Sazuna/UAT_keywords huggingface dataset:
Probing the Cosmic Baryon Distribution and the Impact of Active Galactic Nuclei Feedback with Fast Radio Bursts in CROCODILE Simulation. We investigate the missing baryon problem using fast radio bursts (FRBs) to trace cosmic baryons. Our CROCODILE simulations, performed with the GADGET3/4-OSAKA smoothed particle hydrodynamics code, include star formation, supernova, and active galactic nuclei (AGN) feedback. We generate light cones from large-scale structure simulations to compute gas density profiles and dispersion measures (DMs) measurable by FRBs. Our results show that AGN feedback reduces central gas densities in halos, reshaping the boundary between the circumgalactic medium and intergalactic medium (IGM). Zoom-in simulations reveal that AGN feedback significantly modulates the DM contributions from foreground halos along different sight lines. Using the DM─redshift (DM─z) relation and comparing it to the Macquart relation, we constrain the diffuse baryon mass fraction at z = 1 to  fdiff=0.865−0.165+0.101  (fiducial) and  fdiff=0.856−0.162+0.101  (NoBH), which include contributions from both IGM (fIGM) and halos (fHalos), serving as upper limits. We also quantify the redshift evolution of fdiff and fIGM, and provide the fitting results. Our study provides a framework for understanding baryon distribution across cosmic structures, FRB host galaxies, and the role of AGN in shaping foreground DM contributions.

Keywords: Galaxy dark matter halos, Hydrodynamical simulations, Circumgalactic medium, Cosmological parameters from large-scale structure, Intergalactic medium, Radio transient sources
McFACTS. II. Mass Ratio─Effective Spin Relationship of Black Hole Mergers in the Active Galactic Nucleus Channel. We use the Monte Carlo For AGN Channel Testing and Simulation (McFACTS; https://www.github.com/mcfacts/mcfacts) code to study the effect of active galactic nucleus (AGN) disk and nuclear star cluster (NSC) model parameters on predicted mass distributions for LIGO─Virgo─KAGRA compact binaries forming in AGN disks. The assumptions we vary include the black hole (BH) initial mass function (IMF), disk model, disk size, disk lifetime, NSC model, and the prograde-to-retrograde fraction of newly formed BH binaries. Broadly, we find that dense, moderately short-lived AGN disks are preferred for producing a (q, χeff) anticorrelation like those identified from existing gravitational-wave observations. Additionally, a BH IMF (IMF ∝ M−2) is preferred over a more top-heavy IMF (M−1). To produce results consistent with observations, the preferred fraction of prograde to retrograde is &gt;90%.

Keywords: Active galactic nuclei, Gravitational waves, Black holes
Detection of the Extended Gamma-Ray Emission around PSR J1627-4706 with Fermi-LAT. Based on nearly 16 yr of Fermi Large Area Telescope observations we have detected an extended GeV gamma-ray source with a significance of ∼7.6σ, spatially coincident with the old pulsar PSR J1627-4706. The gamma-ray morphology is well characterized by a two-dimensional Gaussian spatial template, exhibiting a 68% containment radius of ∼0 .° 35. The observed gamma-ray emission exhibits a single power-law spectral distribution with an index of 1.97 ± 0.06 in the energy range of 500 MeV─1 TeV. We have investigated several potential origins for this emission, including a supernova remnant (SNR), pulsar wind nebula (PWN), and pulsar halo scenario. The relatively low spin-down luminosity and high characteristic age of PSR J1627-4706 make both the PWN and pulsar halo interpretations unlikely. While a putative SNR could potentially account for the gamma-ray spectrum through either leptonic or hadronic processes, the lack of corresponding shell-type structure in other wavelengths presents a significant challenge to this explanation.

Keywords: Gamma-ray sources, Supernova remnants, Cosmic rays
Diversity of Cold Worlds: Predicted Near-to-mid-infrared Spectral Signatures of a Cold Brown Dwarf with Potential Auroral Heating. Recent James Webb Space Telescope NIRSpec observations have revealed strong methane emission at 3.326 μm in the ≍482 K brown dwarf CWISEP J193518.59−154620.3 (W1935). Atmospheric modeling suggests the presence of a ≍300 K thermal inversion in its upper atmosphere, potentially driven by auroral activity. We present an extension of the retrieved spectra of W1935 with and without inversion spanning 1─20 μm to identify thermal inversion─sensitive spectral features and explore the origin of the object's peculiar characteristics. Our analysis indicates that atmospheric heating contributes approximately 15% to the bolometric luminosity. The model with inversion predicts an additional similar-strength methane emission feature at 7.7 μm and tentative ammonia emission features in the mid-infrared. Wavelengths beyond ∼2 μm are significantly influenced by the inversion, except for the 4.1─5.0 μm CO2 and CO features that originate from atmospheric layers deeper than the region where the inversion occurs. W1935 appears as an outlier in Spitzer/IRAC mid-infrared color─magnitude diagrams (CMDs) based on the mCh1 − mCh2 (IRAC 3.6─4.5 μm) color but exhibits average behavior in all other combinations that trace clear sequences. This anomaly is likely due to the Ch2 filter probing vertical mixing-sensitive CO2 and CO features that do not correlate with temperature or spectral type. We find that the thermal inversion tends to produce bluer mCh1 − mCh2 colors, so the overluminous and/or redder position of W1935 in diagrams involving this color cannot be explained by the thermal inversion. This analysis provides insights into the intriguing dispersion of cold brown dwarfs in mid-infrared CMDs and sheds light on their spectral diversity.

Keywords: Planetary atmospheres, Brown dwarfs, Y dwarfs, Exoplanet atmospheres
Puffed-up Inner Rings and Razor-thin Outer Rings in Structured Protoplanetary Disks. The vertical distribution of pebbles in protoplanetary disks is a fundamental property influencing planet formation, from dust aggregation to the assembly of planetary cores. In the outer region of protoplanetary disks, the intensity of the optically thin but geometrically thick dust ring decreases along the minor axis due to reduced line-of-sight optical depth. Multi-ring disks thus provide an excellent opportunity to study the radial variation of the vertical properties of dust. We investigate the vertical dust distribution in six protoplanetary disks with resolved double rings, using high-resolution Atacama Large Millimeter/submillimeter Array Band 6 continuum observations. By modeling the azimuthal intensity variations in these rings, we constrain the dust scale heights for each ring. Our results reveal a dichotomy: inner rings exhibit puffed-up dust layers with heights comparable to the gas scale height, while outer rings are significantly more settled, with dust scale heights less than 20% of the gas scale height. This suggests a radial dependence in dust settling efficiency within the disks, potentially driven by localized planetary interactions or the global radial dependency of the vertical shear instability. We discuss the implications of these findings for dust trapping, planet formation, and protoplanetary disk evolution. Our work highlights the importance of vertical dust distribution in understanding the early stages of planet formation and suggests that outer (&gt;80 au), settled rings are preferred sites for planet formation over inner (&lt;80 au), turbulent rings.

Keywords: Submillimeter astronomy, Dust continuum emission, Protoplanetary disks, Planet formation
Monte Carlo Simulation of the Compton Scattering and Disk Reflection of a Cylinder with Hot Electrons Moving Away from a Black Hole. For accreting black holes (BHs), the lamp-post scenario is a simple and popular model: A hot and point-like corona is located above the BH, irradiating the accretion disk with hard X-ray radiation, which is believed to be generated by inverse Compton scattering in the corona. Although the lamp-post model successfully explains the disk reflection component, it fails to address the origin of seed photons and the geometry of the hot corona, because this model simplistically treats the corona as a point-like source generating a cutoff power law spectrum. In this paper, we make simulations for a possible physical realization of the lamp-post scenario: The shape of the scattering zone is set to be a cylinder, corresponding to the jet base near a BH. The source of seed photons in this system is assumed to be the multicolor blackbody radiation of the accretion disk. In our simulations, the Compton scattering process is simulated with a custom Monte Carlo program based on the Geant4 package, and the disk reflection process is simulated with the xilconv model in XSPEC. Our simulation results have confirmed that the relativistic motion of the jet can weaken or even completely suppress the reflection of the accretion disk, and simultaneously, the Comptonization of disk photons in the jet can still make a major contribution to the observed X-ray spectrum in the high-energy range. We discuss the implications of our simulation results, in light of the recent observations of a very weak reflection component in the presence of a strong hard X-ray radiation from the outburst of Swift J1727.8-1613.

Keywords: X-ray astronomy, Relativistic jets, Monte Carlo methods, Black holes
The z = 7.08 Quasar ULAS J1120+0641 May Never Reach a "Normal" Black Hole to Stellar Mass Ratio. JWST observations of quasars in the Epoch of Reionization have revealed that many lie in host galaxies that are severely undermassive relative to the supermassive black holes. It is unclear how these systems will evolve to the tight local relation between stellar mass and black hole mass. We search for companions around the z = 7.08 quasar ULAS J1120+0641 using JWST/NIRCam narrow-, medium-, and wide-band photometry to identify [O III] emitters at the quasar redshift, and explore the potential for growth of the host galaxy through future mergers. We find 22 sources near the quasar's redshift across our two 4.4 arcmin2 fields, indicating that the environment of ULAS J1120+0641 is strongly overdense in z ∼ 7.1 galaxies relative to the field. We estimate the potential future mass budget of the quasar host galaxy by summing the current stellar and gas masses of the quasar host and surrounding galaxies, and correcting for incompleteness and selection effects. With no further black hole growth, ULAS J1120+0641 is unlikely to reach an MBH/M* ratio less than ∼2.5% at z = 0, still much higher than typical for local galaxies. However, such systems—a quiescent black hole in a low-luminosity galaxy—may have escaped detection locally if they are sufficiently distant.

Keywords: Protoclusters, High-redshift galaxies, James Webb Space Telescope, Quasars
The Structure and Formation Histories of Low-mass Quiescent Galaxies in the A2744 Cluster Environment. Low-mass quiescent galaxies are thought to predominantly reside in overdense regions, as environmental effects are often invoked to explain their shutdown of star formation. These longer-timescale quenching mechanisms—such as interactions with hot gas in the intracluster medium and dynamical encounters with other cluster galaxies—leave imprints on galaxy morphologies, emphasizing the importance of quantifying the structures of low-mass quiescent galaxies in galaxy clusters at z &lt; 0.5. Using spectrophotometric data from the UNCOVER and MegaScience programs, we present the first measurement of the quiescent size─mass relation between  7&lt;log(M⋆/M⊙)&lt;10  using JWST imaging, based on a sample of 1531 galaxies in the z = 0.308 A2744 galaxy cluster. The resulting size─mass relation has a significantly higher scatter than similar-redshift field samples, despite comparable best-fit relations in both the dwarf and intermediate-mass regimes. Both "progenitor bias," where larger, diskier low-mass galaxies enter the cluster at later epochs, and a general expansion of galaxy structure from dynamical interactions could be at play. This evolutionary framework is further supported by the tentative evidence that older low-mass quiescent galaxies in the cluster are more spheroidal. The star formation histories derived for our cluster sample imply their formation and quenching occurs relatively late, at z &lt; 1.5. In this scenario, the progenitor population would have disky axis-ratio distributions at cosmic noon, in agreement with recent observations. While this leaves ample time for dynamical interactions to maintain quiescence and drive the observed subsequent morphological evolution postquenching, the data disfavor an onset of quenching due to the environment.

Keywords: Galaxy clusters, Galaxy structure, James Webb Space Telescope, Galaxy evolution, Galaxy quenching
The Stellar Abundances and Galactic Evolution Survey (SAGES). IV. Surface Gravity Estimation and Giant─Dwarf Separation with the DDO51 Filter. Reliable estimation of stellar surface gravity (log g) for a large sample is crucial for evaluating stellar evolution models and understanding galactic structure; however, it is not easy to accomplish due to the difficulty in gathering a large spectroscopic data set. A photometric sky survey using a specific filter, on the other hand, can play a substantial role in the assessment of log g. The Stellar Abundances and Galactic Evolution Survey (SAGES) utilizes eight filters to provide accurate stellar parameters for ∼107 stars, with its DDO51 intermediate-band filter specifically designed for robust log g determination. In this work, the observed SAGES uSC and vSAGES photometry and the synthetic photometry in the g, r, i, and DDO51 bands derived from Gaia XP spectra are employed to investigate the importance of the DDO51 filter in the determination of log g. We applied machine learning-based extinction correction and employed XGBoost models, trained on stellar parameters from Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), to predict log g using photometric data. By comparing the model-predicted log g with LAMOST values, we find that including the DDO51 filter improves the accuracy of log g estimates by 21.0% (from 0.224 to 0.177 dex) overall and by 26.5% (from 0.302 to 0.222 dex) for G- and K-type stars as compared to those obtained without DDO51. The DDO51 filter is also validated to be particularly effective for metal-poor stars ([Fe/H] &lt; −1.0), where it significantly mitigates systematic biases. Our findings highlight the diagnostic power of the SAGES DDO51 filter, providing enhanced stellar characterization vital for future in-depth studies of the Milky Way.

Keywords: Stellar photometry, Stellar abundances, Surface gravity, Stellar physics, Photometry
Observational Study of Chromospheric Jets In and Around a Sunspot Observed by NVST and SDO. To better understand the characteristics, driving mechanisms, and potential heating contributions of chromospheric jets, we analyze two contrasting types: one originating from within the sunspot penumbra (inside jets) and the other originating from outside the penumbra (outside jets). Statistical analysis of 100 jets (50 inside jets and 50 outside jets) reveals that inside jets have a projected velocity range of 4─14 km s−1, a length range of 1─4 Mm, a width range of 0.2─0.6 Mm, and a lifetime range of 135─450 s, with mean values of 7.90 km s−1, 2.61 Mm, 0.41 Mm, and 260 s, respectively. About 52% of inside jets are associated with brightenings in Hα blue wing images, and some show high-temperature signatures, suggesting a connection with localized energy release. In contrast, outside jets have higher velocities (8─50 km s−1, average 19.04 km s−1), greater lengths (average 6.26 Mm, up to 27.27 Mm), slightly larger widths (average 0.46 Mm), and longer lifetimes (135─630 s, average 327 s). They typically originate from regions of opposite magnetic polarities and are associated with magnetic flux emergence and extreme-ultraviolet brightenings. Some outside jets correspond to coronal jets with inverted Y-shaped structures and temperatures exceeding one million Kelvin. Our results suggest that both jet types are driven by magnetic reconnection occurring in distinct magnetic field configurations and contribute to chromospheric and coronal heating.

Keywords: Solar activity, Solar chromosphere, Solar magnetic fields
The Infrared Complex Refractive Index and Band Strengths of Coronene Thin Films. Polycyclic aromatic hydrocarbon (PAH) molecules have long been theorized to be present in a multitude of interstellar environments. The radio-frequency detections of specific cyanosubstituted PAH molecules in the Taurus Molecular Cloud have provided new evidence that PAHs can be abundant in the interstellar medium. In particular, the recent detection of cyanocoronene strongly implies the existence of interstellar coronene. In this paper, we determined the infrared index of refraction and band strengths of coronene thin films vacuum-deposited at 5.1 K. Our values of the imaginary part of the index of refraction and the corresponding coronene band strengths are generally smaller in magnitude than those determined by previous efforts. These index of refraction and band strength values will be useful for interpreting infrared observations of high-extinction interstellar regions or planetary or exoplanetary atmospheres where condensed-phase coronene is likely to be present or for calculating upper limits on the interstellar coronene abundances.

Keywords: Molecular spectroscopy, Polycyclic aromatic hydrocarbons, Interstellar medium
Advanced Weights for IXPE Polarization Analysis. As the Imaging X-ray Polarimetry Explorer (IXPE) measures increasingly faint sources, the need for precise polarimetry extraction becomes paramount. In addition to previously described neural-net weights, we introduce here point-spread function weights and particle background weights, which can be critical for faint sources. In some cases these can be augmented by time/phase and energy weights. We provide a publicly available analysis tool to incorporate these new weights, validate our method on simulated data, and test it on archival IXPE observations. Together these weights decrease the area of the polarization uncertainty contour by a factor of 2 compared to baseline IXPE analysis and will be essential for background-limited IXPE observations.

Keywords: X-ray astronomy, Gamma-ray bursts, Astrostatistics techniques, Pulsars, Polarimetry
Spatial Distribution of Secondary Electrons' Synchrotron Emission: Property and Implication. Galactic γ-ray sources can be produced by either high-energy protons via proton─proton collisions or electrons/positrons via inverse Compton scattering. Distinguishing between the hadronic and leptonic origin of γ-ray emission in Galactic sources remains challenging. Measurements of nonthermal X-ray spectra of these sources, which could originate from primary electrons in the leptonic scenario or secondary electrons/positrons in the hadronic scenario, have been suggested as an efficient way of discriminating between these scenarios. In this work, we investigate the morphology of the X-ray emission from secondary electrons/positrons. By calculating the surface brightness profile and the photon index profile of X-ray emission, we find that secondary electrons produce a distinctively flat X-ray surface brightness profile. Our results suggest that, in addition to the X-ray spectrum, the X-ray morphology is crucial to determine the radiation mechanism of ultrahigh-energy γ-ray sources and help to identify sources of PeV cosmic rays.

Keywords: Non-thermal radiation sources, High energy astrophysics
Helium-burning Blue Large-amplitude Pulsators: A Population Study with BPASS. Blue large-amplitude pulsators (BLAPs) are a class of radially pulsating stars with effective temperatures ranging from 20,000 to 35,000 K and pulsation periods between 7 and 75 minutes. This study utilizes the Binary Population and Spectral Synthesis code to investigate helium-burning stars as a formation channel for BLAPs in the Milky Way. The progenitor stars have initial masses of 3─6 M⊙, resulting in BLAPs with final masses of 0.5─1.2 M⊙. Based on a constant star formation rate of 3 M⊙ yr−1 and solar metallicity (Z = 0.020), population synthesis predicts approximately 14,351 helium-burning BLAPs in the Milky Way: 12,799 with main sequence (MS) companions and 1551 with evolved/compact-object companions. Helium-burning BLAPs show prolonged lifetimes in the pulsation region and a narrow stellar age range for entering this regime (log(t/yr) = 8.0─8.6), unlike pre-white dwarf models. BLAPs with MS companions typically form via Roche lobe overflow, leading to longer orbital periods (∼100 days). Those with evolved/compact-object companions form through common envelope evolution, resulting in shorter periods. While Galactic extinction makes most BLAPs faint (apparent magnitudes &gt;25), future surveys like WFST and VRO LSST are expected to detect approximately 500─900. This research establishes helium-burning stars as a significant BLAP contributor and offers testable predictions regarding their binary properties and Galactic distribution.

Keywords: Blue large-amplitude pulsators, Binary stars, Pulsating variable stars
A Pseudo-Newtonian Stationary Circumbinary Slim Disk Model. We present a pseudo-Newtonian stationary circumbinary slim disk model. We extend the slim disk formalism by including the binary tidal torque and solve the resulting steady-state equations to determine the circumbinary disk structure. We compare the binary slim disk solutions with corresponding binary thin disk solutions, calculate the disk spectrum, explore the impact of different parameters on the system, and estimate the binary shrinkage timescale. We find that (1) due to the different disk density profiles, the integrated tidal torque exerted on the disk is significantly smaller for the slim disk than for the thin disk; as a result, thin disks onto binary black holes can be significantly more radiatively efficient than slim disks. (2) The presence of the secondary alters the emission of the circumbinary disk, making it different from the spectrum of a single black hole active galactic nucleus. (3) The tidal torque boosts the viscous torque in the outer part of the disk (at radii greater than the binary separation), which is strongly dependent on the disk parameters, including the binary mass ratio q, the orbital separation a, the viscous parameter α, and the accretion rate  Ṁ . (4) The vertical component of the potential of the secondary slightly decreases the integrated tidal torque. However, both the vertical and radial components of the potential of the secondary have small impacts on the disk radiative flux. (5) Using the integrated disk tidal torque backreacting on the secondary at different orbital separations, we find that the disk provides an efficient way to shrink the binary orbital separation.

Keywords: Accretion, Black hole physics, Interdisciplinary astronomy
Formation of Unsaturated Carbon Chains through Carbon Chemisorption on Solid CO. The interaction of carbon atoms with solid carbon monoxide (CO) is a fundamental process in astrochemistry, influencing the formation of complex organic molecules in interstellar environments. This study investigates the adsorption and reaction mechanisms of carbon atoms on solid CO under cryogenic conditions, employing a combination of experimental techniques, including the combination of photostimulated desorption and resonance-enhanced multiphoton ionization and infrared spectroscopy, alongside quantum chemical calculations. The results reveal the formation of oxygenated carbon chains, such as CCO, C3O2, and C5O2, as well as CO2. The findings highlight the role of chemisorption and subsequent reactions in driving molecular complexity on solid CO, with implications for the chemical evolution of interstellar ices and the potential formation of prebiotic molecules.

Keywords: Interstellar molecules, Interstellar dust, Laboratory astrophysics, Molecular clouds, Astrochemistry