Sazuna/UAT_keywords huggingface dataset:
Scaling Relations of the Dusty Torus with Luminosity and the Broad-line Region. We measure and compare the size of the dusty torus with active galactic nucleus (AGN) luminosity and the size of the broad-line region (BLR), using a sample of 182 AGNs with the best Hβ lag measurements. After correcting for accretion-disk contamination, torus sizes are determined from the time lags of the Wide-field Infrared Survey Explorer W1 and W2 band light curves relative to the optical band variability based on the interpolated cross-correlation function analysis and the Multiple and Inhomogeneous Component Analysis. We find that the torus size from the W1-band (W2-band) tightly correlates with the 5100 Å continuum luminosity with an intrinsic scatter of 0.15─0.16 dex and the best-fit slope of 0.35 ± 0.03 (0.33 ± 0.03), which is clearly shallower than the expected 0.5 slope from the sublimation radius─luminosity relation. We find a moderate negative trend that higher Eddington AGNs tend to have smaller torus sizes than expected from the best-fit, suggesting the Eddington ratio plays a role in flattening the torus size─luminosity relation. By comparing the torus size with the Hβ reverberation time lag for a subsample of 67 AGNs, we find that the torus size is a factor of ∼10 and ∼14 larger than the BLR size, respectively for W1 and W2 bands. The torus size based on the W1 (W2) band correlates with the BLR size with the best-fit slope of 1.28 ± 0.16 (1.10 ± 0.15), which is comparable but slightly steeper than a linear correlation.

Keywords: Reverberation mapping, Active galactic nuclei
Plasma-astrophysical Mechanism as a Probe to Unravel the Nature of Polarized Pulsar Radio Emission. Despite numerous theories on pulsars, a consensus on a reliable emission mechanism explaining their diverse observational characteristics remains elusive. In this paper, we couple the plasma process of stimulated Raman scattering (SRS) with the emission geometry of radio pulsars. SRS, involving energy transfer from curvature radiation photons to weakly damped electron-plasma modes, allows us to simulate integrated pulse profiles. We compute the growth rate of plasma modes across phase factors and reproduce soliton pulse profiles using nonlinear Schrödinger equations, driven by the pondermotive force in a typical plasma environment. We also examine collisional damping across plasma species. Notably, we show that circular polarization (CP) decreases with lower nonlinear parameter η (density perturbation ratio along two orthogonal basis vectors in our synergy). A similar problem was addressed via Bayesian analysis of magnetar radio emission data in Nature Astronomy; our approach offers a theoretical explanation using a plasma-astrophysical-based mechanism. We argue that SRS can explain various pulsar phenomena, including polarization angle swing reversals, percentage changes in circular and linear polarization nature, and depolarization.

Keywords: Radio pulsars
Formation of a Coronal Hole by a Quiet-Sun Filament Eruption. A coronal hole formed as a result of a quiet-Sun filament eruption close to the solar disk center on 2014 June 25. We studied this formation using images from the Atmospheric Imaging Assembly (AIA), magnetograms from the Helioseismic and Magnetic Imager, and a differential emission measure analysis derived from the AIA images. The coronal hole developed in three stages: (1) formation, (2) migration, and (3) stabilization. In the formation phase, the emission measure (EM) and temperature started to decrease 6 hr before the filament erupted. Then, the filament erupted and a large coronal dimming formed over the following 3 hr. Subsequently, in a phase lasting 15.5 hr, the coronal dimming migrated by ≍150″ from its formation site to a location where potential field source surface extrapolations indicate the presence of open magnetic field lines, marking the transition into a coronal hole. During this migration, the coronal hole drifted across quasi-stationary magnetic elements in the photosphere, implying the occurrence of magnetic interchange reconnection at the boundaries of the coronal hole. In the stabilization phase, the magnetic properties and area of the coronal hole became constant. The EM of the coronal hole decreased, which we interpret as a reduction in plasma density due to the onset of plasma outflow into interplanetary space. As the coronal hole rotated toward the solar limb, it merged with a nearby preexisting coronal hole. At the next solar rotation, the coronal hole was still apparent, indicating a lifetime of &gt;1 solar rotation.

Keywords: The Sun, Solar filaments, Solar filament eruptions, Solar corona, Solar coronal holes
Longtime Monitoring of TeV Radio Galaxies with HAWC. We present the monitoring of the TeV-emitting radio galaxies M87, NGC 1275, 3C 264, and IC 310 with the High-Altitude Water Cherenkov Observatory (HAWC) over a period of approximately 7.5 yr. The analysis includes light curves at daily, weekly, and monthly timescales for the four sources. We report the detection of gamma-ray emission from M87 with a significance exceeding 5σ, providing the integrated TeV spectrum from the longest temporal coverage to date. The source is well described as a point-like source modeled by a power-law spectrum with spectral index Γ = 2.53 ± 0.29 and a flux of (7.09 ± 1.24) × 10−13 cm−2 s−1 TeV−1 at 1 TeV. The maximum energy of the detected emission in M87, at 1σ confidence level, reaches 26.5 TeV. HAWC's observation of M87 reveals a low flux spectrum for the longest observation to date of this radio galaxy. 3C 264 is marginally detected with a significance slightly below 4σ, while NGC 1275 and IC 310 are not detected. The weekly light curves show an increased number of fluxes above 2σ for M87 starting in 2019 and for 3C 264 starting in 2018, which can be interpreted as the moments at which these sources start to exhibit an enhanced steady TeV emission. Cumulative significance analysis reveals quantitative evidence for long-term variability. M87 shows enhanced emission from 2019, while 3C 264 exhibits increased activity from 2018, resembling variable sources like Markarian 421 rather than steady sources like the Crab. This supports the importance of monitoring radio galaxies to identify periods of higher activity and flares, enabling further multimessenger studies.

Keywords: Radio galaxies, Active galactic nuclei, High energy astrophysics
Power-law Emission-line Wings and Radiation-driven Superwinds in Local Lyman Continuum Emitters. We investigate broad emission-line wings, reaching ≤800 km s−1, observed in 26 galaxies with Lyman continuum (LyC) observations, primarily from the Low-redshift Lyman Continuum Survey. Using Magellan/MIKE, Very Large Telescope/X-shooter, and WHT/ISIS high-resolution spectroscopy, we show that this fast gas appears to probe the dominant feedback mechanisms linked to LyC escape. We find that in 14 galaxies, the wings are best-fit with power laws of slope α ∼ −3.5 to −1.6, with four others best fit by Gaussians of width σBW ∼ 300 km s−1; the remaining eight show ambiguous wing morphologies. Gaussian wings are found only at low O32 = [O III]λ5007/[O II]λ3726, 3729 and high metallicity, while power-law wings span the full range of these parameters. The general evidence suggests a dual-mode paradigm for LyC escape: radiation-driven superwinds traced by power-law wings and supernova-driven feedback traced by Gaussian wings. For the former, the &lt;3 Myr-old, pre-supernova stellar population correlates with more luminous, faster winds. The data also show that radiation-driven wind parameters like wind luminosity and power-law slope α depend on the UV luminosity more than the optically thick covering fraction, consistent with "picket-fence" radiative transfer. Observed α values flatten with both escaping LyC luminosity and higher extinction, while still preserving the anticorrelation between these two quantities. Additionally, the differential between red and blue slopes implies that extinction and dense gas are centrally concentrated relative to the wind emission. Overall, our results show that power-law emission-line wings probe LyC-driven winds and LyC escape in metal-poor starbursts.

Keywords: Starburst galaxies, Interstellar line emission, Stellar feedback, Emission line galaxies, Galaxy winds, Lyman-alpha galaxies
So Long Kolmogorov: The Forward and Backward Turbulence Cascades in a Supernovae-driven, Multiphase Interstellar Medium. The interstellar medium (ISM) of disk galaxies is turbulent, and yet the fundamental nature of ISM turbulence, the energy cascade, is not understood in detail. In this study, we use high-resolution simulations of a hydrodynamical, gravitationally stratified, supernovae (SNe) driven, multiphase ISM to probe the nature of a galactic turbulence cascade. Through the use of velocity flux transfer functions split into interactions between compressible uc and incompressible us modes, we show that there exists a large-to-small-scale cascade in both uc and us when mediated by an additional us mode. But the us cascade is highly nonlocal. Moreover, there is a uc-mediated component of the us cascade that proceeds in the opposite direction—an inverse cascade from small-to-large scales. The cascade feeds flux into scales well beyond the scale height, energizing the winds and fueling the direct cascades. Both the strongly nonlocal and the inverse us cascades happen on scales that have a power-law us energy spectrum, highlighting how degenerate the spectrum is to the true underlying physical processes. We directly show that the inverse cascade comes from us modes interacting with expanding SNe remnants (SNRs) and that us modes are generated to leading order via baroclinic, highly corrugated cooling layers between warm (T ≲ 104 K) and hot (T ≫ 104 K) gas in these SNRs. Finally, we outline a complete phenomenology for SNe-driven turbulence in a galactic disk, estimate a 10−16 G Biermann field generated from SNR cooling layers, and highlight the strong deviations that SNe-driven turbulence has from the conventional Kolmogorov model.

Keywords: Interstellar dynamics, Core-collapse supernovae, Warm ionized medium, Interstellar medium, Supernovae
Rotation of Polarization Angle in Gamma-Ray Burst Prompt Phase. III. The Influence of the Magnetic Field Orientation. Polarization is very sensitive to the configuration of the magnetic field in the radiation region. In addition to polarization curve and polarization spectrum, studies of the polarization angle (PA) rotation spectrum are also crucial. In this paper, we use a simple parametric magnetic reconnection model with a large-scale aligned magnetic field in the radiation region to study the effects of field orientation on the PA rotations. Under different field orientations, variations of the PA rotation with parameters and the PA rotation spectra are studied. We find that the conclusions obtained in our previous works are almost independent of the field orientations. The area of the parameter space with ∆PA &gt; 10° will shrink as the value of field orientation (δ) increases for 0° &lt; δ &lt; 90°. The ∆PA values would be the same for two complementary field orientations. For two particular magnetic field orientations (δ = 0° and 90°), the ∆PA would also only be 0° or 90° within the burst duration.

Keywords: Starlight polarization, Gamma-ray bursts
Composition of Planetary Debris Around the White Dwarf GD 362. White dwarf stars with high abundances of heavy elements in their atmospheres and infrared excesses are believed to be accreting planetary material. GD 362 is one of the most heavily polluted white dwarfs and has an exceptionally strong mid-infrared excess, reprocessing 2.4% of the star's light into the mid-infrared. We present a high signal-to-noise, medium-resolution spectrum of GD 362 obtained with JWST, covering 0.6─17 μm, along with photometry out to 25.5 μm. The mid-infrared spectrum is dominated by an exceptionally strong 9─11 μm silicate feature, which can be explained by a combination of olivine and pyroxene silicate minerals. Grains such as carbon, hotter than silicates, are required to explain the near-infrared emission. The silicates and carbon reside in a disk from 140 to 1400 stellar radii, and the disk scale height is greater than half the stellar radius. The elemental abundances of the solid material, relative to Si, are within a factor of 2 of meteoritic (CI chondrites) for C, O, Mg, Al, and Fe, with Al elevated and O slightly depleted. A similar pattern is observed for the abundances of accreted material in the stellar photosphere. Hydrogen is an exception, because no significant H-bearing minerals or water were detected in the disk, despite a large H abundance in the photosphere.

Keywords: Dust composition, Infrared spectroscopy, White dwarf stars, James Webb Space Telescope, Debris disks
Monitoring of 3C 286 with ALMA, IRAM, and SMA from 2006 to 2025: Stability, Synchrotron Ages, and Frequency-dependent Polarization Attributed to Core-shift. We present the results of multifrequency monitoring of the radio quasar 3C 286, conducted using three instruments: the Atacama Large Millimeter/submillimeter Array (ALMA) at 91.5, 103.5, 233.0, and 343.4 GHz, the IRAM 30 m Telescope at 86 and 229 GHz, and the Submillimeter Array at 225 GHz. The IRAM measurements from 2006 to 2024 show that the total flux of 3C 286 is stable within measurement uncertainties, indicating long-term stability up to 229 GHz, when applying a fixed kelvin-to-jansky conversion factor throughout its data set. ALMA data from 2018 to 2024 exhibit a decrease in flux, of which up to 4% could be attributed to an apparent increase in the absolute brightness of Uranus, the primary flux calibrator for ALMA with the ESA4 model. Taken together, these results suggest that the intrinsic total flux of 3C 286 has remained stable up to 229 GHz over the monitoring period. The polarization properties of 3C 286 are stable across all observing frequencies. The electric vector position angle (EVPA) gradually rotates as a function of wavelength squared, which is well described by a single power law over the full frequency range. We therefore propose using the theoretical EVPA values from this model curve for absolute EVPA calibration between 5 and 343.4 GHz. The Faraday rotation measure (RM) increases as a function of frequency up to (3.2 ± 1.5) × 104 rad m−2, following ∣RM∣ ∝ να with α = 2.05 ± 0.06. This trend is consistent with the core-shift effect expected in a conical jet.

Keywords: Radio jets, Polarimetry, Calibration, Active galactic nuclei, Radio interferometry, Radio astronomy
H I 21 cm Absorption Associated with Foreground Galaxies on Top of Quasars. A systematic search for H I 21 cm absorption in quasar─galaxy pairs (QGPs) provides a powerful means to map the distribution of cold gas around high-redshift star-forming galaxies. Fiber spectroscopy of high-redshift quasars enables the serendipitous detection of foreground star-forming galaxies at extremely small impact parameters, forming a unique subset of QGPs known as galaxies on top of quasars (GOTOQs). In this study, we present results from a pilot upgraded Giant Metrewave Radio Telescope survey of three GOTOQs, where we achieved a remarkable 100% detection rate of H I 21 cm absorption. By combining our findings with the existing literature, we establish that GOTOQs constitute a distinct population in terms of H I 21 cm absorption, with significantly higher detection rates than those observed in damped Lyα-based or metal absorption-based searches. For the GOTOQs, we find a strong correlation between the line-of-sight reddening and the H I 21 cm optical depth, characterized by  ∫τdv(kms−1)=13.58−2.35+2.75E(B−V)+0.68−1.27+1.06 , consistent with the Milky Way sightlines. We also show that the H I 21 cm optical depth declines with the impact parameter, and find a tentative trend for the H I 21 cm detection rates to also decline with the impact parameter. With upcoming wide-field spectroscopic surveys expected to substantially expand the catalog of known GOTOQs, the success of this pilot survey lays the foundation for constructing a statistically significant sample of intervening H I 21 cm absorbers.

Keywords: Quasar absorption line spectroscopy, Circumgalactic medium
The Sonora Substellar Atmosphere Models. VI. Red Diamondback: Extending Diamondback with SPHINX for Brown Dwarf Early Evolution. We extend the Sonora Diamondback brown dwarf evolution models to higher effective temperatures to treat the evolution of younger, higher-mass objects. Due to an upper temperature limit of Teff = 2400 K in the original Sonora Diamondback model grid, high-mass objects (M ≥ 0.05 M⊙ = 52.4 MJ) were limited to ages of ≳100 Myr. To include the early evolution of brown dwarfs at Teff &gt; 2400 K, we use existing and new SPHINX cloud-free model atmosphere calculations of temperature structures of M-type atmospheres. These atmospheres range from Teff 2000 to 4000 K, log(g) 3.0 to 5.5, and metallicity [M/H] −0.5 to +0.5. This combination of Diamondback and SPHINX atmospheres, with a transition across Teff 2000─2400 K, allows us to calculate evolution tracks, and infrared photometry and colors, for ages &gt;1 Myr and masses from above the hydrogen-burning minimum mass down to planetary masses. The Hayashi phase of massive brown dwarf evolution (ages &lt; 10─100 Myr) at low surface gravity leads to nearly constant Teff values, at effective temperatures much lower than would be obtained from simply extrapolating backward from evolution tracks at older ages.

Keywords: M dwarf stars, Atmospheric evolution, Brown dwarfs, Early stellar evolution, Hayashi track, L dwarfs, Y dwarfs, Stellar atmospheric opacity, Young stellar objects, Stellar atmospheres, T dwarfs
The JWST Early Release Science Program for Direct Observations of Exoplanetary Systems. VI. Evidence for Radially Evolving Icy Grains in the HD 141569A Disk via NIRCam Coronagraphic Imaging. We present JWST NIRCam coronagraphic observations of the HD 141569A circumstellar disk, obtained as part of the JWST Early Release Science program. The observations recover the multi-ringed structure seen in previous shorter-wavelength observations, but at filters centered on the ∼3 μm water ice absorption feature and a complementary continuum region (F300M and F360M, respectively). The observations reveal apparent absorption between the F300M and F360M filters that decreases with radius, with a notable change around 200 au, between the innermost and outermost two rings. These results are consistent whether the data is reduced via deconvolution or through a forward-modeling approach. We demonstrate that these changes suggest a radial decrease in the water ice mass fraction by a factor of ∼3─10 and possibly a change in minimum grain size. We do not detect any point sources within the system and can exclude planetary companions 2 Jupiter masses and greater beyond 1″ radius (∼111 au). These observations and the subsequent analysis illustrate a robust pathway for using JWST/NIRCam to characterize the distribution of water ice in other circumstellar disks. We highlight some of the early lessons learned from this work that we hope will be useful for future circumstellar disk observation planning and analysis.

Keywords: High contrast techniques, Infrared observatories, Exoplanet astronomy, Coronagraphic imaging, James Webb Space Telescope, Space observatories, Direct imaging, Circumstellar disks
Resolving the Nuclear Environments of Tidal Disruption Event Host Galaxies within 45 pc. Using Hubble Space Telescope/Space Telescope Imaging Spectrograph observations, we present the highest-spatial-resolution spectroscopic study to date of four tidal disruption event (TDE) host galaxies, with the best observed being the post-starburst host of ASASSN-14li. The stellar population of ASASSN-14li's host, within 44 pc of the nucleus, reveals a younger recent starburst (∼340 Myr) compared to the population at an offset radius of 88 pc that excludes the nucleus (∼550 Myr), a radial age gradient suggesting gas inflows from a minor merger. We estimate a stellar density of ∼5900 ± 800 M⊙ pc−3 within 30 pc of the nucleus of ASASSN-14li's host, exceeding densities expected for nuclear star clusters. High-ionization "coronal" emission lines, [Fe VI] λ5677, [Fe VII] λ6087, and [Fe X] λ6375, are also detected within the nuclear spectra of the hosts of ASASSN-14li and PTF09ge, importantly alongside the nondetection of [O III] at the same scale. We similarly do not detect [O III] in the nuclear region of ASASSN-14ae's host despite its presence in the Sloan Digital Sky Survey spectrum. The different ionization radiation levels detected at various radii from TDE host nuclei may indicate echoes of earlier accretion episodes, including, potentially, a prior TDE. We posit that a minor merger driving gas inflow to the nucleus could drive the enhanced TDE rates in post-starburst galaxies, inducing variation in nuclear gas properties and star formation history on &lt;150 pc scales in TDE hosts.

Keywords: Supermassive black holes, Tidal disruption, Post-starburst galaxies
The "Little Dark Dot": Evidence for Self-interacting Dark Matter in the Strong Lens SDSS J0946+1006?. Previous studies, based on precise modeling of a gravitationally lensing image, have identified what may be an extremely compact, dark perturber in the well-known lensing system SDSS J0946+1006 (the "Jackpot"). Its remarkable compactness challenges the standard cold dark matter paradigm. In this paper, we explore whether such a compact perturber could be explained as a core-collapse halo described by the self-interacting dark matter (SIDM) model. Using the isothermal Jeans method, we compute the density profiles of core-collapse halos across a range of masses. Our comparison with observations indicates that a core-collapse halo has an inner density profile and mass enclosed within 1 kpc that fit the data well, but only if the halo has a total mass of ∼1011 M⊙. While a halo of this mass should host a detectable galaxy, the current observational upper limit on the perturber's luminosity remains uncertain. Resolving whether or not the data support the presence of a core-collapse SIDM halo therefore requires future deep observations to measure its luminosity.

Keywords: Galaxy dark matter halos, Strong gravitational lensing, Dark matter
A Gaussian Process Framework for Testing General Relativity with Gravitational Waves. Gravitational-wave astronomy provides a promising avenue for the discovery of new physics beyond general relativity as it probes extreme curvature and ultrarelativistic dynamics. However, in the absence of a compelling alternative to general relativity, it is difficult to carry out an analysis that allows for a wide range of deviations. To that end, we introduce a Gaussian process framework to search for deviations from general relativity in gravitational-wave signals from binary black hole mergers with minimal assumptions. We employ a kernel that enforces our prior beliefs that—if gravitational waveforms deviate from the predictions of general relativity—the deviation is likely to be localised in time near the merger with some characteristic frequency. We demonstrate this formalism with simulated data and apply it to events from the Gravitational-Wave Transient Catalog 3. We find no evidence for a deviation from general relativity. We limit the fractional deviation in gravitational-wave strain to as low as 7% (90% credibility) of the strain of GW190701_203306.

Keywords: Black holes, General relativity, Gravitational waves, Gaussian Processes regression, Compact objects