Sazuna/UAT_keywords huggingface dataset:
Multimessenger Diagnostics of the Engine behind Core-collapse Supernovae. Core-collapse supernova explosions play a wide role in astrophysics by producing compact remnants (neutron stars or black holes) and the synthesis and injection of many heavy elements into their host galaxy. Because they are produced in some of the most extreme conditions in the universe, they can also probe physics in extreme conditions (matter at nuclear densities and extreme temperatures and magnetic fields). To quantify the impact of supernovae on both fundamental physics and our understanding of the universe, we must leverage a broad set of observables of this engine. In this paper, we study a subset of these probes using a suite of one-dimensional, parameterized mixing models: ejecta remnants from supernovae, ultraviolet, optical and infrared light curves, and transient gamma-ray emission. We review the other diagnostics and show how the different probes tie together to provide a more clear picture of the supernova engine. Join us in improving and evolving this document through active community engagement. Instructions are provided at this link: https://github.com/clfryer/MM-SNe.

Keywords: Supernova neutrinos, Dust destruction, Gamma-ray sources, Type II supernovae, Gravitational wave sources, Dust formation, Supernova remnants, X-ray sources
Search for Extended Sources of Neutrino Emission in the Galactic Plane with IceCube. The Galactic plane, harboring a diffuse neutrino flux, is a particularly interesting target in which to study potential cosmic-ray acceleration sites. Recent gamma-ray observations by HAWC and LHAASO have presented evidence for multiple Galactic sources that exhibit a spatially extended morphology and have energy spectra continuing beyond 100 TeV. A fraction of such emission could be produced by interactions of accelerated hadronic cosmic rays, resulting in an excess of high-energy neutrinos clustered near these regions. Using 10 years of IceCube data comprising track-like events that originate from charged-current muon neutrino interactions, we perform a dedicated search for extended neutrino sources in the Galaxy. We find no evidence for time-integrated neutrino emission from the potential extended sources studied in the Galactic plane. The most significant location, at 2.6σ post-trials, is a 1.°7 sized region coincident with the unidentified TeV gamma-ray source 3HWC J1951+266. We provide strong constraints on hadronic emission from several regions in the galaxy.

Keywords: Neutrino astronomy
An Optically Discovered Outburst from XTE J1859+226. Using the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2 × 1035 erg s-1, implying an Eddington fraction of about 3 × 10-4. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 1011 cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.

Keywords: Low-mass x-ray binary stars, X-ray binary stars
A High-level Ab Initio Study of the Destruction of Methanimine under UV Radiation. The photodecomposition of methanimine (CH2NH) in the interstellar medium through several possible pathways is investigated by means of high-level multireference configuration interaction ab initio calculations. Among these pathways are photodissociation pathways involving hydrogen-atom elimination from both the CH2 and NH groups, and fragmentation into CH2 and NH. Potential-energy curves for the ground and several excited electronic states, as well as nonadiabatic couplings between them, are calculated. Possible dissociation mechanisms are discussed for the different pathways. It is found that the minimum excitation energy required for methanimine dissociation is above 7 eV. By using a two-dimensional representation of methanimine, CH2NH → CHNH2 isomerization is explored as an additional methanimine decomposition pathway. Hydrogen-atom elimination from the CH2 group is also investigated along the isomerization pathway. The results show that the isomerization proceeds by overcoming a transition state that in the first two excited states would require excitation energies similar to or somewhat lower than the typical minimum energies needed for breaking the molecule through the fragmentation pathways. Therefore, CH2NH → CHNH2 isomerization can effectively contribute to methanimine decomposition, competing efficiently with the photodissociation pathways. The radiation content present in the interstellar medium makes possible the occurrence of all the pathways studied.

Keywords: Photodissociation reactions, Complex organic molecules
A CHIME/FRB Study of Burst Rate and Morphological Evolution of the Periodically Repeating FRB 20180916B. FRB 20180916B is a repeating fast radio burst (FRB) with a 16.3 day periodicity in its activity. In this study, we present morphological properties of 60 FRB 20180916B bursts detected by CHIME/FRB between 2018 August and 2021 December. We recorded raw voltage data for 45 of these bursts, enabling microseconds time resolution in some cases. We studied variation of spectro-temporal properties with time and activity phase. We find that the variation in dispersion measure (DM) is ≲1 pc cm-3 and that there is burst-to-burst variation in scattering time estimates ranging from ~0.16 to over 2 ms, with no discernible trend with activity phase for either property. Furthermore, we find no DM and scattering variability corresponding to the recent change in rotation measure from the source, which has implications for the immediate environment of the source. We find that FRB 20180916B has thus far shown no epochs of heightened activity as have been seen in other active repeaters by CHIME/FRB, with its burst count consistent with originating from a Poissonian process. We also observe no change in the value of the activity period over the duration of our observations and set a 1σ upper limit of 1.5 × 10-4 day day-1 on the absolute period derivative. Finally, we discuss constraints on progenitor models yielded by our results, noting that our upper limits on changes in scattering and DM as a function of phase do not support models invoking a massive binary companion star as the origin of the 16.3 day periodicity.

Keywords: Radio bursts, Radio transient sources
Solar-Stellar Connection: X-Ray Flares to Energetic (E &gt; 10 MeV) Particle Events. Energetic particle environments are an important factor for the viability of life on exoplanets surrounding flare stars. In the heliosphere, large gradual solar energetic (E &gt; 10 MeV) particle (SEP) events are produced by shocks from fast coronal mass ejections (CMEs). Extensive observations of solar X-ray flares, CMEs, and SEP events can provide guidance for flare star models of stellar energetic particle (StEP) events, for which stellar flares, but only rarely the associated CMEs, are observed. Comparing an extensive list of peak fluxes, timescales, and peak temperatures of 585 ≥ M3.0 solar X-ray flares with the occurrence of associated SEP events of peak flux Ip &gt; 1.4 proton flux units, enhanced with proxy decametric-hectometric type II radio bursts, we determine guidelines for StEP event outcomes, given only stellar X-ray flare inputs. Longer timescales and lower peak temperatures of X-ray flares with a given peak X-ray flux Fp are more favorable for occurrence of associated SEP/StEP events, which, however, are only a minority of all solar flare outcomes. Most solar flares do not result in SEP events, invalidating scaling laws between stellar flares, CMEs, and StEP events. We discuss recent observations and models of the flare-CME relationship and suggest that StEP intensities Ip may often be overestimated.

Keywords: Solar flares, Exoplanets, Solar energetic particles, Solar coronal mass ejection shocks, Astrobiology, Stellar flares, Stellar coronal mass ejections
A Magnetically Driven Disk Wind in the Inner Disk of PDS 70. PDS 70 is so far the only young disk where multiple planets have been detected by direct imaging. The disk has a large cavity when seen at submillimeter and near-infrared wavelengths, which hosts two massive planets. This makes PDS 70 the ideal target to study the physical conditions in a strongly depleted inner disk shaped by two giant planets, and in particular to test whether disk winds can play a significant role in its evolution. Using X-Shooter and HARPS spectra, we detected for the first time the wind-tracing [O I] 6300 Å line, and confirm the low-moderate value of mass-accretion rate in the literature. The [O I] line luminosity is high with respect to the accretion luminosity when compared to a large sample of disks with cavities in nearby star-forming regions. The FWHM and blueshifted peak of the [O I] line suggest an emission in a region very close to the star, favoring a magnetically driven wind as the origin. We also detect wind emission and high variability in the He I 10830 Å line, which is unusual for low accretors. We discuss that, although the cavity of PDS 70 was clearly carved out by the giant planets, the substantial inner-disk wind could also have had a significant contribution to clearing the inner disk. *Based on observations collected at the European Southern Observatory under ESO programs 098.C-0739, 0104.C-0418, 105.205R, 106.20Z8, and 1101.C-0557.

Keywords: High resolution spectroscopy, Weak-line T Tauri stars, Classical T Tauri stars, Protoplanetary disks, Variable stars, Stellar accretion disks
The Ultraviolet to Mid-infrared Extinction Law of the Taurus Molecular Cloud Based on the Gaia DR3, GALEX, APASS, Pan-STARRS1, 2MASS, and WISE Surveys. Interstellar-dust extinction law is essential for interpreting observations. In this work, we investigate the ultraviolet (UV)-mid-infrared (IR) extinction law of the Taurus molecular cloud and its possible variations. We select 504,988 dwarf stars (4200 K ≤ T eff ≤ 8000 K) and 4757 giant stars (4200 K ≤ T eff ≤ 5200 K) based on the stellar parameters of Gaia DR3 as tracers. We establish the T eff-intrinsic color relations and determine the intrinsic color indices and color excesses for different types of stars. In the determination of color excess ratios (CERs), we analyze and correct the curvature of CERs and derive the UV-mid-IR CERs of 16 bands. We consider different effective wavelengths for different types of stars when converting CERs to relative extinction and obtain the extinction law with a better wavelength resolution. In addition, we analyze the possible regional variation of extinction law and derive the average extinction law of R V = 3.13 ± 0.32 for the Taurus molecular cloud. Only 0.9% of subregions have deviations &gt;3σ, indicating limited regional variation in the extinction law. We also discuss the effect of Gaia T eff overestimation on the determination of the Taurus extinction law and find that the effect is negligible.

Keywords: Reddening law, Interstellar reddening, Interstellar dust extinction, Interstellar extinction
Left Ringing: Betelgeuse Illuminates the Connection between Convective Outbursts, Mode Switching, and Mass Ejection in Red Supergiants. Betelgeuse, the nearest red supergiant, dimmed to an unprecedented level in early 2020. The star emerged from this "Great Dimming" episode with its typical, roughly 400 days pulsation cycle halved, and a new dominant period of around 200 days. The dimming event has been attributed to a surface mass ejection, in which rising material drove shocks through the stellar atmosphere and expelled some material, partially obscuring the star as it formed molecules and dust. In this paper, we use hydrodynamic simulations to reveal the connections between Betelgeuse's vigorously convective envelope, the surface mass ejection, and the pulsation mode switching that ensued. An anomalously hot convective plume, generated rarely but naturally in the star's turbulent envelope, can rise and break free from the surface, powering an upwelling that becomes the surface mass ejection. The rising plume also breaks the phase coherence of the star's pulsation, causing the surface to keep expanding even as the deeper layers contract. This drives a switch from the 400 days fundamental mode of pulsation, in which the whole star expands and contracts synchronously, to the 200 days first overtone, where a radial node separates the interior and exterior of the envelope moving in opposite phase. We predict that the star's convective motions will damp the overtone oscillation and Betelgeuse will return to its previous, 400 days fundamental-mode pulsation in the next 5-10 yr. With its resolved surface and unprecedentedly detailed characterization, Betelgeuse opens a window to episodic surface mass ejection in the late-stage evolution of massive stars.

Keywords: Red supergiant stars, Stellar convection envelopes, Hydrodynamics, Pulsating variable stars
Characterizing Pulsars Detected in the Rapid ASKAP Continuum Survey. We present the detection of 661 known pulsars observed with the Australian SKA Pathfinder (ASKAP) telescope at 888 MHz as part of the Rapid ASKAP Continuum Survey (RACS). Detections were made through astrometric coincidence and we estimate the false alarm rate of our sample to be ~0.5%. Using archival data at 400 and 1400 MHz, we estimate the power-law spectral indices for the pulsars in our sample and find that the mean spectral index is -1.78 ± 0.6. However, we also find that a single power law is inadequate for modeling all the observed spectra. With the addition of flux densities between 150 MHz and 3 GHz from various imaging surveys, we find that up to 40% of our sample show deviations from a simple power-law model. Using Stokes V measurements from the RACS data, we measured the circular polarization fraction for 9% of our sample and find that the mean polarization fraction is ~10% (consistent between detections and upper limits). Using the dispersion-measure-derived distance, we estimate the pseudo-luminosity of the pulsars and do not find any strong evidence for a correlation with the pulsars' intrinsic properties.

Keywords: Neutron stars, Radio interferometry, Radio pulsars, Pulsars
Prospects for Cryovolcanic Activity on Cold Ocean Planets. We have estimated total internal heating rates and depths to possible subsurface oceans for 17 planets that may be cold ocean planets, low-mass exoplanets with equilibrium surface temperatures and/or densities that are consistent with icy surfaces and a substantial H2O content. We have also investigated the potential for tidally driven cryovolcanism and exosphere formation on these worlds. Estimated internal heating rates from tidal and radiogenic sources are large enough that all planets in our study may harbor subsurface oceans, and their geological activity rates are likely to exceed the geological activity rates on Jupiter's moon Europa. Several planets are likely to experience enhanced volcanic activity rates that exceed that of Io. Owing to their relatively thin ice shells and high rates of internal heating, Proxima Cen b and LHS 1140 b are the most favorable candidates for telescopic detection of explosive, tidally driven cryovolcanism. Estimates for thin ice shells on Proxima Cen b, LHS 1140 b, Trappist-1f, and several Kepler planets suggest that any H2O vented into space during explosive cryovolcanic eruptions on these worlds could be sourced directly from their subsurface oceans. Like the icy moons in our outer solar system, cold ocean planets may be astrobiologically significant worlds that harbor habitable environments beneath their icy surfaces. These possibilities should be considered during analyses of observational data for small exoplanets from current and upcoming telescopes and during planning for a future space telescope mission aimed at characterization of potentially habitable exoplanets (e.g., Habitable Worlds Observatory).

Keywords: Ocean planets, Exoplanets, Super Earths, Exoplanet tides, Exoplanet surfaces, Exoplanet surface characteristics, Habitable planets, Exoplanet atmospheres, Volcanism
Electromagnetic Cascade Emission from Neutrino-coincident Tidal Disruption Events. The potential association between Tidal Disruption Events and high-energy astrophysical neutrinos implies the acceleration of cosmic rays. These accelerated particles will initiate electromagnetic (EM) cascades spanning from keV to GeV energies via the processes related to neutrino production. We model the EM cascade and neutrino emissions by numerically solving the time-dependent transport equations, and discuss the implications for AT2019dsg and AT2019fdr in the X-ray and γ-ray bands. We show that the γ-ray constraints from Fermi can constrain the size of the radiation zone and the maximum energy of injected protons, and that the corresponding expected neutrino event numbers in follow-up searches are limited to be less than about 0.1. Depending on the efficiency of p γ interactions and the time at which the target photons peak, the X-ray and γ-ray signals can be expected closer to the peak of the optical-ultraviolet luminosity or to the time of the neutrino production.

Keywords: Neutrino astronomy, Tidal disruption, Radiative processes
Direct Observations of Reconnection Fronts in Earth's Turbulent Magnetosheath. Reconnection fronts (RFs), ion-scale magnetic transients characterized by dramatic enhancement of reconnected magnetic fields, have been documented as crucial energy transfer regions during magnetic reconnection. RFs have hitherto been observed only in the planetary (e.g., Earth, Saturn, Mars, and Venus) magnetotails. Whether RFs can exist in other magnetospheric regions remains unclear. Here, using high-cadence data from NASA's Magnetospheric Multiscale mission, we present the first observation of successive RFs in Earth's turbulent magnetosheath. The RFs were detected inside an ion diffusion region and several di (ion inertial length) away from reconnection X-line. In addition, we find that the strongest energy conversion occurs at the RF rather than at the X-line. The present observation indicates that RFs may be universal in the planetary magnetosphere and play a crucial role in the reconnection dynamics.

Keywords: Space plasmas
Standardized Luminosity of the Tip of the Red Giant Branch Utilizing Multiple Fields in NGC 4258 and the CATs Algorithm. The tip of the red giant branch provides a luminous standard candle for calibrating distance ladders that reach Type Ia supernova (SN Ia) hosts. However, recent work reveals that tip measurements vary at the ~0.1 mag level for different stellar populations and locations within a host, which may lead to inconsistencies along the distance ladder. We pursue a calibration of the tip using 11 Hubble Space Telescope fields around the maser host, NGC 4258, that is consistent with SN Ia hosts by standardizing tip measurements via their contrast ratios. We find F814W-band tips that exhibit a full 0.3 mag range and 0.1 mag dispersion. We do not find any correlation between H I column density and the apparent tip to 0.04 ± 0.03 mag/cm-2. We search for a tip-contrast relation (TCR) and measure the TCR within the fields of NGC 4258 of -0.015 ± 0.008 mag/R, where R is the contrast ratio. This value is consistent with the TCR originally discovered in the GHOSTS sample of -0.023 ± 0.005 mag/R. Combining these measurements, we find a global TCR of -0.021 ± 0.004 mag/R and a calibration of ${M}_{I}^{\mathrm{TRGB}}=-4.025\pm 0.035-(R-4)\times 0.021$ mag. We also use stellar models to simulate single age and metallicity stellar populations with [Fe/H] from -2.0 to -0.7 and ages from 3 to 12 Gyr and reconstruct the global TCR found here to a factor of ~2. This work is combined in a companion analysis with tip measurements of nearby SN Ia hosts to measure H 0.

Keywords: Luminosity function, Red giant tip, Observational cosmology, Standard candles, Distance indicators, Hubble constant, Calibration, Red giant stars, Absolute magnitude, Stellar distance
Optical Identification of the Shortest-period Spider Pulsar System M71E. M71E is a spider pulsar (i.e., a millisecond pulsar with a tight binary companion) with the shortest known orbital period of P = 53.3 minutes, which was discovered by Pan et al. Their favored evolutionary model suggests that it bridges between two types of spider pulsars, namely, it descended from a "redback" and will become a "black widow." Using Hubble Space Telescope (HST) archival imaging data, we report the first optical identification of its companion COM-M71E. The HST and pulsar timing coordinates are in excellent agreement (within ~10 mas). If M71E is associated with the globular cluster M71, our measured brightness of COM-M71E (m F606W ≈ 25.3) is broadly consistent with the expectation from Pan et al.'s preferred binary evolutionary model of a stripped dwarf companion, while it is also compatible with an ultralow-mass degenerate companion. Future multiwavelength photometric and spectroscopic observations can characterize the companion and test the evolutionary scenarios.

Keywords: Globular star clusters, Optical identification, Binary pulsars, Millisecond pulsars
Application of the Thermodynamics of Radiation to Dyson Spheres as Work Extractors and Computational Engines and Their Observational Consequences. I apply the thermodynamics of radiation to Dyson spheres as machines that do work or computation and examine their observational consequences. I identify four properties of Dyson spheres that complicate typical analyses: globally, they may do no work in the usual sense; they use radiation as the source and sink of energy; they accept radiation from a limited range of solid angles; and they conserve energy flux globally. I consider three kinds of activities: computation at the Landauer limit; dissipative activities, in which the energy of a sphere's activities cascades into waste heat, as for a biosphere; and "traditional" work that leaves the sphere, such as radio emission. I apply the Landsberg formalism to derive efficiency limits in all three cases and show that optical circulators provide an "existence proof" that greatly simplifies the problem and allows the Landsberg limit to be plausibly approached. I find that for computation and traditional work, there is little to no advantage to nesting shells (as in a "Matrioshka Brain"); that the optimal use of mass is generally to make very small and hot Dyson spheres; that for "complete" Dyson spheres, we expect optical depths of several; and that in all cases the Landsberg limit corresponds to a form of the Carnot limit. I explore how these conclusions might change in the face of complications, such as the sphere having practical efficiencies below the Landsberg limit (using the endoreversible limit as an example), no use of optical circulators, and swarms of materials instead of shells.

Keywords: Search for extraterrestrial intelligence, Technosignatures, Astrobiology, Chemical thermodynamics