the 1809 keV γ-line and from the superabundance of 26Mg in comparison with the most abundant Mg isotope (A = 24) in meteorites. For this reason, high precision is necessary also in the investigation of the stable 27Al and 24Mg isotopes. Moreover, these nuclei enter the so-called MgAl cycle, playing an important role in the production of Al and Mg. Recently, high-resolution stellar surveys have shown that the Mg-Al anticorrelation in red-giant stars in globular clusters may hide the existence of multiple stellar populations, and that the relative abundances of Mg isotopes may not be correlated with Al. The common thread running through these astrophysical scenarios is the 27Al(p,α)24Mg reaction, which is the main 27Al destruction channel and directly correlates its abundance with the 24Mg one. Since available reaction rates show large uncertainties owing to the vanishingly small cross section at astrophysical energies, we have applied the Trojan Horse Method to deduce the reaction rate with no need of extrapolation. The indirect measurement made it possible to assess the contribution of the 84 keV resonance and to lower upper limits on the strength of nearby resonances. In intermediate-mass AGB stars experiencing hot bottom burning, a sizeable increase in surface aluminum abundance is observed at the lowest masses, while 24Mg is essentially unaffected by the change in the reaction rate.

Keywords: Nucleosynthesis, Hydrogen burning, Nuclear abundances, Asymptotic giant branch stars, Nuclear astrophysics, Stellar nucleosynthesis