Sazuna/UAT_keywords huggingface dataset:
Evidence of Grain Alignment by Magnetically Enhanced Radiative Torques from Multiwavelength Dust Polarization Modeling of HL Tau. The Atacama Large Millimeter/Submillimeter Array has revolutionized the field of dust polarization in protoplanetary disks across multiple wavelengths. Previous observations and empirical modeling have suggested multiple mechanisms of dust polarization toward HL Tau, including grain alignment and dust scattering. However, a detailed modeling of dust polarization based on grain alignment physics is not yet available. Here, using an updated POLARIS code, we perform numerical modeling of dust polarization arising from both grain alignment by the magnetically enhanced radiative torque mechanism and self-scattering to reproduce the HL Tau polarization observed at three wavelengths of 0.87, 1.3, and 3.1 mm. Our modeling results show that the observed multiwavelength polarization could be reproduced only when large grains contain embedded iron inclusions and those with slow internal relaxation must have wrong internal alignment (i.e., the grain's major axis parallel to its angular momentum). The abundance of iron embedded inside grains in the form of clusters is constrained to be ≳16%, and the number of iron atoms per cluster is N cl ∼ 9 × 102. Maximum grain sizes probed at wavelengths of λ = 0.87, 1.3, and 3.1 mm are constrained at ∼60, 80, and 90 μm, respectively.

Keywords: Polarimetry, Magnetic fields, Protoplanetary disks, Circumstellar dust, Radio astronomy
The COS-Holes Survey: Connecting Galaxy Black Hole Mass with the State of the CGM. We present an analysis of Hubble Space Telescope COS/G160M observations of C IV in the inner circumgalactic medium (CGM) of a novel sample of eight z ∼ 0, L ≈ L ⋆ galaxies, paired with UV-bright QSOs at impact parameters (R proj) between 25 and 130 kpc. The galaxies in this stellar-mass-controlled sample (log10 M ⋆/M ⊙ ∼ 10.2–10.9 M ⊙) host supermassive black holes (SMBHs) with dynamically measured masses spanning log10 M BH/M ⊙ ∼ 6.8–8.4; this allows us to compare our results with models of galaxy formation where the integrated feedback history from the SMBH alters the CGM over long timescales. We find that the C IV column density measurements (N C IV; average log10 N C IV,CH = 13.94 ± 0.09 cm‑2) are largely consistent with existing measurements from other surveys of N C IV in the CGM (average log10 N C IV,Lit = 13.90 ± 0.08 cm‑2), but do not show obvious variation as a function of the SMBH mass. By contrast, specific star formation rate (sSFR) is highly correlated with the ionized content of the CGM. We find a large spread in sSFR for galaxies with log10 M BH/M ⊙ &gt; 7.0, where the CGM C IV content shows a clear dependence on galaxy sSFR but not M BH. Our results do not indicate an obvious causal link between CGM C IV and the mass of the galaxy's SMBH; however, through comparisons to the EAGLE, Romulus25, and IllustrisTNG simulations, we find that our sample is likely too small to constrain such causality.

Keywords: Galaxy formation, Quasar absorption line spectroscopy, Circumgalactic medium
AT2018fyk: Candidate Tidal Disruption Event by a (Super)Massive Black Hole Binary. The tidal disruption event (TDE) AT2018fyk has unusual X-ray, UV, and optical light curves that decay over the first ∼600 days, rebrighten, and decay again around 1200 days. We explain this behavior as a one-off TDE associated with a massive black hole (BH) binary. The sharp drop-offs from t −5/3 power laws at around 600 days naturally arise when one BH interrupts the debris fallback onto the other BH. The BH mass M ∙ derived from fitting X-ray spectra with a slim disk accretion model and, independently, from fitting the early UV/optical light curves, is smaller by 2 orders of magnitude than predicted from the M ∙─σ * host galaxy relation, suggesting that the debris is accreted onto the secondary, with the fallback cut off by the primary. Furthermore, if the rebrightening were associated with the primary, it should occur around 5000 days, not the observed 1200 days. The secondary's mass and dimensionless spin is  M∙,s=2.7−1.5+0.5×105M⊙  and a ∙,s &gt; 0.3 (X-ray spectral fitting), while the primary's mass is M ∙,p = 107.7±0.4 M ⊙ (M ∙─σ * relation). An intermediate mass BH secondary is consistent with the observed UV/optical light-curve decay, i.e., the secondary's outer accretion disk is too faint to produce a detectable emission floor. The time of the first accretion cutoff constrains the binary separation to be (6.7 ± 1.2) × 10−3 pc. X-ray spectral fitting and timing analyses indicate that the hard X-rays arise from a corona above the secondary's disk. The early UV/optical emission, suggesting a super-Eddington phase for the secondary, possibly originates from shocks arising from debris circularization.

Keywords: Accretion, Black hole physics, Tidal disruption, X-ray transient sources
Experimental Vapor Pressure Determination for C<SUB>2</SUB>H<SUB>4</SUB>, C<SUB>2</SUB>H<SUB>6</SUB>, CH<SUB>3</SUB>OH, CH<SUB>4</SUB>, CO, CO<SUB>2</SUB>, H<SUB>2</SUB>O, and N<SUB>2</SUB> Molecules for Astrophysical Relevant Temperatures. Implications for the Presence of Volatiles in Kuiper Belt Objects and Trans-Neptunian Objects. Vapor pressure is a relevant quantity that is necessary in order to improve the study of the atmosphere dynamics that take place within astrophysical scenarios. The aim of this study was to obtain the vapor pressure values of the following molecules: C2H4, C2H6, CH3OH, CH4, CO, CO2, H2O, and N2 through experimentation, as well as to determine their empirical relationship with the temperature, applying the results to the persistence of volatiles in trans-Neptunian objects (TNOs) and Kuiper Belt objects (KBOs). The experimental determination was performed by measuring the sublimation rate for each molecule at different temperatures. The Hertz–Knudsen equation was used to obtain the vapor pressures for the aforementioned molecules, taking the necessary considerations into account, and the sublimation rate was measured using a quartz crystal microbalance. In order to check the validity of the methods used, the results obtained for water ice were compared with those of previous studies from the literature. The values obtained for CO, N2, and CH4 are of particular interest in the study of the TNOs' and KBOs' atmosphere composition. The results of this study improve the understanding of the surface and atmospheric composition of objects in the cold scenarios of the solar system, in particular, in KBOs and TNOs.

Keywords: Planetary atmospheres, Surface ices, Experimental techniques
A Multiwavelength, Multiepoch Monitoring Campaign of Accretion Variability in T Tauri Stars from the ODYSSEUS Survey. I. HST Far-UV and Near-UV Spectra. The classical T Tauri star (CTTS) stage is a critical phase of the star and planet formation process. In an effort to better understand the mass accretion processes, which can dictate future stellar evolution and planet formation, a multiepoch, multiwavelength photometric and spectroscopic monitoring campaign of four CTTSs (TW Hya, RU Lup, BP Tau, and GM Aur) was carried out in 2021 and 2022/2023 as part of the Outflows and Disks around Young Stars: Synergies for the Exploration of ULLYSES Spectra program. Here we focus on the Hubble Space Telescope (HST) UV spectra obtained by the HST Director's Discretionary Time UV Legacy Library of Young Stars as Essential Standards (ULLYSES) program. Using accretion shock modeling, we find that all targets exhibit accretion variability, varying from short increases in accretion rate by up to a factor of 3 within 48 hr to longer decreases in accretion rate by a factor of 2.5 over the course of 1 yr. This is despite the generally consistent accretion morphology within each target. Additionally, we test empirical relationships between accretion rate and UV luminosity and find stark differences, showing that these relationships should not be used to estimate the accretion rate for an individual target. Our work reinforces that future multiepoch and simultaneous multiwavelength studies are critical in our understanding of the accretion process in low-mass star formation.

Keywords: T Tauri stars, Star formation, Ultraviolet spectroscopy, Stellar accretion
SpectAcLE: An Improved Method for Modeling Light Echo Spectra. Light echoes give us a unique perspective on the nature of supernovae and nonterminal stellar explosions. Spectroscopy of light echoes can reveal details on the kinematics of the ejecta, probe asymmetry, and reveal details of ejecta interaction with circumstellar matter, thus expanding our understanding of these transient events. However, the spectral features arise from a complex interplay between the source photons, the reflecting dust geometry, and the instrumental setup and observing conditions. In this work, we present an improved method for modeling these effects in light echo spectra, one that relaxes the simplifying assumption of a light-curve-weighted sum, and instead estimates the true relative contribution of each phase of a transient event to the observed spectrum. We discuss our logic, the gains we obtain over light echo analysis methods used in the past, and prospects for further improvements. Lastly, we show how the new method improves our analysis of echoes from Tycho's supernova (SN 1572) as an example.

Keywords: Reflection nebulae, Supernovae
Extraction of Sunspots from Chinese Sunspot Drawings Based on Semisupervised Learning. China has six observing stations, providing over 52,000 handwritten sunspot drawings from 1947–2016. The observing stations are the Purple Mountain Astronomical Observatory (PMO), Yunnan Astronomical Observatory (YNAO), Qingdao Observatory Station (QDOS), Sheshan Observatory Station (SSOS), Beijing Planetarium (BJP), and Nanjing University (NJU). In this paper, we propose a new cotraining semisupervised learning method combining a semantic segmentation method named dynamic mutual training (DMT) boundary-guided semantic segmentation (BGSeg), i.e., DMT_BGSeg, which makes full use of the labeled data from PMO and the unlabeled data from the other five stations to detect and segment sunspot components in all sunspot drawings of the six Chinese stations. The sunspot is detected and segmented. Additionally, each sunspot is split into four types of components: pore, spot, umbra, and hole. The testing results show the mIoU values of PMO, YNAO, BJP, NJU, QDOS and SSOS are 85.29, 72.65, 73.82, 64.28, 62.26, and 60.07, respectively. The results of the comparison also show that DMT_BGSeg is effective in detecting and segmenting sunspots in Chinese sunspot drawings. The numbers and areas of sunspot components are measured separately. All of the detailed data are publicly shared on China-VO, which will advance the comprehensive augmentation of the global historical sunspot database and further the understanding of the long-term solar activity cycle and solar dynamo.

Keywords: Neural networks, Sunspots, Sunspot cycle, Sunspot number
Mapping the Milky Way in 5D with 170 Million Stars. We present Augustus, a catalog of distance, extinction, and stellar parameter estimates for 170 million stars from 14 mag &lt; r &lt; 20 mag and with ∣b∣ &gt; 10° drawing on a combination of optical to near-infrared photometry from Pan-STARRS, 2MASS, UKIDSS, and unWISE along with parallax measurements from Gaia DR2 and 3D dust extinction maps. After applying quality cuts, we find 125 million objects have "high-quality" posteriors with statistical distance uncertainties of ≲10% for objects with well-constrained stellar types. This is a substantial improvement over the distance estimates derived from Gaia parallaxes alone and in line with the recent results from Anders et al. We find the fits are able to reproduce the dereddened Gaia color─magnitude diagram accurately, which serves as a useful consistency check of our results. We show that we are able to detect large, kinematically coherent substructures in our data clearly relative to the input priors, including the Monoceros Ring and the Sagittarius Stream, attesting to the quality of the catalog. Our results are publicly available at doi:10.7910/DVN/WYMSXV. An accompanying interactive visualization can be found at http://allsky.s3-website.us-east-2.amazonaws.com.

Keywords: Parallax, Sky surveys, Photometry, Stellar distance, Milky Way Galaxy
The Formation of Filaments and Dense Cores in the Cocoon Nebula (IC 5146). We present 850 μm linear polarization and C18O (3 ‑ 2) and 13CO (3 ‑ 2) molecular line observations toward the filaments (F13 and F13S) in the Cocoon Nebula (IC 5146) using the JCMT POL-2 and Heterodyne Array Receiver Program instruments. F13 and F13S are found to be thermally supercritical with identified dense cores along their crests. Our findings include that the polarization fraction decreases in denser regions, indicating reduced dust grain alignment efficiency. The magnetic field vectors at core scales tend to be parallel to the filaments, but disturbed at the high density regions. Magnetic field strengths measured using the Davis–Chandrasekhar–Fermi method are 58 ± 31 and 40 ± 9 μG for F13 and F13S, respectively, and it reveals subcritical and sub-Alfvénic filaments, emphasizing the importance of magnetic fields in the Cocoon region. Sinusoidal C18O (3 ‑ 2) velocity and density distributions are observed along the filaments' skeletons, and their variations are mostly displaced by ∼1/4 × the wavelength of the sinusoid, indicating core formation occurred through the fragmentation of a gravitationally unstable filament, but with shorter core spacings than predicted. Large-scale velocity fields of F13 and F13S, studied using 13CO (3 ‑ 2) data, present a V-shape transverse velocity structure. We propose a scenario for the formation and evolution of F13 and F13S, along with the dense cores within them. A radiation shock front generated by a B-type star collided with a sheet-like cloud about 1.4 Myr ago. The filaments became thermally critical due to mass infall through self-gravity ∼1 Myr ago, and subsequently, dense cores formed through gravitational fragmentation, accompanied by the disturbance of the magnetic field.

Keywords: Star forming regions, Molecular clouds, Interstellar magnetic fields, Interstellar medium, Submillimeter astronomy, Polarimetry
Revisiting γ-Ray Emission of the Supernova Remnant RCW 103. We analyze more than 15 yr of γ-ray data obtained with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) for the region of the young supernova remnant (SNR) RCW 103, since the nearby source 4FGL J1616.2‑5054e, counterpart to HESS J1616‑518 and ≃13‧ away from the SNR, is determined to be extended in the more recent Fermi-LAT source catalog. Different templates for 4FGL J1616.2‑5054e and RCW 103 are tested, and we find that a point source (PS) with a power-law (PL) spectrum at the southern limb of the SNR best describes the detected γ-ray emission. The photon index of the PL emission is Γ ≃ 2.31 (or α ≃ 2.4 in a log-parabola model), softer than the previously reported Γ ≃ 2.0 when the counterpart to HESS J1616‑518 was considered to be a PS (which likely caused misidentification of extended emission at RCW 103). In order to produce the γ-ray emission in a hadronic scenario, we estimate that protons with an index ∼2.4 PL energy distribution are needed. These results fit with those from multiwavelength observations that have indicated the remnant at the southern limb is interacting with a molecular cloud.

Keywords: Supernova remnants, Gamma-rays
Expansion and Spectral Softening of the Dust-scattering Rings of GRB 221009A. An expanding X-ray halo or rings appear when short pulses of X-ray radiation from a background source are scattered by clouds of dust in the Milky Way. We study the X-ray rings of the brightest gamma-ray burst (GRB) 221009A, detected by the Swift X-Ray Telescope. The rings center on the GRB position, and their angular radii increase with time. We identify five major expanding rings, and our modeling of their expansion history suggests that they are scattered off from five dusty clouds at distances of 0.4─13 kpc from the observer. Given an assumed prompt X-ray fluence of this GRB, the fluxes of those rings suggest that these clouds have dust grain column densities of 107∼8 cm−2. More interestingly, our time-dependent spectral analysis of these rings shows that they all experience spectral softening, i.e., getting softer as they expand, with spectral indices ranging from 2.2 to 5, consistent with what the dust-scattering model predicts.

Keywords: Gamma-ray bursts
Bridging Model–Data Discrepancies in Mars' Dayside Ionosphere: Exploring Varying Reaction Rate Coefficients. Measurements of concentrations of neutral and ion species in the upper atmosphere of Mars by the Neutral Gas and Ion Mass Spectrometer (NGIMS) on board the Mars Atmosphere and Volatile EvolutioN mission have served as model input and/or for comparison with model output in numerous earlier studies of the Martian dayside ionosphere. While many models reproduce the altitudinal density profiles of key ion species within a factor of a few, it has proven challenging to achieve a level of agreement within tens of percent for multiple ion species over a wide range of altitudes. We explore means to overcome this issue while keeping with a reduced chemical model and utilizing the assumptions of photochemical equilibrium and that the NGIMS data are devoid of any measurement errors. We entertain, for instance, the idea that the rate coefficient for the charge-transfer reaction between  CO2+  and O may vary with altitude as a result of a pressure-controlled internal energy distribution of the  CO2+  population.

Keywords: Space plasmas, Mars, Planetary ionospheres, Reaction rates
Variable Radio Emission of Neutron Star X-Ray Binary Ser X–1 during Its Persistent Soft State. Ser X–1 is a low-mass neutron star X-ray binary and has been persistently accreting since its discovery in the 1960s. It has always been observed to be in a soft spectral state and has never showed substantial long-term X-ray variability. Ser X–1 has one previous radio observation in the literature in which radio emission was detected during this soft state, which is contrary to the behavior of black hole X-ray binaries. We have recently obtained 10 randomly sampled radio epochs of Ser X–1 in order to further investigate its anomalous soft-state radio emission. Out of 10 epochs, we find 8 nondetections and 2 detections at 10 GHz flux densities of 19.9 ± 4.2 μJy and 32.2 ± 3.6 μJy, respectively. We do not detect polarization in either epoch, ruling out very high polarization levels (≲63% and 34%). We compare these Ser X–1 results to other X-ray binaries and consider explanations for its long-term variable radio behavior.

Keywords: Neutron stars, Low-mass x-ray binary stars, X-ray binary stars, Radio jets
High-energy Neutrinos from Outflows Powered by the Kicked Remnants of Binary Black Hole Mergers in Active Galactic Nucleus Accretion Disks. Merging of stellar-mass binary black holes (BBHs) could take place within the accretion disks of active galactic nuclei (AGN). The resulting BH remnant is likely to accrete the disk gas at a super-Eddington rate, launching a fast, quasi-spherical outflow (wind). Particles will be accelerated by shocks driven by the wind, subsequently interacting with the shocked disk gas or radiation field through hadronic processes and resulting in the production of high-energy neutrinos and potential electromagnetic (EM) emission. This study delves into the intricate evolution of the shock driven by a merged BH wind within an AGN disk. Subsequently, we calculated the production of neutrinos and the expected detection numbers for a single event, along with their contributions to the overall diffuse neutrino background. Our analysis, which considers various scenarios, reveals considerable neutrino production and possible detection by IceCube for nearby events. The contribution of merged BH winds on the diffuse neutrino background is minor due to the low event rate density, but it can be improved to some extent for some optimistic parameters. We also propose that there could be two neutrino/EM bursts, one originating from the premerger BBH wind and the other from the merged BH wind, with the latter typically having a delay to the gravitational wave (GW) event of around tens of days. When combined with the anticipated GWs emitted during the BBH merger, such a system emerges as a promising candidate for joint observations involving neutrinos, GWs, and EM signals.

Keywords: Black holes, High energy astrophysics, Neutrino astronomy, Active galactic nuclei, Gravitational waves
The Mass Density of Merging Binary Black Holes over Cosmic Time. The connection between the binary black hole (BBH) mergers observed by LIGO-Virgo-KAGRA and their stellar progenitors remains uncertain. Specifically, the fraction ϵ of stellar mass that ends up in BBH mergers and the delay time τ between star formation and merger carry information about the astrophysical processes that produce merging BBHs. We model the merger rate in terms of cosmic star formation, coupled with a metallicity-dependent efficiency ϵ and a distribution of delay times τ, and infer these parameters with data from the Third Gravitational-Wave Transient Catalog. The progenitors to merging BBHs preferentially form in low-metallicity environments with a low-metallicity efficiency of  log10ϵ&lt;Zt=‑3.99‑0.87+0.68  and a high-metallicity efficiency of  log10ϵ&lt;Zt=‑4.60‑0.34+0.30  at 90% credibility. The data also prefer short delay times. For a power-law distribution p(τ) ∝ τ  α , we find  τmin&lt;1.9Gyr  and α &lt; ‑1.32 at 90% credibility. Our model allows us to extrapolate the mass density in BBHs to high redshifts. We cumulatively integrate our density rate over time to get the total density of merging stellar-mass BBHs as a function of redshift. Today, BBH mergers are only ∼0.01% of the total stellar-mass density created by &gt;10 M ⊙ progenitors. However, because massive stars are short lived, there may be more mass in merging BBHs than in living massive stars as early as ∼2.5 Gyr ago. We also compare to the mass in supermassive black holes, finding that the densities were comparable ∼12.5 Gyr ago, but their densities quickly increased to ∼75 times the density in merging stellar-mass BBHs by z ∼ 1.

Keywords: Binary stars, Black holes, Massive stars, Stellar mass black holes, Gravitational wave sources, Gravitational wave astronomy, Gravitational waves, Compact objects, Stellar remnants, Metallicity, Astrophysical black holes
Super-Eddington Magnetized Neutron Star Accretion Flows: A Self-similar Analysis. The properties of super-Eddington accretion disks exhibit substantial distinctions from the sub-Eddington ones. In this paper, we investigate the accretion process of a magnetized neutron star (NS) surrounded by a super-Eddington disk. By constructing self-similar solutions for the disk structure, we study in detail an interaction between the NS magnetosphere and the inner region of the disk, revealing that this interaction takes place within a thin boundary layer. The magnetosphere truncation radius is found to be approximately proportional to the Alfvén radius, with a coefficient ranging between 0.34–0.71, influenced by the advection and twisting of a magnetic field, NS rotation, and radiation emitted from an NS accretion column. Under super-Eddington accretion, the NS can readily spin up to become a rapid rotator. The proposed model can be employed to explore the accretion and evolution of NSs in diverse astrophysical contexts, such as ultraluminous X-ray binaries or active galactic nucleus disks.

Keywords: Neutron stars, Accretion, Compact objects