Sazuna/UAT_keywords huggingface dataset:
Thermal Sunyaev–Zel'dovich Effect in the Circumgalactic Medium. II. Dependence on Star Formation. We measure the thermal Sunyaev–Zel'dovich effect in the circumgalactic medium (CGM) of ≈2.5 million M200 = 1012‑14M⊙ WISE × DESI galaxies out to z = 1.2. We split the sample into quiescent (0.7 million) and star-forming (1.8 million) galaxies, exploring the relation between the thermal pressure of the CGM and star formation for the first time. We develop and implement a novel probabilistic approach to cross-correlate the galaxy catalog with the Atacama Cosmology Telescope + Planck data by taking into account the uncertainties in redshift, mass, and star formation rate. The signal-to-noise ratio of the stacked Compton-y value in the CGM varies from 4.9σ to 18.5σ, depending on the sample size and the CGM signal strength within the relevant mass bin. We detect the CGM signal down to M200 = 1012.3 M⊙, and provide a stringent upper limit at M200 &lt; 1012.3 M⊙. The data fit well with the standard generalized Navarro–Frenk–White profile of thermal pressure and do not require a flatter or steeper profile. This suggests a significant impact of cooling and the absence of dominant feedback. In galaxies with M200 ≈ 1012.3‑12.8 M⊙ halos, the volume-filling CGM is likely the largest contributor to the galactic baryons at their virial temperatures of ∼106‑6.4 K. For M200 &gt; 1012.8 ! M⊙ halos, the most massive phase of the CGM is likely at a subvirial temperature of ≳106 K. The thermal energy of the CGM of quiescent galaxies follows the self-similar relation with mass, but the star-forming galaxies deviate from this relation. This indicates that the impact of nongravitational factors varies among halos of different degrees of star-forming activity.

Keywords: Hot intergalactic medium, Galactic winds, Galaxy environments, Millimeter astronomy, Observational cosmology, Cosmic microwave background radiation, Sunyaev-Zeldovich effect, Hot ionized medium, Galaxy evolution, Circumgalactic medium, Extragalactic astronomy, Galaxy processes
The Formation of Ultra-short-period Planets under the Influence of the Nearby Planetary Companions. Ultra-short-period (USP) planets, defined as those with orbital periods shorter than 1 day, provide valuable insights into planetary evolution under strong stellar tidal interactions. In this work, we investigate the formation of USP planets in two-planet systems consisting of an inner terrestrial planet accompanied by an outer hot Jupiter (HJ). Our simulation results show USP planets can form through a process driven by secular perturbations from the outer companion, which induce eccentricity excitation, tidal dissipation, and subsequent orbital decay of the inner planet. The probability of USP formation is governed by key factors, including the mass ratio between two planets, their orbital eccentricities, and the tidal dissipation process. 6.7% of our simulations form USP planets, and USP planets form most efficiently when the mass ratio is around 4 M⊕/MJ, with the inner planet less than 8 M⊕. Furthermore, the eccentricity of the outer HJ plays a crucial role—moderate eccentricities (eouter &lt; 0.1) favor USP formation, whereas higher eccentricities (eouter &gt; 0.1) enhance the likelihood of orbital instability, often resulting in a lonely HJ. USP planets form more efficiently when the tidal dissipation function of the inner planet is comparable to the values estimated for terrestrial planets in the solar system. Comparison with observed planetary systems reveals that systems with large mass ratios or nearly circular outer planets tend to produce short-period (SP) planets instead of USP planets. Our findings offer a potential explanation for the most commonly observed system architectures, which predominantly feature either an HJ with an inner SP planet or a lonely HJ.

Keywords: Exoplanet dynamics, Exoplanet evolution, Exoplanet formation
Estimating the Initial Mass of the Gaia─Enceladus Dwarf Galaxy with a Chemical Evolution Model. This work investigates the initial mass and chemical evolution history of the Gaia─Enceladus dwarf galaxy. We combine spectroscopic data from APOGEE with astrometric data from Gaia Data Release 3 to identify Gaia─Enceladus candidate stars via a machine learning pipeline using t-SNE and HDBSCAN. By focusing on kinematic and chemical parameters, especially [Fe/H], [Mg/Fe], [Al/Fe], and [Mn/Fe], we uncover a population of metal-poor, high-eccentricity stars that align with literature criteria for Gaia─Enceladus debris. We then apply the OMEGA+ chemical evolution model, incorporating Markov Chain Monte Carlo fitting of the observed abundance trends in the [Mg/Fe]─[Fe/H] plane. Our best-fitting model indicates a gas mass of  4.93−0.72+0.32×109M⊙  for Gaia─Enceladus, placing it at the higher end of previously suggested masses. The model scenario suggests a short star formation timescale, substantial outflows, and a rapid buildup of metals mainly driven by core-collapse supernovae, with a lesser contribution from Type Ia supernovae. Comparison with observational data in other chemical planes (e.g., [Mg/Mn]─[Al/Fe]) supports this scenario, emphasizing a distinct evolution path relative to the Milky Way. Additionally, our results provide indirect evidence that star formation in Gaia─Enceladus likely ceased within the first 4 Gyr, consistent with earlier inferences of an early merger event. These findings highlight the power of chemical evolution modeling in reconstructing the origin and mass of ancient accreted systems. Overall, we show that Gaia─Enceladus, through rapid star formation and strong outflows, contributed a significant fraction of the metal-poor stellar halo of the Milky Way.

Keywords: Milky Way formation, Galaxy chemical evolution, Dwarf galaxies, Milky Way evolution, Milky Way Galaxy
Identification of Nonlinear Damping of Transverse Loop Oscillations by KHI-induced Turbulence. Kink oscillations in coronal loops have been extensively studied for their potential contributions to coronal heating and their role in plasma diagnostics through coronal seismology. A key focus is the strong damping of large-amplitude kink oscillations, which observational evidence suggests is nonlinear. However, directly identifying the nonlinearity is a challenge. This work presents an analytic formula describing nonlinear standing kink oscillations dissipated by turbulence, characterised by a time-varying damping rate and period drift. We investigate how the damping behaviour depends on the driving amplitude and loop properties, showing that the initial damping time τ is inversely proportional to the velocity disturbance over the loop radius, Vi/R. Using Markov Chain Monte Carlo fitting with Bayesian inference, the nonlinear function better fits an observed decaying kink oscillation than traditional linear models, including exponential damping, suggesting its nonlinear nature. By applying a Bayesian model comparison, we establish regimes in which nonlinear and linear resonant absorption mechanisms dominate based on the relationship between the damping rate τ/P and Vi/R. Additionally, analysis of two specific events reveals that while one favours the nonlinear model, the other is better explained by the linear model. Our results suggest that this analytical approximation of nonlinear damping due to turbulence provides a valid and reliable description of large-amplitude decaying kink oscillations in coronal loops.

Keywords: Solar coronal loops, Solar coronal waves, Solar corona
Comprehensive Statistical Analysis of Initial Lorentz Factor and Jet Opening Angle of Gamma-Ray Bursts. The initial Lorentz factor (Γ0) and jet half-opening angle (θjet) of gamma-ray bursts (GRBs) are critical physical parameters for understanding the dynamical evolution of relativistic jets and the true energy release of GRBs. We compile a sample of 89 GRBs that exhibit an onset bump feature in their early optical or GeV light curves, 42 of which also display a jet break feature, and derive their Γ0 and θjet values. Using this sample, we reexamine the correlations between Γ0 and the prompt emission parameters (isotropic energy Eiso, peak luminosity Liso, and peak energy Ep). Our results confirm the previously reported Γ0−Eiso (Liso), Γ0−Ep,z, and Eiso (Liso)−Ep−Γ0 relations for both homogeneous interstellar medium (ISM) and Wind density profiles (Wind). Notably, we find that the short GRB 090510 complies with the Γ0−Eiso relation, but significantly deviates from the Γ0−Liso and Γ0−Ep,z relations. We systematically investigate the influence of θjet on Γ0 and find a weak dependence, which reads Γ0 (ISM) ∝ θjet−0.18±0.15  (ISM) and Γ0 (Wind) ∝  θjet−0.72±0.14  (Wind). Additionally, we report, for the first time, three new three-parameter correlations, i.e.,  Eiso∝θjet−0.52±0.26  (ISM)  Γ02.21±0.28  (ISM) and  Eiso∝θjet−0.65±0.21  (Wind)  Γ02.08±0.19  (Wind);  Liso∝θjet−0.35±0.27  (ISM)  Γ02.46±0.29  (ISM) and  Liso∝θjet−0.29±0.28 (Wind)  Γ02.37±0.25  (Wind); and  Ep,z∝θjet−0.15±0.19  (ISM)  Γ01.11±0.21  (ISM) and  Ep,z∝θjet−0.17±0.23  (Wind)  Γ01.09±0.21  (Wind). These tight Eiso (or Liso, Ep,z)−Γ0−θjet correlations likely arise from the combined effects of radiation mechanisms, jet structure, and outflow dynamics in GRBs. In addition, we further explore the relations between the initial Lorentz factor and the jet-corrected energy, and find Γ0 (ISM) ∝ Eγ,520.22±0.04  (ISM) and Γ0 (Wind) ∝ Eγ,520.40±0.06  (Wind); and Γ0 (ISM) ∝ Lγ,520.20±0.04  (ISM) and Γ0 (Wind) ∝ Lγ,520.30±0.06  (Wind). We also find that the jet-corrected correlations remain significant, suggesting that these relations are intrinsic to the physical nature of GRBs. However, the increased dispersion after correction implies that underlying differences persist among individual GRBs.

Keywords: Gamma-ray bursts
Gravitational Binding and Star Formation in Molecular Clouds of the Milky Way. The gravitational binding and star-forming properties of molecular clouds in the Milky Way (MW) are estimated from CO cloud observations and from a model of pressure-bounded virial equilibrium (PVE). Two CO surveys are analyzed with the standard CO conversion factor. The main results are as follows. (1) For each survey the cloud virial parameter  αvir  increases by a factor ~2 from galactocentric radius  Rgal=4  to  15  kpc. (2) PVE models match these trends only if the surface densities of survey clouds and nearby stars are comparable. This evidence of environmental influence resembles that seen in other disk galaxies. (3) Many survey clouds form stars even though their virial parameter exceeds the critical value  αvir≈2 . In PVE such clouds with constant velocity dispersion have stable equilibrium and  cannot form stars by simple global collapse. (4) However, simulations show that  αvir≈2  clouds with dissipating turbulence may form filaments, cores, and protostars with little global contraction. Such clouds can match the MW star formation rate if their protostellar cores have a mass fraction  ∼10‑3 . A simple model predicts that the star-forming age of a cloud is proportional to the ratio of its young stellar objects (YSOs) to its mass. (5) Clouds within 500 pc of the Sun are predicted to have star-forming ages 1–10 Myr and average YSO age ∼2 Myr, matching evolutionary models. The Orion A cloud is predicted to have ∼60 Class 0 protostars, ∼2900 YSOs, and a star formation efficiency SFE  ≈ 0.02, in good agreement with observed estimates.

Keywords: Star formation, Interstellar clouds
Improved Limits on the 21 cm Signal at z = 6.5–7.0 with the Murchison Widefield Array Using Gaussian Information. We explore the properties of interferometric data from high-redshift 21 cm measurements using the Murchison Widefield Array (MWA). These data contain the redshifted 21 cm signal, contamination from continuum foreground sources, and radiometric noise. The 21 cm signal from the Epoch of Reionization (EoR) is expected to be highly Gaussian, which motivates the use of the power spectrum as an effective statistical tool for extracting astrophysical information. We find that foreground contamination introduces non-Gaussianity into the distribution of measurements and then use this information to separate Gaussian from the non-Gaussian signal. We present improved upper limits on the 21 cm EoR power spectrum from the MWA using a Gaussian component of the data, based on the existing analysis from C. D. Nunhokee et al. 2025. This is extracted as the best-fitting Gaussian to the measured data. Our best 2σ (thermal+sample variance) limit for 268 hr of data improves from (30.2 mK)2 to (23.0 mK)2 at z = 6.5 for the East–West polarization, and from (39.2 mK)2 to (21.7 mK)2 = 470 mK2 in North–South. The best limits at z = 6.8 (z = 7.0) improve to P &lt; (25.9 mK)2 (P &lt; (32.0 mK)2) and k = 0.18h Mpc‑1 (k = 0.21h Mpc‑1). Results are compared with realistic simulations, which indicate that leakage from foreground contamination is a source of the non-Gaussian behavior.

Keywords: Reionization, Interferometers, H I line emission
FEAST: JWST/NIRCam View of the Resolved Stellar Populations of the Interacting Dwarf Galaxies NGC 4485 and NGC 4490. We present new JWST/NIRCam observations of the interacting dwarf galaxy system NGC 4485–NGC 4490 (aka Arp 269), obtained as part of the Cycle 1 Feedback in Emerging Extragalactic Star Clusters (FEAST) program. NGC 4485 and NGC 4490 form the closest known pair of interacting late-type dwarf galaxies (at ∼7.4 Mpc), excluding the Magellanic Clouds. Near-infrared color–magnitude diagrams (CMDs) reveal a wide range of stellar populations in both galaxies, including young (≲200 Myr) upper main-sequence stars, core helium-burning stars, and oxygen-rich asymptotic giant branch (AGB) stars. We also identify intermediate-age (∼200 Myr–1 Gyr) carbon-rich AGB stars and a well-populated old (≳1 Gyr) red giant branch. The CMDs show two distinct bursts of star formation beginning ∼30 and ∼200 Myr ago, the latter consistent with the most recent pericenter passage predicted by N-body simulations. The spatial distribution of stars reveals a tidal bridge extending from NGC 4485 and connecting to the disk of NGC 4490. Compact star-forming regions are seen along NGC 4490's spiral arms, possibly originating from its infrared nucleus. A significant metallicity gradient is observed in the young stellar populations forming the bridge. These findings suggest that during the last pericenter passage, gas was stripped from NGC 4485 via tidal forces or ram pressure, accreted by NGC 4490, and mixed with in situ material, fueling ongoing star formation. This system provides a unique nearby laboratory for studying how tidal interactions shape the star formation and chemical enrichment history of dwarf galaxies.

Keywords: Dwarf galaxies, Star formation, Galaxy stellar content, Galaxy interactions
Wave Responses to Magnetosheath Boundary Motion at Saturn: Mirror Modes and Electromagnetic Ion Cyclotron Waves. Saturn's magnetosheath provides a natural laboratory for studying the generation and evolution of low-frequency plasma waves that play a key role in regulating temperature anisotropy and mediating wave–particle interactions. Using magnetic field and plasma measurements from the Cassini spacecraft, we investigate the occurrence of mirror mode waves (MMWs) and electromagnetic ion cyclotron (EMIC) waves in relation to the large-scale motion of Saturn's magnetosheath boundaries, namely, the bow shock and magnetopause. A systematic classification of spacecraft crossings reveals that although MMWs are pervasive across all dynamic conditions, their morphology transitions between peak-like and dip-like structures depending on the direction of boundary motion. EMIC waves occur preferentially during outward motion of the bow shock, particularly on the dawnside, where recent upstream pressure reductions may have driven boundary expansion and formed localized low-beta regions favorable for cyclotron instability. These findings highlight the importance of time-dependent boundary dynamics in shaping the wave environment of planetary magnetosheaths, with broader implications for energy dissipation and plasma stability in rapidly rotating planetary magnetospheres and other astrophysical plasmas with evolving boundaries.

Keywords: Planetary magnetospheres, Saturn, Space plasmas
Radial Evolution of Turbulence Spectra on the Jovian Magnetosheath Flanks: Juno Observations. The Jovian magnetosheath provides a unique environment for examining the radial evolution of magnetosheath turbulence due to its large spatial extent. Utilizing magnetic field measurements from the Juno spacecraft, this study examines the radial evolution of magnetic field turbulence on the flanks of the Jovian magnetosheath. We find that turbulence on the dawn flank evolves significantly after crossing the bow shock. In contrast, the dusk flank exhibits a flattening of the power spectrum at MHD scales, attributed to the presence of mirror modes. Wave analysis based on the singular value decomposition method confirms the role of mirror modes in causing spectral flattening. Statistical results reinforce the connection between mirror modes and spectral flattening and reveal a dawn–dusk asymmetry in the distribution of mirror modes.

Keywords: Interplanetary turbulence, Planetary magnetospheres
A Unified Model of Solar Prominence Formation with Self-consistent Heating. Several models have been proposed to explain the formation of solar prominences, among which the evaporation─condensation model and the direct injection model are the most popular ones. In our previous study, we proposed to unify these two models: in both models, the formation of solar prominence is due to localized heating, presumably via magnetic reconnection. When the localized heating is located in the upper chromosphere, the cold in situ plasmas are heated to coronal temperatures, then evaporated to the corona, and finally condensate to form a prominence. Such a process is manifested as the evaporation─condensation model. When the localized heating is located in the lower chromosphere, the enhanced in situ pressure would push the cold plasmas in the upper chromosphere to the corona directly, which is manifested as the direct injection model. While the idea was confirmed by the one-dimensional hydrodynamic simulations, the heating was imposed ad hoc. In order to simulate the localized heating more self-consistently, we perform two-dimensional magnetohydrodynamic simulations in this paper, where the localized heating is naturally realized by magnetic reconnection at different heights. The simulations further validate our model. In addition, mass circulation in the solar atmosphere is also briefly discussed.

Keywords: Solar filaments, Solar prominences
Spatial Models of R-process Remnants and their γ-Ray Detectability. We investigate the detectability of gamma-ray emission from long-lived radioactive isotopes in r-process-enriched remnants, focusing on how assumptions about their spatial distribution introduce uncertainty into detection prospects. Using a suite of physically motivated models for the Galactic distribution of kilonova and supernova remnants, we simulate synthetic remnant populations and compute their time-evolving gamma-ray spectra. We then compare these flux predictions to the sensitivity limits of next-generation instruments such as a Compton Spectrometer and Imager (COSI) and High-Energy X-ray Probe (HEX-P). We find that even under optimistic assumptions, detection probabilities with COSI are extremely low (≪1%), and that marginal improvements are only possible with instruments like HEX-P if prior localization is available. The choice of spatial distribution model can lead to more than an order-of-magnitude variation in expected line fluxes at low instrument sensitivities, underscoring the role of spatial modeling as a dominant source of uncertainty. Nevertheless, instrumental capability remains the fundamental bottleneck, and a hybrid mission combining COSI-like sky coverage with HEX-P-level line sensitivity would be required to make detection more probable than not.

Keywords: Neutron stars, Explosive nucleosynthesis, Gamma-ray lines, Gamma-ray sources, R-process
JWST/NIRSpec Observations of High-ionization Emission Lines in Galaxies at High Redshift. JWST spectroscopy has built large emission line samples at z ≳ 4, but it has yet to confidently reveal many galaxies with the hard radiation fields commonly associated with active galactic nucleus photoionization. While this may indicate a weaker UV ionizing spectrum in many z &gt; 4 active galactic nuclei or obscuration from dense neutral gas and dust, the complete picture remains unclear owing to the small number of deep rest-UV spectra. Here, we characterize the strength of high-ionization lines in 53 new galaxies observed with NIRSpec R = 2700 grating spectroscopy. We present new detections of narrow N V λ1240 in two galaxies. One is a previously confirmed z = 6.98 little red dot (LRD) with broad Hβ, and the other is a z = 8.72 galaxy with a narrow-line spectrum. Neither source exhibits C IV or He II emission, indicating large N V/C IV and N V/He II ratios that may reflect a combination of nitrogen-enhancement and resonant scattering effects. We investigate the incidence of narrow high-ionization lines in a large database of 851 NIRSpec grating spectra, and we separately quantify the fraction of LRDs with narrow high-ionization UV emission lines. Our results likely suggest that hard radiation fields are indeed present in a small subset of LRDs ( 12.5‑10.4+23.7% ) and UV-selected galaxies ( 2.2‑1.0+1.7% ) at z &gt; 4. The identification of narrow high-ionization lines in the population of LRDs with strong Balmer absorption suggests that the dense neutral hydrogen gas may not uniformly cover the nucleus. The strong N V (coupled with weak C IV and He II) suggests that efforts to identify high-ionization lines should extend down in wavelength to the N V doublet.

Keywords: Active galactic nuclei, High-redshift galaxies
The SDSS-V Black Hole Mapper Reverberation Mapping Project: Multiline Dynamical Modeling of a Highly Variable Active Galactic Nucleus with Decade-long Light Curves. We present dynamical modeling of the broad-line region (BLR) of the highly variable active galactic nucleus (AGN) SDSS J141041.25+531849.0 (z = 0.359) using photometric and spectroscopic monitoring data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping project and the current fifth-generation SDSS Black Hole Mapper program, spanning from early 2013 to early 2023. We model the geometry and kinematics of the BLR in the Hβ, Hα, and Mg II emission lines for three different time periods to measure the potential change of structure within the BLR across time and line species. We find a moderately face-on  (ifull-state=29.68−3.62+4.74deg)  thick-disk  (θopn,full−state=42.04−3.96+4.32deg)  geometry for most BLRs, with a joint estimate for the mass of the supermassive black hole for each of three time periods, yielding  log10(MBH/M⊙)=8.10−0.03+0.03  when using the full data set. The inferred individual virial factor f ∼ 1.6 is moderately smaller than the average factor for a local sample of dynamically modeled AGNs. There is strong evidence for nonvirial motion, with over 70% of clouds on inflowing/outflowing orbits. We analyze the change in model parameters across emission lines, finding the radii of BLRs for the emission lines are consistent with the following relative sizes RHβ ≲ RMgII ≲ RHα. Comparing results across time, we find Rlow-state ≲ Rhigh-state, with the change in BLR size for Hβ being more significant than for the other two lines. The data also reveal complex, time-evolving, and potentially transient dynamics of the BLR gas over a decade-long timescale, encouraging for future dynamical modeling of fine-scale BLR kinematics.

Keywords: Supermassive black holes, Astronomy data modeling, Active galactic nuclei, Quasars