Sazuna/UAT_keywords huggingface dataset:
The Relationship Between the Kinematics of Coronal Mass Ejections and the Brightness of the Corona. We present an investigation into an apparent relationship between white-light coronal brightness and the kinematics of flare-associated coronal mass ejections (CMEs). Using a unique data set, known as the Large Angle and Spectrometric Coronagraph Coronal Brightness Index (CBI), we conduct a study that explores the brightness in the lower solar corona and its relationship to the velocity of flare-associated CMEs. We analyze all M- and X-class flares that took place on or near the limbs of the Earth-facing disk of the Sun between 1996 and 2022, determine if these flares are associated with CMEs, and record the projection-corrected velocity of the eruptions if they occurred. Using the CBI data set, we evaluate the brightness in the corona directly overlying the flare source locations between 2.4 and 6.2 solar radii, and we find that above a certain level of coronal brightness, the likelihood of a high-velocity CME significantly decreases. This result implies that coronal brightness could be an important indicator of the kinematics of solar CMEs. We also highlight and discuss the unique nature of active region 12192 in 2014, observing that its unprecedented overlying coronal brightness may be related to the low CME productivity of that region.

Keywords: Solar corona, Solar active regions, Solar flares, Solar coronal mass ejections
Intergalactic Absorption Confounding Circumgalactic Observations. The origin of warm ions in the circumgalactic medium (CGM) surrounding massive galaxies remains a mystery. In this paper, we argue that a significant fraction of the observed warm-ion columns may arise in the intergalactic medium (IGM) surrounding galactic halos. We use a simple spherical collapse model of the dark matter halos and their baryonic content to compute the evolving ion fractions within and outside virial halos. We show that the photoionized IGM may produce a thick blanket of warm ions around the CGM, with column densities comparable to observed values near galaxies, which may therefore contaminate CGM observations. We compare our results with observations, and find that our models qualitatively reproduce the overall O VI columns as well as their trend with the impact parameter and halo mass. We find that the IGM contribution to the observed column depends on galaxy mass and impact parameter, and becomes comparable to the total observed values in galaxies with virial masses exceeding a few times 1011 M⊙, as well as across much of the observed area (b ≳ 0.5Rvir) of lower-mass halos. We therefore suggest that theoretical interpretations of CGM-survey observations must consider the possible contribution of the surrounding IGM. We note that more sophisticated (3D) models are required to consider the possibility of nonunity covering fractions suggested by the data. Although our simplified model suggests that it may be possible to kinematically distinguish between CGM and IGM origins through the absorption-line profiles, this distinction is likely unfeasible.

Keywords: Galaxy dark matter halos, Quasar absorption line spectroscopy, Intergalactic medium, Hubble Space Telescope, Ultraviolet surveys, Circumgalactic medium, Warm-hot intergalactic medium, Galaxies
Cosmic Ray Mediated Thermal Fronts in the Warm-hot Circumgalactic Medium. We investigate the 1D plane-parallel front connecting the warm (104 K) and hot (106 K) phases of the circumgalactic medium (CGM), focusing on the influence of cosmic rays (CRs) in shaping these transition layers. We find that cosmic rays dictate the thermal balance while other fluxes (thermal conduction, radiative cooling, and gas flow) adjust to compensate. We compute column densities and ratios for the transition-temperature ions Si IV, C IV, O VI, and N V, and compare them with observational data. While most models struggle to simultaneously reproduce the observed Si IV/C IV and C IV/O VI ratios, a subset with intermediate magnetic field strength (e.g., B = 20 μG) shows overlap with the data, although we make no claims for their uniqueness. These discrepancies suggest that the models perform better at reproducing higher-temperature ions but underestimate the contribution from cooler, photoionized regions. Compared to models without CRs, CR-mediated fronts in sufficiently strong magnetic fields produce broader transition layers and higher ion ratios, indicating that CRs can significantly alter the thermal and ionization structure of the CGM. Our results suggest that CR heating may help explain some observed ion columns under specific conditions, though additional physics may be needed for full agreement with observations.

Keywords: Circumgalactic medium, Cosmic rays
The Extended GeV Gamma-Ray Emission from HESS J1503-582 with Fermi-LAT. We present the discovery of extended GeV gamma-ray emissions spatially correlated with the unidentified very-high-energy (VHE; &gt; 100 GeV) gamma-ray source HESS J1503-582, utilizing data from Pass 8 of the Fermi Large Area Telescope. The GeV gamma-ray spectrum of HESS J1503-582 is optimally characterized by a power-law model with an index of 1.90, spanning the energy range from 1 GeV to 1 TeV. The gamma-ray emission is spatially coincident with the "Forbidden Velocity Wing" (FVW) 319.8+0.3, a characteristic 21 cm H I line structure that extends to velocities beyond those allowed by Galactic rotation. Taking into account the fact that several FVWs have been identified as old supernova remnants (SNRs), a potential SNR associated with FVW 319.8+0.3 is discussed to explain the multiwavelength data of HESS J1503-582. While both leptonic and hadronic models are capable of accounting for the multiwavelength observations of HESS J1503-582, the cutoff energies and total energy contents of particles challenge the acceleration capability of an old SNR with a slow expanding shell. While a hypothetical OB association or a pulsar halo could potentially account for the high total energy contents of particles and the low magnetic field strength, the absence of any detections of such objects challenges these proposed scenarios.

Keywords: Gamma-ray sources, Supernova remnants
Dynamics of Subsurface Flows in Solar Active Regions during the 2024 May Storm. In 2024 May, the Sun exhibited intense magnetic activity, marked by numerous high-intensity flares resulting from the interaction and merging of NOAA active regions (ARs) 13664 and 13668 in the southern hemisphere and AR 13663 in the northern hemisphere. Notably, AR 13664 displayed an extended lifetime, remaining visible after a full solar rotation and continuing to produce significant flaring activity. In this study, we investigate the evolution of subphotospheric plasma flows associated with these ARs during their disk passage using ring-diagram analysis of Solar Dynamics Observatory/Helioseismic and Magnetic Imager Dopplergrams. We analyze flow divergence, vorticity, and kinetic helicity across depths from the surface to 25 Mm, revealing pronounced temporal and depth-dependent variations. Our observations indicate that the majority of flares occur on the days when the Normalized Helicity Gradient Variance, a measure of kinetic helicity spread, peaks or on the following day. Furthermore, we examine the relationship between subsurface flow dynamics and surface magnetic properties of these complex ARs to understand the interaction between them.

Keywords: Solar active region velocity fields, Solar active region magnetic fields, Solar flares, Solar interior, Helioseismology, Solar active regions, Solar physics, Solar activity, Solar storm
Temporal and Structural Properties of Sunspot Small Short-living Group and Large Long-living Group Populations. We investigate the properties of two types of solar active regions: the small short-living groups (SSGs) and the large long-living groups (LLGs). The combined distribution of areas of active regions is bimodal. When deconvolved, the distributions of each population show a clear presence of cyclic variations with LLG and SSG number varying in phase with each other. We see these in-phase variations and the lognormal distribution of SSG/LLG areas as indications that both types of groups originate from the same mechanism, the solar dynamo action. However, the data also suggest that near-surface convection may play a role. The maxima in the bimodal distribution of sunspot group areas (one for LLG and the other for SSG components) coincide with the typical sizes of the supergranules for the LLG population and mesogranules for the SSG population, which suggests that the large-scale convection patterns may affect the sunspot group formation.

Keywords: Solar cycle, Supergranulation, Sunspot groups, Mesogranulation, Sunspot cycle
Distance to the Galactic Center 7' Halo from H I Absorption. Using archival data, we have made an H I absorption study of the 7 '  halo surrounding the Sgr A complex, observed toward the Galactic center (GC) region. We find strong H I absorption near velocities of −53 km s−1, which is due to the 3 kpc arm, placing it beyond 5 kpc from us. We further examined the H I absorption properties toward five different parts of the 7 '  halo. Absorption by the +50 km s−1 GC cloud is seen toward only three parts of the halo, but not toward the other two regions. Strong emissions in CO and CS are, however, identified toward all the above five parts of the halo by the +50 km s−1 GC molecular cloud. This does show that the 7 '  halo is partly behind and partly in front of the 50 km s−1 cloud. To our knowledge, this for the first time clearly shows the 7 '  halo to be located at the same distance as the +50 km s−1 molecular cloud, i.e., at the GC region.

Keywords: Galactic center, Interstellar line absorption, Interstellar clouds, Interstellar medium, Nebulae, Radio interferometry, Radio astronomy
The TYPHOON Stellar Population Synthesis Survey. II. Pushing Full Spectral Fitting to the Limit in the Nearby Grand Design Barred Spiral M83. We apply population synthesis techniques to analyze TYPHOON long slit spectra of the starburst barred spiral galaxy M83. The analysis covers a central square of 5' side length. We determine the spatial distribution of dust through the analysis of reddening and extinction, together with star formation rates, ages, and metallicities of young and old stellar populations. For the first time, a spatial one-to-one comparison of metallicities derived from full spectral fitting techniques with those obtained from individual young stellar probes has been carried out. The comparison with blue supergiant stars, young massive star clusters, and super star clusters shows a high degree of concordance when wavelength coverage in the B band is available. The metallicity of the young population is supersolar and does not show a radial metallicity gradient along the investigated part of the disk, in agreement with our chemical evolution model. However, a notable decrease in metallicity is observed in a tightly confined region at the galaxy center, coinciding with circumnuclear orbits. We attribute this to matter infall either from the circumgalactic medium, a dwarf galaxy interloper, or, alternatively, to active-galactic-nucleus-interrupted chemical evolution. We confirm the presence of a dust cavity with a diameter of 260 pc close to the galaxy center. Dust absorption and molecular CO emission are spatially well correlated. We find an anticorrelation between RV, the ratio of dust attenuation to reddening, and the emission strength of molecular species present in photodissociation regions. We confirm our results by using alternative fitting algorithms and stellar libraries.

Keywords: Interstellar dust, Galaxy chemical evolution, Stellar populations, Barred spiral galaxies, Metallicity
Forecasting the Fast Radio Burst Population Observed through Galaxy Cluster Lenses. High-redshift fast radio bursts (FRBs) are expected to be extremely powerful probes of our Universe. However, while a significant number of FRBs are expected to exist at high redshift, detecting them has been difficult, with only a handful robustly confirmed at redshifts greater than one. In many other fields, gravitational lensing from galaxy clusters has enabled high-redshift detections by magnifying background sources. In this work we forecast the populations of FRBs expected to be detected by the Canadian Hydrogen Intensity Mapping Experiment (CHIME) and upcoming instrument Canadian Hydrogen Observatory and Radio Transient Detector (CHORD), for blank fields and by lensing through a range of strong lensing galaxy clusters, based on existing, observationally driven cluster models. We find that the presence of a galaxy cluster of mass M ≥ 5 × 1014 M ⊙ within the detection beam of a transit telescope will approximately double the rate of detected high-redshift (z ≥ 1 CHIME, z ≥ 2 CHORD) FRBs for that beam. Consequently, we find that knowledge of cluster positions can be used by instruments like CHIME or CHORD in tandem with novel observational strategies to isolate a sample of high-redshift FRBs with ≳50% purity at a rate of ≲3 per year. This would provide a statistically high-redshift sample of mostly gravitationally lensed FRBs that would be ideal candidates for optical follow-up, constraining the FRB–star formation relation and for use in cosmological studies including measuring H 0, characterising dark matter substructures and probing reionization.

Keywords: Galaxy clusters, Radio bursts, Gravitational lensing, Radio transient sources
Self-organized Criticality across 13 Orders of Magnitude in the Solar–Stellar Connection. The observed size distributions of solar and stellar flares are found to be consistent with the predictions of the fractal-diffusive self-organized criticality (FD-SOC) model, which predicts power-law slopes with universal constants of αF = (9/5) = 1.80 for the flux, and αE = (5/3) ≈ 1.67 for the fluence or energy, respectively. In this study, we explore the solar–stellar connection under this aspect, which extends over an unprecedented dynamic range of 13 orders of magnitude between the smallest detected solar nanoflare event (Emin = 1024 erg) and the largest superflare (Emax = 1037 erg) on solar-like G-type stars, observed with the Kepler mission. The FD-SOC model predicts a scaling law of L ∝ E(2/9) for the length scale L as a function of the flare energy E, which limits the largest flare size to Lmax ≲ 0.14 R⊙for solar flares, and Lstellar ≲ 1.04 R⊙ for stellar flares on G-type stars. Overall, we conclude that the universality of power laws (and their slopes) is a consequence of SOC properties (fractality, classical diffusion, scale-freeness, volume-flux proportionality), rather than identical physical processes at different wavelengths.

Keywords: Stellar flares
Dust-obscured Galaxies with Broken Power-law Spectral Energy Distributions Discovered by UNIONS. We report on the spectral energy distributions (SEDs) of infrared (IR)-bright dust-obscured galaxies (DOGs) with (i ‑ [22])AB ≥ 7.0. Using photometry from the deep and wide Ultraviolet Near-Infrared Optical Northern Survey, combined with near-IR (NIR) and mid-IR data from the UKIRT Infrared Deep Sky Survey and the Wide-field Infrared Survey Explorer, we successfully identified 382 DOGs in ∼170 deg2. Among them, the vast majority (376 DOGs) were classified into two subclasses: bump DOGs (132/376) and power-law (PL) DOGs (244/376), which are dominated by star formation and active galactic nuclei (AGNs), respectively. Through the SED analysis, we find that roughly half (120/244) of the PL DOGs show broken power-law (BPL) SEDs. The significant red slope from optical to NIR in the SEDs of these "BPL DOGs" probably reflects their large amount of dust extinction. In other words, BPL DOGs are more heavily obscured AGNs, compared to PL DOGs with non-BPL SEDs.

Keywords: Active galaxies, Infrared galaxies, Galaxies
A JWST/MIRI View of the Interstellar Medium in M83. I. Resolved Molecular Hydrogen Properties, Star Formation, and Feedback. We present a spatially resolved (∼3 pc pixel−1) analysis of the distribution, kinematics, and excitation of warm H2 gas in the nuclear starburst region of M83. Our JWST/MIRI integral field unit spectroscopy reveals a clumpy reservoir of warm H2 (&gt;200 K) with a mass of ∼2.3 × 105 M⊙ in the area covered by all four Medium Resolution Spectrometer (MRS) channels. We additionally use the [Ne II] 12.8 μm and [Ne III] 15.5 μm lines as tracers of the star formation rate (SFR), ionizing radiation hardness, and kinematics of the ionized interstellar medium (ISM), finding tantalizing connections to the H2 properties and stellar populations (e.g., broad and blueshifted [Ne II] emission coincident with a region with &gt;5 Myr old stellar populations, low SFR, and low H2 surface density.) Finally, qualitative comparisons to the trove of public, high-spatial-resolution multiwavelength data available on M83 shows that our MRS spectroscopy potentially traces all stages of the process of creating massive star clusters, from the embedded protocluster phase through the dispersion of ISM from stellar feedback.

Keywords: Molecular gas, Infrared spectroscopy, Galaxy evolution, Galaxy chemical evolution
The Shape and Mass of the Galactic Dark Matter Halo from the Axisymmetric Jeans Model. We explore the density profile, shape, and virial mass of the Milky Way's dark matter halo, using K giants (KGs) from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and Sloan Digital Sky Survey (SDSS)/SEGUE as well as blue horizontal branch stars (BHBs) from SDSS. Incorporating Gaia DR3 proper motions, we first investigate the velocity ellipsoid distribution within the (R, ∣z∣) space. The ellipsoids projected onto the (vR, vz) plane exhibit near-spherical alignment. We then probe the underlying dark matter distribution, using the axisymmetric Jeans equations with multi-Gaussian expansion and spherically aligned Jeans anisotropic modeling (JAMsph), allowing for different flattened dark matter density models. For each model, we apply two fitting approaches: fitting the KGs and BHBs separately or fitting them simultaneously as two dynamical tracers in one gravitational potential. We find consistent results for the dark matter density profiles, r200, and M200 within a 1σ confidence region for models constrained by KGs, BHBs, and both. We find the strongest consistency between KGs and BHBs in constraining dark matter profiles for models incorporating radially varying halo flattening (q(rgc)), which suggests the Milky Way's dark matter halo shape evolves with Galactocentric distance (rgc). Specifically, the halo flattening parameter qh decreases within rgc &lt; 20 kpc and increases for rgc &gt; 20 kpc. In this model,  Mtot(&lt;60kpc)=0.533‑0.054+0.061×1012  M⊙, r200 is 188 ± 15 kpc, and M200 is estimated at  0.820‑0.186+0.210×1012M⊙ .

Keywords: K giant stars, Milky Way dark matter halo, Horizontal branch stars, Milky Way mass
Oscillatory Line-driven Winds: The Role of Atmospheric Stratification. Time-dependent numerical studies of line-driven winds using the Sobolev approximation have a history spanning over three decades. In many of these studies, the wind solutions display notorious oscillations. Two clues suggest the oscillations originate at the wind base: (i) simulations reach a steady state without oscillations when the base density is sufficiently low, and (ii) the oscillation dominant frequency is comparable to the Lamb cutoff frequency, ωc, of acoustic waves propagating in a stratified hydrostatic atmosphere. Recently, Dannen et al. observed another clue: When the line force significantly weakens due to ionization, the winds become increasingly sensitive to the self-excited oscillations. Here, we present a set of simulations and perturbation analyses that further elucidate the source and characteristics of oscillations. We found that the line force adds wave energy and amplifies perturbations with frequencies near ωc. This selective amplification results from the coupling between the natural tendency of velocity perturbations to grow in a stratified atmosphere and from the line force dependence on the velocity gradient, per the Castor─Abbott─Klein line-driven wind theory. We also found that the variability stems from self-excitation that occurs in the exponential atmosphere due to the nonlinearity introduced by the absolute value of the velocity gradient in the line force prescription. We conclude that self-consistently calculating ionization is insufficient for modeling the dynamics in the subsonic atmosphere. Instead, future wind or unified models should relax the Sobolev approximation, or model the radiative transfer to properly capture the resulting radiation-induced instabilities and dynamics at the wind base.

Keywords: Galactic winds, Computational methods, Active galactic nuclei
Global Resistive Magnetohydrodynamic Accretion Flows around Spinning Active Galactic Nuclei: Impact of Resistivity on the Magnetically Arrested Disk State. In this study, we investigate the effect of resistivity on the dynamics of global magnetohydrodynamic accretion flows (Res-MHD) around a spinning supermassive black hole. We perform a comparative study of two-dimensional (2D) and three-dimensional (3D) resistive models around black holes. We examine accretion flow dynamics considering globally uniform resistivity values ranging from ∼0 to 0.1. During the simulation time of t ≲ 1000tg, we find that the mass accretion rate is comparable for both the 2D and 3D models. However, as the flow becomes increasingly turbulent, nonaxisymmetric effects begin to dominate, resulting in significant differences in the mass accretion rates between the 3D and 2D. All the resistive models in a highly magnetized flow belong to the magnetically arrested disk (MAD) state. We propose an efficient and physically motivated approach to examine the magnetic state by estimating the spatial average plasma beta parameter across the computational domain. We find that when the average plasma beta is close to or below unity (βave ≲ 1), the accretion flow enters the MAD state. Additionally, we find that high-resistivity flow reduces magnetorotational instability turbulence in the accretion flow, while the turbulence structures remain qualitatively similar in low-resistivity flows. Moreover, we observe indications of plasmoid formations in low-resistivity flow compared to high-resistivity flow. Furthermore, we do not find a clear relationship between the variability of the accretion rate, magnetic flux, and resistivity. Lastly, our findings suggest that low-resistivity models produce higher-power jets than those with higher resistivity.

Keywords: Accretion, Black hole physics, Magnetohydrodynamics, Supermassive black holes, Solar magnetic reconnection, Relativistic jets, Stellar accretion disks