Sazuna/UAT_keywords huggingface dataset:
Explaining Nonmerger Gamma-Ray Bursts and Broad-lined Supernovae with Close Binary Progenitors with Black Hole Central Engines. For over 25 yr, the origin of long-duration gamma-ray bursts (lGRBs) has been linked to the collapse of rotating massive stars. However, we have yet to pinpoint the stellar progenitor powering these transients. Moreover, the dominant engine powering the explosions remains open to debate. Observations of both lGRBs, supernovae associated with these GRBs, such as broad-line (BL) stripped-envelope (type Ic) supernovae (hereafter, Ic-BL), supernovae (SNe), and perhaps superluminous SNe, fast blue optical transients, and fast x-ray transients, may provide clues to both engines and progenitors. In this paper, we conduct a detailed study of the tight-binary formation scenario for lGRBs, comparing this scenario to other leading progenitor models. Combining this progenitor scenario with different lGRB engines, we can compare to existing data and make predictions for future observational tests. We find that the combination of the tight-binary progenitor scenario with the black hole accretion disk engine can explain lGRBs, low-luminosity GRBs, ultra-long GRBs, and Ic-BL. We discuss the various progenitor properties required for these different subclasses and note such systems would be future gravitational-wave merger sources. We show that the current literature on other progenitor-engine scenarios cannot explain all of these transient classes with a single origin, motivating additional work. We find that the tight-binary progenitor with a magnetar engine is excluded by existing observations. The observations can be used to constrain the properties of stellar evolution, the nature of the GRB, and the associated SN engines in lGRBs and Ic-BL. We discuss the future observations needed to constrain our understanding of these rare, but powerful, explosions.

Keywords: Type Ic supernovae, Massive stars, Gamma-ray bursts, Supernovae
X-Ray Radiative Transfer Calculation Based on a Physics-based Model of the Subparsec-scale Gases around an Active Galactic Nucleus and Its Application to NGC 3783. Although the X-ray spectra of Seyfert 1 galaxies exhibit absorption lines of He-like iron and H-like iron at blueshifted velocities of approximately 500 km s−1, the physical origin of these absorption lines remains uncertain. In this study, we performed X-ray radiative transfer based on the subparsec-scale thermally driven outflows. The initial step involved calculating the photoionization equilibrium using the Cloudy code, which is based on three-dimensional radiative hydrodynamic simulations. Subsequently, X-ray radiative transfer was performed using the Monte Carlo Simulation for Astrophysics and Cosmology code. Our findings indicate that when the angle of inclination ranges within 55°─65°, the transmitted component of the X-ray spectrum displays absorption lines of He-like and H-like iron, exhibiting a blueshift of approximately 500 km s−1. The results suggest that the absorption lines are generated by a photoionized gas within 0.005 pc. Additionally, the results indicate that the scattered component of the X-ray spectrum exhibits emission lines originating from neutral iron fluorescence, He-like iron, and H-like iron. The emission lines are broadened by approximately 7000 km s−1 due to the Keplerian rotation. Furthermore, the model reproduced the H-like iron and H-like iron absorption lines in NGC 3783 observed by the Chandra High Energy Transmission Grating.

Keywords: Supermassive black holes, High energy astrophysics, Seyfert galaxies, X-ray active galactic nuclei, Astrophysical black holes
Out on a Limb: The Signatures of East–West Asymmetries in Transmission Spectra from General Circulation Models. In the era of JWST, observations of hot Jupiter atmospheres are becoming increasingly precise. As a result, the signatures of limb asymmetries due to temperature or abundance differences and the presence of aerosols can now be directly measured using transmission spectroscopy. Using a grid of general circulation models with varying irradiation temperatures (1500–4000 K) and prescriptions of cloud formation, we simulate 3D ingress/egress and morning-/evening-limb transmission spectra. We aim to assess the impact that clouds, 3D temperature structure, and nonuniform distribution of gases have on the observed spectra, and how these inhomogeneities can be identified. A second goal is to assess the relative merits of two separate methods (ingress/egress versus morning-/evening-limb spectroscopy) for isolating atmospheric asymmetries. From our models, it is evident that an east–west temperature difference is the leading-order effect for producing ingress/egress or morning-/evening-limb spectral differences. We additionally find that clouds contribute strongly to the observed limb asymmetry at moderate irradiation temperatures in our grid (∼2000 K &lt; Tirr &lt; 3500 K). At lower temperatures clouds equally dominate the optical depth on both limbs, while at higher temperatures the entire terminator region remains cloud free. We develop limb asymmetry metrics that can be used to assess the degree of east–west asymmetry for a given planet and predict trends in these metrics with respect to irradiation temperature that are indicative of various physical processes. Our results are useful for predicting and diagnosing the signatures of limb asymmetries in JWST spectra.

Keywords: Theoretical models, Hot Jupiters, Transmission spectroscopy, Radiative transfer simulations, Exoplanet atmospheres
Accretion and Recovery in Giant Eruptions of Massive Stars. Giant eruptions are episodic high-rate mass-loss events that massive stars experience in the late-stage of their evolution before exploding as a core-collapse supernova. If a giant eruption occurs in a binary system, the companion star can accrete part of the mass. We use numerical simulations to analyze how the companion responds to accretion and how its structure and evolution are altered. We run a grid of massive stars with masses from 20 M⊙ to 60 M⊙, and accretion rates from 10‑4 to 0.1 M⊙ yr‑1, over a duration of 20 yr. For accretion rates ≲0.01 M⊙ yr‑1, the star remains on the hotter side of the HR diagram with a minor increase in luminosity without expanding because the accretion timescale exceeds the thermal time scale by a larger factor. Mass loss through stellar winds leads to a minor drop in luminosity shortly after the accretion phase as the star enters the recovery phase. For ≳0.01 M⊙ yr‑1, the companion star experiences a sudden increase in luminosity by about one order of magnitude, inflates, and cools. Under the accreted gas layer, the star retains its structure and continues to eject radiation-driven wind during the recovery phase, namely the time it takes to regain equilibrium. Eventually, the accreted material mixes with the inner layers of the star and the star continues to evolve as a more massive star.

Keywords: Accretion, Massive stars, Stellar evolution, Stellar winds
Evidence for GeV Gamma-Ray Emission from Intense GRB 240529A During the Afterglow's Shallow Decay Phase. X-ray light curves of gamma-ray burst (GRB) afterglows exhibit various features, with the shallow decay phase being particularly puzzling. While some studies report the absence of the X-ray shallow decay for hyperenergetic GRBs, recently discovered GRB 240529A shows a clear shallow decay phase with an isotropic gamma-ray energy of 2.2 × 1054 erg, making it a highly unusual case compared to typical GRBs. In order to investigate the physical mechanism of the shallow decay, we perform the Fermi-Large Area Telescope (LAT) analysis of GRB 240529A along with the Swift-X-Ray Telescope analysis. We find no jet break feature in the X-ray light curve and then give the lower bound of the collimation-corrected jet energy of &gt;1052 erg, which is close to the maximum rotational energy of a magnetar. Our LAT data analysis reveals evidence of GeV emission with a statistical significance of 4.5σ during the shallow decay phase, which can be interpreted as the first case for hyperenergetic GRBs with a typical shallow decay phase. The GeV to keV flux ratio is calculated to be 4.2 ± 2.3. Together with the X-ray spectral index, this indicates an inverse Compton origin of the GeV emission. Multiwavelength modeling based on time-dependent simulations tested two promising models, the energy injection and wind models. Both models can explain the X-ray and gamma-ray data, while our modeling demonstrates that gamma-ray observations, along with future GeV–TeV observations by the Cherenkov Telescope Array Observatory, will distinguish between them.

Keywords: Gamma-ray bursts, Non-thermal radiation sources, High energy astrophysics
Spatially Resolved Circumgalactic Medium around a Star-forming Galaxy Driving a Galactic Outflow at z ≍ 0.8. We report the small-scale spatial variation in cool (T ∼ 104 K) Mg II absorption detected in the circumgalactic medium (CGM) of a star-forming galaxy at z ≍ 0.8. The CGM of this galaxy is probed by a spatially extended bright background gravitationally lensed arc at z = 2.76. The background arc continuously samples the CGM of the foreground galaxy at a range of impact parameters between 54 and 66 kpc. The Mg II absorption strengths vary by more than a factor of 2 within these ranges. A power-law fit to the fractional variation of absorption strengths yields a coherence length of 5.8 kpc within this range of impact parameters. This suggests a high degree of spatial coherence in the CGM of this galaxy. The host galaxy is driving a strong galactic outflow with a mean outflow velocity ≍ −179 km s−1 and mass outflow rate  Ṁout≥64−27+31  M⊙ yr−1 traced by blueshifted Mg II and Fe II absorption lines. The galaxy itself has a spatially extended emission halo with a maximum spatial extent of ≍33 kpc traced by [O II], [O III], and Hβ emission lines. The extended emission halo shows kinematic signatures of corotating halo gas with solar metallicity. Taken together, these observations suggest evidence of a baryon cycle that is recycling the outflowing gas to form the next generation of stars.

Keywords: Galactic winds, Galaxy evolution, Circumgalactic medium
The NANOGrav 12.5 yr Data Set: Probing Interstellar Turbulence and Precision Pulsar Timing with PSR J1903+0327. Free electrons in the interstellar medium refract and diffract radio waves along multiple paths, resulting in angular and temporal broadening of radio pulses that limits pulsar timing precision. We determine multifrequency, multiepoch scattering times for the large dispersion measure millisecond PSR J1903+0327 by developing a three-component model for the emitted pulse shape that is convolved with a best-fit pulse broadening function (PBF) identified from a family of thin-screen and extended-media PBFs. We show that the scattering time, τ, at a fiducial frequency of 1500 MHz changes by approximately 10% over a 5.5 yr span with a characteristic timescale of approximately 100 days. We also constrain the spectral index and inner scale of the wavenumber spectrum of electron density variations along this line of sight. We find that the scaling law for τ versus radio frequency is strongly affected by any mismatch between the true and assumed PBF or between the true and assumed intrinsic pulse shape. We show using simulations that refraction is a plausible cause of the epoch dependence of τ, manifesting as changes in the PBF shape and 1/e timescale. Finally, we discuss the implications of our scattering results on pulsar timing including time of arrival delays and dispersion measure misestimation.

Keywords: Interstellar scattering, Interstellar scintillation, Millisecond pulsars
MG1-1995959: An Eclipsing Binary Star with a Pronounced O'Connell Effect. MG1-1995959 is a short-period (∼0.586 day) eclipsing binary, exhibiting at times an extraordinarily large O'Connell effect (OE), for which this paper reports its discovery, time series photometry, and spectroscopic observation. The photometry is scattered across years 2001–2023, with spectroscopic observations from 2023. Photometric curves exhibit classical OE asymmetries, whereby maxima following primary and secondary eclipses are of different magnitudes. Short time span photometric time series provide static characterizations of OE stars yielding incomplete representations of critical macrobehavior. In contrast, MG1-1995959 photometry is of sufficient duration to indicate pronounced changes in such behavior, suggesting that intense observing programs can provide key benchmark data to better inform complex modeling efforts. Spectra indicate the primary to be K1 Vk(e), and the secondary type is ∼K5 V. PHOEBE modeling of the light curve from 2014 enables estimation of key stellar parameters (primary/secondary): Teff [K] (5110/4260), and, in solar units, mass (0.86/0.68) and radius (0.93/0.65). The inclination of the system was found to be ∼78°. PHOEBE modeling of light curves from 2013, 2022, and 2023 is presented, demonstrating (1) the light curves can be well fit by invoking distributions of star spots, (2) optimal spot sizes and distributions vary dramatically as a function of time, and (3) this is a powerful tool with which to investigate the short term evolution of this star. MG1-1995959 is an accessible star with dynamic and unusual behavior deserving of intensive study to better understand nuances of the OE and the nature of late-type main-sequence stars.

Keywords: Starspots, Binary stars, Stellar chromospheres, Eclipsing binary stars, Eclipsing binary minima timing method
Impact of the Cosmic Web on the Properties of Galaxies in IllustrisTNG Simulations. We investigate the influence of the cosmic web on galaxy properties in the IllustrisTNG simulations. To disentangle the effects of galaxy groups and cosmic filaments, we divide the cosmic web environment into four categories: group, group-dominated region, filament-dominated region, and field. By controlling for stellar mass, we reveal evident differences in specific star formation rates (sSFRs), quenched fraction, gas fractions, local density, and stellar ages among central galaxies in different cosmic web environments, particularly for lower-mass galaxies. However, these differences largely diminish when the effect of local overdensity is further accounted for, indicating its dominant role. Additionally, we observe distinct differences in these properties among satellite galaxies across environments, mainly driven by stellar mass, halo mass, and overdensity. Notably, residual differences between satellites in field and filament-dominated regions persist even after controlling for these factors, suggesting a stronger susceptibility of satellite galaxies to filaments compared to central galaxies. Our findings highlight the importance of differentiating between central and satellite to accurately assess the environmental effects of the cosmic web. Our analysis suggests that the relationship between galaxy properties and their distance from filaments arises from a combination of factors, including stellar and halo mass, groups, overdensity, and the intrinsic influence of the cosmic web. Additionally, we find that the effect of the cosmic web on galaxy properties is reduced at z = 0.5, compared to z = 0. Furthermore, central galaxies near thick filaments tend to exhibit slightly to moderately lower sSFR and cold gas fractions compared to those near thin filaments.

Keywords: Hydrodynamical simulations, Cosmic web, Galaxy evolution, Large-scale structure of the universe
VLA FRAMEx. II. Radio Spectra of Nearby Active Galactic Nuclei at Subarcsecond Resolution. We present 4–12 GHz in-band spectral energy distributions with accompanying 6 GHz and 10 GHz imaging results for a volume-complete sample (&lt;40 Mpc) of hard X-ray selected active galactic nuclei observed with the Karl G. Jansky Very Large Array (VLA) in its A-array configuration. Despite expectations, only 12 out of 25 of these targets have been detected by the Very Long Baseline Array (VLBA) at milliarcsecond resolution in our previous studies, and we aim to understand why the circumnuclear radio emission resolves away at the subparsec spatial scales. We find that the sources not detected by the VLBA are also the faintest sources observed with the VLA. We explore the spectral structure derived from the nuclear emission and measure a mean spectral index of &lt;α&gt; = ‑0.69 with a scatter of σα = 0.18 for the sources not detected by the VLBA, indicative of optically thin synchrotron emission. The 12 sources detected by the VLBA primarily have flat (‑0.5 ≤ α ≤ 0.0) or inverted (α &gt; 0) spectral indices. Nine of the sources have statistically significant curvature, with only one that was not detected by the VLBA. In NGC 3079, we model an approximately flat spectrum for the excess emission observed by the VLA that is likely produced entirely beyond parsec spatial scales.

Keywords: Radio active galactic nuclei, Radio astronomy, Active galaxies, Active galactic nuclei
The M<SUB>BH</SUB>─M<SUB>∗</SUB> Relation of the Hyperluminous Dust-obscured Quasars up to z ∼ 4. Hot dust-obscured galaxies (Hot DOGs) are a rare population of hyperluminous dust-obscured quasars discovered by the Wide-field Infrared Survey Explorer (WISE) all-sky survey. The heavy circumnuclear dust obscuration allows only a small amount of scattered light from the obscured quasar to escape, enabling the decomposition of the stellar component from the total flux. The presence of scattered light enables the redshift of the source and the properties of the black hole to be obtained from the Sloan Digital Sky Survey (SDSS) and SDSS-related literature. From WISE and SDSS data, we select 11 hyperluminous Hot DOGs at z = 1.5─3.7 with bolometric luminosities Lbol ≳ 1047 erg s−1. We investigate the MBH─M⋆ relation in these sources using Bayesian spectral energy distribution fitting or with extra constraints from Hubble Space Telescope image decomposition. Stellar masses are successfully derived for eight Hot DOGs. We find high Eddington ratios λEdd in these Hot DOGs, with the median value of 1.05 and the maximum value close to 3. The super-Eddington accretion may be associated with the overdense environments of Hot DOGs. We find no significant differences in the MBH/M⋆ of these Hot DOGs compared to the local relation, suggesting that these dust-obscured quasars are the progenitors of massive early-type galaxies. We speculate that the subsequent evolution of Hot DOGs may be significantly influenced by active galactic nucleus feedback and remain on the local relation.

Keywords: Supermassive black holes, High-redshift galaxies, Active galactic nuclei, Galaxy evolution
Intermediate-mass-ratio Inspirals with General Dynamical Friction in Dark Matter Minispikes. Intermediate-mass-ratio inspirals (IMRIs) may be surrounded by dark matter (DM) minispikes. The dynamical friction from these DM minispike structures can affect the dynamics and the gravitational-wave (GW) emission of the IMRIs. We analyze the effects of general dynamical friction, with a particular contribution from DM particles moving faster than the stellar-mass black hole in an eccentric IMRI. Our calculations show that these DM particles tend to increase the eccentricity of the orbit; therefore, the evolution of the eccentricity depends on the competition between the fast-moving DM particles and the slow-moving DM particles. The results show that the dynamical friction enhances the eccentricity when γsp ≲ 2.0, and the general dynamical friction is able to increase the eccentricity. We also analyze the effects of general dynamical friction on the GW characteristic strain. The results indicate that the characteristic strain is suppressed at lower frequencies, and the peak value of the characteristic strain occurs at higher frequencies as the power-law index of the DM minispike γsp increases. For the first time, a relation between the frequency peak value of the characteristic strain of GWs and γsp is established. Using this analytical relation, the presence of DM and its halo density may potentially be determined from future GW data.

Keywords: Dark matter, Gravitational waves, Black holes
Oscillatory Magnetic Reconnection at a Coronal Bright Point. Coronal bright points (CBPs) are typical small-scale coronal brightenings that consist of a bundle of miniature coronal loops. Using the ultrahigh-resolution coronal images from the Extreme Ultraviolet Imager on board Solar Orbiter, we report the first observational evidence of oscillatory magnetic reconnection at a CBP. The reconnection is characterized by two bursty phases defined by a reconnection reversal. In the first phase, a current sheet (C1) was found to form in front of an expanding loop of the bright point. Interestingly, C1 shortened to a null point during 10 minutes after reaching its maximum length (∼2.4 Mm). Less than 3 minutes later, a new current sheet (C2) was clearly seen to grow out from the null point, but along an orthogonal direction relative to C1. C2 reached a maximum length of ∼4 Mm in 10 minutes and then became short and invisible in the next few minutes as the reconnection declined. The magnetic reconnection is evidenced by the brightening, plasma flow, and temperature increase at the ends of both C1 and C2. No significant magnetic cancellation or emergence but gradual convergence occurred during the few hours before the reconnection underneath the CBP. The transition from C1 to C2 suggests the occurrence of coronal oscillatory reconnection, whereby the inflow and outflow regions in the first phase become the outflow and inflow regions in the second phase, respectively. It is further found that the oscillatory reconnection could slightly modulate the change in brightness of the CBP. We propose that oscillatory reconnection has the potential to continuously heat solar small-scale structures without destroying their overall magnetic configurations.

Keywords: Solar corona, Solar magnetic reconnection
Analysis of Jet Dynamics and Collimation Characteristics of 0241+622 on Parsec Scales. We conducted a detailed analysis of the jet structure and dynamics of the source 0241+622 on milliarcsecond scales. We stacked images from multiple epochs to better recover the cross section of the jet. By analyzing the relationship between jet width and distance, we observed that the jet exhibits a parabolic shape from the core, spanning a region from 0.12 to 6.1 mas. This structure suggests the acceleration and collimation processes of the jet. Beyond 18 mas from the core, the jet adopts a conical shape, and the expansion speed of the jet becomes faster within the range from 4500 to 6500 mas. We obtained the core shift of this source using five pairs of data from the Very Long Baseline Array at 1.6 to 43 GHz. Based on previous studies, through proper motion analysis of the jet components, we estimated the angle between the jet and the line of sight to be approximately 65 .° 7, so 1 mas corresponds to 0.95 pc (deprojected distance). We then obtained the velocity field of the source within 3.14 mas from the central black hole and found that the jet exhibits accelerated motion within this range. At approximately 6.1 mas from the core, we observed that the jet width begins to decrease, which we identified as possibly corresponding to the Bondi radius of this source. The reduction in jet width may be related to changes in the external environmental pressure, particularly within the Bondi radius, indicating that the jet dynamics and collimation characteristics are strongly influenced by the surrounding medium conditions.

Keywords: Relativistic jets, Active galactic nuclei, Radio jets