Sazuna/UAT_keywords huggingface dataset:
Impact of Radiation Feedback on the Formation of Globular Cluster Candidates during Cloud-Cloud Collisions. To understand the impact of radiation feedback during the formation of a globular cluster (GC), we simulate a head-on collision of two turbulent giant molecular clouds (GMCs). A series of idealized radiation-hydrodynamic simulations is performed, with and without stellar radiation or Type II supernovae. We find that a gravitationally bound, compact star cluster of mass M GC ~ 105 M ⊙ forms within ≈3 Myr when two GMCs with mass M GMC = 3.6 × 105 M ⊙ collide. The GC candidate does not form during a single collapsing event but emerges due to the mergers of local dense gas clumps and gas accretion. The momentum transfer due to the absorption of the ionizing radiation is the dominant feedback process that suppresses the gas collapse, and photoionization becomes efficient once a sufficient number of stars form. The cluster mass is larger by a factor of ~2 when the radiation feedback is neglected, and the difference is slightly more pronounced (16%) when extreme Lyα feedback is considered in the fiducial run. In the simulations with radiation feedback, supernovae explode after the star-forming clouds are dispersed, and their metal ejecta are not instantaneously recycled to form stars.

Keywords: Globular star clusters, Young massive clusters, High-redshift galaxies
Understanding Accretion Variability through TESS Observations of Taurus. Interpreting the short-timescale variability of the accreting, young, low-mass stars known as Classical T Tauri stars remains an open task. Month-long, continuous light curves from the Transiting Exoplanet Survey Satellite (TESS) have become available for hundreds of T Tauri stars. With this vast data set, identifying connections between the variability observed by TESS and short-timescale accretion variability is valuable for characterizing the accretion process. To this end, we obtained short-cadence TESS observations of 14 T Tauri stars in the Taurus star formation region along with simultaneous ground-based, UBVRI-band photometry to be used as accretion diagnostics. In addition, we combine our data set with previously published simultaneous near-UV-near-IR Hubble Space Telescope spectra for one member of the sample. We find evidence that much of the short-timescale variability observed in the TESS light curves can be attributed to changes in the accretion rate, but note significant scatter between separate nights and objects. We identify hints of time lags within our data set that increase at shorter wavelengths, which we suggest may be evidence of longitudinal density stratification of the accretion column. Our results highlight that contemporaneous, multiwavelength observations remain critical for providing context for the observed variability of these stars.

Keywords: Protoplanetary disks, Stellar accretion
Mean-field Analysis on Large-scale Magnetic Fields at High Reynolds Numbers. Solar magnetic fields comprise an 11 yr activity cycle, represented by the number of sunspots. The maintenance of such a solar magnetic field can be attributed to fluid motion in the convection zone, i.e., a dynamo. This study conducts the mean-field analyses of the global solar dynamo simulation presented by Hotta et al. (2016). Although the study succeeds in producing coherent large-scale magnetic fields at high Reynolds numbers, the detailed physics of the maintenance of these fields have not been fully understood. This study extracts the α tensor and the turbulent magnetic diffusivity tensor β through mean-field analyses. The turbulent magnetic diffusivity exhibits a significant decrease toward high Reynolds numbers. The decrease in the turbulent magnetic diffusivity suppresses the energy conversion of large-scale field to small-scale field. This implies that the decrease in the turbulent magnetic diffusivity contributes to the maintenance of a large-scale magnetic field at high Reynolds numbers. A significant downward turbulent pumping is observed; it is enhanced in the weak phase of the large-scale field. This study proposes a cyclic reversal process of a large-scale field, which is dominantly driven by the α effect and is possibly triggered by downward pumping.

Keywords: Solar convective zone, Magnetohydrodynamics, Solar dynamo, Solar magnetic fields
Delivery of Gas onto the Circumplanetary Disk of Giant Planets: Planetary-mass Dependence of the Source Region of Accreting Gas and Mass Accretion Rate. Gas accretion onto the circumplanetary disks and the source region of accreting gas are important to reveal dust accretion that leads to satellite formation around giant planets. We performed local three-dimensional high-resolution hydrodynamic simulations of an isothermal and inviscid gas flow around a planet to investigate the planetary-mass dependence of the gas accretion bandwidth and gas accretion rate onto circumplanetary disks. We examined cases with various planetary masses corresponding to M p = 0.05-1M Jup at 5.2 au, where M Jup is the current Jovian mass. We found that the radial width of the gas accretion band is proportional to {M}_{{\rm{p}}}^{1/6}$ for the low-mass regime with M p ≲ 0.2M Jup while it is proportional to M p for the high-mass regime with M p ≳ 0.2M Jup. We found that the ratio of the mass accretion rate onto the circumplanetary disk to that into the Hill sphere is about 0.4 regardless of the planetary mass for the cases we examined. Combining our results with the gap model obtained from global hydrodynamic simulations, we derive a semi-analytical formula of mass accretion rate onto circumplanetary disks. We found that the mass dependence of our three-dimensional accretion rates is the same as the previously obtained two-dimensional case, although the qualitative behavior of accretion flow onto the circumplanetary disk is quite different between the two cases.

Keywords: Planetary system formation, Planetary science, Galilean satellites, Planet formation, Jovian satellites
Turbulence and Accretion: A High-resolution Study of the B5 Filaments. High-resolution observations of the Perseus B5 "core" have previously revealed that this subsonic region actually consists of several filaments that are likely in the process of forming a quadruple stellar system. Since subsonic filaments are thought to be produced at the ~0.1 pc sonic scale by turbulent compression, a detailed kinematic study is crucial to test such a scenario in the context of core and star formation. Here we present a detailed kinematic follow-up study of the B5 filaments at a 0.009 pc resolution using the VLA and GBT combined observations fitted with multicomponent spectral models. Using precisely identified filament spines, we find a remarkable resemblance between the averaged width profiles of each filament and Plummer-like functions, with filaments possessing FWHM widths of ~0.03 pc. The velocity dispersion profiles of the filaments also show decreasing trends toward the filament spines. Moreover, the velocity gradient field in B5 appears to be locally well ordered (~0.04 pc) but globally complex, with kinematic behaviors suggestive of inhomogeneous turbulent accretion onto filaments and longitudinal flows toward a local overdensity along one of the filaments.

Keywords: Interstellar line emission, Interstellar filaments, Star forming regions, Molecular clouds, Dense interstellar clouds, Star formation, Interstellar clouds, Interstellar medium
The Hubble Tension Revisited: Additional Local Distance Ladder Uncertainties. In a recent paper, we investigated possible systematic uncertainties related to the Cepheid color-luminosity calibration method and their influence on the tension between the Hubble constant as inferred from distances to Type Ia supernovae and the cosmic microwave background as measured with the Planck satellite. Here, we study the impact of other sources of uncertainty in the supernova distance ladder, including Cepheid temperature and metallicity variations, supernova magnitudes, and GAIA parallax distances. Using Cepheid data in 19 Type Ia supernova host galaxies from Riess et al., anchor data from Riess et al., and a set of recalibrated Milky Way Cepheid distances, we obtain H 0 = 71.9 ± 2.2 km s-1 Mpc-1, 2.0σ from the Planck value. Excluding Cepheids with estimated color excesses \hat{E}(V-I)=0.15$ mag to mitigate the impact of the Cepheid color-luminosity calibration, the inferred Hubble constant is H 0 = 68.1 ± 2.6 km s-1 Mpc-1, removing the tension with the Planck value.

Keywords: Hubble constant, Type Ia supernovae, Cepheid distance, Interstellar extinction
Investigating the Origin of X-Ray Jets: A Case Study of Four Hybrid Morphology MOJAVE Blazars. We carried out Chandra, Hubble Space Telescope (HST), and Very Large Array observations of four MOJAVE blazars that have previously been classified as hybrid (FR I/II) blazars in terms of radio morphology but not total radio power. The motivation of this study is to determine the X-ray emission mechanism in jets, these being different in FR I and FR II jets. We detected X-ray jet emission with sufficient signal to noise in two blazars, viz. PKS 0215+015 and TXS 0730+504. We carried out spectral energy distribution modeling of the broadband emission from the jet regions in these sources and found that a single synchrotron emission model is ruled out due to the deep upper limits obtained from HST optical and IR data. The inverse Compton-cosmic microwave background model can reproduce the X-ray jet emission in both sources although the model requires extreme jet parameters. Both our sources possess FR II-like radio powers and our results are consistent with previous studies suggesting that radio power is more important than FR morphology in determining the emission mechanism of X-ray jets.

Keywords: Jets, Active galaxies, BL Lacertae objects, Quasars
Conservation of Total Wave Action in the Expanding Solar Wind. The conservation of wave action in moving plasmas has been well known for over half a century. However, wave action is not conserved when multiple wave modes propagate and coexist close to the degeneration condition (where the sound speed equals the Alfvén speed, i.e., plasma β ~ 1). Here, we show that the violation of conservation is due to wave mode conversion, and that the total wave action summed over the interacting modes is still conserved. Though the result is general, we focus on MHD waves and identify three distinctive mode-conversion mechanisms, i.e., degeneracy, linear mode conversion, and resonance, and provide an intuitive physical picture for the mode-conversion processes. We use one-dimensional MHD simulations with the Expanding Box Model to simulate the nonlinear evolution of monochromatic MHD waves in the expanding solar wind. The simulation results validate the theory; total wave action therefore remains an interesting diagnostic for studies of waves and turbulence in the solar wind.

Keywords: Space plasmas, Magnetohydrodynamics, Solar wind, Plasma astrophysics
The Photon Ring in M87*. We report measurements of the gravitationally lensed secondary image-the first in an infinite series of so-called "photon rings"-around the supermassive black hole M87* via simultaneous modeling and imaging of the 2017 Event Horizon Telescope (EHT) observations. The inferred ring size remains constant across the seven days of the 2017 EHT observing campaign and is consistent with theoretical expectations, providing clear evidence that such measurements probe spacetime and a striking confirmation of the models underlying the first set of EHT results. The residual diffuse emission evolves on timescales comparable to one week. We are able to detect with high significance a southwestern extension consistent with that expected from the base of a jet that is rapidly rotating in the clockwise direction. This result adds further support to the identification of the jet in M87* with a black hole spin-driven outflow, launched via the Blandford-Znajek process. We present three revised estimates for the mass of M87* based on identifying the modeled thin ring component with the bright ringlike features seen in simulated images, one of which is only weakly sensitive to the astrophysics of the emission region. All three estimates agree with each other and previously reported values. Our strongest mass constraint combines information from both the ring and the diffuse emission region, which together imply a mass-to-distance ratio of ${4.20}_{-0.06}^{+0.12}\,\mu \mathrm{as}$ and a corresponding black hole mass of (7.13 ± 0.39) × 109 M ⊙, where the error on the latter is now dominated by the systematic uncertainty arising from the uncertain distance to M87*.

Keywords: Black hole physics, Computational astronomy, Astronomy data modeling, Very long baseline interferometry, General relativity, Submillimeter astronomy
CO Excitation and its Connection to Star Formation at 200 pc in NGC 1365. We report high-resolution (2″ ~ 200 pc) mappings of the central region of the nearby barred spiral galaxy NGC 1365 in the CO(1-0) and CO(2-1) emission lines. The 2-1/1-0 ratio of integrated intensities shows a large scatter (0.15) with a median value of 0.67. We also calculate the ratio of velocity dispersions and peak temperatures and find that in most cases the velocity dispersion ratio is close to unity and thus the peak temperature ratio is comparable to the integrated intensity ratio. This result indicates that both CO(1-0) and CO(2-1) lines trace similar components of molecular gas, with their integrated intensity (or peak temperature) ratios reflecting the gas density and/or temperature. Similar to recent kiloparsec-scale studies, these ratios show a positive correlation with a star formation rate indicator (here we use an extinction-corrected Hα map), suggesting that molecular gas associated with recent star formation is denser and/or warmer. We also find that some CO spectra show two peaks owing to complicated kinematics, and such two components likely trace molecular gas at different conditions. This result demonstrates the importance of spectral fitting to measure integrated intensities and their ratios more accurately.

Keywords: Molecular gas, Barred spiral galaxies, Star formation, CO line emission
Prospect of Detecting TeV Halos with LHAASO: In the Framework of the Anisotropic Diffusion Model. The particle diffusion coefficients of TeV pulsar halos observed so far are inferred to be significantly smaller than the typical value of the interstellar medium (ISM). The anisotropic diffusion model ascribes the slow diffusion to the cross-field diffusion, assuming sub-Alfvénic turbulence in the ISM around the pulsar if the viewing angle between the observer's line-of-sight (LOS) to the pulsar and the local mean field direction is small. In general, the TeV halo's morphology under this model highly depends on the viewing angle, and an elongated, asymmetric morphology is predicted if the LOS is not approximately aligned with the local mean field direction. While the specific requirement of a small viewing angle is supposedly established only for a small fraction of TeV halos, TeV halos with apparent asymmetric morphology have not been detected. In this paper, we will study the expectation of TeV halos measured by the TeV-PeV gamma-ray detector LHAASO in the framework of anisotropic diffusion model, with a particular focus on the influence of the viewing angle on the detectability. We show that a TeV halo is more detectable with a smaller viewing angle, and this selection effect may explain why the morphologies of all three detected TeV halos so far are consistent with being spherical. We also demonstrate that LHAASO is capable of detecting asymmetric TeV halos after several years of operation with reasonable source parameters. This can serve as a critical test of the anisotropic diffusion model.

Keywords: Gamma-ray sources, Extended radiation sources, Cosmic ray sources, Pulsars
Evolution of Alfvén Waves in the Solar Wind. Monochromatic Driver. We use a 2.5D magnetohydrodynamic model to investigate the propagation of azimuthally driven Alfvén waves with different periods and their interaction with the solar wind. In the absence of waves, the dipole field is stretched into a helmet streamer by the solar wind. The wind speeds near the equator are lower than those in the mid and high latitudes. Magnetic reconnection in the equatorial plasma sheet regularly triggers a breakup and expulsion of a plasmoid. We next inject monochromatic Alfvén waves with a moderate amplitude of 9 km s-1 and a period of τ = 1000 s at the coronal base. A cavity showing features of forward and backward propagating modes is formed. The backward waves are able to accelerate the background plasma at mid and high latitudes through the nonlinear coupling to compressional waves. The size of the cavity increases with the period of the Alfvén waves as long as the outer boundary remains in the sub-Alfvénic wind. When τ = 4000 s, we find enhanced acceleration and heating of the solar wind plasma as well as suppression of the reconnection in the equatorial plasma sheet. The amplitudes of the backward Alfvén waves remain large inside the cavity and modify its size. The cavity ceases to exist as its outer boundary gradually moves into the super-Alfvénic wind and the large amplitude backward waves are swept away by the wind. Results suggest that Alfvén waves with moderate amplitudes can modify the dynamics and the energetics of the solar wind plasma with the embedded magnetic field.

Keywords: Slow solar wind, Magnetohydrodynamics, Fast solar wind, Solar physics, Alfven waves
Magnetohydrodynamic Simulation of Multiple Coronal Mass Ejections: An Effect of "Pre-events". Coronal mass ejections (CMEs) are a major source of solar wind disturbances that affect the space plasma and magnetic field environment along their propagation path. Accurate prediction of the arrival of a CME at Earth or any point in the heliosphere is still a daunting task. In this study we explore an often overlooked factor-the effects of "pre-events" that can alter the propagation of a CME due to a preceding CME. A data-driven magnetohydrodynamic numerical model is used to simulate the propagation of multiple CMEs and their driven shocks that occurred in 2012 July. The simulation results are validated with in situ solar wind plasma and magnetic field measurements at 1 au, testing the appropriateness of our simulation results for interpreting the CME/shock evolution. By comparing the simulation results with and without preceding CMEs, we find that the trailing CME can be accelerated by the "wake" of a preceding CME. A detailed analysis suggests that the acceleration is caused partially by an increase in the background solar wind and partially by the so-called "snowplow" effect, with the latter being the major contributor for the 2012 July event.

Keywords: Solar coronal mass ejection shocks, Interplanetary shocks, Solar coronal mass ejections, Magnetohydrodynamical simulations
Gravelamps: Gravitational Wave Lensing Mass Profile Model Selection. We present the package GRAVELAMPS, which is designed to analyze gravitationally lensed gravitational wave signals in order to constrain the mass density profile of the lensing object. GRAVELAMPS does this via parameter estimation using the framework of BILBY, which enables estimation of both the lens and the source parameters. The package can be used to study both microlensing and macrolensing cases, where the lensing mass distribution is described by a point-mass and extended-mass density profile, respectively. It allows the user to easily and freely switch between a full wave optics and approximate geometric optics description. The performance of GRAVELAMPS is demonstrated via simulated analysis of both microlensing and macrolensing events, illustrating its capability for both parameter estimation and model selection in the wave optics and hybrid environments. To further demonstrate the utility of the package, the real gravitational-wave event GW170809 was analyzed using GRAVELAMPS; this event was found to yield no strong evidence supporting the lensing hypothesis, consistent with previously published results.

Keywords: Astronomy software, Strong gravitational lensing, Astronomy data analysis, Gravitational wave astronomy, Gravitational lensing, Gravitational microlensing
The Impact of Cosmic Rays on the Kinematics of the Circumgalactic Medium. We use hydrodynamical simulations of two Milky Way-mass galaxies to demonstrate the impact of cosmic-ray pressure on the kinematics of cool and warm circumgalactic gas. Consistent with previous studies, we find that cosmic-ray pressure can dominate over thermal pressure in the inner 50 kpc of the circumgalactic medium (CGM), creating an overall cooler CGM than that of similar galaxy simulations run without cosmic rays. We generate synthetic sight lines of the simulated galaxies' CGM and use Voigt profile-fitting methods to extract ion column densities, Doppler-b parameters, and velocity centroids of individual absorbers. We directly compare these synthetic spectral line fits with HST/COS CGM absorption-line data analyses, which tend to show that metallic species with a wide range of ionization potential energies are often kinematically aligned. Compared to the Milky Way simulation run without cosmic rays, the presence of cosmic-ray pressure in the inner CGM creates narrower O VI absorption features and broader Si III absorption features, a quality that is more consistent with observational data. Additionally, because the cool gas is buoyant due to nonthermal cosmic-ray pressure support, the velocity centroids of both cool and warm gas tend to align in the simulated Milky Way with feedback from cosmic rays. Our study demonstrates that detailed, direct comparisons between simulations and observations, focused on gas kinematics, have the potential to reveal the dominant physical mechanisms that shape the CGM.

Keywords: Cosmic rays, Hydrodynamical simulations, Galaxy evolution, Circumgalactic medium
X-Ray Spectroscopy in the Microcalorimeter Era 4: Optical Depth Effects on the Soft X-Rays Studied with CLOUDY. In this paper, we discuss atomic processes modifying the soft X-ray spectra from optical depth effects like photoelectric absorption and electron scattering suppressing the soft X-ray lines. We also show the enhancement in soft X-ray line intensities in a photoionized environment via continuum pumping. We quantify the suppression/enhancement by introducing a "line modification factor (f mod)." If 0 ≤ f mod ≤ 1, the line is suppressed, which could be the case in both collisionally ionized and photoionized systems. If f mod ≥ 1, the line is enhanced, which occurs in photoionized systems. Hybrid astrophysical sources are also very common, where the environment is partly photoionized and partly collisionally ionized. Such a system is V1223 Sgr, an Intermediate Polar binary. We show the application of our theory by fitting the first-order Chandra Medium Energy Grating (MEG) spectrum of V1223 Sgr with a combination of CLOUDY-simulated additive cooling-flow and photoionized models. In particular, we account for the excess flux for O VII, O VIII, Ne IX, Ne X, and Mg XI lines in the spectrum found in a recent study, which could not be explained with an absorbed cooling-flow model.

Keywords: Atomic spectroscopy, X-ray binary stars