Sazuna/UAT_keywords huggingface dataset:
Asymmetric Nuclear Matter in Relativistic Mean-field Models with Isoscalar- and Isovector-meson Mixing. Using the relativistic mean-field model with nonlinear couplings between the isoscalar and isovector mesons, we study the properties of isospin-asymmetric nuclear matter. Not only the vector mixing, ω  μ  ω  μ  ρ  ν  ρ  ν , but also the quartic interaction due to the scalar mesons, σ 2 δ 2, is taken into account to investigate the density dependence of nuclear symmetry energy, E sym, and the neutron star properties. It is found that the δ meson increases E sym at high densities, whereas the σ-δ mixing makes E sym soft above the saturation density. Furthermore, the δ meson and its mixing have a large influence on the radius and tidal deformability of a neutron star. In particular, the σ-δ mixing reduces the neutron star radius; thus, the present calculation can simultaneously reproduce the dimensionless tidal deformabilities of a canonical 1.4 M ⊙ neutron star observed from the binary neutron star merger GW170817 and the compact binary coalescence GW190814.

Keywords: Neutron stars, Relativistic mechanics, Gravitational waves, Nuclear physics
Revisiting Black Hole Hyperaccretion in the Center of Gamma-Ray Bursts for the Lower Mass Gap. The ultrarelativistic jets triggered by neutrino annihilation processes or Blandford-Znajek (BZ) mechanisms in stellar-mass black hole (BH) hyperaccretion systems are generally considered to power gamma-ray bursts (GRBs). Due to the high accretion rate, the central BHs might grow rapidly on a short timescale, providing a new way to understand the lower mass gap problem. In this paper, we use the BH hyperaccretion model to investigate BH mass growth based on observational GRB data. The results show that (i) if the initial BH mass is set as 3 M ⊙, the neutrino annihilation processes are capable of fueling the BHs to escape the lower mass gap for more than half of long-duration GRBs (LGRBs), while the BZ mechanism is inefficient in triggering BH growth for LGRBs; (ii) the mean BH mass growth in the case of LGRBs without observable supernova (SN) association is much larger than that in the case of LGRBs associated with SNe for both mechanisms, which implies that more massive progenitors or lower SN explosion energies prevail throughout the former cases; (iii) for the short-duration GRBs, the mean BH mass growth is satisfied with the mass supply limitation in the scenario of compact object mergers, but the hyperaccretion processes are unable to rescue BHs from the gap in binary neutron star (NS) mergers or the initial BH mass being 3 M ⊙ after NS-BH mergers.

Keywords: Accretion, Gamma-ray bursts, Neutrino astronomy, Magnetic fields, Astrophysical black holes
Massive Black Hole Formation in Dense Stellar Environments: Enhanced X-Ray Detection Rates in High-velocity Dispersion Nuclear Star Clusters. We analyze Chandra X-ray Observatory imaging of 108 galaxies hosting nuclear star clusters (NSCs) to search for signatures of massive black holes (BHs). NSCs are extremely dense stellar environments with conditions that can theoretically facilitate massive BH formation. Recent work by Stone et al. finds that sufficiently dense NSCs should be unstable to the runaway growth of a stellar-mass BH into a massive BH via tidal captures. Furthermore, there is a velocity dispersion threshold (40 km s-1) above which NSCs should inevitably form a massive BH. To provide an observational test of these theories, we measure X-ray emission from NSCs and compare it to the measured velocity dispersion and tidal capture runaway timescale. We find that NSCs above the 40 km s-1 threshold are X-ray detected at roughly twice the rate of those below (after accounting for contamination from X-ray binaries). These results are consistent with a scenario in which dense, high-velocity NSCs can form massive BHs, providing a formation pathway that does not rely on conditions found only at high redshift.

Keywords: Intermediate-mass black holes, Nucleated dwarf galaxies, Astrophysical black holes, Low-luminosity active galactic nuclei
A Partial Filament Eruption in Three Steps Induced by External Magnetic Reconnection. We present an investigation of partial filament eruption on 2012 June 17 in the active region NOAA 11504. For the first time, we observed the vertical splitting process during the partial eruption with high-resolution narrowband images at 10830 Å. The active filament was rooted in a small δ-sunspot of the active region. Particularly, it underwent the partial eruption in three steps, i.e., the precursor, the first eruption, and the second eruption, while the latter two were associated with a C1.0 flare and a C3.9 flare, respectively. During the precursor, slow magnetic reconnection took place between the filament and the adjoining loops that also rooted in the δ-sunspot. The continuous reconnection not only caused the filament to split into three groups of threads vertically but also formed a new filament, which was growing and accompanied brightening took place around the site. Subsequently, the growing filament erupted together with one group splitted threads, resulted in the first eruption. At the beginning of the first eruption, a subsequent magnetic reconnection occurred between the erupting splitted threads and another ambient magnetic loop. After about 3 minutes, the second eruption occurred as a result of the eruption of two larger unstable filaments induced by the magnetic reconnection. The high-resolution observation provides a direct evidence that magnetic reconnection between filament and its ambient magnetic fields could induce the vertical splitting of the filament, resulting in partial eruption.

Keywords: Solar active region magnetic fields, Solar magnetic reconnection, Solar active region filaments, Solar filaments, Solar filament eruptions, Magnetic fields
The Decoupled Kinematics of High-z QSO Host Galaxies and Their Lyα Halos. We present a comparison of the interstellar medium traced by [C II] (Atacama Large Millimeter/submillimeter Array), and ionized halo gas traced by Lyα (Multi Unit Spectroscopic Explorer), in and around QSO host galaxies at z ~ 6. To date, 18 QSOs at this redshift have been studied with both MUSE and high-resolution ALMA imaging; of these, 8 objects display a Lyα halo. Using data cubes matched in velocity resolution, we compare and contrast the spatial and kinematic information of the Lyα halos and the host galaxies' [C II] (and dust-continuum) emission. We find that the Lyα halos extend typically 3-30 times beyond the interstellar medium of the host galaxies. The majority of the Lyα halos do not show ordered motion in their velocity fields, whereas most of the [C II] velocity fields do. In those cases where a velocity gradient can be measured in Lyα, the kinematics do not align with those derived from the [C II] emission. This implies that the Lyα emission is not tracing the outskirts of a large rotating disk, which is a simple extension of the central galaxy seen in [C II] emission. It rather suggests that the kinematics of the halo gas are decoupled from those of the central galaxy. Given the scattering nature of Lyα, these results need to be confirmed with James Webb Space Telescope Integral Field Unit observations that can constrain the halo kinematics further using the nonresonant Hα line.

Keywords: Lyman-alpha galaxies, Supermassive black holes, Quasars
High-precision Calibration of the Fluxgate Magnetometer Offset Vector in the Terrestrial Magnetosheath. High-precision magnetic field measurements are of great significance for the in-depth study of the physical processes in the astrophysical plasma environment. To obtain accurate natural magnetic fields, in-flight calibration is one key step to obtaining zero offset of the spaceborne fluxgate magnetometer (FGM). Mirror mode structures, widely existing in the solar wind and planetary magnetosheaths and magnetospheres, can be used to calculate the zero offset. However, it is difficult to obtain an accurate zero offset by the current methods using mirror mode structures in the planetary magnetosheath. Here, we develop a new method to calculate the zero offset of the spaceborne FGM using magnetic dips, which are a kind of mirror mode structure. This method is based on the assumption that the magnetic field is zero in the cross section of the magnetic dip. Our method is able to calculate the zero offset using only one magnetic dip. We test this method by using the data from the Magnetospheric Multiscale Mission, and find that the calculation errors of 78.1% of the estimated zero offsets are &lt;0.5 nT when using 25 magnetic dips in the terrestrial magnetosheath. This suggests that our method is able to achieve a high accuracy of the zero offset in the planetary magnetosheath.

Keywords: Planetary magnetospheres, Solar wind, Magnetic fields
Magnetohydrodynamic Simulations of Spicular Jet Propagation Applied to Lower Solar Atmosphere Model. II. Case Studies with Tilted Jets. We report on numerical simulations of a propagating momentum pulse, representing an inclined jet structure in a stratified lower solar atmosphere model. Here, the numerical jets were generated via injection of a momentum pulse misaligned with the radial magnetic field, which resulted in a collimated structure that mimicked the observed inclined jet features in the chromosphere. The influence of inclination angle was examined for a variety of initial driver conditions (amplitude, period) and magnetic field magnitudes to identify their potential role in determining the morphological and dynamical characteristics of chromospheric jets. The numerical jets in our computational domain were consistent with the observed magnitudes of apex height and cross-sectional width for average inclination of chromospheric features. Furthermore, with an increasing misalignment between the momentum pulse and ambient magnetic field, the simulated structures showed a drop in the maximum apex height and length, while an increase in cross-sectional width magnitudes. Our numerical experiments also revealed the development of a pulse-like transverse motions in jets along with high density edges/nodes in the direction of jet displacement. It is postulated that dynamic kink instability might be responsible for the observed kinematic behavior of the inclined jet structures in the solar chromosphere.

Keywords: The Sun, Solar spicules, Solar physics, Solar chromosphere, Magnetohydrodynamical simulations
The Extended Tidal Tails of NGC 7089 (M2). Using photometry and proper motions from Gaia Early Data Release 3, we detect a 45° long trailing stellar debris stream associated with the old, metal-poor globular cluster NGC 7089. With a width on the order of 100 pc, the extended stream appears to be as dynamically cold as the coldest known streams found to date. There is some evidence for an extended leading tail extending between 28° and 37° from the cluster, though the greater distance of this tail, combined with proper motions that are virtually indistinguishable from those of foreground stars, make the detection much less certain. The proper motion profile and the path on the sky of the trailing tail are not well matched using a simple Galactic potential composed purely of a disk, bulge, and spherical halo. However, the addition of a moving, massive (M = 1.88 × 1011 M ⊙) Large Magellanic Cloud brings the model predictions into much better agreement with the observables. We provide tables of the most highly ranked candidate stream stars for follow-up by ongoing and future spectroscopic surveys.

Keywords: Galaxy structure, Stellar streams
Surface Brightness Profile of Lyman-α Halos out to 320 kpc in HETDEX. We present the median-stacked Lyman-α (Lyα) surface brightness profiles of 968 spectroscopically selected Lyα emitting galaxies (LAEs) at redshifts 1.9 &lt; z &lt; 3.5 in the early data of the Hobby-Eberly Telescope Dark Energy Experiment. The selected LAEs are high-confidence Lyα detections with high signal-to-noise ratios observed with good seeing conditions (point-spread function FWHM &lt;1.″4), excluding active galactic nuclei. The Lyα luminosities of the LAEs are 1042.4-1043 erg s-1. We detect faint emission in the median-stacked radial profiles at the level of $(3.6\pm 1.3)\times {10}^{-20}\,\mathrm{erg}\,{{\rm{s}}}^{-1}\,{\mathrm{cm}}^{-2}\,{\mathrm{arcsec}}^{-2}$ from the surrounding Lyα halos out to r ≃ 160 kpc (physical). The shape of the median-stacked radial profile is consistent at r &lt; 80 kpc with that of much fainter LAEs at 3 &lt; z &lt; 4 observed with the Multi Unit Spectroscopic Explorer (MUSE), indicating that the median-stacked Lyα profiles have similar shapes at redshifts 2 &lt; z &lt; 4 and across a factor of 10 in Lyα luminosity. While we agree with the results from the MUSE sample at r &lt; 80 kpc, we extend the profile over a factor of two in radius. At r &gt; 80 kpc, our profile is flatter than the MUSE model. The measured profile agrees at most radii with that of galaxies in the Byrohl et al. cosmological radiative transfer simulation at z = 3. This suggests that the surface brightness of a Lyα halo at r ≲ 100 kpc is dominated by resonant scattering of Lyα photons from star-forming regions in the central galaxy, whereas at r &gt; 100 kpc, it is dominated by photons from galaxies in surrounding dark matter halos.

Keywords: Lyman-alpha galaxies, High-redshift galaxies, Circumgalactic medium
Systematics in the Spectral Energy Distribution Fitting Parameter Estimation of Composite Galaxies. Derivation of physical properties of galaxies using spectral energy distribution (SED) fitting is a powerful method, but can suffer from various systematics arising from model assumptions. Previously, such biases were mostly studied in the context of individual galaxies. In this study, we investigate potential biases arising from performing the SED fitting on the combined light of two galaxies, as would be the case in postmerger systems. We use the GALEX-SDSS-WISE Legacy Catalog of z &lt; 0.3 galaxies to identify 9000 galaxy pairs that could eventually merge. For these we investigate if the UV/optical SED fitting accurately determines the stellar mass and (specific) star formation rate (sSFRs) if the pair was unresolved (merged). The sum of the stellar masses (and star formation rates (SFRs)) of individual galaxies in the pair establishes the ground truth for these quantities. For star-forming galaxies no biases (&lt;0.1 dex) are found in the stellar mass, SFR, or sSFRs. Moderate systematics in SFR (~0.1 dex) are found for systems with an extreme contrast in dust content between the two galaxies. We conclude that biases that would arise in the determination of masses and SFRs of postmerger systems on account of the two original galaxies having potentially very different star formation histories and different dust properties are small and that the approach with simple two-component star formation histories is adequate. The approach presented in this study, using flux compositing with empirically determined ground truth, offers new opportunities for testing the results of SED fitting in general.

Keywords: Galaxy masses, Spectral energy distribution, Galaxy mergers, Galaxy properties
Tracing Molecular Gas Mass in z ≃ 6 Galaxies with [C II]. We investigate the fine-structure [C II] line at 158 μm as a molecular gas tracer by analyzing the relationship between molecular gas mass (M mol) and [C II] line luminosity (L [C II]) in 11,125 z ≃ 6 star-forming, main-sequence galaxies from the SIMBA simulations, with line emission modeled by the Simulator of Galaxy Millimeter/Submillimeter Emission. Though most (~50%-100%) of the gas mass in our simulations is ionized, the bulk (&gt;50%) of the [C II] emission comes from the molecular phase. We find a sublinear (slope 0.78 ± 0.01) $\mathrm{log}{L}_{[{\rm{C}}\,{\rm\small{II}}]}\mbox{--}\mathrm{log}{M}_{\mathrm{mol}}$ relation, in contrast with the linear relation derived from observational samples of more massive, metal-rich galaxies at z ≲ 6. We derive a median [C II]-to-M mol conversion factor of α [C II] ≃ 18 M ⊙/L ⊙. This is lower than the average value of ≃30 M ⊙/L ⊙ derived from observations, which we attribute to lower gas-phase metallicities in our simulations. Thus, a lower, luminosity-dependent conversion factor must be applied when inferring molecular gas masses from [C II] observations of low-mass galaxies. For our simulations, [C II] is a better tracer of the molecular gas than CO J = 1-0, especially at the lowest metallicities, where much of the gas is CO-dark. We find that L [C II] is more tightly correlated with M mol than with star formation rate (SFR), and both the $\mathrm{log}{L}_{[{\rm{C}}\,{\rm\small{II}}]}\mbox{--}\mathrm{log}{M}_{\mathrm{mol}}$ and $\mathrm{log}{L}_{[{\rm{C}}\,{\rm\small{II}}]}\mbox{--}\mathrm{log}\,\mathrm{SFR}$ relations arise from the Kennicutt-Schmidt relation. Our findings suggest that L [C II] is a promising tracer of the molecular gas at the earliest cosmic epochs.

Keywords: Molecular gas, Interstellar medium, High-redshift galaxies, Astronomical simulations
General Relativistic Radiation Magnetohydrodynamics Simulations of Black Hole Accretion Disks: Comparison of Methods Based on Variable Eddington Tensor and Based on M1 Closure. We perform 2.5-dimensional general relativistic radiation magnetohydrodynamics simulations of black hole accretion disks and disk winds in the range of mass accretion rate from 0.1 to 104.5 times the Eddington limit. In this paper, we compare the results of the INAZUMA code, in which the frequency-integrated time-dependent radiation transfer equation is solved in order to evaluate the Eddington tensor, with those of the first momentum (M1) approximation method. In both methods, accretion disks and disk winds appear, and there is no remarkable difference in accretion rate, outflow rate, or luminosity. However, the significant difference in the radiation field appears around the rotation axis. In the M1 method, the radial component of the radiation flux tends to be amplified owing to unphysical radiation collisions. Such an enhancement of the outward radiation flux does not appear in INAZUMA. Also, the problem of radiation not reaching the rotation axis occurs with M1, but not with INAZUMA. Our results indicate that the radiation transfer equation should be solved to obtain the accurate radiation field in the optically thin region around the rotation axis.

Keywords: Black hole physics, Radiative magnetohydrodynamics, High energy astrophysics, General relativity, Magnetohydrodynamical simulations
Quenching and the UVJ Diagram in the SIMBA Cosmological Simulation. Over the past decade, rest-frame color-color diagrams have become popular tools for selecting quiescent galaxies at high redshift, breaking the color degeneracy between quiescent and dust-reddened star-forming galaxies. In this work, we study one such color-color selection tool-the rest-frame U - V versus V - J diagram-by employing mock observations of cosmological galaxy formation simulations. In particular, we conduct numerical experiments assessing both trends in galaxy properties in UVJ space and the color-color evolution of massive galaxies as they quench at redshifts z ~ 1-2. We find that our models broadly reproduce the observed UVJ diagram at z = 1-2, including (for the first time in a cosmological simulation) reproducing the population of extremely dust-reddened galaxies in the top right of the UVJ diagram. However, our models primarily populate this region with low-mass galaxies and do not produce as clear a bimodality between star-forming and quiescent galaxies as is seen in observations. The former issue is due to an excess of dust in low-mass galaxies and relatively gray attenuation curves in high-mass galaxies, while the latter is due to the overpopulation of the green valley in SIMBA. When investigating the time evolution of galaxies on the UVJ diagram, we find that the quenching pathway on the UVJ diagram is independent of the quenching timescale, and instead dependent primarily on the average specific star formation rate in the 1 Gyr prior to the onset of quenching. Our results support the interpretation of different quenching pathways as corresponding to the divergent evolution of post-starburst and green valley galaxies.

Keywords: Galaxy quenching, Post-starburst galaxies, Two-color diagrams
Gas-phase Metallicity Profiles of Star-forming Galaxies in the Modified Accretion Disk Framework. Simulations indicate that the inflow of gas of star-forming galaxies is almost coplanar and corotating with the gas disk, and that the outflow of gas driven by stellar winds and/or supernova explosions is preferentially perpendicular to the disk. This indicates that the galactic gas disk can be treated as a modified accretion disk. In this work, we focus on the metal enhancement in galactic disks in this scenario of gas accretion. Assuming that the star formation rate surface density (ΣSFR) is of exponential form, we obtain the analytic solution of gas-phase metallicity with only three free parameters: the scale length of ΣSFR (h R), the metallicity of the inflowing gas, and the mass-loading factor defined as the wind-driven outflow rate surface density per ΣSFR. According to this simple model, the negative gradient of gas-phase metallicity is a natural consequence of the radial inflow of cold gas that is continuously enriched by in situ star formation as it moves toward the disk center. We fit the model to the observed metallicity profiles for six nearby galaxies chosen to have well-measured metallicity profiles extending to very large radii. Our model can well characterize the overall features of the observed metallicity profiles. The observed profiles usually show a floor at the outer regions of the disk, corresponding to the metallicity of inflow gas. Furthermore, we find the h R of ΣSFR inferred from these fits agree well with independent estimates from ΣSFR profiles, supporting the basic model.

Keywords: Galaxy chemical evolution, Metallicity, Galaxies
Estimation of the NiCu Cycle Strength and Its Impact on Type I X-Ray Bursts. Type I X-ray bursts (XRBs) are powered by thermonuclear burning on proton-rich unstable nuclides. The construction of burst models with accurate knowledge of nuclear physics is required to properly interpret burst observations. Numerous studies that have investigated the sensitivities of burst models to nuclear inputs have commonly extracted the strength of the NiCu cycle in the rp process, determined by the 59Cu(p,α)56Ni and 59Cu(p,γ)60Zn thermonuclear reaction rates, as critical in the determination of reaction flow in the burst. In this study, the strength of the cycle at the XRB temperature range was estimated based on published experimental data. The nuclear properties of the compound nucleus 60Zn were evaluated for the 59Cu(p,α)56Ni and 59Cu(p,γ)60Zn reaction rate calculations. Monte Carlo rate calculations were conducted to include the large uncertainties of nuclear properties in the calculations. In the current work, a weak NiCu cycle is expected, whereas the rates adopted by the previous studies suggest a strong NiCu cycle. Model simulations were performed with the new rates to assess the impact on Type I XRBs. The results show that the estimated cycle strength does not strongly influence the model predictions of the burst light curve or synthesized abundances.

Keywords: Nuclear astrophysics, Astrophysical processes, Nuclear reaction cross sections