Sazuna/UAT_keywords huggingface dataset:
MeV-GeV Gamma-Ray Emission from SNR G327.1-1.1 Discovered by the Fermi-LAT. We report the discovery of MeV-GeV γ-ray emission by the Fermi-LAT positionally coincident with the TeV pulsar wind nebula (PWN) HESS J1554-550 within the host supernova remnant (SNR) G327.1-1.1. The γ-ray emission is point-like and faint but significant (&gt;4σ) in the 300 MeV-2 TeV energy range. We report here the Fermi-LAT analysis of the observed γ-ray emission followed by a detailed multiwavelength investigation to understand the nature of the emission. The central pulsar powering the PWN within G327.1-1.1 has not been detected in any wave band; however, it is likely embedded within the X-ray nebula, which is displaced from the center of the radio nebula. The γ-ray emission is faint and therefore a pulsation search to determine if the pulsar may be contributing is not feasible. Prior detailed multiwavelength reports revealed an SNR system that is old, τ ~ 18,000 yr, where the interaction of the reverse shock with the PWN is underway or has recently occurred. We find that the γ-ray emission agrees remarkably well with a detailed broadband model constructed in a prior report based on independent hydrodynamical and semianalytic simulations of an evolved PWN. We further investigate the physical implications of the model for the PWN evolutionary stage incorporating the new Fermi-LAT data and attempt to model the distinct particle components based on a spatial separation analysis of the displaced PWN counterparts.

Keywords: X-ray astronomy, Supernova remnants, Radiative processes, Spectral energy distribution, Pulsar wind nebulae, Gamma-ray astronomy
Rocky Histories: The Effect of High Excitations on the Formation of Rocky Planets. Rocky planets both in and outside of our solar system are observed to have a range of core-mass fractions (CMFs). Imperfect collisions can preferentially strip mantle material from a planet, changing its CMF, and are therefore thought to be the most likely cause of this observed CMF variation. However, previous work that implements these collisions into N-body simulations of planet formation has struggled to reliably form high CMF super-Earths. In this work, we specify our initial conditions and simulation parameters to maximize the prevalence of high-energy, CMF-changing collisions in order to form planets with highly diverse CMFs. High-energy collisions have a large v imp/v esc ratio, so we maximize this ratio by starting simulations with high eccentricity and inclination disks to increase the difference in their orbital velocities, maximizing v imp. Additionally, we minimize v esc by starting with small embryos. The final planets undergo more high-energy, debris-producing collisions, and experience significant CMF change over their formation. However, we find that a number of processes work together to average out the CMF of a planet over time; therefore, we do not consistently form high CMF, high-mass planets. We do form high CMF planets below 0.5 M ⊕. Additionally, we find, in these highly eccentric environments, loss of debris mass due to collisional grinding has a significant effect on final planet masses and CMFs, resulting in smaller planets and a higher average planet CMF. This work highlights the importance of improving measurements of high-density planets to better constrain their CMFs.

Keywords: Extrasolar rocky planets, Exoplanet formation, Super Earths
Estimating the Convective Turnover Time. The introduction of the Rossby number (R0), which incorporates the convective turnover time (τ), in 1984 was a pioneering idea for understanding the correlation between stellar rotation and activity. The convective turnover time, which cannot be measured directly, is often inferred using existing τ-mass or τ-color relations, typically established based on an ensemble of different types of stars by assuming that τ is a function of mass. In this work, we use Gaia Early Data Release 3 to demonstrate that the masses used to establish one of the most cited τ-mass relations are overestimated for G-type dwarfs and significantly underestimated for late M dwarfs, offsets that affect studies using this τ-mass relation to draw conclusions. We discuss the challenges of creating such relations then and now. In the era of Gaia and other large data sets, stars used to establish these relations require characterization in a multidimensional space, rather than via the single-characteristic relations of the past. We propose that new multidimensional relations should be established based on updated theoretical models and all available stellar parameters for different interior structures from a set of carefully vetted single stars, so that the convective turnover time can be estimated more accurately.

Keywords: M dwarf stars, Hertzsprung Russell diagram, Stellar activity
Does the Lockstep Growth between Black Holes and Bulges Create Their Mass Relation?. Recent studies have revealed a strong relation between the sample-averaged black hole (BH) accretion rate (BHAR) and star formation rate (SFR) among bulge-dominated galaxies-i.e., "lockstep" BH-bulge growth-in the distant universe. This relation might be closely connected to the BH-bulge mass correlation observed in the local universe. To further understand BH-bulge coevolution, we present Atacama Large Millimeter/submillimeter Array (ALMA) CO(2-1) or CO(3-2) observations of seven star-forming bulge-dominated galaxies at z = 0.5-2.5. Using the ALMA data, we detect significant (&gt;3σ) CO emission from four objects. For our sample of seven galaxies, we measure (or constrain with upper limits) their CO line fluxes and estimate their molecular gas masses (M gas). We also estimate their stellar masses (M star) and SFRs, by modeling their spectral energy distributions. Using these physical properties, we derive the gas depletion timescales (τ dep ≡ M gas/SFR) and compare them with the bulge/BH growth timescales (τ grow ≡ M star/SFR ~ M BH/BHAR). Our sample generally has τ dep shorter than τ grow by a median factor of ≳4, indicating that the cold gas will be depleted before significant bulge/BH growth takes place. This result suggests that BH-bulge lockstep growth is mainly responsible for maintaining the mass relation, not creating it. We note that our sample is small and limited to z &lt; 2.5; JWST and ALMA will be able to probe to higher redshifts in the near future.

Keywords: Supermassive black holes, Molecular gas, Galaxy bulges, Star formation, Spectral energy distribution
Deep Learning-based Fast Spectral Inversion of Hα and Ca II 8542 Line Spectra. A multilayer spectral inversion (MLSI) model has recently been proposed for inferring the physical parameters of plasmas in the solar chromosphere from strong absorption lines taken by the Fast Imaging Solar Spectrograph (FISS). We apply a deep neural network (DNN) technique in order to produce the MLSI outputs with reduced computational costs. We train the model using two absorption lines, Hα and Ca II 8542 Å, taken by FISS, and 13 physical parameters obtained from the application of MLSI to 49 raster scans (~2,000,000 spectra). We use a fully connected network with skip connections and multi-branch architecture to avoid the problem of vanishing gradients and to improve the model's performance. Our test shows that the DNN successfully reproduces the physical parameters for each line with high accuracy and a computing time of about 0.3-0.4 ms per line, which is about 250 times faster than the direct application of MLSI. We also confirm that the DNN reliably reproduces the temporal variations of the physical parameters generated by the MLSI inversion. By taking advantage of the high performance of the DNN, we plan to provide physical parameter maps for all the FISS observations, in order to understand the chromospheric plasma conditions in various solar features.

Keywords: Solar chromosphere, Spectroscopy, Neural networks
Compton-thick AGN in the NuSTAR Era. IX. A Joint NuSTAR and XMM-Newton Analysis of Four Local AGN. We present the results of the broadband X-ray spectral analysis of simultaneous NuSTAR and XMM-Newton observations of four nearby Compton-thick active galactic nuclei (AGN) candidates selected from the Swift Burst Alert Telescope 150 month catalog. This work is part of a larger effort to identify and characterize all Compton-thick (N H ≥ 1024 cm-2) AGN in the local universe (z ≤ 0.05). We used three physically motivated models-MYTorus, borus02, and UXClumpy-to fit and characterize these sources. Of the four candidates analyzed, 2MASX J02051994-0233055 was found to be an unobscured (N H &lt; 1022 cm-2) AGN, 2MASX J04075215-6116126 and IC 2227 to be Compton-thin (1022 cm-2 &lt; N H &lt; 1024 cm-2) AGN, and one, ESO 362-8, was confirmed to be a Compton-thick AGN. Additionally, every source was found to have a statistically significant difference between their line-of-sight and average torus hydrogen column density, further supporting the idea that the obscuring material in AGN is inhomogeneous. Furthermore, half of the sources in our sample (2MASX J02051994-0233055 and 2MASX J04075215-6116126) exhibited significant luminosity variation in the last decade, suggesting that this might be a common feature of AGN.

Keywords: X-ray active galactic nuclei, Active galactic nuclei
Probing Accretion Turbulence in the Galactic Center with EHT Polarimetry. Magnetic fields grown by instabilities driven by differential rotation are believed to be essential to accretion onto black holes. These instabilities saturate in a turbulent state; therefore, the spatial and temporal variability in the horizon-resolving images of Sagittarius A* (Sgr A*) will be able to empirically assess this critical aspect of accretion theory. However, interstellar scattering blurs high-frequency radio images from the Galactic center and introduces spurious small-scale structures, complicating the interpretation of spatial fluctuations in the image. We explore the impact of interstellar scattering on the polarized images of Sgr A* and demonstrate that for credible physical parameters, the intervening scattering is non-birefringent. Therefore, we construct a scattering mitigation scheme that exploits horizon-resolving polarized millimeter/submillimeter VLBI observations to generate statistical measures of the intrinsic spatial fluctuations and therefore the underlying accretion flow turbulence. An optimal polarization basis is identified, corresponding to measurements of the fluctuations in magnetic field orientation in three dimensions. We validate our mitigation scheme using simulated data sets and find that current and future ground-based experiments will readily be able to accurately measure the image-fluctuation power spectrum.

Keywords: Interstellar scattering, Very long baseline interferometry, Radio interferometry, Polarimetry
Complexity of the Upper Solar Atmosphere Revealed from Spectropolarimetry during a Solar Eclipse. We analyze linear polarimetric spectrum data of solar emission lines with different formation temperatures in a visible light band from 516.3-532.6 nm, obtained during the 2013 Gabon solar eclipse using the prototype Fiber Arrayed Solar Optical Telescope. Complexities are found from the chromosphere through the transition zone to the corona at the spatial resolution limit of 2″ and temporal resolution of seconds. The observations show irregular spatial and spectral variations in linear polarization amplitudes, directions, and profile shapes. Within the observational band, spectral lines with different formation temperatures can have comparable polarization amplitudes in one spatial volume but one order difference in another, and at the same spatial volume, the amplitudes can differ by one order at different lines. The polarization amplitudes do not consistently increase with elongation in local regions. The variation in the direction of the polarization along the elongation is found from the green coronal line and the transition zone line more frequently than from the chromospheric lines. Such a variation in orientation is not synchronous for the different lines. Finally, Stokes Q/I profiles of the broad lines, such as the magnesium triplet and the green coronal line, show very diverse and complicated patterns. After pixel binning, we show that some of the complexity may be caused by the integration over different polarization sources at subresolution scales and/or along the line of sight in the optically thin layers with complex geometric corrugations.

Keywords: Solar atmosphere, Solar chromosphere, Solar corona
Implicit Large-eddy Simulations of Global Solar Convection: Effects of Numerical Resolution in Nonrotating and Rotating Cases. Simulating deep solar convection and its coupled mean-field motions is a formidable challenge where few observational results constrain models that suffer from the nonphysical influence of the grid resolution. We present hydrodynamic global implicit large-eddy simulations of deep solar convection performed with the EULAG-MHD code, and we explore the effects of grid resolution on the properties of rotating and nonrotating convection. The results, based on low-order moments and turbulent spectra, reveal that convergence in nonrotating simulations may be achieved at resolutions not much higher than these considered here. The flow is highly anisotropic, with the energy contained in horizontal divergent motions exceeding their radial counterpart by more than three orders of magnitude. By contrast, in rotating simulations, the largest energy is in the toroidal part of the horizontal motions. As the grid resolution increases, the turbulent correlations change in such a way that a solar-like differential rotation, obtained in the simulation with the coarser grid, transitions to an antisolar differential rotation. The reason for this change is the contribution of the effective viscosity to the balance of the forces driving large-scale flows. As the effective viscosity decreases, the angular momentum balance improves, yet the force balance in the meridional direction lessens, favoring a strong meridional flow that advects angular momentum toward the poles. The results suggest that obtaining the correct distribution of angular momentum may not be a mere issue of numerical resolution. Accounting for additional physics, such as magnetism or the near-surface shear layer, may be necessary in simulating the solar interior.

Keywords: Hydrodynamical simulations, Solar interior, Solar differential rotation, Solar meridional circulation
Nonlinear Outcome of Coagulation Instability in Protoplanetary Disks. II. Dust-ring Formation Mediated by Backreaction and Fragmentation. In our previous work (Paper I), we demonstrated that coagulation instability results in dust concentration against depletion due to the radial drift and accelerates dust growth locally. In this work (Paper II), we perform numerical simulations of coagulation instability taking into account effects of backreaction to gas and collisional fragmentation of dust grains. We find that the slowdown of the dust drift due to backreaction regulates dust concentration in the nonlinear growth phase of coagulation instability. The dust-to-gas surface density ratio increases from 10-3 up to ~10-2. Each resulting dust ring tends to have a mass of ≃0.5 M ⊕ - 1.5 M ⊕ in our disk model. In contrast to Paper I, the dust surface density profile shows a local plateau structure at each dust ring. In spite of the regulation at the nonlinear growth, the efficient dust concentration reduces their collision velocity. As a result, dust grains can grow beyond the fragmentation barrier, and the dimensionless stopping time reaches unity, as in Paper I. The necessary condition for the efficient dust growth is (1) weak turbulence of α &lt; 1 × 10-3 and (2) a large critical velocity for dust fragmentation (&gt;1 m s-1). The efficient dust concentration in outer regions will reduce the inward pebble flux and is expected to decelerate the planet formation via the pebble accretion. We also find that the resulting rings can be unstable to secular gravitational instability (GI). The subsequent secular GI promotes planetesimal formation. We thus expect that a combination of these instabilities is a promising mechanism for dust-ring and planetesimal formation.

Keywords: Planetesimals, Protoplanetary disks, Circumstellar disks
Adsorption-driven Gas Trapping in Cometary Ice Analogs. Icy planetary bodies carry volatiles in abundances that should reflect the conditions of their formation. However, the interpretation of volatile abundance data from comets is complicated by the fact that the governing parameters and underlying mechanism of volatile trapping are poorly constrained. To unravel the mechanism of gas trapping in water ice and shed light on the origin of comets, gas-trapping experiments were conducted under isothermal conditions with a focus on the relationship between adsorption properties and the quantities of trapped gas. The adsorption data suggest that the adsorption energies of ice surfaces are heterogeneous, and surface properties depend on initial ice-deposition temperatures as well as on the effect of thermal annealing. Sites with different adsorption energies result in temperature dependence of contributing adsorption sites. Moreover, adsorption sites characterized by higher energy contribute predominantly at low pressures, relevant to the protosolar nebula, and at higher temperatures. When new ice was added to the well-characterized ice surface under controlled Ar pressure, the amount of trapped gas was proportional to the amount of gas adsorbed on the newly generated external surface, suggesting the burial of adsorbed gas as the primary mechanism of gas trapping. The ratio of trapped to newly adsorbed gas reflecting the internal to external surface areas ranged between 5 and 20. Assuming the formation of comparable water ice under the pressure-temperature profile of the protosolar nebula, Ar/H2O~10-5 reported from 67P/Churyumov-Gerasimenko could have formed at about 40 K.

Keywords: Laboratory astrophysics, Ice formation
Effects of Background Periodic Flow on MHD Fast-wave Propagation to a Coronal Loop. This paper investigates the propagation of MHD fast waves into a cylindrical coronal loop through an inhomogeneous stationary flow region. The background flow is assumed to have a small, spatially periodic structure in addition to a constant speed. This study focuses on the absorption of the wave energy in Alfvén resonance, comparing it with the constant flow case. A new flow (absorption) regime is induced by the periodic flow structure, which enhances the absorption for the antiparallel flow and inverse absorption (overreflection) for the parallel flow with respect to the axial wavevector, depending on the transitional layer and flow profiles. A giant overreflection and anomalous absorption behavior arises for some flow configurations. In the other flow regimes, its effect on the absorption is shown to be weak.

Keywords: Solar activity, Solar coronal loops, Alfven waves, Solar coronal waves
Contracting and Expanding Binary Black Holes in 3D Low-mass AGN Disks: The Importance of Separation. LIGO/Virgo has detected several binary black hole (BBH) merger events that may have originated in the accretion disks of active galactic nuclei (AGNs). These events require individual black hole masses that fall within the pair instability supernova mass gap, and therefore these black holes may have been grown from hierarchical mergers. AGN disks are a prime environment for hierarchical mergers and thus a potential location for the progenitors of BBH gravitational wave events. Understanding how a BBH embedded in an AGN disk interacts with the surrounding environment is thus crucial for determining whether this interaction can lead to its merger. However, there are few high-fidelity simulations of this process, and almost all are two-dimensional. We present the results from 3D, high-resolution, local shearing-box simulations of an embedded BBH interacting with an AGN disk. In these first simulations of their kind, we focus on determining the mass accretion rate and the orbital evolution rate at different BBH separations. We find that circular, equal-mass BBHs with separations greater than 10% of their Hill radius contract while accreting at a super-Eddington rate. At smaller separations, however, our 3D simulations find that BBHs expand their orbits. This result suggests that it may be difficult for an AGN disk to push a BBH to merger, but we discuss several mechanisms, including MHD turbulence and radiative and mechanical feedback, which could alleviate this difficulty.

Keywords: Hydrodynamical simulations, Active galactic nuclei, Binary stars, Black holes
Measuring Optical Extinction toward Young Stellar Objects Using Diffuse Interstellar Bands. Line-of-sight extinction estimates of well-studied young T Tauri and Herbig Ae/Be stars are based on many different measurements and analysis methods. This has resulted in wide scatter among the published A  V  values for the same star. In this work, we discuss the challenges in measuring extinction to actively accreting and especially outbursting young stellar objects (YSOs). We then explore a method not previously applied to young stars utilizing diffuse interstellar bands (DIBs). In early-type stars, narrow correlations exist between the DIB equivalent widths and the column density of interstellar material, and therefore the line-of-sight extinction. Here, we measure the equivalent widths of the 5780 and 6614 Å DIB features in a sample of actively accreting YSOs, and apply a DIB-reddening calibration to estimate reddening and subsequently extinction. Our calibration is newly derived from a composite of available literature data and fully accounts for the scatter in these measurements. We also compare the DIBs-inferred optical line-of-sight extinction values with previous extinction estimates for our sample stars.

Keywords: Diffuse interstellar bands, FU Orionis stars, Young stellar objects, Pre-main sequence stars, Interstellar extinction
Oblique Quasi-kink Modes in Solar Coronal Slabs Embedded in an Asymmetric Magnetic Environment: Resonant Damping, Phase and Group Diagrams. There has been considerable interest in magnetoacoustic waves in static, straight, field-aligned, 1D equilibria where the exteriors of a magnetic slab are different between the two sides. We focus on trapped, transverse fundamental, oblique quasi-kink modes in pressureless setups, where the density varies continuously from a uniform interior (with density ρ i) to a uniform exterior on either side (with density ρ L or ρ R), assuming ρ L ≤ ρ R ≤ ρ i. The continuous structuring and oblique propagation make our study new, relative to pertinent studies, and lead to wave damping via the Alfvén resonance. We compute resonantly damped quasi-kink modes as resistive eigenmodes, and isolate the effects of system asymmetry by varying ρ i/ρ R from the "Fully Symmetric" (ρ i/ρ R = ρ i/ρ L) to the "Fully Asymmetric" limit (ρ i/ρ R = 1). We find that the damping rates possess a nonmonotonic ρ i/ρ R-dependence as a result of the difference between the two Alfvén continua, and resonant absorption occurs only in one continuum when ρ i/ρ R is below some threshold. We also find that the system asymmetry results in two qualitatively different regimes for the phase and group diagrams. The phase and group trajectories lie essentially on the same side (different sides) relative to the equilibrium magnetic field when the configuration is not far from a "Fully Asymmetric" ("Fully Symmetric") one. Our numerical results are understood by making analytical progress in the thin-boundary limit, and discussed for imaging observations of axial standing modes and impulsively excited wavetrains.

Keywords: Solar coronal seismology, Magnetohydrodynamics, Solar coronal waves