Sazuna/UAT_keywords huggingface dataset:
Comparison of Electron Capture Rates in the N = 50 Region using 1D Simulations of Core-collapse Supernovae. Recent studies have highlighted the sensitivity of core-collapse supernovae (CCSNe) models to electron-capture (EC) rates on neutron-rich nuclei near the N = 50 closed-shell region. In this work, we perform a large suite of one-dimensional CCSN simulations for 200 stellar progenitors using recently updated EC rates in this region. For comparison, we repeat the simulations using two previous implementations of EC rates: a microphysical library with parametrized N = 50 rates (LMP), and an older independent-particle approximation (IPA). We follow the simulations through shock revival up to several seconds post-bounce, and show that the EC rates produce a consistent imprint on CCSN properties, often surpassing the role of the progenitor itself. Notable impacts include the timescale of core collapse, the electron fraction and mass of the inner core at bounce, the accretion rate through the shock, the success or failure of revival, and the properties of the central compact remnant. We also compare the observable neutrino signal of the neutronization burst in a DUNE-like detector, and find consistent impacts on the counts and mean energies. Overall, the updated rates result in properties that are intermediate between LMP and IPA, and yet slightly more favorable to explosion than both.

Keywords: Neutrino astronomy, Supernova neutrinos, Reaction rates, Core-collapse supernovae
On the Convergence of the Milky Way and M31 Kinematics from Cosmological Simulations. The kinematics of the Milky Way (MW) and M31, the dominant galaxies in the Local Group (LG), can be used to estimate the LG total mass. New results on the M31 proper motion have recently been used to improve that estimate. Those results are based on kinematic priors that are sometimes guided and evaluated using cosmological N-body simulations. However, the kinematic properties of simulated LG analogs could be biased due to the effective power spectrum truncation induced by the small size of the parent simulation. Here we explore the dependence of LG kinematics on the simulation box size to argue that cosmological simulations need a box size on the order of 1 Gpc in order to claim convergence on the LG kinematic properties. Using a large enough simulation, we find M31 tangential and radial velocities relative to the MW to be in the range ${v}_{\tan }={105}_{-59}^{+94}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ and ${v}_{\mathrm{rad}}=-{108}_{-81}^{+68}\,\mathrm{km}\,{{\rm{s}}}^{-1}$ , respectively. This study highlights that LG kinematics derived from N-body simulations have to be carefully interpreted, taking into account the size of the parent simulation.

Keywords: Local Group, Andromeda Galaxy, N-body simulations, Milky Way Galaxy
The Effect of Nanoflare Flows on EUV Spectral Lines. The nanoflare model of coronal heating is one of the most successful scenarios to explain, within a single framework, the diverse set of coronal observations available with the present instrument resolutions. The model is based on the idea that the coronal structure is formed by elementary magnetic strands which are tangled and twisted by the displacement of their photospheric footpoints by convective motions. These displacements inject magnetic stress between neighboring strands that promotes current sheet formation, reconnection, plasma heating, and possibly also particle acceleration. Among other features, the model predicts the ubiquitous presence of plasma flows at different temperatures. These flows should, in principle, produce measurable effects on observed spectral lines in the form of Doppler shifts, line asymmetries and nonthermal broadenings. In this work we use the two-dimensional cellular automaton model (2DCAM) developed in previous works, in combination with the enthalpy-based thermal evolution of loops (EBTEL) model, to analyze the effect of nanoflare heating on a set of known EUV spectral lines. We find that the complex combination of the emission from plasmas at different temperatures, densities and velocities, in simultaneously evolving unresolved strands, produces characteristic properties in the constructed synthetic lines, such as Doppler shifts and nonthermal velocities up to tens of km s-1 for the higher analyzed temperatures. Our results might prove useful to guide future modeling and observations, in particular, regarding the new generation of proposed instruments designed to diagnose plasmas in the 5-10 MK temperature range.

Keywords: Solar coronal lines, Solar coronal loops, Solar coronal heating, Solar corona
Spectropolarimetry of the Thermonuclear Supernova SN 2021rhu: High Calcium Polarization 79 Days after Peak Luminosity. We report spectropolarimetric observations of the Type Ia supernova (SN) SN 2021rhu at four epochs: -7, +0, +36, and +79 days relative to its B-band maximum luminosity. A wavelength-dependent continuum polarization peaking at 3890 ± 93 Å and reaching a level of ${p}_{\max }\,=\,1.78 \% \pm 0.02$ % was found. The peak of the polarization curve is bluer than is typical in the Milky Way, indicating a larger proportion of small dust grains along the sight line to the SN. After removing the interstellar polarization, we found a pronounced increase of the polarization in the Ca II near-infrared triplet, from ~0.3% at day -7 to ~2.5% at day +79. No temporal evolution in high-resolution flux spectra across the Na I D and Ca II H and K features was seen from days +39 to +74, indicating that the late-time increase in polarization is intrinsic to the SN as opposed to being caused by scattering of SN photons in circumstellar or interstellar matter. We suggest that an explanation for the late-time rise of the Ca II near-infrared triplet polarization may be the alignment of calcium atoms in a weak magnetic field through optical excitation/pumping by anisotropic radiation from the SN.

Keywords: Spectropolarimetry, Supernovae
Temperature and Differential Emission Measure Profiles in Turbulent Solar Active Region Loops. We examine the temperature structure of static coronal active region loops in regimes where thermal conductive transport is driven by Coulomb collisions, by turbulent scattering, or by a combination of the two. (In the last case collisional scattering dominates the heat transport at lower levels in the loop where temperatures are low and densities are high, while turbulent scattering dominates the heat transport at higher temperatures/lower densities.) Temperature profiles and their corresponding differential emission measure distributions are calculated and compared to observations, and earlier scaling laws relating the loop apex temperature and volumetric heating rate to the loop length and pressure are revisited. Results reveal very substantial changes, compared to the wholly collision-dominated case, to both the loop scaling laws and the temperature/density profiles along the loop. They also show that the well-known excess of differential emission measure at relatively low temperatures in the loop may be a consequence of the flatter temperature gradients (and so increased amount of material within a specified temperature range) that results from the predominance of turbulent scattering in the upper regions of the loop.

Keywords: Solar ultraviolet emission, Solar coronal loops, Solar active regions, Solar physics, Solar activity, Active solar corona
Magnetic Field Structure, Doppler Shift, and Intensity of Active Regions and Their Connections with the Solar Wind. The properties of active regions and their connections with the solar wind are important issues. In this study, nine isolated active regions near the solar disk center were chosen. The relationships between blueshift, intensity, magnetic concentrated areas (MCAs), and the potential-field source-surface (PFSS) open magnetic field of active regions were analyzed. Whether an active region contributes to the solar wind was identified only based on the relationship between the properties of in situ solar wind and the large structure of the corona. Then the two phenomena (blueshift and PFSS open magnetic field) for inferring whether an active region contributes to the solar wind were tested. We find that the blueshift areas appear in all cases and the average Doppler speed ranges from -6 to -23 km s-1. The blueshift areas generally root inside MCAs and are far from the neutral lines. The intensity of blueshift areas negatively correlates with the blueshift speed. Statistically, 10 of 16 blueshift areas are associated with the PFSS open magnetic field lines, and all 10 PFSS open magnetic field areas are accompanied by blueshift. We demonstrate that a polarity of an active region generally contributes to the solar wind if it is associated with a PFSS open magnetic field. There are 9 of 10 (13 of 16) PFSS open magnetic field areas (blueshift regions) associated with the solar wind. The results of this study should help determine the observation target of SPICE on board the Solar Orbiter whose scientific goal is connecting the Sun and the heliosphere.

Keywords: Solar surface, Solar active regions, Solar wind, Solar physics
To Rain or Not to Rain: Correlating GOES Flare Class and Coronal Rain Statistics. Post-flare arcades are well-known components of solar flare evolution, which have been observed for several decades. Coronal rain, cascades of catastrophically cooled plasma, outlines the loops and provides eye-catching evidence of the recent flare. These events are acknowledged to be common, but the scientific literature does not include any statistical overview documenting just how common the phenomenon actually is. This study reviews Solar Dynamics Observatory Atmospheric Imaging Assembly (SDO AIA) observations of 241 flares collected from the Space Weather Prediction Center database between 2011 and 2018. The flares cover the entire strength range of the C, M, and X GOES classes, and are distributed evenly across the SDO-observed majority of Solar Cycle 24. We find that post-flare arcade rain occurs for nearly all X- and most M-class flares, but that it tapers off rapidly within C-class flares. There appears to be a cut-off point around C5, below which the occurrence of post-flare arcade rain drops significantly. There is also a general positive correlation between GOES class and the average duration of post-flare rain events. Post-flare arcade rain events in X- and M-class flares appear to track with the sunspot number, providing a potential new tool for estimating, if not predicting, solar cycle strength. Furthermore, arcades are observed to persist for up to several days after the originating flare, transitioning from hosting post-flare rain to typical quiescent active region condensations. These results open up further avenues for future research, including new methods to estimate energy deposition and to gain greater insight into steady active region heating.

Keywords: Solar flares, Solar coronal loops, Solar physics, Solar corona, Solar coronal mass ejections, Active solar corona
Evidence That Shocks Destroy Small PAH Molecules in Low-luminosity Active Galactic Nuclei. We combined mapping-mode mid-infrared Spitzer spectra with complementary infrared imaging to perform a spatially resolved study of polycyclic aromatic hydrocarbon (PAH) emission from the central regions of 66 nearby galaxies, roughly evenly divided into star-forming systems and low-luminosity active galactic nuclei (AGNs). In conjunction with similar measurements available for quasars, we aim to understand the physical properties of PAHs across a broad range of black hole accretion power, with the goal of identifying observational diagnostics that can be used to probe the effect of AGNs on the host galaxy. Whereas the PAH emission correlates tightly with far-ultraviolet luminosity in star-forming regions, the spatially resolved regions of AGNs tend to be PAH deficient. Moreover, AGN regions exhibit on average smaller PAH 6.2 μm/7.7 μm and larger PAH 11.3 μm/7.7 μm band ratios. Although the current data are highly restrictive, they suggest that these anomalous PAH band ratios cannot be explained by the effects of the AGN radiation field alone. Instead, they hint that small grains may be destroyed by the combined effects of radiative processes and shocks, which are plausibly linked to jets and outflows preferentially associated with highly sub-Eddington, radiatively inefficient AGNs. While quasars also present a PAH deficit and unusual PAH band ratios, their characteristics differ in detail compared to those observed in more weakly accreting AGNs, a possible indicator of fundamental differences in their modes of energy feedback.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Interstellar emissions, Low-luminosity active galactic nuclei, Active galactic nuclei, Star formation, Interstellar medium, Shocks
A Comparative Study of Ionospheric Response to Solar Flares at Earth, Venus, and Mars. It has been widely recognized that the ionosphere of the terrestrial planet responds greatly to the enhanced X-ray and extreme ultraviolet radiation during solar flares. However, little attention has been paid to the comparative study of the ionospheric response between different Earth-like planets. In this work, we investigate the responses of the ionospheres of Earth, Venus, and Mars to the 2017 September 6 solar flares, with self-consistent planetary ionospheric models. The result shows that the electron density increases significantly in the relatively low ionosphere region, and its maximum relative change displays profound differences between planets. The ion temperatures at Earth and Venus share a similar response to flares, but differ from those at Mars, which relates to the background atmospheric conditions. For the electron temperature response to the X9.3 flare, at Earth it increases with a maximum magnitude of 250 K, in contrast to the decrease of ~45 K at Venus and ~40 K at Mars. The vertical plasma velocity at all three planets exhibits enhancement during solar flares. As a result, the upward flux increases by 2.16 × 1012 m-2 s-1 at 800 km of Earth, 3.79 × 1010 m-2 s-1, and 8.45 × 109 m-2 s-1 at 400 km of Venus and Mars. This is the first self-consistent simulation of the flare-induced enhancement of upward plasma flow at Venus and Mars.

Keywords: Planetary ionospheres, Solar flares, Planetary science
Detecting Magnetospheric Radio Emission from Giant Exoplanets. As radio astronomy enters a golden age, ground-based observatories are reaching sensitivities capable of unlocking a new and exciting field of exoplanet observation. Radio observation of planetary auroral emission provides unique and complementary insight into planetary science not available via orthodox exoplanet observation techniques. Supplying the first measurements of planetary magnetic fields, rotation rates, and orbital obliquities, we gain necessary and crucial insight into our understanding of the star-planet relationships, geophysics, composition, and habitability of exoplanets. Using a stellar-wind-driven Jovian approximation, we present analytical methods for estimating magnetospheric radio emission from confirmed exoplanets. Predicted radio fluxes from cataloged exoplanets are compared against the wavelengths and sensitivities of current and future observatories. Candidate exoplanets are downselected based on the sky coverage of each ground-based observatory. Orbits of target exoplanets are modeled to account for influential orbit-dependent effects in anticipating time-varying exoplanet radio luminosity and flux. To evaluate the angular alignment of exoplanetary beamed emission relative to Earth's position, the equatorial latitude of exoplanetary auroral emission is compared against Earth's apparent latitude on the exoplanet. Predicted time-dependent measurements and recommended beamformed observations for ground-based radio arrays are provided, along with a detailed analysis of the anticipated emission behavior for τ Boo b.

Keywords: Radio astronomy, Brown dwarfs, Exoplanets, Aurorae, Stellar winds, Star-planet interactions, Magnetic fields, Habitable planets
Genesis and Coronal-jet-generating Eruption of a Solar Minifilament Captured by IRIS Slit-raster Spectra. We present the first Mg II slit-raster spectra from the Interface Region Imaging Spectrograph (IRIS) that fully capture the genesis and coronal-jet-generating eruption of a central-disk solar minifilament. The minifilament arose in a negative-magnetic-polarity coronal hole. The Mg II spectroheliograms verify that the minifilament plasma temperature is chromospheric. The Mg II spectra show that the erupting minifilament's plasma has blueshifted upflow in the onset of the jet spire and simultaneous redshifted downflow at the location of the compact jet bright point (JBP). From the Mg II spectra together with Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) EUV images and SDO/Helioseismic and Magnetic Imager (HMI) magnetograms, we find: (i) the minifilament forms above a flux-cancelation neutral line at an edge of a negative-polarity network flux clump; (ii) during the onset of the minifilament's fast eruption and jet spire, the JBP begins brightening over the flux-cancelation neutral line. From IRIS2 inversion of the Mg II spectra, the JBP's Mg II bright plasma has electron density, temperature, and downward (redshift) Doppler speed of 1012 cm-3, 6000 K, and 10 km s-1, respectively, and the growing spire shows clockwise spin. We speculate: (i) during the slow rise of the erupting minifilament-carrying a twisted flux rope, the top of the erupting flux-rope loop, by writhing, makes its field direction opposite to that of the encountered ambient far-reaching field; (ii) the erupting kink then can reconnect with the far-reaching field to create the spire and reconnect internally to create the JBP. We conclude that this coronal jet is normal in that magnetic flux cancelation builds a minifilament-carrying twisted flux rope and triggers the JBP-generating and jet-spire-generating eruption of the flux rope.

Keywords: Jets, Solar ultraviolet emission, Quiet solar chromosphere, Solar magnetic reconnection, Solar magnetic fields, Spectroscopy, Solar corona, Solar coronal holes
Connecting MeerKAT Radio Continuum Properties to GAMA Optical Emission-line and WISE Mid-infrared Activity. The identification of active galactic nuclei (AGNs) in large surveys has been hampered by seemingly discordant classifications arising from differing diagnostic methods, usually tracing distinct processes specific to a particular wavelength regime. However, as shown in Yao et al., the combination of optical emission-line measurements and mid-infrared photometry can be used to optimize the discrimination capability between AGN and star formation activity. In this paper we test our new classification scheme by combining the existing GAMA-WISE data with high-quality MeerKAT radio continuum data covering 8 deg2 of the GAMA G23 region. Using this sample of 1841 galaxies (z &lt; 0.25), we investigate the total infrared (derived from 12 μm) to radio luminosity ratio, q (TIR), and its relationship to optical-infrared AGN and star-forming (SF) classifications. We find that while q (TIR) is efficient at detecting AGN activity in massive galaxies generally appearing quiescent in the infrared, it becomes less reliable for cases where the emission from star formation in the host galaxy is dominant. However, we find that the q (TIR) can identify up to 70% more AGNs not discernible at optical and/or infrared wavelengths. The median q (TIR) of our SF sample is 2.57 ± 0.23, consistent with previous local universe estimates.

Keywords: Radio active galactic nuclei, Active galactic nuclei
One-off and Repeating Fast Radio Bursts: A Statistical Analysis. According to the number of detected bursts, fast radio bursts (FRBs) can be classified into two categories, i.e., one-off FRBs and repeating ones. We make a statistical comparison of these two categories based on the first FRB catalog of the Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst Project. Using the Anderson-Darling, Kolmogorov-Smirnov, and Energy statistic tests, we find significant statistical differences (p-value &lt; 0.001) in the burst properties between the one-off FRBs and the repeating ones. More specifically, after controlling for distance, we find that the peak luminosities of one-off FRBs are, on average, higher than the repeating ones; the pulse temporal widths of repeating FRBs are, on average, longer than the one-off ones. The differences indicate that these two categories could have distinct physical origins. Moreover, we discuss the subpopulations of FRBs and provide statistical evidence to support the existence of subpopulations in one-off FRBs and in repeating ones.

Keywords: Radio bursts, High energy astrophysics, Radio transient sources
Red Supergiant Stars in IC 1613 and Metallicity-dependent Mixing Length in the Evolutionary Model. We report a spectroscopic study on red supergiant stars (RSGs) in the irregular dwarf galaxy IC 1613 in the Local Group. We derive the effective temperatures (T eff) and metallicities of 14 RSGs by synthetic spectral fitting to the spectra observed with the MMIRS instrument on the MMT telescope for a wavelength range from 1.16 to 1.23 μm. A weak bimodal distribution of the RSG metallicity centered on [Fe/H] = -0.65 is found, which is slightly lower than or comparable to that of the Small Magellanic Cloud (SMC). There is no evidence for spatial segregation between the metal-rich ([Fe/H] &gt; -0.65) and -poor ([Fe/H] &lt; -0.65) RSGs throughout the galaxy. The mean effective temperature of our RSG sample in IC 1613 is higher by about 250 K than that of the SMC. However, no correlation between T eff and metallicity within our RSG sample is found. We calibrate the convective mixing length (α MLT) by comparing stellar evolutionary tracks with the RSG positions on the H-R diagram, finding that models with α MLT = 2.2-2.4H  P  can best reproduce the effective temperatures of the RSGs in IC 1613 for both Schwarzschild and Ledoux convection criteria. This result supports our previous finding that a metallicity-dependent mixing length is needed to explain the RSG temperatures observed in the Local Group, but we find that this dependence becomes relatively weak for RSGs having a metallicity equal to or less than the SMC metallicity.

Keywords: Late-type supergiant stars, Dwarf irregular galaxies, Red supergiant stars
Empirical Dust Attenuation Model Leads to More Realistic UVJ Diagram for TNG100 Galaxies. Dust attenuation varies substantially from galaxy to galaxy and as of yet cannot be reproduced from first principles in theoretical models. In Nagaraj et al., we developed the first Bayesian population model of dust attenuation as a function of stellar population properties and projected galaxy shape, built on spectral energy distribution fits of nearly 30,000 galaxies in the 3D-HST grism survey with broadband photometric coverage from the rest-frame UV to IR. In this paper, we apply the model, named "DustE," to galaxies from the large-volume cosmological simulation TNG100 at z = 1. We produce a UVJ diagram and compare it with one obtained in previous work by applying approximate radiative transfer to the simulated galaxies. We find that the UVJ diagram based on our empirical model is in better agreement with observations than the previous effort, especially in the number density of dusty star-forming galaxies. We also construct the intrinsic dust-free UVJ diagram for TNG100 and 3D-HST galaxies at z ~ 1, finding qualitative agreement but residual differences at the 10%-20% level. These differences may be caused by the finding that TNG100 galaxies have, on average, 29% younger stellar populations and possibly higher metallicities than observed galaxies.

Keywords: Galaxy evolution, High-redshift galaxies, Spectral energy distribution, Hierarchical models