Sazuna/UAT_keywords huggingface dataset:
Suprathermal Ion Energy Spectra and Anisotropies near the Heliospheric Current Sheet Crossing Observed by the Parker Solar Probe during Encounter 7. We present observations of ≳10-100 keV nucleon-1 suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of &lt;0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track the magnetic field polarity reversal and show up to ~10:1 anti-sunward, field-aligned flows and beams closer to the HCS that become nearly isotropic farther from the HCS; (4) the He spectrum steepens either side of the HCS, and the He, O, and Fe spectra exhibit power laws of the form ~E -4-E 6; and (5) maximum energies E  X  increase with the ion's charge-to-mass (Q/M) ratio as ${E}_{X}/{E}_{H}\propto {({Q}_{X}/{M}_{X})}^{\delta }$ , where δ ~ 0.65-0.76, assuming that the average Q states are similar to those measured in gradual and impulsive solar energetic particle events at 1 au. The absence of velocity dispersion in combination with strong field-aligned anisotropies closer to the HCS appears to rule out solar flares and near-Sun coronal-mass-ejection-driven shocks. These new observations present challenges not only for mechanisms that employ direct parallel electric fields and organize maximum energies according to E/Q but also for local diffusive and magnetic-reconnection-driven acceleration models. Reevaluation of our current understanding of the production and transport of energetic ions is necessary to understand this near-solar, current-sheet-associated population of ST ions.

Keywords: Solar magnetic reconnection, Heliosphere, The Sun, Interplanetary particle acceleration, Interplanetary magnetic fields
A Multiparameter Degeneracy in Microlensing Events with Extreme Finite Source Effects. For microlenses with sufficiently low mass, the angular radius of the source star can be much larger than the angular Einstein ring radius of the lens. For such extreme finite source effect (EFSE) events, finite source effects dominate throughout the duration of the event. Here, we demonstrate and explore a continuous degeneracy between multiple parameters of such EFSE events. The first component in the degeneracy arises from the fact that the directly observable peak change of the flux depends on both the ratio of the angular source radius to the angular Einstein ring radius and the fraction of the baseline flux that is attributable to the lensed source star. The second component arises because the directly observable duration of the event depends on both the impact parameter of the event and the relative lens-source proper motion. These two pairwise degeneracies become coupled when the detailed morphology of the light curve is considered, especially when including a limb-darkening profile of the source star. We derive these degeneracies mathematically through analytic approximations and investigate them further numerically with no approximations. We explore the likely physical situations in which these mathematical degeneracies may be realized and potentially broken. As more and more low-mass lensing events (with ever decreasing Einstein ring radii) are detected with improving precision and increasing cadence from microlensing surveys, one can expect that more of these EFSE events will be discovered. In particular, the detection of EFSE microlensing events could increase dramatically with the Roman Space Telescope Galactic Bulge Time Domain Survey.

Keywords: Gravitational microlensing, Free floating planets, Finite-source photometric effect, Primordial black holes
Empirical Constraints on Core-collapse Supernova Yields Using Very Metal-poor Damped Lyα Absorbers. We place empirical constraints on the yields from zero- and low-metallicity core-collapse supernovae (CCSNe) using abundances measured in very metal-poor (VMP; [Fe/H] ≤ -2) damped Lyα absorbers (DLAs). For some abundance ratios ([N,Al,S/Fe]), VMP DLAs constrain the metal yields of the first SNe more reliably than VMP stars. We compile a large sample of high-S/N VMP DLAs from over 30 yr of literature, most with high-resolution spectral measurements. We infer the initial-mass-function-averaged CCSNe yield from the median values from the DLA abundance ratios of C, N, O, Al, Si, S, and Fe (over Fe and O). We assume that the DLAs are metal-poor enough that they represent galaxies in their earliest stages of evolution, when CCSNe are the only nucleosynthetic sources of the metals we analyze. We compare five sets of zero- and low-metallicity theoretical yields to the empirical yields derived in this work. We find that the five models agree with the DLA yields for ratios containing Si and S. Only one model (Heger &amp; Woosley 2010, hereafter HW10) reproduced the DLA values for N, and one other model (Limongi &amp; Chieffi 2018, hereafter LC18) reproduced [N/O]. We found little change in the theoretical yields with the adoption of an SN explosion landscape (where certain progenitor masses collapse into black holes, contributing no yields) onto HW10, but fixing explosion energy to progenitor mass results in wide disagreements between the predictions and DLA abundances. We investigate the adoption of a simple, observationally motivated initial distribution of rotational velocities for LC18 and find a slight improvement.

Keywords: Population III stars, Quasar absorption line spectroscopy, Nucleosynthesis, Core-collapse supernovae, Damped Lyman-alpha systems
ALMA Reveals a Large Overdensity and Strong Clustering of Galaxies in Quasar Environments at z 4. We present an Atacama Large Millimeter/submillimeter Array (ALMA) survey of CO(4-3) line emitting galaxies in 17 quasar fields at z ~ 4 aimed at performing the first systematic search of dusty galaxies in high-z quasar environments. Our blind search of galaxies around the quasars results in five CO emitters with S/N ≥ 5.6 within a projected radius of R ≲ 1.5 h -1 cMpc and a velocity range of δv = ±1000 km s-1 around the quasar. In blank fields, we expect to detect only 0.28 CO emitters within the same volume, implying a total overdensity of ${17.6}_{-7.6}^{+11.9}$ in our fields, and indicating that quasars trace massive structures in the early universe. We quantify this overdensity by measuring the small-scale clustering of CO emitters around quasars, resulting in a cross-correlation length of ${r}_{0,\mathrm{QG}}={8.37}_{-2.04}^{+2.42}\,{h}^{-1}\,$ cMpc, assuming a fixed slope γ = 1.8. This contradicts the reported mild overdensities (x1.4) of Lyα emitters (LAEs) in the same fields at scales of R ≲ 7 h -1 cMpc, which are well described by a cross-correlation length ${3.0}_{-1.4}^{+1.5}$ times lower than that measured for CO emitters. We discuss some possibilities to explain this discrepancy, including low star formation efficiency, and excess of dust in galaxies around quasars. Finally, we constrain, for the first time, the clustering of CO emitters at z ~ 4, finding an autocorrelation length of r 0,CO = 3.14 ±1.71 h -1 cMpc (with γ = 1.8). Our work, together with the previous study of LAEs around quasars, traces simultaneously the clustering properties of both optical and dusty galaxy populations in quasars fields, stressing the importance of multiwavelength studies, and highlighting important questions about galaxy properties in high-z dense environments.

Keywords: Quasar-galaxy pairs, Quasars, Large-scale structure of the universe, Clustering, CO line emission, Submillimeter astronomy, High-redshift galaxies
WALLABY Pre-pilot Survey: The Effects of Tidal Interaction on Radial Distribution of Color in Galaxies of the Eridanus Supergroup. We study the tidal interaction of galaxies in the Eridanus supergroup, using H I data from the pre-pilot survey of the Widefield ASKAP L-band Legacy All-sky Blind surveY. We obtain optical photometric measurements and quantify the strength of tidal perturbation using a tidal parameter S sum. For low-mass galaxies of M * ≲ 109 M ⊙, we find a dependence of decreasing H I to optical disk size ratio with increasing S sum, but no dependence of H I spectral line asymmetry with S sum. This is consistent with the behavior expected under tidal stripping. We confirm that the color profile shape and color gradient depend on the stellar mass, but there is an additional correlation of low-mass galaxies having their color gradients within 2R 50 increasing with higher S sum. For these low-mass galaxies, the dependence of color gradients on S sum is driven by the color becoming progressively redder in the inner disk when tidal perturbations are stronger. For high-mass galaxies, there is no dependence of color gradients on S sum, and we find a marginal reddening throughout the disks with increasing S sum. Our result highlights tidal interaction as an important environmental effect in producing the faint end of the star formation suppressed sequence in galaxy groups.

Keywords: Galaxy environments, Galaxy evolution, Galaxies, Interstellar atomic gas
The (Black Hole Mass)-(Spheroid Stellar Density) Relations: M <SUB>BH</SUB>-μ (and M <SUB>BH</SUB>-Σ) and M <SUB>BH</SUB>-ρ. This paper is the fourth in a series presenting (galaxy morphology, and thus galaxy formation)-dependent black hole (BH) mass, M BH, scaling relations. We have used a sample of 119 galaxies with directly measured M BH and host spheroid parameters obtained from multicomponent decomposition of, primarily, 3.6 μm Spitzer images. Here, we investigate the correlations between M BH and the projected (apparent) luminosity density μ, the projected stellar mass density Σ, and the de-projected (internal) stellar mass density ρ, for various spheroid radii. We discover the predicted M BH-μ 0,sph relation and present the first M BH-μ  e,sph and M BH-ρ e,int,sph diagrams displaying slightly different (possibly curved) trends for early- and late-type galaxies (ETGs and LTGs, respectively) and an offset between ETGs with (fast-rotators, ES/S0) and without (slow-rotators, E) a disk. The scatter about various M BH-&lt;Σ&gt;R,sph (and &lt;ρ&gt; r,sph) relations is shown to systematically decrease as the enclosing aperture (and volume) increases, dropping from 0.69 dex when using the spheroid "compactness," &lt;Σ&gt;1kpc,sph, to 0.59 dex when using &lt;Σ&gt;5kpc,sph. We also reveal that M BH correlates with the internal density, ρ soi,sph, at the BH's sphere-of-influence radius, such that core-Sérsic (high Sérsic index, n) and (low-n) Sérsic galaxies define different relations with total rms scatters 0.21 dex and 0.77 dex, respectively. The M BH-&lt;ρ&gt;soi,sph relations will help with direct estimation of tidal disruption event rates, binary BH lifetimes, and together with other BH scaling relations, improve the characteristic strain estimates for long-wavelength gravitational waves pursued with pulsar timing arrays and space-based interferometers.

Keywords: Supermassive black holes, Late-type galaxies, Galaxy spheroids, Scaling relations, Galaxy evolution, Early-type galaxies
Investigating the Cross Sections of Coronal Mass Ejections through the Study of Nonradial Flows with STEREO/PLASTIC. The solar wind, when measured close to 1 au, is found to flow mostly radially outward. There are, however, periods when the flow makes angles up to 15° away from the radial direction, both in the east-west and north-south directions. Stream interaction regions (SIRs) are a common cause of east-west flow deflections. Coronal mass ejections (CMEs) may be associated with nonradial flows in at least two different ways: (1) the deflection of the solar wind in the sheath region, especially close to the magnetic ejecta front boundary, may result in large nonradial flows; and (2) the expansion of the magnetic ejecta may include a nonradial component, which should be easily measured when the ejecta is crossed away from its central axis. In this work, we first present general statistics of nonradial solar wind flows as measured by STEREO/PLASTIC throughout the first 13 yr of the mission, focusing on solar cycle variation. We then focus on the larger deflection flow angles and determine that most of these are associated with SIRs near solar minimum and with CMEs near solar maximum. However, we find no clear evidence of strongly deflected flows, as would be expected if large deflections around the magnetic ejecta or ejecta with elliptical cross sections with large eccentricities were common. We use these results to develop a better understanding of CME expansion and the nature of magnetic ejecta, and point to shortcomings in our understanding of CMEs.

Keywords: Interplanetary physics, Solar wind, Magnetic fields, Solar coronal mass ejections
A Search for Correlated Low-energy Electron Antineutrinos in KamLAND with Gamma-Ray Bursts. We present the results of a time-coincident event search for low-energy electron antineutrinos in the KamLAND detector with gamma-ray bursts (GRBs) from the Gamma-ray Coordinates Network and Fermi Gamma-ray Burst Monitor. Using a variable coincidence time window of ±500 s plus the duration of each GRB, no statistically significant excess above the background is observed. We place the world's most stringent 90% confidence level upper limit on the electron antineutrino fluence below 17.5 MeV. Assuming a Fermi-Dirac neutrino energy spectrum from the GRB source, we use the available redshift data to constrain the electron antineutrino luminosity and effective temperature.

Keywords: Gamma-ray bursts, Cosmological neutrinos
Simulation of Stark-broadened Hydrogen Balmer-line Shapes for DA White Dwarf Synthetic Spectra. White dwarfs (WDs) are useful across a wide range of astrophysical contexts. The appropriate interpretation of their spectra relies on the accuracy of WD atmosphere models. One essential ingredient of atmosphere models is the theory used for the broadening of spectral lines. To date, the models have relied on Vidal et al., known as the unified theory of line broadening (VCS). There have since been advancements in the theory; however, the calculations used in model atmosphere codes have only received minor updates. Meanwhile, advances in instrumentation and data have uncovered indications of inaccuracies: spectroscopic temperatures are roughly 10% higher and spectroscopic masses are roughly 0.1 M ⊙ higher than their photometric counterparts. The evidence suggests that VCS-based treatments of line profiles may be at least partly responsible. Gomez et al. developed a simulation-based line-profile code Xenomorph using an improved theoretical treatment that can be used to inform questions around the discrepancy. However, the code required revisions to sufficiently decrease noise for use in model spectra and to make it computationally tractable and physically realistic. In particular, we investigate three additional physical effects that are not captured in the VCS calculations: ion dynamics, higher-order multipole expansion, and an expanded basis set. We also implement a simulation-based approach to occupation probability. The present study limits the scope to the first three hydrogen Balmer transitions (Hα, Hβ, and Hγ). We find that screening effects and occupation probability have the largest effects on the line shapes and will likely have important consequences in stellar synthetic spectra.

Keywords: Plasma physics, Fundamental parameters of stars, White dwarf stars, DA stars, Stellar atmospheres
A Model-independent Radio Telescope Dark Matter Search. A novel search technique for ultralight dark matter has been developed and carried out over a narrow range in the L band, utilizing the recent Breakthrough Listen public data release of three years of observation with the Green Bank Telescope. The search concept depends only on the assumption of decay or annihilation of virialized dark matter to a quasimonochromatic radio line, and additionally that the frequency and intensity of the line be consistent with most general properties expected of the phase space of our Milky Way halo. Specifically, the search selects for a line that exhibits a Doppler shift with position according to the solar motion through a static Galactic halo and similarly varies in intensity with the position with respect to the Galactic center. Over the frequency range 1.73-1.83 GHz, radiative annihilation of dark matter is excluded above &lt;σ v&gt; = 1.2 × 10-47 cm3 s-1 and for decay above λ = 4.1 × 10-35 s-1. The analysis of the full Breakthrough Listen GBT data set by this method (25,000 spectra, 1.1-11.6 GHz) is currently underway.

Keywords: Radio spectroscopy, Technosignatures, Radio astronomy, Dark matter, Doppler shift
Global Structure and Dominant Particle Acceleration Mechanism of the Heliosheath: Definitive Conclusions. During its exploration of the heliosheath, the region that lies between the termination shock of the solar wind and the heliopause that separates the solar wind from the local interstellar medium, the Voyager 1 spacecraft (V1) in 2012 encountered an apparent boundary where there was a precipitous decrease in energetic particles accelerated in the heliosheath, the so-called anomalous cosmic rays (ACRs), and from the occasional plasma density measurements on V1, a density comparable to the expected density in the interstellar medium. In 2013, the Voyager principal investigators announced that this apparent boundary was the heliopause and that V1 had entered the interstellar medium. In 2014, Fisk &amp; Gloeckler presented a detailed model that demonstrated that the apparent boundary was simply an internal surface within the heliosheath, across which compressed solar wind flows and will continue to flow until it encounters the actual heliopause. There is compelling observational evidence that the model of Fisk &amp; Gloeckler for the nose region of the heliosheath is correct: V1 did not cross the heliopause in 2012 and is not now in the interstellar medium. There is also compelling observational evidence that the ACRs are accelerated in the heliosheath by the pump acceleration mechanism of Fisk &amp; Gloeckler. The success of the models of Fisk &amp; Gloeckler confirms that the plasma in the nose region of the heliosheath consists of two separate components, the pickup ions and ACRs, and the thermal solar wind, and as a unique plasma is worthy of more study and, if possible, more exploration.

Keywords: Heliopause, Heliosheath, Heliosphere, Termination shock
High-resolution VLBI Observations of and Modeling the Radio Emission from the Tidal Disruption Event AT2019dsg. A tidal disruption event (TDE) involves the shredding of a star in the proximity of a supermassive black hole (SMBH). The nearby (≈230 Mpc) relatively radio-quiet, thermal-emission-dominated source AT2019dsg is the first TDE with a potential neutrino association. The origin of nonthermal emission remains inconclusive; possibilities include a relativistic jet or a subrelativistic outflow. Distinguishing between them can address neutrino production mechanisms. High-resolution very long baseline interferometry 5 GHz observations provide a proper motion of 0.94 ± 0.65 mas yr-1 (3.2 ± 2.2 c; 1σ). Modeling the radio emission favors an origin from the interaction between a decelerating outflow (velocity ≈0.1 c) and a dense circumnuclear medium. The transition of the synchrotron self-absorption frequency through the observation band marks a peak flux density of 1.19 ± 0.18 mJy at 152.8 ± 16.2 days. An equipartition analysis indicates an emission-region distance of ≥ 4.7 × 1016 cm, magnetic field strength ≥ 0.17 G, and number density ≥ 5.7 × 103 cm-3. The disruption involves a ≈2 M ⊙ star with a penetration factor ≈1 and a total energy output of ≤ 1.5 × 1052 erg. The outflow is radiatively driven by the accretion of stellar debris onto the SMBH. Neutrino production is likely related to the acceleration of protons to peta-electron-volt energies and the availability of a suitable cross section at the outflow base. The present study thus helps exclude jet-related origins for nonthermal emission and neutrino production, and constrains nonjetted scenarios.

Keywords: Supermassive black holes, Neutrino astronomy, Tidal disruption, Very long baseline interferometry, Transient sources, Radio astronomy
The Effects of Magnetic Fields and Outflow Feedback on the Shape and Evolution of the Density Probability Distribution Function in Turbulent Star-forming Clouds. Using a suite of 3D hydrodynamical simulations of star-forming molecular clouds, we investigate how the density probability distribution function (PDF) changes when including gravity, turbulence, magnetic fields, and protostellar outflows and heating. We find that the density PDF is not lognormal when outflows and self-gravity are considered. Self-gravity produces a power-law tail at high densities, and the inclusion of stellar feedback from protostellar outflows and heating produces significant time-varying deviations from a lognormal distribution at low densities. The simulation with outflows has an excess of diffuse gas compared to the simulations without outflows, exhibits an increased average sonic Mach number, and maintains a slower star formation rate (SFR) over the entire duration of the run. We study the mass transfer between the diffuse gas in the lognormal peak of the PDF, the collapsing gas in the power-law tail, and the stars. We find that the mass fraction in the power-law tail is constant, such that the stars form out of the power-law gas at the same rate at which the gas from the lognormal part replenishes the power law. We find that turbulence does not provide significant support in the dense gas associated with the power-law tail. When including outflows and magnetic fields in addition to driven turbulence, the rate of mass transfer from the lognormal to the power law, and then to the stars, becomes significantly slower, resulting in slower SFRs and longer depletion times.

Keywords: Giant molecular clouds, Star formation, Stellar feedback
Flexible and Accurate Evaluation of Gravitational-wave Malmquist Bias with Machine Learning. Many astronomical surveys are limited by the brightness of the sources, and gravitational-wave searches are no exception. The detectability of gravitational waves from merging binaries is affected by the mass and spin of the constituent compact objects. To perform unbiased inference on the distribution of compact binaries, it is necessary to account for this selection effect, which is known as Malmquist bias. Since systematic error from selection effects grows with the number of events, it will be increasingly important over the coming years to accurately estimate the observational selection function for gravitational-wave astronomy. We employ density estimation methods to accurately and efficiently compute the compact binary coalescence selection function. We introduce a simple pre-processing method, which significantly reduces the complexity of the required machine-learning models. We demonstrate that our method has smaller statistical errors at comparable computational cost than the method currently most widely used allowing us to probe narrower distributions of spin magnitudes. The currently used method leaves 10%-50% of the interesting black hole spin models inaccessible; our new method can probe &gt;99% of the models and has a lower uncertainty for &gt;80% of the models.

Keywords: Gravitational wave astronomy, Gravitational waves, Gravitational wave sources