Sazuna/UAT_keywords huggingface dataset:
Cosmicflows-4: The Catalog of ∼10,000 Tully-Fisher Distances. We present the distances of 9792 spiral galaxies lying within 15,000 km s-1 using the relation between luminosity and rotation rate of spiral galaxies. The sample is dominantly, but not exclusively, drawn from galaxies detected in the course of the ALFALFA H I survey with the Arecibo Telescope. Relations between H I line widths and luminosity are calibrated at SDSS u, g, r, i, z bands and WISE W1 and W2 bands. By exploiting secondary parameters, particularly color indices, we address discrepancies between measured distances at different wave bands with unprecedented detail. We provide a catalog that includes reduced kinematic, photometric, and inclination parameters. We also describe a machine-learning algorithm, based on the random forest technique, that predicts the dust attenuation in spirals lacking infrared photometry. We determine a Hubble Constant value of H0 = 75.1 ± 0.2(stat.), with potential systematics up to ±3 km s-1 Mpc-1.

Keywords: Inclination, Galaxy distances, Sky surveys, Spiral galaxies, Large-scale structure of the universe, Distance measure, H I line emission, Hubble constant, Galaxy photometry, Random Forests, Catalogs
Swift/BAT and RXTE/ASM Observations of the 35 day X-Ray Cycle of Hercules X-1. Swift/BAT and RXTE/ASM observations have monitored the X-ray binary system Her X-1 for approximately 14.5 yr each, and both were monitoring Her X-1 for a period of ∼5.5 yr. Here we study the 35 day cycle using these observations. Using a cross-correlation method we find the times of peaks of the 35 day cycles for ∼150 cycles observed by Swift/BAT and ∼150 cycles observed by RXTE/ASM. These cycles include ∼60 observed with both instruments. The noise level of the RXTE/ASM measurements is larger than that of Swift/BAT, resulting in larger uncertainty in peak times. The distribution of 35 day cycle lengths can be fit with a Gaussian with mean 34.79 days and σ of 1.1 days. The distribution of orbital phases of 35 day cycle peaks is well fit by a uniform distribution, with 76% of the cycles, plus a Gaussian distribution peaked at orbital phase ∼0.5, with 24% of the cycles. We construct the long-term average 35 day lightcurve in the 15-50 keV band from Swift/BAT, and in the 2-12 keV band from RXTE/ASM. The high-energy band shows more variability in the short high state and the low-energy band shows more variability in the main high state. This is consistent with a precessing accretion disk model as the cause of the 35 day cycle.

Keywords: Neutron stars, X-ray photometry, Hz Herculis x-ray binary stars
Forward Modeling of Particle Acceleration and Transport in an Individual Solar Flare. The aim of this study is to generate maps of the hard X-ray emission produced by energetic electrons in a solar flare and compare them with observations. The ultimate goal is to test the viability of the combined MHD/test-particle approach for data-driven modeling of active events in the solar corona and their impact on the heliosphere. Based on an MHD model of X-class solar flare observed on 2017 September 8, we calculate trajectories of a large number of electrons and protons using the relativistic guiding-center approach. Using the obtained particle trajectories, we deduce the spatial and energy distributions of energetic electrons and protons, and calculate bremsstrahlung hard X-ray emission using the "thin-target" approximation. Our approach predicts some key characteristics of energetic particles in the considered flare, including the size and location of the acceleration region, energetic particle trajectories and energy spectra. Most importantly, the hard X-ray bremsstrahlung intensity maps predicted by the model are in good agreement with those observed by RHESSI. Furthermore, the locations of proton and electron precipitation appear to be close to the sources of helioseismic response detected in this flare. Therefore, the adopted approach can be used for observationally driven modeling of individual solar flares, including manifestations of energetic particles in the corona, as well as the inner heliosphere.

Keywords: Solar energetic particles, Computational methods, Solar flares, Solar x-ray flares
Constraining Low-luminosity Gamma-Ray Bursts as Ultra-high-energy Cosmic Ray Sources Using GRB 060218 as a Proxy. We study the connection between low-luminosity gamma-ray bursts (llGRBs) and ultra-high-energy cosmic rays (UHECRs) using the canonical low-luminosity GRB 060218 as a proxy. We focus on the consequential synchrotron emission from electrons that are coaccelerated in the UHECR acceleration region, comparing this emission to observations. Both the prompt and afterglow phases are considered. For the prompt phase, we assume the coaccelerated electrons are injected with a power-law distribution instantaneously (without additional heating or reacceleration), which results in bright optical-UV emission in tension with observations. For the afterglow phase, we constrain the total kinetic energy of the blast wave by comparing electron thermal synchrotron radiation to available radio data at ∼ 3 days. Considering mildly relativistic outflows with bulk Lorentz factor Γ ≳ 2 (slower transrelativistic outflows are not treated), we find that the limited available energy does not allow for GRB 060218-like afterglows to be the main origin of UHECRs. This analysis independently constrains the prompt phase as a major UHECR source as well, given that the prompt energy budget is comparable to that of the afterglow kinetic energy. More generally, our study demonstrates that synchrotron emission from thermal electrons is a powerful diagnostic of the physics of mildly relativistic shocks.

Keywords: Gamma-ray bursts, Ultra-high-energy cosmic radiation
A Measurement of the Hubble Constant Using Gravitational Waves from the Binary Merger GW190814. We present a test of the statistical method introduced by Bernard F. Shutz in 1986 using only gravitational waves to infer the Hubble constant (H0) from GW190814, the first high-probability neutron-star-black hole (NS-BH) merger candidate detected by the Laser Interferometer gravitational-wave Observatory (LIGO) and the Virgo interferometer. We apply a baseline test of this method to the binary neutron star (BNS) merger GW170817 and find ${{\rm{H}}}_{0}={70}_{-18.0}^{+35.0}$ km s-1 Mpc-1 (maximum a posteriori and 68.3% highest density posterior interval) for a galaxy B-band luminosity threshold of ${L}_{B}\geqslant 0.001\,{L}_{B}^{* }$ with a correction for catalog incompleteness. Repeating the calculation for GW190814, we obtain ${{\rm{H}}}_{0}={67}_{-26.0}^{+41.0}$ km s-1 Mpc-1 and ${{\rm{H}}}_{0}={71}_{-30.0}^{+34.0}$ km s-1 Mpc-1 for ${L}_{B}\geqslant 0.001\,{L}_{B}^{* }$ and ${L}_{B}\geqslant 0.626\,{L}_{B}^{* }$ , respectively. Combining the posteriors for both events yields ${{\rm{H}}}_{0}={70}_{-18.0}^{+29.0}$ km s-1 Mpc-1, demonstrating the improvement on constraints when using multiple gravitational-wave events. We also confirm the results of other works that adopt this method, showing that increasing the LB threshold enhances the posterior structure and slightly shifts the distribution's peak to higher H0 values.We repeat the joint inference using the low-spin PhenomPNRT and the newly available combined (SEOBNRv4PHM + IMRPhenomPv3HM) posterior samples for GW170817 and GW190814, respectively, achieving a tighter constraint of ${{\rm{H}}}_{0}={69}_{-14.0}^{+29.0}$ km s-1 Mpc-1.

Keywords: Neutron stars, Bayesian statistics, Black holes, Posterior distribution, Hubble constant, Gravitational waves, Compact objects
The Boltzmann-radiation-hydrodynamics Simulations of Core-collapse Supernovae with Different Equations of State: The Role of Nuclear Composition and the Behavior of Neutrinos. Using the Boltzmann-radiation-hydrodynamics code, which solves the Boltzmann equation for neutrino transport, we present the results of the simulations with the nuclear equations of state (EOSs) of Lattimer and Swesty (LS) and Furusawa and Shen (FS). We extend the simulation time of the LS model and conduct thorough investigations, though our previous paper briefly reported some of the results. Only the LS model shows the shock revival. This seems to originate from the nuclear composition: the different nuclear composition results in the different energy loss by photodissociation and hence the different strength of the prompt convection and the later neutrino-driven convection. The protoneutron star seen in the FS model is more compact than that in the LS model because the existence of multinuclear species softens the EOS. For the behavior of neutrinos, we examined the flux and the Eddington tensor of neutrinos. In the optically thick region, the diffusion of neutrinos and the dragging by the motion of matter determine the flux. In the optically thin region, the free-streaming determines it. The Eddington tensor is compared with that obtained from the M1-closure relation. The M1-closure scheme overestimates the contribution from the velocity-dependent terms in the semitransparent region.

Keywords: Hydrodynamical simulations, Supernova neutrinos, Core-collapse supernovae, Radiative transfer simulations, Supernova dynamics, Nuclear physics
Electromagnetic Emission Driven by Electron Beam Instability in the Jovian Polar Regions. Upward energetic electron beams are often observed simultaneously with the plasma-wave emission in the Jovian polar regions, where the electron cyclotron frequency Ωce is much larger than the plasma frequency ωpe. This study gives a comprehensive wave and instability analysis in the extreme plasma environment with Ωce ≫ ωpe. We find that energetic electron beams can effectively drive the electron acoustic/magnetoacoustic instability. The excited electron acoustic/magnetoacoustic waves distribute from the parallel direction to the highly oblique direction, and their wave frequencies are always below the plasma frequency. These waves are electrostatic at parallel propagation, and exhibit electromagnetic polarization at oblique propagation. These theoretical predictions are qualitatively consistent with the main observed features of electromagnetic fluctuations in the Jovian polar regions. Therefore, we propose that upward electron beam-driven electron acoustic/magnetoacoustic waves can contribute to the plasma-wave emission in Jupiter's polar environments. Furthermore, energetic electron beam-driven electron acoustic/magnetoacoustic waves may exist in Saturn's polar regions and solar flare loops, where the extreme plasma condition Ωce ≫ ωpe is satisfied in these plasma environments.

Keywords: Space plasmas, Solar wind, Planetary magnetospheres, Plasma physics
A NICER View of a Highly Absorbed Flare in GRS 1915+105. After 26 yr in outburst, the black hole X-ray binary GRS 1915+105 dimmed considerably in early 2018; its flux dropped sharply in mid-2019, and it has remained faint ever since. This faint period, the "obscured state," is punctuated by occasional X-ray flares, many of which have been observed by NICER as part of our regular monitoring program. Here we present detailed time-resolved spectroscopy of one bright flare, whose spectrum shows evidence of high column density partial covering absorption and extremely deep absorption lines (equivalent widths over 100 eV in some cases). We study the time-dependent ionization of the obscuring gas with XSTAR, ultimately attributing the absorption to a radially stratified absorber of density ∼1012-1013 cm-3 at ∼few ×1011 cm from the black hole. We argue that a vertically extended outer disk could explain this obscuration. We discuss several scenarios to explain the obscured state, including massive outflows, an increase in the mass accretion rate, and changes in the outer disk that herald the approach of quiescence, but none are entirely satisfactory. Alternative explanations, such as obscuration by the accretion stream impact point, may be testable with current or future data.

Keywords: Accretion, X-ray astronomy, Black holes, Stellar mass black holes, Stellar winds, Astrophysical black holes
Imagery and UV Spectroscopy of the LMC Supernova Remnant N103B Using HST. We present Hubble Space Telescope (HST)/Wide Field Camera 3 multiband imagery of N103B, which is the remnant of a SN Ia in the Large Magellanic Cloud, as well as HST/Cosmic Origins Spectrograph (COS) ultraviolet spectroscopy of the brightest radiatively shocked region. The images show a wide range of morphology and relative emission-line intensities, from smooth Balmer-line dominated collisionless shocks that are due to the primary blast wave to clumpy radiative shock filaments that are due to secondary shocks in density enhancements. The COS data show strong FUV line emissions, despite a moderately high extinction along this line of sight. We use the COS data with previous optical spectra to constrain the shock conditions, we refine the abundance analysis, and we find abundances that are typical of the local interstellar medium within the uncertainties. Under an assumption that the material being shocked was shed from the pre-supernova system, this finding places constraints on any significant enrichment in that material, and thus on the non-degenerate star in what was presumably a single-degenerate SN Ia.

Keywords: Supernova remnants, Emission nebulae, Type Ia supernovae, Nebulae, Shocks
Exploring Hydrodynamic Instabilities along the Infalling High-velocity Cloud Complex A. Complex A is a high-velocity cloud (HVC) that is traversing through the Galactic halo toward the Milky Way's disk. We combine both new and archival Green Bank Telescope observations to construct a spectroscopically resolved H I 21 cm map of this entire complex at a $17.1\lesssim \mathrm{log}({N}_{{\rm{H}}{\rm\small{I}},1\sigma }/{\mathrm{cm}}^{-2})\lesssim 17.9$ sensitivity for a $\mathrm{FWHM}=20\,\mathrm{km}\,{{\rm{s}}}^{-1}$ line and Δθ = 9'1 or 17 ≲ Δdθ ≲ 30 pc spatial resolution. We find that Complex A has a Galactic standard of rest frame velocity gradient of ${\rm{\Delta }}{v}_{\mathrm{GSR}}/{\rm{\Delta }}L=25\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{kpc}}^{-1}$ along its length, that it is decelerating at a rate of $\langle a{\rangle }_{\mathrm{GSR}}=55\,\mathrm{km}\,{\mathrm{yr}}^{-2}$ , and that it will reach the Galactic plane in Δt ≲ 70 Myr if it can survive the journey. We have identified numerous signatures of gas disruption. The elongated and multi-core structure of Complex A indicates that either thermodynamic instabilities or shock-cascade processes have fragmented this stream. We find Rayleigh-Taylor fingers on the low-latitude edge of this HVC; many have been pushed backward by ram pressure stripping. On the high-latitude side of the complex, Kelvin-Helmholtz instabilities have generated two large wings that extend tangentially off Complex A. The tips of these wings curve slightly forward in the direction of motion and have an elevated H I column density, indicating that these wings are forming Rayleigh-Taylor globules at their tips and that this gas is becoming entangled with unseen vortices in the surrounding coronal gas. These observations provide new insights on the survivability of low-metallicity gas streams that are accreting onto L⋆ galaxies.

Keywords: High-velocity clouds, Galaxy evolution, Hydrodynamics, Circumgalactic medium
A JWST Preview: Adaptive-optics Images of H<SUB>2</SUB>, Br-γ, and K-continuum in Carina's Western Wall. We present the first wide-field near-infrared adaptive-optics images of Carina's Western Wall (G287.38-0.62), one of the brightest and most well-defined irradiated interfaces known in a region of massive star formation. The new narrowband H2 2.12 μm, Br-γ and K-continuum images from Gemini South trace the photoevaporative flow from the cloud and identify locations where UV radiation from the surrounding massive stars excites molecular hydrogen to fluoresce. With a field of view of ∼1'5 × 2'9 and spatial resolution between 60 and 110 mas, the new images show a spectacular level of detail over a large area, and presage what the James Webb Space Telescope (JWST) should achieve. The Wall is convex in shape, with a large triangular-shaped extension near its apex. The interface near the apex consists of 3-4 regularly spaced ridges with projected spacings of ∼2000 au, suggestive of a large-scale dynamically important magnetic field. The northern edge of the Wall breaks into several swept-back fragments of width ∼1800 au that resemble Kelvin-Helmholtz instabilities, and the southern part of the Wall also shows complex morphologies including a sinusoidal-like variation with a half-wavelength of 2500 au. Though the dissociation front must increase the density along the surface of the Wall, it does not resolve into pillars that point back to the ionization sources, as could occur if the front triggered new stars to form. We discovered that MHO 1630, an H2 outflow with no clear driving source in the northern portion of the Wall, consists of a series of bow shocks arrayed in a line.

Keywords: Radiative magnetohydrodynamics, Herbig-Haro objects, Stellar jets, Photodissociation regions, Star formation, Astrophysical fluid dynamics
The X-Ray Reactivation of the Radio Bursting Magnetar SGR J1935+2154. A few years after its discovery as a magnetar, SGR J1935+2154 started a new burst-active phase on 2020 April 27, accompanied by a large enhancement of its X-ray persistent emission. Radio single bursts were detected during this activation, strengthening the connection between magnetars and fast radio bursts. We report on the X-ray monitoring of SGR J1935+2154 from ∼3 days prior to ∼3 weeks after its reactivation, using Swift, the Nuclear Spectroscopic Telescope Array (NuSTAR), and the Neutron Star Interior Composition Explorer (NICER). We detected X-ray pulsations in the NICER and NuSTAR observations, and constrained the spin period derivative to $| \dot{P}| \lt 3\times {10}^{-11}$ s s-1 (3σ c.l.). The pulse profile showed a variable shape switching between single and double-peaked as a function of time and energy. The pulsed fraction decreased from ∼34% to ∼11% (5-10 keV) over ∼10 days. The X-ray spectrum was well fit by an absorbed blackbody model with temperature decreasing from kTBB ∼ 1.6 to 0.45-0.6 keV, plus a nonthermal power-law component (Γ ∼ 1.2) observed up to ∼25 keV with NuSTAR. The 0.3-10 keV X-ray luminosity increased in less than 4 days from $\sim 6\times {10}^{33}{d}_{6.6}^{2}$ erg s-1 to about $3\times {10}^{35}{d}_{6.6}^{2}$ erg s-1 and then decreased again to $2.5\times {10}^{34}{d}_{6.6}^{2}$ erg s-1 over the following 3 weeks of the outburst, where d6.6 is the source distance in units of 6.6 kpc. We also detected several X-ray bursts, with properties typical of short magnetar bursts.

Keywords: Neutron stars, X-ray transient sources, Magnetars, X-ray bursts, Radio pulsars
Single-hemisphere Dynamos in M-dwarf Stars. M-dwarf stars below a certain mass are convective from their cores to their photospheres. These fully convective objects are extremely numerous, very magnetically active, and the likely hosts of many exoplanets. Here we study, for the first time, dynamo action in simulations of stratified, rotating, fully convective M-dwarf stars. Importantly, we use new techniques to capture the correct full ball geometry down to the center of the star. We find surprising dynamo states in these systems, with the global-scale mean fields confined strongly to a single hemisphere, in contrast to prior stellar dynamo solutions. These hemispheric-dynamo stars are likely to have profoundly different interactions with their surroundings, with important implications for exoplanet habitability and stellar spindown.

Keywords: M dwarf stars, Astrophysical fluid dynamics, Stellar magnetic fields, Magnetohydrodynamical simulations
The Solar Wind Angular Momentum Flux as Observed by Parker Solar Probe. The long-term evolution of the Sun's rotation period cannot be directly observed, and is instead inferred from trends in the measured rotation periods of other Sun-like stars. Assuming the Sun spins down as it ages, following rotation rate ∝ age-1/2, requires the current solar angular momentum (AM) loss rate to be around 6 × 1030 erg. Magnetohydrodynamic models, and previous observations of the solar wind (from the Helios and Wind spacecraft), generally predict a values closer to 1 × 1030 erg or 3 × 1030 erg, respectively. Recently, the Parker Solar Probe (PSP) observed tangential solar wind speeds as high as ∼50 km s-1 in a localized region of the inner heliosphere. If such rotational flows were prevalent throughout the corona, it would imply that the solar wind AM-loss rate is an order of magnitude larger than all of those previous estimations. In this Letter, we evaluate the AM flux in the solar wind, using data from the first two orbits of PSP. The solar wind is observed to contain both large positive (as seen during perihelion), and negative AM fluxes. We analyze two solar wind streams that were repeatedly traversed by PSP; the first is a slow wind stream whose average AM flux fluctuates between positive and negative values, and the second is an intermediate speed stream that contains a positive AM flux (more consistent with a constant flow of AM). When the data from PSP are evaluated holistically, the average equatorial AM flux implies a global AM-loss rate of around (2.6-4.2) × 1030 erg (which is more consistent with observations from previous spacecraft).

Keywords: Solar rotation, Solar wind, Stellar physics, Solar physics, Solar evolution, Stellar rotation, Stellar evolution
A Disk-driven Resonance as the Origin of High Inclinations of Close-in Planets. The recent characterization of transiting close-in planets has revealed an intriguing population of sub-Neptunes with highly tilted and even polar orbits relative to their host star's equator. Any viable theory for the origin of these close-in, polar planets must explain (1) the observed stellar obliquities, (2) the substantial eccentricities, and (3) the existence of Jovian companions with large mutual inclinations. In this work, we propose a theoretical model that satisfies these requirements without invoking tidal dissipation or large primordial inclinations. Instead, tilting is facilitated by the protoplanetary disk dispersal during the late stage of planet formation, initiating a process of resonance sweeping and parametric instability. This mechanism consists of two steps. First, a nodal secular resonance excites the inclination to large values; then, once the inclination reaches a critical value, a linear eccentric instability is triggered, which detunes the resonance and ends inclination growth. The critical inclination is pushed to high values by general relativistic precession, making polar orbits an inherently post-Newtonian outcome. Our model predicts that polar, close-in sub-Neptunes coexist with cold Jupiters in low stellar obliquity orbits.

Keywords: Exoplanet dynamics, Exoplanet evolution, Exoplanet formation, Protoplanetary disks