Sazuna/UAT_keywords huggingface dataset:
Figure Rotation of IllustrisTNG Halos. We use the TNG50 and TNG50 dark matter (DM)-only simulations from the IllustrisTNG simulation suite to conduct an updated survey of halo figure rotation in the presence of baryons. We develop a novel methodology to detect coherent figure rotation about an arbitrary axis and for arbitrary durations, and we apply it to a catalog of 1577 DM halos from the DM-only run and 1396 DM halos from the DM+baryons (DM+B) run that are free of major mergers. Figure rotation was detected in 94% of DM-only halos and 82% of the DM+B halos. The pattern speeds of rotations lasting ≳1h -1 Gyr were log-normally distributed with medians of 0.25 h km s-1 kpc-1 for DM-only in agreement with past results, but 14% higher at 0.29 h km s-1 kpc-1 in the DM+B halos. We find that rotation axes are typically aligned with the halo minor or major axis in 57% of DM-only halos and in 62% of DM+B halos. The remaining rotation axes were not strongly aligned with any principal axis but typically lie in the plane containing the halo minor and major axes. Longer-lived rotations showed greater alignment with the halo minor axis in both simulations. Our results show that, in the presence of baryons, figure rotation is marginally less common, shorter-lived, faster, and better aligned with the minor axis than in DM-only halos. This updated understanding will be consequential for future efforts to constrain figure rotation in the Milky Way dark halo using the morphology and kinematics of tidal streams.

Keywords: Galaxy dark matter halos, Dark matter distribution, Milky Way dark matter halo, Galaxy evolution, Milky Way evolution
HST UV Spectroscopy of the Dwarf Starburst Galaxy Pox 186. Studying the galaxies responsible for reionization is often conducted through local reionization-era analogs; however, many of these local analogs are too massive to be representative of the low-mass star-forming galaxies that are thought to play a dominant role in reionization. The local, low-mass dwarf starburst galaxy Pox 186 is one such system with physical conditions representative of a reionization-era starburst galaxy. We present deep ultraviolet (UV) spectroscopy of Pox 186 to study its stellar population and ionization conditions and to compare these conditions to other local starburst galaxies. The new Cosmic Origins Spectrograph data are combined with archival observations to cover ~1150-2000 Å and allow for an assessment of Pox 186's stellar population, the relative enrichment of C and O, and the escape of ionizing photons. We detect significant Lyα and low-ionization state absorption features, indicative of previously undetected neutral gas in Pox 186. The C/O relative abundance, log(C/O) = -0.62 ± 0.02, is consistent with other low-metallicity dwarf galaxies and suggests a comparable star formation history in these systems. We compare UV line ratios in Pox 186 to those of dwarf galaxies and photoionization models, and we find excellent agreement for the ratios utilizing the intense C III], O III], and double-peaked C IV lines. However, the UV and optical He II emission is faint and distinguishes Pox 186 from other local starburst dwarf galaxies. We explore mechanisms that could produce faint He II, which have implications for the low-mass reionization-era galaxies that may have similar ionization conditions.

Keywords: Starburst galaxies, Dwarf galaxies, Chemical abundances, Ultraviolet spectroscopy
CMR Exploration. II. Filament Identification with Machine Learning. We adopt magnetohydrodynamic simulations that model the formation of filamentary molecular clouds via the collision-induced magnetic reconnection (CMR) mechanism under varying physical conditions. We conduct radiative transfer using RADMC-3D to generate synthetic dust emission of CMR filaments. We use the previously developed machine-learning technique CASI-2D along with the diffusion model to identify the location of CMR filaments in dust emission. Both models show a high level of accuracy in identifying CMR filaments in the test data set, with detection rates of over 80% and 70%, respectively, at a false detection rate of 5%. We then apply the models to real Herschel dust observations of different molecular clouds, successfully identifying several high-confidence CMR filament candidates. Notably, the models are able to detect high-confidence CMR filament candidates in Orion A from dust emission, which have previously been identified using molecular line emission.

Keywords: Magnetohydrodynamics, Interstellar filaments, Convolutional neural networks, Molecular clouds, Interstellar magnetic fields, Interstellar medium
Eruptivity Criteria for Solar Coronal Flux Ropes in Magnetohydrodynamic and Magnetofrictional Models. We investigate which scalar quantity or quantities can best predict the loss of equilibrium and subsequent eruption of magnetic flux ropes in the solar corona. Our models are initialized with a potential magnetic arcade, which is then evolved by means of two effects on the lower boundary: first, a gradual shearing of the arcade, modeling differential rotation on the solar surface; and second, supergranular diffusion. These result in flux cancellation at the polarity inversion line and the formation of a twisted flux rope. We use three model setups: full magnetohydrodynamics (MHD) in cartesian coordinates, and the magnetofrictional (MF) model in both cartesian and polar coordinates. The flux ropes are translationally invariant, allowing for very fast computational times and thus a comprehensive parameter study, comprising hundreds of simulations and thousands of eruptions. Similar flux rope behavior is observed using either magnetofriction or MHD, and there are several scalar criteria that could be used as proxies for eruptivity. The most consistent predictor of eruptions in either model is the squared current in the axial direction of the rope, normalized by the relative helicity, although a variation on the previously proposed eruptivity index is also found to perform well in both the MF and MHD simulations.

Keywords: Solar magnetic fields, Solar coronal mass ejections, Solar corona
Probing Ultralate Reionization: Direct Measurements of the Mean Free Path over 5 &lt; z &lt; 6. The mean free path of ionizing photons, λ mfp, is a critical parameter for modeling the intergalactic medium (IGM) both during and after reionization. We present direct measurements of λ mfp from QSO spectra over the redshift range 5 &lt; z &lt; 6, including the first measurements at z ≃ 5.3 and 5.6. Our sample includes data from the XQR-30 VLT large program, as well as new Keck/ESI observations of QSOs near z ~ 5.5, for which we also acquire new [C II] 158 μm redshifts with ALMA. By measuring the Lyman continuum transmission profile in stacked QSO spectra, we find ${\lambda }_{\mathrm{mfp}}={9.33}_{-1.80}^{+2.06}$ , ${5.40}_{-1.40}^{+1.47}$ , ${3.31}_{-1.34}^{+2.74}$ , and ${0.81}_{-0.48}^{+0.73}$ pMpc at z = 5.08, 5.31, 5.65, and 5.93, respectively. Our results demonstrate that λ mfp increases steadily and rapidly with time over 5 &lt; z &lt; 6. Notably, we find that λ mfp deviates significantly from predictions based on a fully ionized and relaxed IGM as late as z = 5.3. By comparing our results to model predictions and indirect λ mfp constraints based on IGM Lyα opacity, we find that the evolution of λ mfp is consistent with scenarios wherein the IGM is still undergoing reionization and/or retains large fluctuations in the ionizing UV background well below redshift 6.

Keywords: Reionization, High-redshift galaxies, Quasar absorption line spectroscopy, Intergalactic medium
A Reanalysis of the Isolated Black Hole Candidate OGLE-2011-BLG-0462/MOA-2011-BLG-191. There are expected to be ~108 isolated black holes (BHs) in the Milky Way. OGLE-2011-BLG-0462/MOA-2011-BLG-191 (OB110462) is the only such BH with a mass measurement to date. However, its mass is disputed: Lam et al. measured a lower mass of 1.6-4.4 M ⊙, while Sahu et al. and Mróz et al. measured a higher mass of 5.8-8.7 M ⊙. We reanalyze OB110462, including new data from the Hubble Space Telescope (HST) and rereduced Optical Gravitational Lensing Experiment (OGLE) photometry. We also rereduce and reanalyze the HST data set with newly available software. We find significantly different (~1 mas) HST astrometry than Lam et al. in the unmagnified epochs due to the amount of positional bias induced by a bright star ~0.″4 from OB110462. After modeling the updated photometric and astrometric data sets, we find the lens of OB110462 is a ${6.0}_{-1.0}^{+1.2}{M}_{\odot }$ BH. Future observations with the Nancy Grace Roman Space Telescope, which will have an astrometric precision comparable or better to HST but a field of view 100× larger, will be able to measure hundreds of isolated BH masses via microlensing. This will enable the measurement of the BH mass distribution and improve understanding of massive stellar evolution and BH formation channels.

Keywords: Gravitational microlensing, Hubble Space Telescope, Stellar mass black holes, Astrometric microlensing effect
An Updated Reference Frame for the Galactic Inner Parsec. Infrared observations of stellar orbits about Sgr A* probe the mass distribution in the inner parsec of the Galaxy and provide definitive evidence for the existence of a massive black hole. However, the infrared astrometry is relative and is tied to the radio emission from Sgr A* using stellar SiO masers that coincide with infrared-bright stars. To support and improve this two-step astrometry, we present new astrometric observations of 15 stellar SiO masers within 2 pc of Sgr A*. Combined with legacy observations spanning 25.8 yr, we reanalyze the relative offsets of these masers from Sgr A* and measure positions and proper motions that are significantly improved compared to the previously published reference frame. Maser positions are corrected for epoch-specific differential aberration, precession, nutation, and solar gravitational deflection. Omitting the supergiant IRS 7, the mean position uncertainties are 0.46 mas and 0.84 mas in R.A. and decl., and the mean proper motion uncertainties are 0.07 mas yr-1 and 0.12 mas yr-1, respectively. At a distance of 8.2 kpc, these correspond to position uncertainties of 3.7 and 6.9 au and proper motion uncertainties of 2.7 and 4.6 km s-1. The reference frame stability, the uncertainty in the variance-weighted mean proper motion of the maser ensemble, is 8 μas yr-1 (0.30 km s-1) in R.A. and 11 μas yr-1 (0.44 km s-1) in decl., which represents a 2.3-fold improvement over previous work and a new benchmark for the maser-based reference frame.

Keywords: Astronomical coordinate systems, Supermassive black holes, Galactic center, Stellar motion, Stellar kinematics, Radio astrometry, Silicon monoxide masers, Circumstellar masers, Astrophysical masers, Astrometry, Proper motions, Astrophysical black holes
Enhanced Size Uniformity for Near-resonant Planets. Super-Earths within the same close-in, compact planetary system tend to exhibit a striking degree of uniformity in their radius, mass, and orbital spacing, and this "peas-in-a-pod" phenomenon itself serves to provide one of the strongest constrains on planet formation at large. While it has been recently demonstrated from independent samples that such planetary uniformity occurs for both configurations near and distant from mean motion resonance, the question thus remains if the strength of this uniformity itself differs between near-resonant and nonresonant configurations such that the two modes may be astrophysically distinct in their evolution. We thus provide in this work a novel comparative size uniformity analysis for 48 near-resonant and 251 nonresonant multiplanet systems from the California Kepler Survey catalog, evaluating uniformity both across systems and between planetary pairs within the same system. We find that while multiplanet configurations exhibit strong peas-in-a-pod size uniformity regardless of their proximity to resonance, near-resonant configurations display enhanced intra-system size uniformity as compared to their analogous nonresonant counterparts at the level of both entire systems and subsystem planetary pairs and chains. These results are broadly consistent with a variety of formation paradigms for multiple-planet systems, such as convergent migration within a turbulent protoplanetary disk or planet-planet interactions incited by postnebular dynamical instabilities. Nevertheless, further investigation is necessary to ascertain whether the nonresonant and near-resonant planetary configurations respectively evolve via a singular process or mechanisms that are dynamically distinct.

Keywords: Exoplanet dynamics, Exoplanets, Super Earths, Exoplanet systems, Orbital resonances, Exoplanet astronomy, Exoplanet evolution
Modeling of the High-velocity Jet Powered by the Massive Star MWC 349A. MWC 349A is a massive star with a well-known circumstellar disk rotating following a Keplerian law, and an ionized wind launched from the disk surface. Recent observations with the Atacama Large Millimeter/submillimeter Array (ALMA) carried out toward this system, however, have revealed an additional high-velocity component in the strong, maser emission of hydrogen radio recombination lines (RRLs), suggesting the presence of a high-velocity ionized jet. In this work, we present 3D non-LTE radiative transfer modeling of the emission of the H30α and H26α maser lines, and of their associated radio continuum emission, toward MWC 349A. By using the MORELI code, we reproduce the spatial distribution and kinematics of the high-velocity emission of the H30α and H26α maser lines with a high-velocity ionized jet expanding at a velocity of ~250 km s-1, surrounded by MWC 349A's wide-angle ionized wind. The bipolar jet, which is launched from MWC 349A's disk, is poorly collimated and slightly misaligned with respect to the disk rotation axis. Thanks to the unprecedented sensitivity and spatial accuracy provided by ALMA, we also find that the already known, wide-angle ionized wind decelerates as it expands radially from the ionized disk. We briefly discuss the implications of our findings for understanding the formation and evolution of massive stars. Our results show the huge potential of RRL masers as powerful probes of the innermost ionized regions around massive stars and of their high-velocity jets.

Keywords: Massive stars, Stellar jets, Circumstellar masers, Stellar winds, Stellar accretion disks, H II regions
Extreme Rarefaction of Solar Wind: A Study on Origin and Characteristics Using Ulysses Observations. From the Ulysses observation of the solar wind between the heliocentric distance r  h  of ~1.0 and ~5.4 au during 1990-2009, we identified 53 intervals when the solar wind exhibited extreme rarefaction, ~2 orders of magnitude decreases in the solar wind proton density N  p  from their ambient values. These extremely low-density solar wind (ELDSW) events, characterized by an average (median) N  p  of ~0.28 ± 0.09 (~0.30) cm-3, ram pressure of ~0.07 ± 0.04 (~0.07 nPa) and mass flux of ~166 ± 84 (~159) 10-22 kg cm-2 s-1 all normalized to 1 au, have an average (median) duration of ~6.0 ± 3.5 days (~5.5 days), and radial extent of ~1.9 ± 1.1 au (~1.9 au). A clear hemispheric asymmetry is noted in their solar/interplanetary origin, with 70% being identified in the south hemisphere, and 30% in the north hemisphere of the heliosphere. About 23% of the events were encountered between r  h  of 2.25 and 4 au, and 77% at r  h  &gt; 4 au, indicating that these are not intrinsic properties of the Sun/solar corona but are created by the evolution of the solar wind with increasing radial distance from the Sun. The majority (49%) of the events occurred during magnetic clouds, 34% in solar wind high-speed stream (HSS) tails, 11% during the proper HSSs, and 6% during interplanetary sheaths. The identification of ELDSWs will have important consequences for their interaction with the magnetospheres of Jupiter and Saturn.

Keywords: Interplanetary medium, Fast solar wind, Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections, Corotating streams
Constraining X-Ray Variability of the Blazar 3C 273 Using XMM-Newton Observations over Two Decades. Blazars exhibit relentless variability across diverse spatial and temporal frequencies. The study of long- and short-term variability properties observed in the X-ray band provides insights into the inner workings of the central engine. In this work, we present timing and spectral analyses of the blazar 3C 273 using the X-ray observations from the XMM-Newton telescope covering the period from 2000 to 2020. The methods of timing analyses include estimation of fractional variability, long- and short-term flux distribution, rms-flux relation, and power spectral density analysis. The spectral analysis include estimating a model-independent flux hardness ratio and fitting the observations with multiplicative and additive spectral models such as power law, log-parabola, broken power law, and blackbody. The blackbody represents the thermal emission from the accretion disk, while the other models represent the possible energy distributions of the particles emitting synchrotron radiation in the jet. During the past two decades, the source flux changed by a factor of three, with a considerable fractional variability of 27%. However, the intraday variation was found to be moderate. Flux distributions of the individual observations were consistent with a normal or log-normal distribution, while the overall flux distribution including all observations appears to be rather multimodal and of a complex shape. The spectral analyses indicate that a log-parabola added to a blackbody gives the best fit for most of the observations. The results indicate a complex scenario in which the variability can be attributed to the intricate interaction between the disk/corona system and the jet.

Keywords: Supermassive black holes, Quasars, Blazars, Flat-spectrum radio quasars, Relativistic jets, Active galactic nuclei, Non-thermal radiation sources
Unveiling the Dynamics of Dense Cores in Cluster-forming Clumps: A 3D Magnetohydrodynamics Simulation Study of Angular Momentum and Magnetic Field Properties. We conducted isothermal magnetohydrodynamics simulations with self-gravity to investigate the properties of dense cores in cluster-forming clumps. Two different setups were explored: a single rotating clump and colliding clumps. We focused on determining the extent to which the rotation and magnetic field of the parental clump are inherited by the formed dense cores. Our statistical analysis revealed that the alignment between the angular momentum of dense cores, ${{\boldsymbol{L}}}_{\mathrm{core}}$ , and the rotational axis of the clump is influenced by the strength of turbulence and the simulation setup. In single rotating clumps, we found that ${{\boldsymbol{L}}}_{\mathrm{core}}$ tends to align with the clump's rotational axis if the initial turbulence is weak. In colliding clumps, however, this alignment does not occur, regardless of the initial turbulence strength. This misalignment in colliding clumps is due to the induced turbulence from the collision and the isotropic gas inflow into dense cores. Our analysis of colliding clumps also revealed that the magnetic field globally bends along the shock-compressed layer, and the mean magnetic field of dense cores, ${{\boldsymbol{B}}}_{\mathrm{core}}$ , aligns with it. Both in single rotating clumps and colliding clumps, we found that the angle between ${{\boldsymbol{B}}}_{\mathrm{core}}$ and ${{\boldsymbol{L}}}_{\mathrm{core}}$ is generally random, regardless of the clump properties. We also analyzed the dynamical states of the formed cores and found a higher proportion of unbound cores in colliding clumps. In addition, the contribution of rotational energy was only approximately 5% of the gravitational energy, regardless of the model parameters for both single and colliding cases.

Keywords: Molecular gas, Star formation, Magnetohydrodynamical simulations
Variability of Magnetic Hot Stars from the TESS Observations. Magnetic hot stars refer to stars that have effective temperatures approximately in the range from 7000-50,000 K, and with large-scale globally organized magnetic fields. These magnetic fields exhibit strengths ranging from tens of Gauss to tens of kilo-Gauss. They are key in understanding the effects caused by magnetic fields in the stellar evolution. However, there are only three magnetic hot stars studied via a combination of spectropolarimetric and asteroseismic modeling. Combined with Transiting Exoplanet Survey Satellite sectors 1-56 data sets, we provided a photometric variability and stochastic low-frequency (SLF) variability study of 118 magnetic hot stars. Nine new rotating variable stars are identified. Using the Bayesian Markov Chain Monte Carlo framework, we fitted the morphologies of SLF variability for magnetic hot stars. Our analysis reveals that the magnetic hot stars in our sample have γ &lt; 5.5 with the vast majority having 1 ≤ γ ≤ 3. The ν char is primarily in the ranges of 0 day-1 &lt; ν char &lt; 6.3 day-1. The amplitude of SLF variability, log α 0, shows a dominant distribution ranging from 0.8-3. No significant correlations are observed between the luminosity and fitting parameters, suggesting no clear dependence of SLF variability on stellar mass for our sample of magnetic hot stars with masses between approximately 1.5 M ☉ &lt; M &lt; 20 M ☉. We found a significant negative correlation between the B p and ν char. This suppression effect of magnetic fields on ν char may be a result of their inhibition of macroturbulence.

Keywords: Early-type variable stars, Asteroseismology, Magnetic fields, Early-type stars
Decomposing the Spectrum of Ultraluminous X-Ray Pulsar NGC 300 ULX-1. A phase-resolved analysis on the X-ray spectrum of ultraluminous X-ray pulsar (ULXP) NGC 300 ULX-1 is performed with data taken with XMM-Newton and NuSTAR on 2016 December 16. In addition to the classical phase-restricting analysis, a method developed in active galactic nuclei studies is newly employed for ULXP. It has revealed that the pulsation cycle of the source can be divided into two intervals in terms of X-ray variability. This suggests the rotating flow consists of at least two representative emission regions. Furthermore, the new method successfully decomposed the spectrum into an independent pair in each interval. One is an unchanging-component spectrum that can be reproduced by a standard disk model with a ${720}_{-120}^{+220}$ km inner radius and a 0.25 ± 0.03 keV peak temperature. The other is the spectrum of the component that coincides with the pulsation. This was explained with a Comptonization of a ${0.22}_{-0.1}^{+0.2}$ keV blackbody and exhibited a harder photon index in the brighter phase interval of two. The results are consistent with a picture that the pulsating emission originates from a funnel-like flow formed within the magnetosphere, and the inner flow exhibiting a harder continuum is observed exclusively when the opening cone points to the observer.

Keywords: Accretion, X-ray astronomy, X-ray binary stars, Pulsars, Ultraluminous x-ray sources