Sazuna/UAT_keywords huggingface dataset:
The ALMA-QUARKS Survey: Evidence of a Candidate High-mass Prestellar Core Aside a Bright-rimmed Cloud IRAS 18290-0924. Although frequently reported in observations, the definitive confirmation of high-mass prestellar cores has remained elusive, presenting a persistent challenge in star formation studies. Using two-band observational data from the 3 mm ATOMS and 1.3 mm QUARKS surveys, we report a high-mass prestellar core candidate, C2, located on the side of the bright-rimmed cloud IRAS 18290-0924. The C2 core identified from the 3 mm continuum data of the ATOMS survey (∼2″, ∼10,000 au at 5.3 kpc) has a mass ranging from 27 to 68 M⊙ for temperatures 10─22 K within a radius of ∼2800 au. The highest-resolution (∼0 .″ 3, ∼1500 au) observations of this source presented to date from the QUARKS survey reveal no evidence of further fragmentation. Further analysis of a total ∼10 GHz bandwidth of molecular line survey does not find star formation activity (e.g., outflows and ionized gas) associated with the core, with a few molecular lines of cold gas detected only. Additionally, virial analysis indicates the C2 core is gravitationally bound (αvir ∼ 0.1−0.3) and thus could be undergoing collapse toward star formation. These results strongly establish a candidate for a high-mass prestellar core, contributing to the very limited number of such sources known to date.

Keywords: Star forming regions, Massive stars, Molecular clouds, Dust continuum emission, Interstellar medium, Submillimeter astronomy
Stellar Cycle Variability in Mount Wilson Stars and Dynamo Models: Rotation Rate and Dynamo Number Dependency. Similar to the solar cycle, the magnetic cycles of other solar-type stars are also variable. How the variability of the stellar cycle changes with the rotation rate or the dynamo number is valuable information for understanding the stellar dynamo process. We examine the variability in stellar magnetic cycles by studying 81 stars from the data of the Mount Wilson Observatory, which started observations in 1966. For 28 stars, we have time series data available until 2003, while for others, the data are limited until 1995. We specifically explore how the variability changes with respect to three rotation-related parameters. We find a modest positive correlation between the variability and the stellar rotation period. In addition, we find suggestive negative correlations between the variability and the inverse squared Rossby number (Ro−2) and the ratio of the mean cycle duration and rotation period ( log(&lt;Pcyc&gt;/Prot)2 ). Variability computed from the magnetic field of stellar dynamo models also shows similar trends. Finally, inspired by previous studies, we examine dynamo number scaling in our model data and find that Ro−0.6 (instead of Ro−2 as suggested in the linear αΩ dynamo theory) and  (&lt;Pcyc&gt;/Prot)0.6  (instead of  log(&lt;Pcyc&gt;/Prot)2  as predicted in previous observations) are a good measure of the dynamo number. In conclusion, our results demonstrate that the stellar magnetic cycle variability decreases with the increase of the rotation rate or the dynamo number.

Keywords: Solar cycle, Magnetohydrodynamics, Sunspots, Stellar magnetic fields, Solar dynamo, Stellar activity, Solar magnetic fields, Solar activity
Irradiated Atmospheres. IV. Effect of Mixing Heat Flux on Chemistry. Vertical mixing disrupts the thermochemical equilibrium and introduces additional heat flux that alters exoplanetary atmospheric temperatures. We investigate how this mixing-induced heat flux affects atmospheric chemistry. Temperature increase in the lower atmosphere by the mixing-induced heat flux alters species abundances there and modifies those in the upper atmosphere through vertical transport. In the lower atmosphere, most species follow thermodynamic equilibrium with temperature changes. In the upper layers, species mixing ratios depend on the positions of quenching levels relative to the regions exhibiting significant mixing-induced temperature variations. When the quenching level resides within such a region (e.g., CO, CH4, and H2O with strong mixing), the mixing ratios in the upper atmosphere are modified due to changes in the quenched ratios affected by the temperature variation in the lower atmosphere. This alters the mixing ratio of other species (e.g., NO and CO2) through the chemical reaction network, whose quenching occurs in the region without much temperature change. The mixing ratios of CH4, H2O, and NH3 decrease in the lower atmosphere with increasing mixing heat flux, similarly reducing these ratios in the upper atmosphere. Conversely, the mixing ratios of CO, CO2, and NO rise in the lower atmosphere, with CO and CO2 also increasing in the upper levels, although NO decreases. Weaker host star irradiation lowers the overall temperature of the planet, allowing a smaller mixing to have a similar effect. We conclude that understanding the vertical mixing heat flux is essential for accurate atmospheric chemistry modeling and retrieval.

Keywords: Exoplanet structure, Exoplanet atmospheric composition , Exoplanet atmospheres
SOFIA FEEDBACK Survey: The Eagle Nebula in [C II] and Molecular Lines. We characterize the physical conditions and energy budget of the M16 H II region using Stratospheric Observatory for Infrared Astronomy FEEDBACK observations of the [C II] 158 μm line. The O stars in the ∼104 M⊙ NGC 6611 cluster powering this H II region have blown at least two cavities into the giant molecular cloud: the large M16 cavity and the small N19 bubble. We detect the spectroscopic signature of an expanding photodissociation region shell toward N19, and traces of a thin, fragmented expanding shell toward M16. Our [C II] observations are resolved to 0.5 km s−1 and 15 .″ 5 and analyzed alongside similarly resolved CO J = 3─2 observations as well as archival data ranging from the radio to X-ray tracing a variety of gas phases spanning dense ∼10 K molecular gas, 104 K photoionized gas, and 1,000,000 K collisionally ionized plasma. With this dataset, we evaluate the coupling of energetic feedback from NGC 6611 and the O9 V star within N19 to the surrounding gas. Winds from NGC 6611 have blown a 20 pc radius cavity constrained in size along the major axis of the natal giant molecular filament, and much of the mechanical wind energy (&gt;90%) has escaped through breaches in the ≲104 M⊙ shell. Reservoirs of dense gas remain within a few parsecs of the cluster. N19, younger than M16 by ≳106 yr, is driven by a combination of mechanical wind energy and thermal pressure from photoionized gas and has swept up ∼103 M⊙ into neutral atomic and molecular shells.

Keywords: Interstellar clouds, Stellar feedback, Photodissociation regions
A UV to X-Ray View of Soft Excess in Type 1 Active Galactic Nuclei. II. Broadband Correlations. The physical origin of soft X-ray excess (SE) is a long-lasting question, with two prevailing theories—"warm corona" and "ionized reflection"—dominating the discussion. In the warm corona scenario, SE originates from upscattered disk photons and should therefore correlate strongly with UV emission. Conversely, in the ionized reflection scenario, SE arises from the illumination of the accretion disk by the hot corona and should primarily correlate with the hard X-ray primary continuum (PC). In this second paper of the series, we investigate the correlations among SE, UV, and PC, leveraging a sample of 59 unobscured type 1 active galactic nuclei compiled in S.-J. Chen et al. Our extensive analysis reveals a strong intrinsic correlation between SE and UV that remains robust after controlling for PC (pnull ≲ 1 × 107). In contrast, the correlation between SE and PC is weaker but still statistically significant (pnull ≲ 5 × 10−2). These findings suggest that, in addition to ionized reflection—a natural outcome of the hot corona illuminating the disk—a warm corona component is essential, and may even dominate, in producing the soft excess. Additionally, we report a mild anticorrelation between SE strength (q) and PC photon index (ΓPC) (pnull = 1 × 10−2), suggesting a potential competition between the warm and hot coronae. Finally, we find that the ΓPC values we derived with SE properly incorporated exhibit a much weaker correlation with λEdd (pnull = 2 × 10−2) than previously reported in the literature. This highlights the critical role of accurately modeling SE in studies of the ΓPC─λEdd relation.

Keywords: X-ray active galactic nuclei, Active galactic nuclei
Wind-AE: A Fast, Open-source 1D Photoevaporation Code with Metal and Multifrequency X-Ray Capabilities. Throughout their lives, short-period exoplanets (&lt;100 days) experience X-ray and extreme-UV (XUV) stellar irradiation that can heat and photoionize planets' upper atmospheres, driving transonic outflows. This photoevaporative mass loss plays a role in both evolution and observed demographics; however, mass-loss rates are not currently directly observable and can only be inferred from models. To that end, we present an open-source fast 1D, XUV multifrequency, multispecies, steady-state, hydrodynamic Parker wind photoevaporation relaxation model based on Murray-Clay et al. The model can move smoothly between high and low flux regimes and accepts custom multifrequency stellar spectra. While the inclusion of high-energy X-rays increases mass-loss rates ( Ṁ ), metals decrease  Ṁ , and the net result for a typical hot Jupiter is a similar  Ṁ  but a hotter, faster, and more gradually ionized wind. We find that mulitfrequency photons (e.g., 13.6─2000 eV) are absorbed over a broader range of heights in the atmosphere, resulting in a wind launch radius, RXUV, that is of order 10 nanobars for all but the highest surface gravity planets. Grids of H/He solar-metallicity atmospheres reveal that, for typical hot Jupiters like HD 209458b, RXUV ≍ 1.1RP─1.8RP for low fluxes, meaning that the energy-limited mass-loss rate,  ṀElim(R) , computed at R = RP is a good approximation. However, for planets with low escape velocities, like many sub-Neptunes and super-Earths, RXUV can be ≫RP, making it necessary to use  ṀElim(R=RXUV)  to avoid significantly underestimating mass-loss rates. For both high escape velocities and large incident fluxes, radiative cooling is significant and energy-limited mass loss overestimates  Ṁ .

Keywords: X-ray astronomy, Photoionization, Hot Jupiters, Exoplanet atmospheric dynamics, Exoplanet atmospheric variability, Super Earths, Extreme ultraviolet astronomy, Exoplanet evolution, Mini Neptunes, Exoplanet atmospheric evolution, Exoplanet atmospheres, Exoplanet atmospheric structure
PROJECT-J: The Shocking H<SUB>2</SUB> Outflow from HH 46. We analyze the H2 emission observed in the HH 46 Class I system as part of PROtostellar JEts Cradle Tested with JWST (PROJECT-J), to investigate the origin and excitation of the warm molecular outflow. We used NIRSpec and MIRI spectral maps (1.6─27.9 μm) to trace the structure and physical conditions of the outflow. By fitting the H2 rotational diagrams with a multitemperature gas model, we derived key physical parameters, including temperature, extinction, column densities, and the ortho-to-para ratio. This information is combined with a detailed kinematical analysis and comparison with irradiated shock models. We find no evidence of H2 temperature or velocity stratification from the axis to the edge of the outflow, as would be expected in MHD disk-wind models and as observed in other outflows. Instead, the observations suggest that the H2 emission arises from shock interactions of jet bow shocks and/or wide-angle winds with the ambient medium and cavity walls. NIRSpec emission and velocity maps reveal expanding molecular shells, likely driven by the less luminous source in the binary system. We infer an accretion rate of ≲10−9 M⊙ yr−1 for the secondary source, approximately one order of magnitude lower than that of the primary. The H2 emission is consistent with excitation by low-velocity (∼10 km s−1) J-type shocks, irradiated by an external UV field that may originate from strong dissociative shocks driven by the atomic jet. Future JWST observations will further constrain the evolution of the expanding shell and the mechanisms driving the outflow.

Keywords: Infrared spectroscopy, Stellar jets, Young stellar objects, Stellar winds, Protostars
A Sharper View of the X-Ray Spectrum of MCG─6-30-15 with XRISM, XMM-Newton, and NuSTAR. We present a time-averaged spectral analysis of the 2024 XRISM observation of the narrow-line Seyfert-1 galaxy MCG─6-30-15, taken contemporaneously with XMM-Newton and NuSTAR. Our analysis leverages a unique combination of broadband and high-resolution X-ray spectroscopy to definitively isolate and characterize both broad and narrow emission and absorption features in this source. The best-fitting model for the joint spectral analysis is very well described by reflection from the inner accretion disk illuminated by a compact corona, modified by multizone ionized absorption from an outflowing wind along the line of sight. The XRISM/Resolve data confirm that a strong, relativistically broadened Fe Kα emission line is required in order to obtain an adequate model fit. The Resolve data additionally verify the presence of a vout ∼ 2300 km s−1 component of this outflowing wind, find tentative evidence for a vout ∼ 20,000 km s−1 wind component, and indicate that the reflection from distant, neutral material may originate in a nonuniform structure rather than the traditional torus of AGN unification schemes. Though a rapid prograde black hole spin is statistically preferred by the best-fitting model, consistent with previous results, the AGN flux variability over the course of the observation complicates the interpretation of the time-averaged spectra. This insight, clarified by the combination of high signal-to-noise and high spectral resolution in the joint data set, emphasizes the importance of time-resolved, high-resolution spectral analysis in unambiguously measuring the physical properties of variable AGN.

Keywords: Accretion, Black hole physics, Active galactic nuclei, High energy astrophysics
Probing the Nature of High-redshift Long GRB 250114A and Its Magnetar Central Engine. GRB 250114A is a long-duration gamma-ray burst (GRB) that triggered the Swift/Burst Alert Telescope with a spectroscopic high redshift at z = 4.732. The light curve of the prompt emission is composed of three distinct emission episodes, which are separated by quiescent gaps ranging from tens to hundreds of seconds. Meanwhile, the X-ray light curve exhibits the canonical X-ray emission that is composed of several power-law segments' superposition of a giant X-ray flare. More interestingly, there is still significant X-ray emission during the quiescent time in the prompt emission, suggesting a continuously active central engine whose power fluctuates across the gamma-ray detectability threshold. In this paper, we propose a magnetar as the central engine of GRB 250114A by fitting the X-ray light curve and infer a magnetic field strength  Bp=13.24−5.84+1.73×1015G  and an initial spin period  P0=14.31−3.16+0.93ms  of magnetar, with a jet correction, fall within a reasonable range. Furthermore, we also compare the prompt emission, X-ray afterglow, Ep─Eγ,iso, and ∊ − distribution of GBR 250114A with those of other high-z sample-GRBs and find no significant statistical differences between them.

Keywords: Gamma-ray bursts
Unveiling the Nature of Superorbital Modulation of SMC X-1 Using NinjaSat. We report a long-term, high-cadence timing and spectral observation of the X-ray pulsar SMC X-1 using NinjaSat—a 6U CubeSat in low-Earth orbit—covering nearly a full superorbital cycle. SMC X-1 is a high-mass X-ray binary exhibiting a 0.7 s X-ray pulsar and a nonstationary superorbital modulation with periods ranging from approximately 40 to 65 days. Its peak luminosity of 1.3 × 1039 erg s−1 makes it a local analog of ultraluminous X-ray pulsars powered by supercritical accretion. We find that the spinup rate during the high state remains consistent with the long-term average, with no significant correlation between the spinup rate and flux. This result indicates that the modulation is primarily geometric rather than accretion-driven. The hardness ratio and spectral shape are stable throughout the entire superorbital cycle, supporting obscuration by optically thick material or energy-independent scattering. In addition, the 2─20 keV pulse profile varies with superorbital phase, which may be explained either by a variable covering fraction, due to geometric obscuration, or by free precession of the neutron star. This represents the first complete measurement of the spinup rate and spectral evolution across a single superorbital cycle in SMC X-1, highlighting the scientific capability of CubeSat-based observatories.

Keywords: Neutron stars, High mass x-ray binary stars, High energy astrophysics, Compact objects
The N<SUB>H</SUB> Distribution of Hard X-Ray Selected Active Galactic Nuclei in the NEP Field. X-ray surveys are one of the most unbiased methods for detecting Compton-thick (CT; NH ≥ 1024 cm−2) active galactic nuclei (AGN), which are thought to comprise up to 60% of AGN within z ≲ 1.0. These CT AGN are often difficult to detect with current instruments, but the X-ray data within the JWST-North Ecliptic Pole (NEP) Time Domain Field present a unique opportunity to study faint and obscured AGN. The NEP contains the deepest NuSTAR survey to date, and X. Zhao et al. detected 60 hard X-ray sources from the combined exposure of NuSTAR's Cycle 5 and 6 observations. In this work, we utilize the NuSTAR Cycle 5+6+8+9 data and simultaneous XMM-Newton observations in order to perform the first spectroscopic analysis of the 60 source catalog. We present this analysis and measure the NH distribution of the sample. We measure an observed CT fraction of  0.13−0.04+0.15  down to an observed 8─24 keV flux of 6.0 × 10−14 erg s cm−2, and we correct our analysis for absorption bias to estimate an underlying CT fraction of  0.32−0.08+0.23 . The derived obscuration distribution and CT fraction are consistent with population synthesis models and previous surveys.

Keywords: Surveys, Active galactic nuclei, X-ray active galactic nuclei, X-ray surveys
Under Pressure: Decoding the Effect of High Densities on Derived Nebular Properties. Recent JWST observations have uncovered a population of compact, high-redshift (z &gt; 6) galaxies exhibiting extreme nebular conditions and enhanced nitrogen abundances that challenge standard chemical evolution paradigms. We present a joint UV and optical abundance analysis using a new suite of Cloudy photoionization models covering a wide density range (ne = 102─109 cm−3), combined with Hubble Space Telescope and JWST spectroscopy for a sample of star-forming galaxies across 0.0 ≲ z ≲ 10.6. We find that assuming uniform, low-density conditions (ne ∼ 102 cm−3) in high-density environments (ne ∼ 105 cm−3) can bias nebular diagnostics by overestimating Te (up to 1800 K), overpredicting  logU  (by &gt;1 dex), and underestimating O/H (up to 0.67 dex), while only modestly inflating N/O. Therefore, robust abundance determinations at high z require a multiphase density model. Using this model, we recalculate O/H and N/O abundances for our sample and present the first  logU  diagnostics and ionization correction factors for high-ionization UV N lines. We find that the UV tracers systematically overestimate N/O by ∼0.3─0.4 dex relative to the optical benchmark. We find that N/O increases with redshift, correlating with both ne and star formation rate surface density (ΣSFR), suggesting that N/O is temporarily enhanced in compact, high-pressure environments. However, the ne evolution with z is more gradual than the (1 + z)3 scaling of virial halo densities, suggesting that ne evolution is shaped by both cosmological structure growth and baryonic processes. These trends point to prompt N/O enrichment potentially driven by very massive stars, with key implications for interpreting UV emission and determining reliable chemical abundances from JWST observations of the early Universe.

Keywords: Galaxy chemical evolution, Chemical abundances, Emission line galaxies, Galaxy abundances, Galaxy evolution, Interstellar medium
The Drivers of the Decline in Supermassive Black Hole Growth at z &lt; 2. It is well established that cosmic supermassive black hole (SMBH) growth peaks at z ≍ 1.5─2, followed by a strong decline of ≍1─1.5 dex toward the present day, with the comoving number density of higher-luminosity active galactic nuclei (AGNs) peaking at higher redshift (referred to as "AGN downsizing"). We leverage the best current measurements of the SMBH accretion distribution, based upon data from nine well-characterized extragalactic fields with a "wedding-cake" design, to investigate and quantify the drivers of the drastic decline in cosmic SMBH growth. The decline in the typical Eddington ratio (λEdd) of AGNs (decreasing by ≍1.35 dex from z ≍ 1.5─2 to z ≍ 0.2) is the dominant driver for the broad decline in SMBH growth, rather than a shift of accretion activity to less-massive SMBHs. As λEdd decreases toward lower redshift, the primary contributor to the cosmic SMBH accretion density (ρBHAR) has shifted from high-λEdd AGNs to low-λEdd AGNs, even though the latter always dominate the comoving AGN number density at z &lt; 4. We also find that the decline in SMBH growth toward lower SMBH mass in less-massive galaxies is primarily due to the decreasing outburst luminosity rather than the duty cycle.

Keywords: Supermassive black holes, X-ray active galactic nuclei, Galaxies
Unexpected Near-Resonant and Metastable States of Young Multiplanet Systems. Recent observations suggest that the incidence of near-resonant planets declines as planetary systems age, making young planetary systems key signposts of early dynamical evolution. Here we investigate the dynamical states of three of the youngest multitransiting planetary systems: AU Mic (three-planet, ∼20 Myr old), V1298 Tau (four-planet, ∼23 Myr old), and TOI-2076 (four-planet, ∼200 Myr old). We find that most planet pairs in these systems lie near resonance with circulating rather than librating resonant angles. As a result, they are more susceptible to dynamical chaos than systems that are either securely locked in resonance or far removed from it. Even modest eccentricities of 0.04─0.08 may drive them to instability on timescales of tens to hundreds of Myr. Moreover, the observed orbital architectures are vulnerable to eccentricity excitation through mechanisms such as divergent resonance crossing triggered by planetesimal scattering. The observed near-resonant state may represent a transitional phase between a librating resonant chain and a mature nonresonant planetary system. Finally, we briefly discuss mechanisms that could give rise to the observed near-resonant configurations, including overstable libration, disk turbulence, and receding disk inner edge.

Keywords: Exoplanet dynamics, Exoplanet evolution, Orbital resonances, Exoplanet systems