Sazuna/UAT_keywords huggingface dataset:
Gravity-dominated Collisions: A Model for the Largest Remnant Masses with Treatment for "Hit and Run" and Density Stratification. We develop empirical relationships for the accretion and erosion of colliding gravity-dominated bodies of various compositions under conditions expected in late-stage solar system formation. These are fast, easily coded relationships based on a large database of smoothed particle hydrodynamics (SPH) simulations of collisions between bodies of different compositions, including those that are water rich. The accuracy of these relations is also comparable to the deviations of results between different SPH codes and initial thermal/rotational conditions. We illustrate the paucity of disruptive collisions between major bodies, as compared to collisions between less massive planetesimals in late-stage planet formation, and thus focus on more probable, low-velocity collisions, though our relations remain relevant to disruptive collisions as well. We also pay particular attention to the transition zone between merging collisions and those where the impactor does not merge with the target, but continues downrange, a "hit-and-run" collision. We find that hit-and-run collisions likely occur more often in density-stratified bodies and across a wider range of impact angles than suggested by the most commonly used analytic approximation. We also identify a possible transitional zone in gravity-dominated collisions where larger bodies may undergo more disruptive collisions when the impact velocity exceeds the sound speed, though understanding this transition warrants further study. Our results are contrary to the commonly assumed invariance of total mass (scale), density structure, and material composition on the largest remnants of giant impacts. We provide an algorithm for adopting our model into N-body planet formation simulations, so that the mass of growing planets and debris can be tracked.

Keywords: Impact phenomena, Hydrodynamical simulations, Hydrodynamics, Solar system terrestrial planets, Planetary science, Planet formation
The Structure and Evolution of Massive Rotating Single and Binary Population III Stars. The aim of this paper is to investigate the effect of rotation on the single and binary evolution for Population III stars. A small grid for a massive Population III star of 130 M⊙ is constructed, and various initial conditions are adjusted to explore the evolution. For comparison, we present the evolution of the models with the metallicity in the Small Magellanic Cloud and analyze the characteristic feature of chemically homogeneous evolution. It is found that Population III stars attain the equilibrium velocities later during synchronization owing to a smaller radius. The equilibrium velocity has been expressed as various timescales. There appears to be a deep dredge-up at hydrogen exhaustion for single Population III stars. It not only increases the helium core but also exchanges chemical elements between the He core and the H-burning shell. This will give rise to a significant amount of nitrogen and neon. Rotational mixing can reduce the specific entropy in the envelope and increase the specific entropy in the core owing to a change of mean molecular weight. Stellar compactness and the luminosity available for stellar expansion are decreased by rotational mixing because of the increase of helium in the envelopes. Mass loss induced by strong stellar winds and Roche lobe overflow can extinguish the hydrogen-burning shell and remove convective envelopes. Therefore, this process does not favor the dredge-up and production of primary nitrogen. The chemical structure for two components in binarities is significantly modified because Roche lobe overflow has an impact on convective cores.

Keywords: Close binary stars
ALMA CO Observations of the Host Galaxies of Long-duration Gamma-Ray Bursts. I. Molecular Gas Scaling Relations. We present the results of CO observations toward 14 host galaxies of long-duration gamma-ray bursts (GRBs) at z = 0.1-2.5 by using the Atacama Large Millimeter/submillimeter Array. We successfully detected CO (3-2) or CO (4-3) emission in eight hosts (z = 0.3-2), which more than doubles the sample size of GRB hosts with CO detection. The derived molecular gas mass is Mgas = (0.2-6) × 1010 M⊙ assuming metallicity-dependent CO-to-H2 conversion factors. By using the largest sample of GRB hosts with molecular gas estimates (25 in total, of which 14 are CO detected), including results from the literature, we compared molecular gas properties with those of other star-forming galaxies (SFGs). The GRB hosts tend to have a higher molecular gas mass fraction (μgas) and a shorter gas depletion timescale (tdepl) as compared with other SFGs at similar redshifts, especially at z ≲ 1. This could be a common property of GRB hosts or an effect introduced by the selection of targets that are typically above the main-sequence line. To eliminate the effect of selection bias, we analyzed μgas and tdepl as a function of the distance from the main-sequence line (δMS). We find that the GRB hosts follow the same scaling relations as other SFGs, where μgas increases and tdepl decreases with increasing δMS. No molecular gas deficit is observed when compared to other SFGs of similar star formation rate and stellar mass. These findings suggest that the same star formation mechanism is expected to be happening in GRB hosts as in other SFGs.

Keywords: Observational astronomy, Gamma-ray bursts, Interstellar line emission, Star formation, Galaxy evolution, CO line emission, Submillimeter astronomy, High-redshift galaxies
Discovery and Timing of Pulsars in the Globular Cluster M13 with FAST. We report the discovery of a binary millisecond pulsar (namely PSR J1641+3627F or M13F) in the globular cluster (GC) M13 (NGC 6205) and timing solutions of M13A to F using observations made with the Five-hundred-meter Aperture Spherical radio Telescope. PSR J1641+3627F has a spin period of 3.00 ms and an orbital period of 1.4 days. The most likely companion mass is 0.13 M⊙. M13A to E all have short spin periods and small period derivatives. We also confirm that the binary millisecond pulsar PSR J1641+3627E (also M13E) is a black widow with a companion mass around 0.02 M⊙. We find that all the binary systems have low eccentricities compared to those typical for GC pulsars and that they decrease with distance from the cluster core. This is consistent with what is expected, as this cluster has a very low encounter rate per binary.

Keywords: Period search , Pulsar timing method, Millisecond pulsars
Gamma-Rays from Kilonovae and the Cosmic Gamma-Ray Background. The recent detection of the gravitational-wave event GW170817, produced by the coalescence of two neutron stars, and of its optical-infrared counterpart, powered by the radioactive decay of r-process elements, has opened a new window onto gamma-ray astronomy: the direct detection of photons coming from such decays. Here, we calculate the contribution of kilonovae to the diffuse gamma-ray background in the MeV range, using recent results on the spectra of the gamma-rays emitted in individual events, and we compare it with that from other sources. We find that the contribution from kilonovae is not dominant in such an energy range, but within current uncertainties, and its addition to other sources might help to fit the observational data.

Keywords: Gamma-ray astronomy, R-process, Gamma-ray transient sources, Nucleosynthesis
Scattering Matrix for the Interaction between Solar Acoustic Waves and Sunspots. II. Theory. The interaction between solar acoustic waves and an isolated sunspot is a scattering problem. A common tool to study scattering problems is the scattering matrix, which is the amplitude for the transition from one mode to another after the interaction. In the previous study (Part I), the scattering matrix elements were determined with the measured scattered wavefunction of the sunspot. In this study (Part II), we obtain an analytical relation between the scattering matrix elements and the perturbed quantities of the background medium of the sunspot region. The sunspot is considered a perturbed region relative to the quiet Sun. The perturbation of the background medium includes the magnetic field, the flow velocity, and perturbed thermodynamics quantities, such as the density and pressure perturbations. Inferring these perturbed quantities from measured quantities is one of the goals of helioseismology. Here, with the help of Green's functions, the scattering matrix elements are expressed as a spatial integral, which contains these unknown perturbed quantities. This integral equation, together with the measured scattering matrix elements, could be used to infer the perturbed quantities with the forward and inversion methods. Besides the typical approximations for solar acoustic waves, two additional assumptions are made here: one is the Born approximation, and the other is that the background medium of the sunspot region does not change with time.

Keywords: Solar physics
Evidence for Returning Disk Radiation in the Black Hole X-Ray Binary XTE J1550-564. We explore the accretion properties of the black hole X-ray binary XTE J1550-564 during its outbursts in 1998/99 and 2000. We model the disk, corona, and reflection components of X-ray spectra taken with the Rossi X-ray Timing Explorer, using the relxill suite of reflection models. The key result of our modeling is that the reflection spectrum in the very soft state is best explained by disk self-irradiation, I.e., photons from the inner disk are bent by the strong gravity of the black hole and reflected off the disk surface. This is the first known detection of thermal disk radiation reflecting off the inner disk. There is also an apparent absorption line at ∼6.9 keV, which may be evidence of an ionized disk wind. The coronal electron temperature (kTe) is, as expected, lower in the brighter outburst of 1998/99, explained qualitatively by more efficient coronal cooling due to irradiating disk photons. The disk inner radius is consistent with being within a few times the innermost stable circular orbit throughout the bright-hard-to-soft states (10 s of rg in gravitational units). The disk inclination is low during the hard state, disagreeing with the binary inclination value, and very close to 90° in the soft state, recovering to a lower value when adopting a blackbody spectrum as the irradiating continuum.

Keywords: Accretion, Black hole physics, Atomic physics, Kerr black holes, Low-mass x-ray binary stars, Astrophysical black holes
The Lyman Alpha Reference Sample. X. Predicting Lyα Output from Star-forming Galaxies Using Multivariate Regression. Understanding the production and escape of Lyα radiation from star-forming galaxies is a long-standing problem in astrophysics. The ability to predict the Lyα luminosity of galaxies would open up new ways of exploring the epoch of reionization (EOR) and estimating Lyα emission from galaxies in cosmological simulations where radiative transfer calculations cannot be done. We apply multivariate regression methods to the Lyman Alpha Reference Sample data set to obtain a relation between the galaxy properties and the emitted Lyα. The derived relation predicts the Lyα luminosity of our galaxy sample to good accuracy, regardless of whether we consider only direct observables (rms dispersion around the relation of ∼0.19 dex) or derived physical quantities (rms ∼ 0.27 dex). We confirm the predictive ability on a separate sample of compact star-forming galaxies and find that the prediction works well, but that aperture effects on measured Lyα luminosity may be important, depending on the redshift of the galaxy. We apply statistical feature selection techniques to determine an order of importance of the variables in our data set, enabling future observations to be optimized for predictive ability. When using physical variables, we are able to determine that the most important predictive parameters are, in order, star formation rate, dust extinction, compactness, and the gas covering fraction. We discuss the application of our results in terms of studying the EOR and intensity mapping experiments.

Keywords: Lyman-alpha galaxies, Starburst galaxies, Multivariate analysis
Magnetohydrodynamic Nonlinearities in Sunspot Atmospheres: Chromospheric Detections of Intermediate Shocks. The formation of shocks within the solar atmosphere remains one of the few observable signatures of energy dissipation arising from the plethora of magnetohydrodynamic waves generated close to the solar surface. Active region observations offer exceptional views of wave behavior and its impact on the surrounding atmosphere. The stratified plasma gradients present in the lower solar atmosphere allow for the potential formation of many theorized shock phenomena. In this study, using chromospheric Ca II λ8542 line spectropolarimetric data of a large sunspot, we examine fluctuations in the plasma parameters in the aftermath of powerful shock events that demonstrate polarimetric reversals during their evolution. Modern inversion techniques are employed to uncover perturbations in the temperatures, line-of-sight velocities, and vector magnetic fields occurring across a range of optical depths synonymous with the shock formation. Classification of these nonlinear signatures is carried out by comparing the observationally derived slow, fast, and Alfvén shock solutions with the theoretical Rankine-Hugoniot relations. Employing over 200,000 independent measurements, we reveal that the Alfvén (intermediate) shock solution provides the closest match between theory and observations at optical depths of log10τ =-4, consistent with a geometric height at the boundary between the upper photosphere and lower chromosphere. This work uncovers first-time evidence of the manifestation of chromospheric intermediate shocks in sunspot umbrae, providing a new method for the potential thermalization of wave energy in a range of magnetic structures, including pores, magnetic flux ropes, and magnetic bright points.

Keywords: Solar photosphere, Solar oscillations, Shocks, Solar chromosphere, Magnetic fields
Kelvin-Helmholtz versus Tearing Instability: What Drives Turbulence in Stochastic Reconnection?. Over the last few years it became clear that turbulent magnetic reconnection and magnetized turbulence are inseparable. It was not only shown that reconnection is responsible for violating the frozen-in condition in turbulence, but also that stochastic reconnection in 3D generates turbulence by itself. The actual mechanism responsible for this driving is still unknown. Processes such as the tearing mode or Kelvin-Helmholtz, among other plasma instabilities, could generate turbulence from irregular current sheets. We address the nature of the driving mechanism for this process and consider the relative role of tearing and Kelvin-Helmholtz instabilities for the process of turbulence generation. In particular, we analyze the conditions for development of these two instabilities within 3D reconnection regions. We show that both instabilities can excite turbulence fluctuations in reconnection regions. However, the tearing mode has a relatively slow growth rate, and at later times it becomes partially suppressed by a component of the magnetic field that runs transversely to the current sheet, which is generated during the growth of turbulent fluctuations. In contrast, the Kelvin-Helmholtz instability quickly establishes itself in the outflow region, and at later times, it dominates the turbulence generation compared to the contribution from the tearing mode. Our results demonstrate that the tearing instability is subdominant to the the Kelvin-Helmholtz instability in terms of generation of turbulence in the 3D reconnection layers, and therefore the self-driven reconnection is turbulent reconnection, and the tearing instability is only important at the initial stage of the reconnection.

Keywords: Interplanetary turbulence, Plasma astrophysics, Solar magnetic reconnection
Forecasting [C II] Line-intensity Mapping Measurements between the End of Reionization and the Epoch of Galaxy Assembly. We combine recent simulation work on the SFR-[C II] correlation at high redshift with empirical modeling of the galaxy-halo connection (via UniverseMachine) to forecast [C II] auto power spectra from z ∼ 4 to z ∼ 8. We compare these to sensitivities realistically expected from various instruments expected to come online in the next decade. If the predictions of our model are correct, [C II] should be detectable up to z ∼ 6 in this generation of surveys, but detecting [C II] past the end of reionization will require a generational leap in line-intensity survey capabilities.

Keywords: Radio astronomy, Theoretical models, High-redshift galaxies
Carbon- and Oxygen-rich Asymptotic Giant Branch (AGB) Stars in the Bulge Asymmetries and Dynamical Evolution (BAaDE) Survey. Detections of SiO masers from the Bulge Asymmetries and Dynamical Evolution (BAaDE) survey more tightly define the region where Oxygen-rich (O) Asymptotic Giant Branch (AGB) stars reside in multiple infrared (IR) color-color diagrams. Using Midcourse Space eXperiment (MSX) and Two Micron All Sky Survey (2MASS) data along with radio spectra from the BAaDE survey, we find that three main populations were observed in the BAaDE survey: O-rich AGB stars of which about 73% host SiO masers, Carbon-rich (C) AGB stars that do not host these masers, and a small contaminating set of possible Young Stellar Objects (YSOs). The distinction between YSOs and AGB stars can be drawn using only MSX data, specifically the [D]-[E] color, while the shorter wavelengths provided by 2MASS are necessary to divide potential C- and O-rich AGB stars. Divisions similar to these have been seen in multiple earlier IR-studies, but BAaDE currently provides a sample of ∼15,000 sources, which far exceeds previous studies in sample size, and, therefore, provides much more distinct divisions. With these IR distinctions in place, we discuss the sources that are exceptions in either their molecular detections or IR colors, as well as the distribution of the three populations in Galactic coordinates.

Keywords: Carbon stars, Galactic bulge, Silicon monoxide masers, Circumstellar masers, Asymptotic giant branch stars
A Search for IceCube Events in the Direction of ANITA Neutrino Candidates. During the first three flights of the Antarctic Impulsive Transient Antenna (ANITA) experiment, the collaboration detected several neutrino candidates. Two of these candidate events were consistent with an ultra-high-energy upgoing air shower and compatible with a tau neutrino interpretation. A third neutrino candidate event was detected in a search for Askaryan radiation in the Antarctic ice, although it is also consistent with the background expectation. The inferred emergence angle of the first two events is in tension with IceCube and ANITA limits on isotropic cosmogenic neutrino fluxes. Here we test the hypothesis that these events are astrophysical in origin, possibly caused by a point source in the reconstructed direction. Given that any ultra-high-energy tau neutrino flux traversing the Earth should be accompanied by a secondary flux in the TeV-PeV range, we search for these secondary counterparts in 7 yr of IceCube data using three complementary approaches. In the absence of any significant detection, we set upper limits on the neutrino flux from potential point sources. We compare these limits to ANITA's sensitivity in the same direction and show that an astrophysical explanation of these anomalous events under standard model assumptions is severely constrained regardless of source spectrum.

Keywords: Neutrino astronomy, High energy astrophysics
Three-dimensional Reconstruction of Filament Axes and Their Writhe Numbers. To reveal the correlation between the morphology of filaments and their writhe, we reconstruct the three-dimensional (3D) paths of the filament axes based on the data set of Atmospheric Imaging Assembly and Extreme Ultraviolet Imager on board the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory, respectively. Then, we calculate the writhe of the reconstructed filament axes with the polar writhe theory. All the cases obey that a projected forward (reverse) S-shaped filament possesses positive (negative) writhe. We conduct a further analysis by constructing theoretical 3D curves with non-centrosymmetric shape and only one maximum in height. It is demonstrated that (1) writhe depends on the relative height (the ratio of the height of the curve and the distance between its two footprints), the position of the highest point, and the position of the crossing point (the intersection of a projected axis curve and the line connecting two footprints); (2) for a filament with absolute value of the crossing angle less than π/3 and relative height less than 0.2, forward (reverse) S-shaped projection results in positive (negative) writhe; and (3) when the highest point and the crossing point are significantly separated, the sign of writhe can be conserved without changing the S shape orientation (forward or reverse) during the eruption.

Keywords: Solar filaments, Solar magnetic fields, Solar prominences
PSR J0030+0451, GW170817, and the Nuclear Data: Joint Constraints on Equation of State and Bulk Properties of Neutron Stars. Very recently the NICER collaboration published the first-ever accurate measurement of mass and radius together for PSR J0030+0451, a nearby isolated quickly rotating neutron star (NS). In this work we set the joint constraints on the equation of state (EoS) and some bulk properties of NSs with the data of PSR J0030+0451, GW170817, and some nuclear experiments. The piecewise polytropic expansion method and the spectral decomposition method have been adopted to parameterize the EoS. The resulting constraints are consistent with each other. Assuming the maximal gravitational mass of nonrotating NS MTOV lies between 2.04M⊙ and 2.4M⊙, with the piecewise method the pressure at twice nuclear saturation density is measured to be 3.19-1.35+2.63 × 1034 dyn cm-2 at the 90% level. For an NS with canonical mass of 1.4M⊙, we have the moment of inertia I1.4= 1.43-0.13+0.30× 1038 kg \cdot m2, tidal deformability Λ1.4 = 370-130+360, radius R1.4 = 12.1-0.8+1.2km, and binding energy BE1.4= 0.16-0.02+0.01 M⊙ at the 90% level, which are improved in comparison to the constraints with the sole data of GW170817. These conclusions are drawn for the mass/radius measurements of PSR J0030+0451 by Riley et al. For the measurements of Miller et al., the results are rather similar.

Keywords: Neutron stars, Neutron star cores, Gravitational waves
Black Hole Mass Function of Coalescing Neutron Star Black Hole Binary Systems: The Prospect of Reconstruction with the Gravitational Wave Observations. The discovery of gravitational waves from compact objects coalescence opens a brand-new window to observe the universe. With more events being detected in the future, statistical examinations would be essential to better understand the underlying astrophysical processes. In this work we investigate the prospect of measuring the mass function of black holes that are merging with the neutron stars. Applying Bayesian parameter estimation for hundreds of simulated neutron star-black hole (NSBH) mergers, we find that the parameters for most of the injected events can be well recovered. We also take a Bayesian hierarchical model to reconstruct the population properties of the masses of black holes, in the presence of a low mass gap, both the mass gap and power-law index (α) of black hole mass function can be well measured, thus we can reveal where the α is different for binary black hole (BBH) and NSBH systems. In the absence of a low mass gap, the gravitational wave data as well as the electromagnetic data can be used to pin down the nature of the merger event and then measure the mass of these very light black holes. However, as a result of the misclassification of BBH into NSBH, the measurement of α is more challenging and further dedicated efforts are needed.

Keywords: Gravitational waves, Compact objects, Black holes