Sazuna/UAT_keywords huggingface dataset:
The First Supermassive Black Hole Mass Measurement in Active Galactic Nuclei Using the Polarization of Broad Emission Line Mg II. Spectropolarimetric efforts in the last few years have developed an efficient method that is based on the profiles of the polarization plane position angle of broad emission lines in active galactic nuclei. Here we present black hole measurements of SBS 1419+538 using spectropolarimetric observations in the Mg II spectral band. The observations are performed by the 6 m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences (SAO RAS) using SCORPIO-2. We found good agreement for this object's estimated supermassive black hole mass using spectropolarimetry compared with the mass obtained using other methods.

Keywords: Supermassive black holes, Spectropolarimetry, Quasars, Active galaxies, Seyfert galaxies, Polarimetry
Cosmologically Coupled Compact Objects: A Single-parameter Model for LIGO-Virgo Mass and Redshift Distributions. We demonstrate a single-parameter route for reproducing higher mass objects as observed in the LIGO-Virgo mass distribution, using only the isolated-binary stellar evolution channel. This single parameter encodes the cosmological mass growth of compact stellar remnants that exceed the Tolman-Oppenheimer-Volkoff limit. Cosmological mass growth appears in known solutions to General Relativity with cosmological boundary conditions. We consider the possibility of solutions with cosmological boundary conditions, which reduce to Kerr on timescales short compared to the Hubble time. We discuss complementary observational signatures of these solutions that can confirm or invalidate their astrophysical relevance.

Keywords: Cosmological evolution, Supernova remnants, Gravitational wave astronomy, Compact objects, Astrophysical black holes
Rapid Evolution of Bald Patches in a Major Solar Eruption. A bald patch (BP) is a magnetic topological feature where U-shaped field lines turn tangent to the photosphere. Field lines threading the BP trace a separatrix surface where reconnection preferentially occurs. Here we study the evolution of multiple, strong-field BPs in AR 12673 during the most intense, X9.3 flare of solar cycle 24. The central BP, located between the initial flare ribbons, largely "disintegrated" within 35 minutes. The more remote, southern BP survived. The disintegration manifested as a 9° rotation of the median shear angle; the perpendicular component of the horizontal field (with respect to the polarity inversion line) changed sign. The parallel component exhibited a step-wise, permanent increase of 1 kG, consistent with previous observations of the flare-related "magnetic imprint." The observations suggest that magnetic reconnection during a major eruption may involve entire BP separatrices, leading to a change of magnetic topology from BPs to sheared arcades.

Keywords: Solar active region magnetic fields, Solar flares, Solar magnetic reconnection
Transport of Interstellar Neutral Helium throughout the Heliosphere. A number of physical processes accompanying the solar wind interaction with the local interstellar medium (LISM) are governed by charge exchange between ions and neutral atoms of interstellar origin. A new, 3D, MHD-plasma/kinetic-neutral model is developed that self-consistently includes both neutral hydrogen and helium atoms, and their feedback on the plasma, through charge exchange and photoionization. Focusing on the transport of interstellar neutral helium, quantitative estimates are provided for bulk properties, deflection angles, and velocity distribution functions (VDFs) along the upwind direction. It is shown that the average deflection of secondary He atoms born in the outer heliosheath (OHS) from their original direction in the LISM is ~12° in front of the heliopause, and occurs in the directions parallel to the plane formed by the velocity and magnetic field vectors in the unperturbed LISM. While these properties are consistent with Interstellar Boundary Explorer observations of the "warm breeze," we show that charge exchange in the OHS leads to remarkable deviations of their VDF from the Maxwellian distribution. He atom filtration in the OHS results in a significant temperature anisotropy and VDF asymmetries, even for the primary helium atoms that experience no charge exchange at all. This is an entirely kinetic phenomenon that shows that primary He atoms observed at 1 au have distributions substantially different from those in the LISM.

Keywords: Heliopause, Astrosphere interstellar medium interactions, Interstellar atomic gas, Heliosphere, Interstellar plasma, Interstellar medium, Charge exchange ionization
The Mass Distribution of Neutron Stars in Gravitational-wave Binaries. The discovery of two neutron star-black hole coalescences by LIGO and Virgo brings the total number of likely neutron stars observed in gravitational waves to six. We perform the first inference of the mass distribution of this extragalactic population of neutron stars. In contrast to the bimodal Galactic population detected primarily as radio pulsars, the masses of neutron stars in gravitational-wave binaries are thus far consistent with a uniform distribution, with a greater prevalence of high-mass neutron stars. The maximum mass in the gravitational-wave population agrees with that inferred from the neutron stars in our Galaxy and with expectations from dense matter.

Keywords: Neutron stars, Bayesian statistics, Gravitational waves, Compact objects
White-light Continuum Observation of the Off-limb Loops of the SOL2017-09-10 X8.2 Flare: Temporal and Spatial Variations. Observations of the Sun's off-limb white-light (WL) flares offer rare opportunities to study the energy release and transport mechanisms in flare loops. One of the best such events was SOL2017-09-10, an X8.2 flare that occurred near the Sun's west limb on 2017 September 10 and produced a WL loop system lasting more than 60 minutes and reaching an altitude higher than 30 Mm. The event was well observed by a suite of ground- and space-based instruments, including the Solar Dynamics Observatory/Helioseismic and Magnetic Imager (SDO/HMI) that captured its off-limb loops in WL continuum near Fe I 6173 Å, and the Atmospheric Imager Assembly (SDO/AIA) that observed its ultraviolet (UV) and extreme-ultraviolet (EUV) counterparts. We found quasi-periodic pulsations in the WL and UV emissions at the flare loop-top with a period around 8.0 minutes. Each pulsation appears to have an EUV counterpart that occurs earlier in time and higher in altitude. Despite many similarities in the WL and UV images and light curves, the WL flux at the loop-top continues to grow for about 16 minutes while the UV fluxes gradually decay. We discuss the implication of these unprecedented observations on the understanding of the enigmatic off-limb WL flare emission mechanisms.

Keywords: Solar activity, Active solar corona, Solar white-light flares, Solar oscillations
A Candidate Kiloparsec-scale Quasar Pair at z = 5.66. We report the discovery of a close quasar pair candidate at z = 5.66, J2037-4537. J2037-4537 is resolved into two quasar images at the same redshift in ground-based observations. Follow-up spectroscopy shows significant differences in both the continuum slopes and emission line properties of the two images. The two quasar images have a projected separation of 1"24 (7.3 kpc at z = 5.66) and a redshift difference of Δz ≲ 0.01. High-resolution images taken by the Hubble Space Telescope do not detect the foreground lensing galaxy. The observational features of J2037-4537 strongly disfavor the lensing hypothesis. If J2037-4537 is a physical quasar pair, it indicates a quasar clustering signal of ~105 at a separation of ~10 proper kpc (pkpc), and gives the first observational constraint on the pair fraction of z &gt; 5 quasars, fpair(r &lt; 30 pkpc) &gt; 0.3%. The properties of J2037-4537 are consistent with those of merger-triggered quasar pairs in hydrodynamical simulations of galaxy mergers.

Keywords: Double quasars, Quasars
Detectable Abundance of Cyanoacetylene (HC<SUB>3</SUB>N) Predicted on Reduced Nitrogen-rich Super-Earth Atmospheres. We predict that cyanoacetylene (HC3N) is produced photochemically in the atmosphere of GJ 1132 b in abundances detectable by the James Webb Space Telescope (JWST), assuming that the atmosphere is hydrogen dominated and rich in molecular nitrogen (N2), methane (CH4), and hydrogen cyanide (HCN), as described by Swain et al. First, we construct line lists and cross sections for HC3N. Then we apply these cross sections and the model atmosphere of Swain et al. to a radiative transfer model in order to simulate the transmission spectrum of GJ 1132 b as it would be seen by JWST, accounting for the uncertainty in the retrieved abundances. We predict that cyanoacetylene features at various wavelengths, with a clear lone feature at 4.5 μm, observable by JWST after one transit. This feature persists within the 1σ uncertainty of the retrieved abundances of HCN and CH4. The signal is detectable for stratospheric temperatures ≲600 K and moderate stratospheric mixing (106 cm2 s-1 ≲ Kzz ≲ 108 cm2 s-1). Our results also indicate that HC3N is an important source of opacity that future retrieval models should consider.

Keywords: Extrasolar rocky planets, Exoplanet atmospheres
Evidence for Gravitational Lensing of GRB 200716C. Observationally, there is a small fraction of gamma-ray bursts (GRBs) with prompt emission observed by Fermi/GBM that are composed of two pulses. Occasionally, the distance to a GRB may be lensed when a high mass astrophysical object resides in the path between the GRB source and observer. In this paper, we describe GRB 200716C, which has a two-pulse emission and duration of a few seconds. We present a Bayesian analysis identifying gravitational lensing in both temporal and spectral properties, and calculate the time delay (Δt ~ 1.92 s) and magnification (γ ~ 1.5) between those two pulses based on the temporal fits. One can roughly estimate the lens mass to be about 2.4 × 105M⊙ in the rest frame. We also calculate the false alarm probability for this detection to be about 0.07% with trial factors, and a present-day number density of about 808Mpc-3 with an energy density Ω ~ 1.4 × 10-3. If the first pulse of this GRB near the trigger time is indeed gravitationally echoed by a second pulse, GRB 200716C may be a short GRB candidate with extended emission.

Keywords: Gamma-ray bursts, Gravitational lensing
Fermi-GBM Observations of GRB 210812A: Signatures of a Million Solar Mass Gravitational Lens. Observing gravitationally lensed objects in the time domain is difficult, and well-observed time-varying sources are rare. Lensed gamma-ray bursts (GRBs) offer improved timing precision for this class of objects, complementing observations of quasars and supernovae. The rate of lensed GRBs is highly uncertain, approximately one in 1000. The Gamma-ray Burst Monitor on board the Fermi Gamma-ray Space Telescope has observed more than 3000 GRBs, making it an ideal instrument to uncover lensed bursts. Here we present observations of GRB 210812A showing two emission episodes, separated by 33.3 s and with a flux ratio of about 4.5. An exhaustive temporal and spectral analysis shows that the two emission episodes have the same pulse and spectral shape, which poses challenges to GRB models. We report multiple lines of evidence for a gravitational lens origin. In particular, modeling the lightcurve using nested sampling, we uncover strong evidence in favor of the lensing scenario. Assuming a point-mass lens, the mass of the lensing object is about 1 million solar masses. High-resolution radio imaging is needed for future lens candidates to derive tighter constraints.

Keywords: Gamma-ray bursts, Gravitational lensing
X-Ray Quasi-periodic Eruptions Driven by Star-Disk Collisions: Application to GSN069 and Probing the Spin of Massive Black Holes. X-ray quasi-periodic eruptions (QPEs) were discovered recently in active galaxies with an unknown driving mechanism. Under the assumption that QPEs are caused by star-disk collisions, we adopt full relativistic method and show that both the orbital parameters of the star and also the mass and spinning of the massive black hole (MBH) can be revealed by using the time of arrival (TOA) of the QPEs. By applying the model to the observed QPEs of GSN069, we find that the star is in a near-circular orbit ( ${e}_{\bullet }={0.05}_{-0.02}^{+0.02}$ ) with a semimajor axis of $\sim {365}_{-49}^{+54}{r}_{{\rm{g}}}$ around an MBH with ${M}_{\bullet }={3.0}_{-0.6}^{+0.9}\times {10}^{5}\,{M}_{\odot }$ . The alternative short and long recurring time of the QPEs of GSN069 can be well explained by the small eccentricity and the orbital precession of the star. We find that the QPEs of GSN069 are possibly driven by a striped stellar core colliding with accretion disk after a partial tidal disruption event around the MBH. For GSN069-like galaxies, if continuous X-ray monitoring of QPE events can be accumulated with uncertainties of TOA ≲100-150 s, the spin of the MBH can be constrained by fitting to QPEs. Our results show that the timing of QPEs can provide a unique probe for measuring the spinning of the MBH and tests of the no-hair theorem.

Keywords: Supermassive black holes, Kerr black holes, Tidal disruption, General relativity, X-ray bursts
Formation of a Solar Filament by Magnetic Reconnection, Associated Chromospheric Evaporation, and Subsequent Coronal Condensation. We present the first observation of a solar filament formed by magnetic reconnection, associated chromospheric evaporation, and subsequent coronal condensation. Driven by shearing motion during flux emergence, a sequential tether-cutting reconnection process occurred and resulted in an M1.3 confined flare accompanied by the formation of a sigmoid structure. It is found that the flare had conjugate compact footpoint brightenings, which correspond to the footpoints of the sigmoid. Furthermore, observational evidence of explosive evaporation is well diagnosed at the conjugate footpoint brightenings in the impulsive phase of the flare. After the flare, continuous cool condensations formed at about the middle section of the sigmoid and then moved in opposite directions along the sigmoid, eventually leading to the formation of the filament. These observations suggest that magnetic reconnection can not only form the magnetic field structure of the filament but also heat the chromospheric footpoints during their formation and drive chromospheric evaporation. As a result, the heated chromospheric plasma may be evaporated into the magnetic field structure of the filament, where the accumulated hot plasma might suffer from thermal instability or nonequilibrium, causing catastrophic cooling and coronal condensation to form the cool, dense material of the filament. This observation lends strong support to the evaporation-condensation model and highlights the crucial role of magnetic reconnection in forming both the magnetic field structure and the cool, dense material of the filaments.

Keywords: Solar flares, Solar prominences, Solar magnetic reconnection, Solar magnetic flux emergence, Solar filaments, Solar magnetic fields, Solar activity
CI Tau: A Controlled Experiment in Disk-Planet Interaction. CI Tau is a young (~2 Myr) T Tauri system with a substantial near-infrared (NIR) excess in its spectral energy distribution (SED), indicating that the protoplanetary disk extends very close to its star. This is seemingly at odds with the radial-velocity discovery of CI Tau b, a ~12 MJ planet at ~0.1 au, which would be expected to carve a wide, deep cavity in the innermost disk. To investigate this apparent contradiction, we run 2D hydrodynamics simulations to study the effect of the planet on the disk, then post-process the results with radiative transfer to obtain an SED. We find that at ~0.1 au, even such a massive companion has little impact on the NIR excess, a result that holds regardless of planetary eccentricity and dust size distribution. Conversely, the observed full-disk signature in CI Tau's SED is consistent with the existence of the hot super-Jupiter CI Tau b. As our simulations uncover, clear transition-disk signatures in SEDs are more likely to be signposts of nascent "warm" Jupiters, located at around 1 au in the future habitable zones of their host stars.

Keywords: Exoplanet detection methods, Hydrodynamics, Protoplanetary disks, Radiative transfer
A High-velocity Scatterer Revealed in the Thinning Ejecta of a Type II Supernova. We present deep, nebular-phase spectropolarimetry of the Type II-P/L SN 2013ej, obtained 167 days after explosion with the European Southern Observatory's Very Large Telescope. The polarized flux spectrum appears as a nearly perfect (92% correlation), redshifted (by ~4000 km s-1) replica of the total flux spectrum. Such a striking correspondence has never been observed before in nebular-phase supernova spectropolarimetry, although data capable of revealing it have heretofore been only rarely obtained. Through comparison with 2D polarized radiative transfer simulations of stellar explosions, we demonstrate that localized ionization produced by the decay of a high-velocity, spatially confined clump of radioactive 56Ni-synthesized by and launched as part of the explosion with final radial velocity exceeding 4500 km s-1-can reproduce the observations through enhanced electron scattering. Additional data taken earlier in the nebular phase (day 134) yield a similarly strong correlation (84%) and redshift, whereas photospheric-phase epochs that sample days 8 through 97 do not. This suggests that the primary polarization signatures of the high-velocity scattering source only come to dominate once the thick, initially opaque hydrogen envelope has turned sufficiently transparent. This detection in an otherwise fairly typical core-collapse supernova adds to the growing body of evidence supporting strong asymmetries across nature's most common types of stellar explosions, and establishes the power of polarized flux-and the specific information encoded by it in line photons at nebular epochs-as a vital tool in such investigations going forward.

Keywords: Spectropolarimetry, Core-collapse supernovae, Late stellar evolution, Type II supernovae, Radiative transfer simulations, Supernovae
The Magellanic Stream at 20 kpc: A New Orbital History for the Magellanic Clouds. We present new simulations of the formation of the Magellanic Stream based on an updated first-passage interaction history for the Magellanic Clouds, including both the Galactic and Magellanic Coronae and a live dark matter halo for the Milky Way. This new interaction history is needed because previously successful orbits need updating to account for the Magellanic Corona and the loosely bound nature of the Magellanic Group. These orbits involve two tidal interactions over the last 3.5 Gyr and reproduce the Stream's position and appearance on the sky, mass distribution, and velocity profile. Most importantly, our simulated Stream is only ~20 kpc away from the Sun at its closest point, whereas previous first-infall models predicted a distance of 100-200 kpc. This dramatic paradigm shift in the Stream's 3D position would have several important implications. First, estimates of the observed neutral and ionized masses would be reduced by a factor of ~5. Second, the stellar component of the Stream is also predicted to be &lt;20 kpc away. Third, the enhanced interactions with the MW's hot corona at this small distance would substantially shorten the Stream's lifetime. Finally, the MW's UV radiation field would be much stronger, potentially explaining the Hα emission observed along most of the Stream. Our prediction of a 20 kpc Stream could be tested by searching for UV absorption lines toward distant MW halo stars projected onto the Stream.

Keywords: Galaxy dynamics, Galaxy physics, Magellanic Clouds, Magellanic Stream
C/2014 UN<SUB>271</SUB> (Bernardinelli-Bernstein): The Nearly Spherical Cow of Comets. Comet C/2014 UN271 (Bernardinelli-Bernstein), incoming from the Oort cloud, is remarkable in having the brightest (and presumably largest) nucleus of any well-measured comet and having been discovered at the heliocentric distance rh ≍ 29 au, farther than any Oort cloud comet. In this work, we describe the discovery process and observations and the properties that can be inferred from images recorded until the first reports of activity in 2021 June. The orbit has i = 95°, with a perihelion of 10.97 au to be reached in 2031 and a previous aphelion at 40,400 ± 260 au. Backward integration of the orbit under a standard Galactic tidal model and known stellar encounters suggests a perihelion of q ≍ 18 au on its previous perihelion passage 3.5 Myr ago; hence, the current data could be the first ever obtained of a comet that has not been inside Uranus's orbit in 4 Gyr. The photometric data show an unresolved nucleus with absolute magnitude Hr = 8.0, colors that are typical of comet nuclei or Damocloids, and no secular trend as it traversed the range 34-23 au. For the r-band geometric albedo pr, this implies a diameter of $150{({p}_{r}/0.04)}^{-0.5}$ km. There is strong evidence of brightness fluctuations at the ±0.2 mag level, but no rotation period can be discerned. A coma, nominally consistent with a "stationary" 1/ρ surface brightness distribution, grew in scattering cross section at an exponential rate from Afρ ≍ 1 to ≍150 m as the comet approached from 28 to 20 au. The activity rate is consistent with a very simple model of sublimation of a surface species in radiative equilibrium with the Sun. The inferred enthalpy of sublimation matches those of CO2 and NH3. More volatile species, such as N2, CH4, and CO, must be far less abundant on the sublimating surfaces.

Keywords: Small Solar System bodies, Comet nuclei, Comet dynamics, Long period comets, Comet origins
Did the Event Horizon Telescope Detect the Base of the Submilliarsecond Tubular Jet in M87?. A high-sensitivity, 7 mm Very Long Baseline Array image of M 87 was previously analyzed in order to estimate the bulk flow jet velocity between 0.4 and 0.65 mas from the point of origin using the asymmetry between the well-characterized double-ridged counter-jet (unique to this image) and the double-ridged jet. We use this same image to estimate the cross-sectional area of this tubular stream. The velocity, acceleration, cross-sectional area, and flux density along this stream determine a unique, perfect magnetohydrodynamic jet solution that satisfies conservation of energy, angular momentum, and mass (a monotonic conversion of Poynting flux to kinetic energy flux along the jet). The solution is protonic and magnetically dominated. The bilateral jet transports ≈1.2 × 10-4M⊙ yr-1 and ≈1.1 × 1042 erg s-1, placing strong constraints on the central engine. A Keplerian disk source that also produces the Event Horizon Telescope (EHT) annulus of emission can supply the energy and mass if the vertical magnetic field at the equator is ~1-3.5 G (depending on location). A Parker spiral magnetic field, characteristic of a wind or jet, is consistent with the observed EHT polarization pattern. Even though there is no image of the jet connecting with the annulus, it is argued that these circumstances are not coincidental and the polarized portion of the EHT emission is mainly jet emission in the top layers of the disk that is diluted by emission from an underlying turbulent disk. This is a contributing factor to the relatively low polarization levels that were detected.

Keywords: Radio active galactic nuclei, Low-luminosity active galactic nuclei, Active galactic nuclei