Sazuna/UAT_keywords huggingface dataset:
Where is the Supervirial Gas? The Supply from Hot Inflows. To understand the presence of the supervirial temperature gas detected in the Milky Way (MW), we present our findings from isolated galaxy simulations of MW-mass systems using GIZMO with the Feedback in Realistic Environments (FIRE-2) stellar feedback model. It unveils the presence of a significant supervirial temperature (T &gt; Tvir) gas component within 20 kpc from the galactic center. We also find that 70%–90% of the total supervirial gas is extraplanar, at 1 &lt; z &lt; 6 kpc and Rcyl &lt; 15 kpc. This supervirial gas has a mass of 1‑2 × 107 M⊙ with typical gas densities are 10‑3.5‑10‑2.5 cm‑3. We find that some of the virial gas (T ∼ 106 K) forms a rotating hot inflow, where gravitational energy is converted to thermal energy mainly via compressive heating. This process causes gas falling close to the rotation axis to reach supervirial temperatures via a combination of compressive heating and shocks just before cooling and joining the disk. Stellar feedback heating accounts for less than 1% of the supervirial gas, indicating its minimal influence despite expectations. Even in scenarios with no stellar feedback effects considered, abundant supervirial gas persists, highlighting the dominance of alternative heating mechanisms. We also show that cosmic rays do not have a significant effect on heating the gas to a supervirial temperature. Our study illuminates the intricate dynamics of hot virial and supervirial gas surrounding MW-mass galaxies, emphasizing the prominent role of infall-driven compressive and shock-heating processes in shaping thermal evolution.

Keywords: Milky Way evolution, Galaxy evolution, Circumgalactic medium
ALMA-JELLY. I. High Resolution CO(2─1) Observations of Ongoing Ram Pressure Stripping in NGC 4858 Reveal Asymmetrical Gas Tail Formation and Fallback. We present new CO(2─1) observations (resolution ∼1″ = 460 pc) of the Coma cluster jellyfish galaxy NGC 4858 obtained from the ALMA-JELLY large program. Analyzing this data alongside complimentary Subaru Hα and Hubble Space Telescope (F600LP / F350LP) observations, we find numerous structural and kinematic features indicative of the effects from strong, inclined ram pressure, including an asymmetric inner gas tail. We estimate a highly inclined disk-wind angle of  ϕDW=75−27+10 . By subtracting a simple circular velocity model, we find (1): gas clumps that are being accelerated by ram pressure, and (2): signatures of gas clumps that had been previously pushed out of the disk but are now falling inward. We also discuss head-tail morphologies in star complexes within the stellar disk that appear to be ram pressure stripping (RPS)-influenced. Lastly, we compare this galaxy to state-of-the-art galaxy "wind tunnel" simulations. We find that this galaxy is one of the best nearby examples of strong and inclined ram pressure gas stripping, and of gas that is perturbed by ram pressure but not fully stripped and falls back. We emphasize the importance of torques due to ram pressure in highly inclined interactions, which help drive gas inward on the side rotating against the wind, contributing to the formation of asymmetric inner RPS tails.

Keywords: Radio astronomy, Galaxies, Galaxy environments
Efficient Ionizers with Low Hβ + [O III] Equivalent Widths: JADES Spectroscopy of a Peculiar High-redshift Population. Early JWST photometric studies discovered a population of UV-faint ( &lt;LUV* ) z ∼ 6.5─8 Lyman break galaxies with spectral energy distributions implying young ages (∼10 Myr) yet relatively weak Hβ + [O III] equivalent widths (EWHβ + [O III] ≍ 400 Å). These galaxies seemingly contradict the implicit understanding that young star-forming galaxies are ubiquitously strong Hβ + [O III] emitters, i.e., extreme emission line galaxies (EW ≳750 Å). Low metallicities, high Lyman continuum escape fractions, and rapidly declining star formation histories have been proposed as primary drivers behind low Hβ + [O III] EWs, but the blend of Hβ + [O III] in photometric studies makes proving one of these scenarios difficult. We aim to characterize this peculiar population with deep spectroscopy from the JWST Advanced Deep Extragalactic Survey. We find that a significant subset of these galaxies at z ≳ 2 with modest Hβ + [O III] EWs (≍300─600 Å) have high ionization efficiencies ( logξion≳25.5Hzerg−1 ). Suppressed [O III] EW values yet elevated Hα and Hβ EW values imply that the level of chemical enrichment is the primary culprit, supported by spectroscopic measurements of metallicities below 12 + log(O/H) ≍ 7.70 (0.1Z⊙). We demonstrate that integrated Hβ + [O III] selections (e.g., Hβ + [O III] EW &gt; 700 Å) exclude the most metal-poor efficient ionizers and favor (1) more chemically enriched systems with comparable extreme radiation fields and (2) older starbursting systems. In contrast, metallicity degeneracies are reduced in Hα space, enabling the identification of these metal-poor efficient ionizers by their specific star formation rate.

Keywords: Starburst galaxies, High-redshift galaxies, Emission line galaxies
Strong Photospheric Heating Indicated by Fe I 6173 Å Line Emission during White-light Solar Flares. Between 2017 and 2024, the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory has observed numerous white-light solar flares (WLFs). HMI spectropolarimetric observations of certain WLFs, in particular the X9.3 flare of 2017 September 6, reveal one or more locations within the umbra or along the umbra/penumbra boundary of the flaring active region where the Fe I 6173 Å line briefly goes into full emission, indicating significant heating of the photosphere and lower chromosphere. For five flares featuring Fe I 6173 Å line-core emission, we perform spectropolarimetric analysis using HMI 90 s cadence Stokes data. For all investigated flares, line-core emission is observed to last for a single 90 s frame and is either concurrent with or followed by an increase in the line continuum intensity lasting one to two frames (90─180 s). Additionally, permanent changes to the Stokes Q, U, and/or V profiles were observed, indicating long-lasting nontransient changes to the photospheric magnetic field. These emissions coincided with local maxima in hard X-ray emission observed by Konus-Wind, as well as local maxima in the time derivative of soft X-ray emission observed by GOES 16-18. Comparison of the Fe I 6173 Å line profile synthesis for the ad hoc heating of the initial empirical VAL-S umbra model and quiescent-Sun (VAL-C-like) model indicates that the Fe I 6173 Å line emission in the white-light flare kernels could be explained by the strong heating of initially cool photospheric regions.

Keywords: Solar flares
A Catalog of Galactic Supernova Remnants and Supernova Remnant Candidates from the EMU/POSSUM Radio Sky Surveys. I.. We use data from the Evolutionary Map of the Universe (EMU) and Polarization Sky Survey of the Universe's Magnetism (POSSUM) radio southern sky surveys, conducted with the Australian Square Kilometre Array Pathfinder (ASKAP) to compile a catalog of Galactic supernova remnants (SNRs) and candidate SNRs within the region of 277 .° 5 ≤ ℓ ≤ 311 .° 7 Galactic longitude, ∣b∣ ≤ 5 .° 4 Galactic latitude, as well as an additional field along the Galactic plane, approximately 315 .° 5 ≤ ℓ ≤ 323 .° 0 Galactic longitude, ‑4.5 ≤ b ≤ 1.5 Galactic latitude. In the areas studied, there are 44 known SNRs and 46 SNR candidates that have been previously identified in the radio. We confirm eight of these candidates as SNRs based on evidence of linear polarization or through the calculation of nonthermal spectral indices. Additionally, we identify possible radio counterparts for seven SNR candidates that were previously only identified in X-rays (four) or optical (three). We also present six new SNRs and 37 new SNR candidates. The results of this study demonstrate the utility of ASKAP for discovering new and potential SNRs and refining the classification of previously identified candidates. In particular, we find that the EMU and POSSUM surveys are particularly well suited for observing high-latitude SNRs and confirming SNR candidates with polarization. The region studied in this work represents approximately one-quarter of the Galactic plane, by longitude, that will eventually be surveyed by EMU/POSSUM, and we expect that the ongoing surveys will continue to uncover new SNRs and SNR candidates.

Keywords: Radio astronomy, Radio source catalogs, Galactic radio sources, Supernova remnants, Pulsar wind nebulae, Radio continuum emission, Spectral index, Polarimetry
Statistical Study on the Solar Wind Turbulence Spectra Upstream of Mars. We statistically analyze the power spectral density (PSD) of magnetic field turbulence in the upstream solar wind of the Martian bow shock by investigating the data from Tianwen-1 and Mars Atmosphere and Volatile Evolution (MAVEN) during 2021 November 13 and December 31. The spectral indices and break frequencies of these PSDs are automatically identified. According to the profiles of the PSDs, we find that they could be classified into three types: A, B, and C. Only less than a quarter of the events exhibit characteristics similar to the 1 au PSDs (Type A). We observe the energy injection in more than one-third of the events (Type B), and the injected energy usually results in the steeper spectral indices of the dissipation ranges. We find the absence of the dissipation range in over one third of the PSDs (Type C), which is likely due to the dissipation occurring at higher frequencies rather than proton cyclotron resonant frequencies. We also find that the two spacecraft observed different types of PSDs in more than half of the investigated episodes, indicating significant variability upstream of the Martian bow shock. For example, the Type-B PSDs are more often seen by Tianwen-1, which was near the flank of the bow shock, than by MAVEN near the nose. This statistical study demonstrates the complicated turbulent environment of the solar wind upstream of the Martian bow shock.

Keywords: Interplanetary turbulence, Mars, Solar wind, Magnetic fields, Pickup ions, Interplanetary physics
FUOr-Aur 0544+3330: A New Young Stellar Object Outburst in the Outskirts of Auriga OB1, Viewed Face-on. We present a newly appreciated FU Ori outburst event that began in 2019 and reached a peak in early 2021. Suspected young stellar object WISE J054452.25+333009.6 experienced substantial brightening, in excess of ‑5 mag at optical wavelengths and ‑2.5 mag at mid-infrared wavelengths. The time from near-quiescence to peak brightness was approximately 24 months. Optical and near-infrared spectra confirm that the outbursting source (hereby designated FUOr-Aur 0544+3330) shows all the hallmarks of the FU Ori class, including the Li I indicator of stellar youth. The mix of ionized and neutral atomic lines, alongside prominent molecular absorption features, is consistent with the expected change in spectral type from earlier in the optical to later types in the near-infrared. The closest analog among well-studied FU Ori objects is V1515 Cyg. Both sources have unusually narrow-lined absorption spectra that can be explained by a face-on disk orientation, such that disk-broadening is minimized and wind-induced blueshift (in e.g., Hα, NaD, Ca II) is maximized. Both the optical through infrared spectral energy distribution and high-resolution spectrum are well-fit by a pure-accretion disk model. Adopting a distance of d = 1.5 kpc, the accretion and central star parameters are  Ṁ=10‑5.48  M⊙ yr‑1, M* = 0.17 M⊙, and Rinner = 1.04 R⊙. Other fitted values are disk inclination i = 5.9 deg and source extinction AV = 1.83 mag. These parameters yield accretion luminosity Lacc = 8.4 L⊙ and maximum disk temperature  Tmax=6218  K.

Keywords: Stellar accretion disks, Young stellar objects, Eruptive variable stars, FU Orionis stars
Monte Carlo Evaluations of Gamma-Ray and Radio Pulsar Populations. Based on well-grounded Galactic neutron star populations formed from radio pulsar population syntheses of canonical pulsars (CPs) and millisecond pulsars (MSPs), we use the latest Fermi Large Area Telescope catalog (4FGL-DR4) to investigate the implications of proposed γ-ray luminosity models. Using Monte Carlo techniques, we calculate the number of CPs and MSPs that would comprise the sample of pulsar-like unidentified sources (PLUIDs) in 4FGL-DR4. While radio beaming fractions were used to scale the sizes of the populations, when forming the mock 4FGL-DR4 samples we make the simplifying assumption that all γ-ray pulsars are beaming toward the Earth. We then explore the observable outcomes of seven different γ-ray luminosity models. Four of the models provide a good match to the observed number of PLUIDs, while three others significantly overpredict the number of PLUIDs. For these latter models, either the average beaming fraction of γ-ray pulsars is more like 25%–50%, or a revision in the luminosity scaling is required. Most of the radio-detectable MSPs that our models predict as part of the PLUIDs within 4FGL-DR4 are, unsurprisingly, fainter than the currently observed sample and at larger dispersion measures. For CPs, in spite of an excellent match to the observed radio population, none of the γ-ray models we investigated could replicate the observed sample of 150 γ-ray CPs. Further work is required to understand this discrepancy. For both MSPs and CPs, we provide encouraging forecasts for targeted radio searches of PLUIDs from 4FGL-DR4 to elucidate the issues raised in this study.

Keywords: Neutron stars
Response of the LMC's Bar to a Recent SMC Collision and Implications for the SMC's Dark Matter Profile. The LMC's stellar bar is offset from the outer disk center, tilted from the disk plane, and does not drive gas inflows. These properties are atypical of bars in gas-rich galaxies, yet the LMC bar's strength and radius are similar to typical barred galaxies. Using N-body hydrodynamic simulations, we show that the LMC's unusual bar is explainable if there was a recent collision (impact parameter ≍2 kpc) between the LMC and SMC. Pre-collision, the simulated bar is centered and coplanar. Post-collision, the simulated bar is offset (≍1.5 kpc) and tilted (≍8 .° 6). The simulated bar offset reduces with time, and comparing with the observed offset (≍0.8 kpc) suggests the timing of the true collision to be 150─200 Myr ago. Then, 150 Myr post-collision, the LMC's bar is centered with its dark matter (DM) halo, whereas the outer disk center is separated from the DM center by ≍1 kpc. The SMC collision produces a tilted-ring structure for the simulated LMC, consistent with observations. Post-collision, the simulated LMC bar's pattern speed decreases by a factor of 2. We also provide a generalizable framework to quantitatively compare the LMC's central gas distribution in different LMC─SMC interaction scenarios. We demonstrate that the SMC's torques on the LMC's bar during the collision are sufficient to explain the observed bar tilt, provided the SMC's total mass within 2 kpc was (0.8─2.4) × 109 M⊙. Therefore, the LMC bar's tilt constrains the SMC's pre-collision DM profile, and requires the SMC to be a DM-dominated galaxy.

Keywords: Hydrodynamical simulations, Galaxy bars, Galaxy interactions, Small Magellanic Cloud, Dwarf galaxies, Large Magellanic Cloud
Fundamental Parameters for Totally Eclipsing Contact Binaries Observed by TESS. Totally eclipsing contact binaries provide a unique opportunity to accurately determine mass ratios through photometric methods alone, eliminating the need for spectroscopic data. Studying low mass ratio (LMR) contact binaries is crucial for advancing our understanding of binary star evolution and the formation of rare optical transients known as red novae. We identified 143 totally eclipsing contact binaries from the Transiting Exoplanet Survey Satellite. These high-precision light curves reveal a distinct O'Connell effect, which we interpret by introducing a cool spot on the primary star. Training a neural network model that includes cool spot parameters can generate a high-precision light curve 2 orders of magnitude faster than Phoebe. Utilizing the neural network (NNnol3) model combined with the Markov Chain Monte Carlo algorithm, we rapidly derived the fundamental parameters of these systems. By leveraging the relationship between orbital period and semimajor axis using the Random Sample Consensus algorithm, we estimated their absolute parameters. Our analysis identified 96 targets with mass ratios below 0.25, all of which were not listed in any previous catalog, thus signifying the discovery of new LMR system candidates. Assuming all 143 binary systems are affected by a third light during parameter estimation, we train a neural network (NNl3) model considering the third light. Then we calculate the residuals between the mass ratio ql3 (considering the third light) and qnol3 (neglecting it). For these residuals, the 25th percentile (Q1) is 0.012, the median (Q2) is 0.026, and the 75th percentile (Q3) is 0.05.

Keywords: Eclipsing binary stars, Binary stars, Contact binary stars
Penetrative Convection in Rotating Tilted f-plane with Multiple Radiative and Convective Layers. In this paper, we conducted a linear instability analysis to investigate penetrative convection in rotating, tilted f-planes with multiple convectively stable and unstable layers. Our findings indicate that penetrative distance decreases with increasing rotational and stratification strengths. We also observed that teleconvection, multiroll convection, and cutoff convection, previously identified in two-layer models, are present in multilayer models. For a three-layer model, the flow exhibits an up-down symmetric pattern for penetrative convection at the poles. However, this symmetry is disrupted in tilted f-planes when the flow drifts in equatorward or poleward directions. At mid- to low latitudes, poleward flow tends to enhance penetration in the upper layers, while equatorward flow facilitates penetration in the lower layers. The disruption of up-down symmetry is also observed in multilayer models with more layers when oscillatory convection occurs. Our findings suggest that upward and downward penetration could be significantly different in stars or planets with multilayer structures. However, under a strong stable composition gradient, the instability is found to be reduced.

Keywords: Stellar convective zones, Solar system gas giant planets, Planetary dynamics
Prestellar Cores in Turbulent Clouds: Properties of Critical Cores. A fraction of the dense cores within a turbulent molecular cloud will eventually collapse to form stars. Identifying the physical criteria for instability and analyzing critical core properties is therefore necessary to star formation theory. Here we quantify the characteristics of an ensemble of "critical cores" on the verge of collapse. This critical epoch was identified in a companion paper, which followed the dynamical evolution of prestellar cores in numerical simulations of turbulent, self-gravitating clouds. We find that radial profiles of density and turbulent velocity dispersion in individual critical cores are consistent with our new model for turbulent equilibrium spheres. While a global linewidth─size relation exists for a cloud with given size and Mach number, the turbulent scaling relations around each core exhibit significant variations. As a result, there is no single density threshold for collapse; instead, cores collapse at a range of densities determined by the local sonic scale and gravitational potential environment. The critical cores in our simulations are mostly transonic; we do not find either purely thermal or highly turbulent cores. In our low Mach number model, which better resolves the characteristic mass and sonic scales, we find marginal evidence that the core mass function (CMF) of critical cores peaks around a characteristic mass scale associated with the large-scale cloud properties. We highlight the importance of constructing the CMF at the critical time for the purpose of testing gravoturbulent fragmentation theories, and derive the resolution requirements to unambiguously identify the peak of the CMF.

Keywords: Star formation, Molecular clouds, Interstellar medium
The Growth and Decay of Individual Sunspots and Pores. An analysis of the photometric growth and decay rates of sunspots and pores was carried out. According to the Solar Dynamics Observatory/Helioseismic and Magnetic Imager data for the period 2010 May–2025 March, ≈3.5 × 105 sunspots and pores were detected and their evolution tracked. The growth and decay rates of sunspots depend nonmonotonically on the area. For small-area sunspots S ≲ 50 μsh, a rapid increase in velocity is observed with increasing area for the growth stage  dSspgr≈0.2·S1.35  and for the decay stage  dSspdc≈0.28·S1.26  μsh day‑1. For sunspots S ≳ 50 μsh, the growth rate depends weakly on the area:  dSspgr≈11.9·S0.32  μsh day‑1. For the decay stage of sunspots with an area of S ≈ 50–150 μsh, the decay rate also depends weakly on the area and can be approximated as  dSspdc≈11·S0.15 . For sunspot areas S ≳ 150 μsh, the decay rate accelerates with increasing area:  dSspdc≈0.14·S0.96  μsh day‑1. For solar pores, the growth and decay rates of solar pores are linearly related to the area. The growth and decay rates for the spots of the leading and trailing polarities are determined. In the range of spot areas S ≈ 100–200 μsh, the growth and decay rates of sunspots of trailing polarity are higher than those of sunspots of leading polarity.

Keywords: Sunspot flow, Bipolar sunspot groups
Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using a Data-driven Systematic Effect Model. Neutral hydrogen serves as a crucial probe for the Cosmic Dawn and the Epoch of Reionization (EoR). Actual observations of the 21 cm signal often encounter challenges such as thermal noise and various systematic effects. To overcome these challenges, we simulate SKA-Low-depth images in the South Celestial Pole field and process them with a deep learning method. We utilized foreground residuals acquired by LOFAR during actual North Celestial Pole field observations, thermal and excess variances calculated via Gaussian process regression, and 21 cm signals generated with 21cmFAST for signal extraction tests. Our approach to overcome these foreground, thermal noise, and excess variance components employs a 3D U-Net neural network architecture for image analysis. When considering thermal noise corresponding to 1752 hr of integration time, U-Net provides reliable 2D power spectrum predictions, and robustness tests ensure that we get realistic EoR signals. Adding foreground residuals, however, causes inconsistencies below the horizon delay line. Lastly, evaluating both thermal noise and excess variances with observations up to 4380 hr and 13,140 hr ensures reliable power spectrum estimations within the EoR window and across nearly all scales, respectively. The incoherence of excess variances in the frequency direction can greatly affect deep learning to extract 21 cm signals.

Keywords: Neural networks, Reionization, Gaussian Processes regression, H I line emission