Sazuna/UAT_keywords huggingface dataset:
Photon Ring Polarimetry with Next-generation Black Hole Imaging. I. M87*. The near-horizon region of a black hole impacts linear (LP) and circular polarization (CP) through strong lensing of photons, adding large-scale symmetries and anti-symmetries to the polarized image. To probe the signature of lensing in polarimetry, we utilize a geometric model of concentric Gaussian rings of equal radius to investigate the transition in the Fourier plane at which the photon ring signal begins to dominate over the direct image. We find analytic, closed-form expressions for the transition radii in total intensity, LP, and CP, wherein the resultant formulae are composed of ratios of tunable image parameters, with the overall "scale" set primarily by the thickness of the direct image. Using these formulae, we compute the transition radii for time-averaged images of M87* simulations at 230 GHz, studying both magnetically arrested disk (MAD) and standard and normal evolution configurations for various spin and electron heating models. We compare geometric values to radii obtained directly from the simulations through a coherent averaging scheme. We find that nearly all MAD models have a photon ring-dominated CP signal on long baselines shorter than Earth's diameter at 230 GHz. Across favored models for the M87* accretion flow identified by the Event Horizon Telescope (EHT) polarimetric constraints, we quantify the sensitivity and antenna size requirements for the next-generation EHT and the Black Hole Explorer orbiter to detect these features. We find that the stringent requirements for CP favor explorations using long baselines on the ground, while LP remains promising on Earth-space baselines.

Keywords: Supermassive black holes, Very long baseline interferometry, Gravitational lensing, Astronomical instrumentation, Polarimetry
Insight-HXMT View of the Black Hole Candidate Swift J1727.8–1613 during Its Outburst in 2023. The transient Galactic black hole candidate Swift J1727.8-1613 went through an outburst for the very first time in 2023 August and lasted for almost 6 months. We study the timing and spectral properties of this source using publicly available archival Insight-HXMT data for the first 10 observation IDs that last from MJD 60181 to 60198 with a total of 92 exposures for each of the three energy bands. We have detected quasi-periodic oscillations (QPOs) in a frequency range of 0.21 ± 0.01–1.86 ± 0.01 Hz by fitting the power density spectrum. Based on the model-fitted parameters and properties of the QPOs, we classify them as type C in nature. We also conclude that the origin of the QPOs could be the shock instabilities in the transonic advective accretion flows around black holes. The spectral analysis was performed using simultaneous data from the three onboard instruments LE, ME, and HE of Insight-HXMT in the broad energy band of 2‑150 keV. To achieve the best fit, spectral fitting required a combination of models, e.g., interstellar absorption, power-law, multicolor disk–blackbody continuum, Gaussian emission/absorption, and reflection by neutral material. From the spectral properties, we found that the source was in an intermediate state at the start of the analysis period and was transitioning to the softer states. The inner edge of the accretion disk moved inward in progressive days following the spectral nature. We found that the source has a high inclination of 78°‑86°. The hydrogen column density from the model fitting varied in the range of (0.12 ± 0.02‑0.39 ± 0.08) × 1022 cm‑2.

Keywords: X-ray binary stars, Black holes, Compact radiation sources, Stellar accretion disks, Shocks
Supernova Shocks in Molecular Clouds: Shocks Driven into Dense Cores in IC 443 and 3C 391. Supernova shocks into dense molecular cores in IC 443 (clumps B, C, and G) and 3C 391 were observed using the Stratospheric Observatory for Infrared Astronomy and complemented by archival data from the Herschel Space Observatory. The pure rotational transitions 0–0 S(1) and S(5) of H2, and the ground-state 110–101 transition of H2O, are all broadened, arising from molecules that survive the passage of the shock front. Theoretical models from the Paris–Durham shock code were analyzed to generate velocity profiles that approximately match the observations. The observations can be fit with two shock conditions, which approximate the range of densities in the preshock molecular cloud. The width and brightness of the S(5) lines require shocks into gas with a density of order 2000 cm‑3, into which the IC 443 blast wave drives shocks with speed 60 km s‑1. The brightness and narrower width of the S(1) lines requires different shocks, into gas with density of order 105 cm‑3, with shock speeds of 10 km s‑1. The H2O velocity distribution is also consistent with these shocks. The existence of shocks into dense gas shows that the bright shocked clumps in IC 443 were prestellar cores. It is unlikely that they will form stars soon after the passage of the shock front, given the input of kinetic and thermal energy from the shocks.

Keywords: Supernova remnants, Shocks, Molecular clouds, Infrared spectroscopy
Global Simulation of the Solar Wind: A Comparison with Parker Solar Probe Observations during 2018–2022. Global magnetohydrodynamic (MHD) models play an important role in the infrastructure of space weather forecasting. Validating such models commonly utilizes in situ solar wind measurements made near the Earth's orbit. The purpose of this study is to test the performance of G3DMHD (a data driven, time-dependent, 3D MHD model of the solar wind) with Parker Solar Probe (PSP) measurements. Since its launch in 2018 August, PSP has traversed the inner heliosphere at different radial distances sunward of the Earth (the closest approach ∼13.3 R ⊙), thus providing a good opportunity to study evolution of the solar wind and to validate heliospheric models of the solar wind. The G3DMHD model simulation is driven by a sequence of maps of the photospheric field extrapolated to the assumed source surface (2.5 R ⊙) using the potential field model from 2018 to 2022, which covers the first 15 PSP orbits. The Pearson correlation coefficient (cc) and the mean absolute scaled error (MASE) are used as the metrics to evaluate the model performance. It is found that the model performs better for both magnetic intensity (cc = 0.75; MASE = 0.60) and the solar wind density (cc = 0.73; MASE = 0.50) than for the solar wind speed (cc = 0.15; MASE = 1.29) and temperature (cc = 0.28; MASE = 1.14). This is due primarily to lack of accurate boundary conditions. The well-known underestimate of the magnetic field in solar minimum years is also present. Assuming that the radial magnetic field becomes uniformly distributed with latitude at or below 18 R ⊙ (the inner boundary of the computation domain), the agreement in the magnetic intensity significantly improves (cc = 0.83; MASE = 0.49).

Keywords: Solar wind, Interplanetary magnetic fields, Heliosphere, Magnetohydrodynamical simulations
Weighing Single-lined Spectroscopic Binaries Using Tidal Effects on Radial Velocities: The Case of V723 Monocerotis. In single-lined spectroscopic binaries (SB1s) where flux variations due to tidal deformation of the primary star (ellipsoidal variations, EVs) are detected, the binary mass can be determined by combining EVs with the primary's radial velocity (RV) variations from orbital motion and information about the primary's radius. This method has been used for mass estimation in close binaries including X-ray systems, but it has been pointed out that contaminating light from sources other than the primary star could introduce systematic errors in the mass and inclination estimates. Here, we focus on the apparent RV variations caused by asymmetric distortion of the absorption lines of the tidally deformed primary star (tidal RV). Because this signal contains information equivalent to that from photometric EVs, it enables mass estimation of the binary system using only the primary star's absorption lines from high-resolution spectroscopic data, providing a potentially more robust approach against contaminating light. We apply the method to the binary system V723 Monocerotis, where both photometric EV and tidal RV signals are detected and successfully determine the component masses using only the primary star's RVs and projected rotational velocity, without relying on absolute flux measurements or stellar evolutionary models. The masses derived from the tidal RV model shows a reasonable agreement with those obtained from EVs after carefully modeling the flux contamination from the secondary. This result demonstrates that tidal RVs provide a useful alternative means for mass estimation in SB1s.

Keywords: Radial velocity, Tidal distortion, Stellar mass black holes, Red giant stars
SN 2021foa: The "Flip-flop" Type IIn/Ibn Supernova. We present a comprehensive analysis of the photometric and spectroscopic evolution of SN 2021foa, unique among the class of transitional supernovae for repeatedly changing its spectroscopic appearance from hydrogen-to-helium-to-hydrogen dominated (IIn-to-Ibn-to-IIn) within 50 days past peak brightness. The spectra exhibit multiple narrow (≍300─600 km s−1) absorption lines of hydrogen, helium, calcium, and iron together with broad helium emission lines with a full width at half-maximum (FWHM) of ∼6000 km s−1. For a steady, wind mass-loss regime, light-curve modeling results in an ejecta mass of ∼8 M ⊙ and circumstellar material (CSM) mass below 1 M ⊙, and an ejecta velocity consistent with the FWHM of the broad helium lines. We obtain a mass-loss rate of ≍2 M ⊙ yr−1. This mass-loss rate is 3 orders of magnitude larger than derived for normal Type II supernovae. We estimate that the bulk of the CSM of SN 2021foa must have been expelled within half a year, about 12 yr ago. Our analysis suggests that SN 2021foa had a helium-rich ejecta that swept up a dense shell of hydrogen-rich CSM shortly after explosion. At about 60 days past peak brightness, the photosphere recedes through the dense ejecta-CSM region, occulting much of the redshifted emission of the hydrogen and helium lines, which results in an observed blueshift (∼−3000 km s−1). Strong mass-loss activity prior to explosion, such as those seen in SN 2009ip-like objects and SN 2021foa as precursor emission, are the likely origin of a complex, multiple-shell CSM close to the progenitor star.

Keywords: Supernovae, Core-collapse supernovae, Stellar mass loss
The AH Pictoris Syndrome: Continuous Trains of Stunted Outbursts in Novalike Variables. Novalike variables are a subgroup of cataclysmic variables (CVs) that—unlike dwarf novae—do not exhibit strong brightenings in their long-term light curves. Variations over timescales of weeks, months, or years are mostly restricted to irregular low-amplitude modulations. However, some of them occasionally suffer from so-called stunted outbursts, that is, small-scale brightenings of less than a magnitude lasting for a couple of days to weeks. There is no consensus about the physical mechanisms behind these outbursts. Here I discuss the common properties of a group of novalike variables (which I call AH Pictoris (AH Pic) stars after its most prominent member) that exhibit a continuous train of successive stunted outbursts over their entire observational history, or at least for several years. The outburst amplitudes are stable in a given system, always ranging between 0.5 and 1 mag in the visual band. The outburst intervals, at an overall range between 12 and 30 days, and the outburst profiles can gradually evolve, but no sudden changes are observed. On shorter timescales the orbital waveforms are not only surprisingly similar, but also evolve in the same way over the outburst cycle. All AH Pic stars have absolute visual magnitudes in the overlap region between the absolute magnitudes of all novalike variables and of quiescent dwarf novae above the CV period gap. So far, I identified seven novalike variables with the consistent photometric behavior that may be termed the AH Pic syndrome. Several more systems may be related objects. The relationship of the AH Pic stars to the anomalous Z Cam stars is discussed.

Keywords: Close binary stars, Nova-like variable stars, Cataclysmic variable stars
Deep Einstein@Home Search for Continuous Gravitational Waves from the Central Compact Objects in the Supernova Remnants Vela Jr. and G347.3-0.5 Using LIGO Public Data. We perform a search for continuous nearly monochromatic gravitational waves from the central compact objects associated with the supernova remnants Vela Jr. and G347.3. Over 1018 different waveforms are considered, covering signal frequencies between 20 and 1300 Hz (20 and 400 Hz) for G347.3-0.5 (Vela Jr.) and a very broad range of frequency derivatives. The data set used for this first search is from the second observing run of LIGO (O2). Thousands of volunteers donating compute cycles through the computing project Einstein@Home have made this endeavor possible. Following the Einstein@Home search, we perform multistage follow-ups of over 5 million waveforms. The threshold for selecting candidates from the Einstein@Home search is such that, after the multistage follow-up, we do not expect any surviving candidate due to noise. The very last stage uses a different data set, namely, the LIGO O3 data. We find no significant signal candidate for either targets. Based on this null result, for G347.3-0.5, we set the most constraining upper limits to date on the amplitude of gravitational-wave signals, corresponding to deformations below 10‑6 in a large part of the search band. At the frequency of best strain sensitivity, near 161 Hz, we set 90% confidence upper limits on the gravitational-wave intrinsic amplitude of  . Over most of the frequency range, our upper limits are a factor of 10 smaller than the indirect age-based upper limit. For Vela Jr., near 163 Hz, we set  . Over most of the frequency range, our upper limits are a factor of 15 smaller than the indirect age-based upper limit. The Vela Jr. upper limits presented here are slightly less constraining than the most recent upper limits of R. Abbott et al., but they apply to a broader set of signals.

Keywords: Supernova remnants, Neutron stars, Gravitational waves
Temporal and Spectral Analysis of the Unique and Second-brightest Gamma-Ray Burst GRB 230307A: Insights from GECAM and Fermi/GBM Observations. In this study, we present the pulse profile of the unique and the second-brightest gamma-ray burst GRB 230307A, and analyze its temporal behavior using a joint GECAM–Fermi Gamma-ray Burst Monitor (GBM) time-resolved spectral analysis. The utilization of GECAM data is advantageous as it successfully captured significant data during the pileup period of the Fermi/GBM. We investigate the evolution of its flux, photon fluence, photon flux, peak energy, and the corresponding hardness–intensity and hardness–flux correlations. The findings within the first 27 s exhibit consistent patterns reported previously, providing valuable insights for comparing observations with predictions from the synchrotron radiation model invoking an expanding shell. Beyond the initial 27 s, we observe a notable transition in the emitted radiation, attributed to high-latitude emission, influenced by the geometric properties of the shells and the relativistic Doppler effects. By modeling the data within the framework of the large-radius internal shock model, we discuss the required parameters as well as the limitations of the model. We conclude that a more complicated synchrotron emission model is needed to fully describe the observational data of GRB 230307A.

Keywords: Gamma-ray bursts, Gamma-ray bursters
A Case Study of Gas Impacted by Black-hole Jets with the JWST: Outflows, Bow Shocks, and High Excitation of the Gas in the Galaxy IC 5063. We present James Webb Space Telescope MIRI data of the inner ∼3 × 2 kpc2 of the galaxy IC 5063, in which the jets of a supermassive black hole interact with the gaseous disk they are crossing. Jet-driven outflows were known to be initiated along or near the jet path and to modify the stability of molecular clouds, possibly altering their star formation properties. The MIRI data, of unprecedented resolution and sensitivity in the infrared, now reveal that there are more than 10 discrete regions with outflows, nearly doubling the number of such known regions. Outflows exist near the radio lobes, at the nucleus, in a biconical structure perpendicular to the jet, and in a bubble moving against the disk. In some of them, velocities above escape velocity are observed. Stratification is also observed, with higher ionization or excitation gas attaining higher velocities. More outflows and bow shocks, found further away from the nucleus than the radio lobes, in regions without significant radio emission, reveal the existence of past or weak radio jets that interacted with the interstellar medium. The coincidence of the bow shocks with the optical extended emission line region (EELR) suggests that the jets also contributed to the gas ionization. Maps of the H2 gas excitation temperature, T ex, indicate that the molecular gas is most excited in regions with radio emission. There, T ex is &gt;100 K higher than in the EELR interior. We argue that a combination of jet-related shocks and cosmic rays is likely responsible for this excess molecular gas excitation.

Keywords: Molecular gas, Radio jets, Galaxy winds, Interstellar medium, Galaxies
Modeling Multiple X-Ray Reflection in Super-Eddington Winds. It has been recently discovered that a few super-Eddington sources undergoing black hole super-Eddington accretion exhibit X-ray reflection signatures. In such new systems, one expects the coronal X-ray emissions to be mainly reflected by optically thick super-Eddington winds instead of thin disks. In this paper, we conduct a series of general-relativistic ray-tracing and Monte Carlo radiative transfer simulations to model the X-ray reflection signatures, especially the characteristic Fe Kα line, produced from super-Eddington accretion flows around nonspinning black holes. In particular, we allow the photons emitted by a lamppost corona to be reflected multiple times in a cone-like funnel surrounded by fast winds. We find that the Fe Kα line profile most sensitively depends on the wind kinematics, while its exact shape also depends on the funnel open angle and corona height. Furthermore, very interestingly, we find that the Fe Kα line can have a prominent double-peak profile in certain parameter spaces, even with a face-on orientation. Moreover, we compare the Fe Kα line profiles produced from super-Eddington and thin disks and show that such lines can provide important insights into the understanding of black hole systems undergoing super-Eddington accretion.

Keywords: Accretion, Black hole physics, X-ray binary stars, Monte Carlo methods, Tidal disruption, Galaxy accretion disks, X-ray active galactic nuclei, Radiative transfer simulations
Cross-correlation of Luminous Red Galaxies with Machine Learning Selected Active Galactic Nuclei in HSC-SSP: Unobscured AGN Residing in More Massive Halos. Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN of different spectral types indicate different evolutionary stages in the coevolution of black holes and galaxies. We present the angular correlation function between an AGN sample selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical photometry and Wide-field Infrared Survey Explorer mid-IR photometry and a luminous red galaxy (LRG) sample from HSC-SSP. We investigate AGN clustering strength as a function of luminosity and spectral features across three independent HSC fields totaling ∼600 deg2, for z ∈ 0.6 −1.2 and AGN with L 6 μm &gt; 3 × 1044 erg s−1. There are ∼28,500 AGN and ∼1.5 million LRGs in our primary analysis. We determine the average halo mass for the full AGN sample (M  h  ≍ 1012.9 h −1 M ⊙), and note that it does not evolve significantly as a function of redshift (over this narrow range) or luminosity. We find that, on average, unobscured AGN (M  h  ≍ 1013.3 h −1 M ⊙) occupy ∼4.5× more massive halos than obscured AGN (M  h  ≍ 1012.6 h −1 M ⊙), at 5σ statistical significance using 1D uncertainties, and at 3σ using the full covariance matrix, suggesting a physical difference between unobscured and obscured AGN, beyond the line-of-sight viewing angle. Furthermore, we find evidence for a halo mass dependence on reddening level within the Type I AGN population, which could support the existence of a dust-obscured phase. However, we also find that quite small systematic shifts in the redshift distributions of the AGN sample could explain current and previously observed differences in M  h .

Keywords: Supermassive black holes, Active galactic nuclei, Galaxy evolution, Quasars
Complex Kinematics of Nebular Gas in Active Galaxies Centered in Cooling X-Ray Atmospheres. [O II] emission maps obtained with the Keck Cosmic Web Imager are presented for four galaxies centered in cooling X-ray cluster atmospheres. Nebular emission extending over tens of kiloparsecs is found in systems covering a broad range of atmospheric cooling rates, cluster masses, and dynamical states. A262's central galaxy hosts a kiloparsec-scale disk. The nebular gas in RX J0820.9+0752 is offset and redshifted with respect to the central galaxy by 10─20 kpc and 150 km s−1, respectively. The nebular gases in PKS 0745−191 and A1835 are being churned to higher velocity dispersion by X-ray bubbles and jets. The churned gas is enveloped by larger-scale, lower-velocity-dispersion (quiescent) nebular emission. The mean line-of-sight speeds of the churned gas, quiescent gas, and the central galaxy each differ by up to ∼150 km s−1; nebular speeds upward of 800 km s−1 are found. Gases with outwardly rising speeds upward of several hundred kilometers per second are consistent with being advected behind and being lifted by the rising bubbles. The peculiar motion between the galaxy, nebular gas, and perhaps the hot atmosphere from which it presumably condensed is affecting the bubble dynamics and may strongly affect thermally unstable cooling, the dispersal of jet energy, and the angular momentum of gas accreting onto the galaxies and their nuclear black holes.

Keywords: AGN host galaxies, Cooling flows, Relativistic jets, Emission nebulae, Galaxy kinematics, X-ray active galactic nuclei, Star formation, Brightest cluster galaxies, Intracluster medium