Sazuna/UAT_keywords huggingface dataset:
GRB Prompt Emission with Anisotropic Electron Distribution. The typical spectrum of the prompt emission of gamma-ray bursts (GRBs) indicates that the electron cooling is suppressed in spite of the strong magnetic field in the standard synchrotron model. Recent particle-in-cell simulations show that the particle acceleration by magnetic reconnection in a magnetically dominated plasma can lead to small pitch angles especially in a low-energy region. Such a small pitch angle prevents electrons from cooling via synchrotron radiation. In this paper, taking into account the effects of the synchrotron cooling and the adiabatic cooling, we numerically calculate the synchrotron spectra with anisotropic electron distributions. If we require a Poynting flux larger than 1050 erg s-1 as the model is motivated by magnetic reconnection, the bulk Lorentz factor of ~1000 and the electron minimum Lorentz factor of γ min ~ 104 are required to reproduce the typical GRB spectrum.

Keywords: Gamma-ray bursts
Effect of Dust in Circumgalactic Halos on the Cosmic Shear Power Spectrum. Weak gravitational lensing is a powerful statistical tool for probing the growth of cosmic structure and measuring cosmological parameters. However, as shown by studies such as by Ménard et al., dust in the circumgalactic region of halos dims and reddens background sources. In a weak lensing analysis, this selects against sources behind overdense regions; since there is more structure in overdense regions, we will underestimate the amplitude of density perturbations σ 8 if we do not correct for the effects of circumgalactic dust. To model the dust distribution we employ the halo model. Assuming a fiducial dust mass profile based on measurements from Ménard et al., we compute the ratio Z of the systematic error to the statistical error for a survey similar to the Nancy Grace Roman Space Telescope reference survey (2000 deg2 area, single-filter effective source density 30 galaxies arcmin-2). For a wave band centered at 1580 nm (H band), we find that Z  H  = 0.37. For a similar survey with wave band centered at 620 nm (r band), we also computed Z  r  = 2.8. Within our fiducial dust model, since Z  r  &gt; 1, the systematic effect of dust will be significant on weak lensing image surveys. We also computed the dust bias on the amplitude of the power spectrum, σ 8, and found it to be for each wave band Δσ 8/σ 8 = -3.1 × 10-4 (H band) or -2.2 × 10-3 (r band) if all other parameters are held fixed (the forecast Roman statistical-only error σ(σ 8)/σ 8 is 9 × 10-4).

Keywords: Large-scale structure of the universe
An ALMA Study of the Massive Molecular Clump N159W-North in the Large Magellanic Cloud: A Possible Gas Flow Penetrating One of the Most Massive Protocluster Systems in the Local Group. Massive dense clumps in the Large Magellanic Cloud can be an important laboratory to explore the formation of populous clusters. We report multiscale ALMA observations of the N159W-North clump, which is the most CO-intense region in the galaxy. High-resolution CO isotope and 1.3 mm continuum observations with an angular resolution of ~0.″25 (~0.07 pc) revealed more than five protostellar sources with CO outflows within the main ridge clump. One of the thermal continuum sources, MMS-2, shows an especially massive/dense nature whose total H2 mass and peak column density are ~104 M ⊙ and ~1024 cm-2, respectively, and harbors massive (~100 M ⊙) starless core candidates identified as its internal substructures. The main ridge containing this source can be categorized as one of the most massive protocluster systems in the Local Group. The CO high-resolution observations found several distinct filamentary clouds extending southward from the star-forming spots. The CO (1-0) data set with a larger field of view reveals a conical, ~30 pc long complex extending toward the northern direction. These features indicate that a large-scale gas compression event may have produced the massive star-forming complex. Based on the striking similarity between the N159W-North complex and the other two previously reported high-mass star-forming clouds in the nearby regions, we propose a "teardrops inflow model" that explains the synchronized, extreme star formation across &gt;50 pc, including one of the most massive protocluster clumps in the Local Group.

Keywords: Local Group, Interstellar filaments, Large Magellanic Cloud, Giant molecular clouds, Interstellar clouds, Star formation, Interstellar medium, Protostars
Quasi-periodic Energy Release and Jets at the Base of Solar Coronal Plumes. Coronal plumes are long, ray-like, open structures that have been considered as possible sources of the solar wind. Their origin in the largely unipolar coronal holes has long been a mystery. Earlier spectroscopic and imaging observations revealed blueshifted plasma and propagating disturbances (PDs) in plumes that are widely interpreted in terms of flows and/or propagating slow-mode waves, but these interpretations (flows versus waves) remain under debate. Recently we discovered an important clue about plume internal structure: dynamic filamentary features called plumelets, which account for most of the plume emission. Here we present high-resolution observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Interface Region Imaging Spectrograph that revealed numerous, quasi-periodic, tiny jets (so-called jetlets) associated with transient brightening, flows, and plasma heating at the chromospheric footpoints of the plumelets. By analogy to larger coronal jets, these jetlets are most likely produced within the plume base by magnetic reconnection between closed and open flux at stressed 3D null points. The jetlet-associated brightenings are in phase with plumelet-associated PDs, and vary with a period of ~3-5 minutes, which is remarkably consistent with the photospheric/chromospheric p-mode oscillation. This reconnection at the open-closed boundary in the chromosphere/transition region is likely modulated or driven by local manifestations of the global p-mode waves. The jetlets extend upward to become plumelets, contribute mass to the solar wind, and may be sources of the switchbacks recently detected by the Parker Solar Probe.

Keywords: Solar wind, Jets, Solar magnetic reconnection, Solar coronal plumes
Electromagnetic Counterparts of Binary-neutron-star Mergers Leading to a Strongly Magnetized Long-lived Remnant Neutron Star. We explore the electromagnetic counterparts that will associate with binary-neutron-star mergers for the case that remnant massive neutron stars survive for ≳0.5 s after the merger. For this study, we employ the outflow profiles obtained by long-term general-relativistic neutrino-radiation magnetohydrodynamics simulations with a mean-field dynamo effect. We show that a synchrotron afterglow with high luminosity can be associated with the merger event if the magnetic fields of the remnant neutron stars are significantly amplified by the dynamo effect. We also perform a radiative transfer calculation for kilonovae and find that, for the highly amplified magnetic field cases, the kilonovae can be bright in the early epoch (t ≤ 0.5 d), while it shows the optical emission which rapidly declines in a few days and the very bright near-infrared emission which lasts for ~10 days. All these features have not been found in GW170817, indicating that the merger remnant neutron star formed in GW170817 might have collapsed to a black hole within several hundreds milliseconds or magnetic-field amplification might be a minor effect.

Keywords: Gravitational wave astronomy, Neutron stars, Radiative transfer simulations
No Evidence of the Significant Grain Growth but Tentative Discovery of Disk Substructure in a Disk around the Class I Protostar L1489 IRS. For revealing the first step of planet formation, it is important to understand how and when dust grains become larger in a disk around a protostar. To investigate the grain growth, we analyze dust continuum emission toward a disk around the Class I protostar L1489 IRS at 0.9 and 1.3 mm wavelengths obtained by the Atacama Large Millimeter/submillimeter Array. The dust continuum emission extends to a disk radius (r) of r ~ 300 au, and the spectral index (α) is derived to be α ~ 3.6 at a radius of r ~ 100-300 au, similar to the interstellar dust. Therefore, the grain growth does not occur significantly in the outer disk (r ~ 100-300 au). Furthermore, we tentatively identify a ring-like substructure at r ~ 90 au even though the spatial resolution and sensitivity are not enough to determine this structure. If this is the real ring structure, the ring position and small dust in the disk outer part are consistent with the idea of the growth front. These results suggest that the L1489 protostellar disk may be the beginning of planet formation.

Keywords: Young stellar objects, Star formation, Dust continuum emission, Protostars, Planet formation
About One-point Statistics of the Ratio of Two Fourier-transformed Cosmic Fields and an Application. The Fourier transformation is an effective and efficient operation of Gaussianization at the one-point level. Using a set of N-body simulation data, we verified that the one-point distribution functions of the dark matter momentum divergence and density fields closely follow complex Gaussian distributions. The one-point distribution function of the quotient of two complex Gaussian variables is introduced and studied. Statistical theories are then applied to model one-point statistics about the growth of individual Fourier modes of the dark matter density field, which can be obtained by the ratio of two Fourier-transformed cosmic fields. Our simulation results proved that the models based on the Gaussian approximation are impressively accurate, and our analysis revealed many interesting aspects of the growth of dark matter's density fluctuation in Fourier space.

Keywords: Astrostatistics distributions, Dark matter distribution, N-body simulations, Large-scale structure of the universe
The Equilibrium Tide: An Updated Prescription for Population Synthesis Codes. We present an updated prescription for the equilibrium tides suitable for population synthesis codes. A grid of 1D evolutionary models was created and the viscous timescale was calculated for each detailed model. A metallicity-dependent power-law relation was fitted to both the convective cores and convective envelopes of the models. The prescription was implemented into the population synthesis code Binary Star Evolution and predicts a 16.5% reduction in the overall number of merges, with those involving main-sequence stars most affected. The new prescription also reduces the overall supernova rate by 3.6% with individual channels being differently affected. The single degenerate Ia supernova occurrence is reduced by 12.8%. The merging of two carbon oxygen white dwarfs to cause a Ia supernova occurs 16% less frequently. The number of subsynchronously rotating stars in close binaries is substantially increased with our prescription, as is the number of noncircularized systems at the start of common-envelope evolution.

Keywords: Stellar populations, Tidal interaction, Stellar evolutionary models, Binary stars
Relationship between the Sunspot Number and Active Day Fraction: An Application for the Maunder Minimum. Long-term solar activity can be studied using several parameters. Some of the most used are based on the sunspot counting. The active day fraction (ADF) is the simplest index derived from this counting. It is reliable in periods of low solar activity such as the Maunder minimum (MM). In this work, we study the relationship between the ADF and the sunspot number. We have obtained that the optimal fit of that relationship is an exponential function whose exponent is a degree 3 polynomial including all data except those with ADF equal to 100%. Then, we use that fit to estimate the sunspot number during the MM from the ADF calculated from the most recent sunspot group number database. Our estimations of the annual sunspot numbers are below 15, except that for 1656, which is 40.8, whereas our estimations of the triennial sunspot numbers are below 10 from 1648 to 1714. We have found peaks of the solar cycle in the middle of the 1650s, 1670s, 1680s, and 1700s but no clear evidence of solar cycle in the 1660s and 1690s, likely due to the scarcity of the available data. Our results agree with previous works obtaining values significantly higher than those of the group sunspot number derived by Hoyt and Schatten in 1998 but still fully compatible with a grand minimum period.

Keywords: Solar cycle, Sunspot number, The Sun, Sunspots, Maunder minimum
The Magnetic Field of the Stripped Primary in the υ Sgr System, a Member of the Rare Class of Hydrogen-deficient Binaries. We present the results of high-resolution spectropolarimetric observations of the optically dominant component in the rare hydrogen-deficient binary system υ Sgr. Only a small number of such systems in a very late phase of helium shell burning are currently known. The mass transfer from the donor star in binary systems usually leads to the stripping of its hydrogen envelope. Consequently, since the mass of the secondary increases, it appears rejuvenated. Using a few ESO FORS 1 low-resolution spectropolarimetric observations of this system, Hubrig et al. announced in 2009 the presence of a magnetic field of the order of -70 to -80 G. Here we report on more recent high-resolution ESO HARPS spectropolarimetric observations showing that the primary in υ Sgr is a spectrum variable star and possesses a weak magnetic field of the order of a few tens of Gauss. The detection of a magnetic field in this rare hydrogen-deficient binary is of particular interest, as such systems are frequently discussed as probable progenitors of core-collapse supernovae and gravitational-wave sources. Future magnetic studies of such systems would be worthwhile to gain deeper insights into the role of magnetic fields in the evolution of massive stars in binary systems.

Keywords: Spectropolarimetry, Stellar magnetic fields, Interacting binary stars, Common envelope binary stars
Quasars with Proper Motions and the Link to Double and Multiple AGNs. Gaia used a large sample of photometrically selected active galactic nuclei (AGNs) and quasars to remove the residual spin of its global proper motion system in order to achieve a maximally inertial reference frame. A small fraction of these reference objects have statistically significant astrometric proper motions in Gaia EDR3. We compile a source sample of 105,593 high-fidelity AGNs with accurate spectroscopically determined redshifts above 0.5 from the SDSS and normalized proper motions below 4. The rate of genuinely perturbed proper motions is at least 0.17%. A smaller high completeness sample of 152 quasars with excess proper motions at a confidence level of 0.9995 is examined in detail. Pan-STARRS images and Gaia-resolved pairs reveal that 29% of the sample are either double sources or gravitationally lensed quasars. An Anderson-Darling test on parameters of a smaller high-reliability sample and their statistical controls reveals 17 significant factors that favor multiplicity and multi-source structure as the main cause of perturbed astrometry. Using a nearest-neighbor distance statistical analysis and counts of close companions in Gaia on a much larger initial sample of AGNs, an excess of closely separated sources in Gaia is detected. At least 0.33% of all optical quasars are genuinely double or multiply imaged. We provide a list of 44 candidate double or multiple AGNs and four previously known gravitational lenses. Many proper motion quasars may be more closely separated, unresolved doubles exhibiting the variability imposed motion effect, and a smaller fraction may be chance alignments with foreground stars causing weak gravitational lensing.

Keywords: Double quasars, Astrometric microlensing effect, Gravitational lensing, Astrometry, Proper motions
Stationary Accretion Flow with Nuclear Burning. We present a series of numerical solutions of spherically symmetric stationary flows with nuclear burning accreted by a neutron star (or black hole). We consider the accretion of matter composed of carbon and oxygen, which mimics the flow after a neutron star is engulfed by a CO star or the CO core of a massive star. It is found that there are two types of transonic solutions depending on the accretion rate. The flow with a low accretion rate reaches the center (or the surface of the central object) at supersonic speeds. The other type with a high accretion rate has another sonic point inside the transonic point and the flow truncates at the sonic point. The critical accretion rate dividing these two types is derived as a function of the mass of the central object and the specific enthalpy in the ambient matter. We discuss implications from the solutions for a new mechanism of super-Chandrasekhar Type Ia supernovae and Type Icn supernovae.

Keywords: Type Ic supernovae, Stellar mergers, Bondi accretion, Interacting binary stars, Carbon burning, Type Ia supernovae, Oxygen burning
Resolved Stellar Mass Maps of Galaxies in the Hubble Frontier Fields: Evidence for Mass Dependency in Environmental Quenching. One of the challenges in understanding the quenching processes for galaxies is connecting progenitor star-forming populations to their descendant quiescent populations over cosmic time. Here we attempt a novel approach to this challenge by assuming that the underlying stellar mass distribution of galaxies is not significantly altered during environmental-quenching processes that solely affect the gas content of cluster galaxies, such as strangulation and ram pressure stripping. Using the deep, high-resolution photometry of the Hubble Frontier Fields, we create resolved stellar mass maps for both cluster and field galaxies, from which we determine 2D Sérsic profiles, and obtain Sérsic indices and half-mass radii. We classify the quiescent cluster galaxies into disk-like and bulge-like populations based on their Sérsic indices, and find that bulge-like quiescent galaxies dominate the quiescent population at higher masses (M ⋆ &gt; 109.5 M ⊙), whereas disk-like quiescent galaxies dominate at lower masses (108.5 M ⊙ &lt; M ⋆ &lt; 109.5 M ⊙). Using both the Sérsic indices and half-mass radii, we identify a population of quiescent galaxies in clusters that are morphological analogs of field star-forming galaxies. These analogs are interpreted to be star-forming galaxies that had been environmentally quenched. We use these morphological analogs to compute the environmental-quenching efficiency, and we find that the efficiency decreases with increasing stellar mass. This demonstrates that environmental quenching is more effective on less massive galaxies and that the effect of environment on quenching galaxies is not completely separable from the effect of mass on quenching galaxies.

Keywords: Galaxy clusters, Galaxies, Galaxy classification systems, Galactic and extragalactic astronomy, Galaxy evolution, Galaxy quenching, Galaxy processes
A Library of Synthetic X-Ray Spectra for Fitting Tidal Disruption Events. We present a tabulated version of our slim-disk model for fitting tidal disruption events (TDEs). We create a synthetic X-ray spectral library by ray-tracing stationary general relativistic slim disks and including gravitational redshift, Doppler, and lensing effects self-consistently. We introduce the library to reduce computational expense and increase access for fitting future events. Fitting requires interpolation between the library spectra; the interpolation error in the synthetic flux is generally &lt;10% (it can rise to 40% when the disk is nearly edge-on). We fit the X-ray spectra of the TDEs ASASSN-14li and ASASSN-15oi, successfully reproducing our earlier constraints on black hole mass M • and spin a • from full on-the-fly ray-tracing. We use the library to fit mock observational data to explore the degeneracies among parameters, finding that (1) spectra from a hotter thermal disk and edge-on inclination angle offer tighter constraints on M • and a •; (2) the constraining power of spectra on M • and a • increases as a power law with the number of X-ray counts, and the index of the power law is higher for hotter thermal disk spectra; (3) multiepoch X-ray spectra partially break the degeneracy between M • and a •; (4) the time-dependent level of X-ray absorption can be constrained from spectral fitting. The tabulated model and slim-disk model are available at https://doi.org/10.25739/hfhz-xn60.

Keywords: X-ray astronomy, Supermassive black holes, Galaxy accretion disks, Galaxy accretion
The Role of O+ and He+ in the Propagation of Kinetic Alfvén Waves in the Earth's Inner Magnetosphere. Interactions between plasma particles and electromagnetic waves play a crucial role in the dynamics and regulation of the state of space environments. From plasma physics theory, the characteristics of the waves and their interactions with the plasma strongly depend on the composition of the plasma, among other factors. In the case of the Earth's magnetosphere, the plasma is usually composed of electrons, protons, O+ ions, and He+ ions, all with their particular properties and characteristics. Here, using plasma parameters relevant for the inner magnetosphere, we study the dispersion properties of kinetic Alfvén waves (KAWs) in a plasma composed of electrons, protons, He+ ions, and O+ ions. We show that heavy ions induce significant changes to the dispersion properties of KAWs, such as polarization, compressibility, and the electric-to-magnetic amplitude ratio, and therefore the propagation of KAWs is highly determined by the relative abundance of He+ and O+ in the plasma. These results, when discussed in the context of observations in the Earth's magnetosphere, suggest that for many types of studies based on theory and numerical simulations, the inclusion of heavy ions should be customary for the realistic modeling of plasma phenomena in the inner magnetosphere or other space environments in which heavy ions can contribute a substantial portion of the plasma, such as planetary magnetospheres and comet plasma tails.

Keywords: Planetary magnetospheres, Space plasmas, Alfven waves
Taylor Microscale and Effective Reynolds Number near the Sun from PSP. The Taylor microscale is a fundamental length scale in turbulent fluids, representing the end of fluid properties and onset of dissipative processes. The Taylor microscale can also be used to evaluate the Reynolds number in classical turbulence theory. Although the solar wind is weakly collisional, it approximately behaves as a magnetohydrodynamic (MHD) fluid at scales larger than the kinetic scale. As a result, classical fluid turbulence theory and formalisms are often used to study turbulence in the MHD range. Therefore, a Taylor microscale can be used to estimate an effective Reynolds number in the solar wind. NASA's Parker Solar Probe (PSP) has reached progressively closer to the Sun than any other spacecraft before. The collected data have revealed many new findings in the near-Sun solar wind. Here, we use the PSP data to estimate the Taylor microscale and effective Reynolds number near the Sun. We find that the Taylor microscale and Reynolds number are small compared to the corresponding near-Earth values, indicating a solar wind that has been less processed by turbulence, with very small-scale dissipative processes near the Sun.

Keywords: Interplanetary turbulence, Space plasmas, Magnetohydrodynamics, Solar wind