Sazuna/UAT_keywords huggingface dataset:
Correction to the Photometric Magnitudes of the Gaia Early Data Release 3. In this Letter, we have carried out an independent validation of the Gaia Early Data Release 3 (EDR3) photometry using approximately 10,000 Landolt standard stars from Clem &amp; Landolt (2013). Using a machine-learning technique, the UBVRI magnitudes are converted into the Gaia magnitudes and colors and then compared to those in the EDR3, with the effect of metallicity incorporated. Our result confirms the significant improvements in the calibration process of the Gaia EDR3. However, modest trends up to 10 mmag with the G magnitude are found for all magnitudes and colors in the 10 &lt; G &lt; 19 mag range, particularly for the bright and faint ends. With the aid of synthetic magnitudes computed on the CALSPEC spectra with the Gaia EDR3 passbands, absolute corrections are further obtained, paving the way for optimal usage of the Gaia EDR3 photometry in high-accuracy investigations.

Keywords: Fundamental parameters of stars, Stellar photometry, Astronomy data analysis
Disk Evolution Study Through Imaging of Nearby Young Stars (DESTINYS): Late Infall Causing Disk Misalignment and Dynamic Structures in SU Aur. Gas-rich circumstellar disks are the cradles of planet formation. As such, their evolution will strongly influence the resulting planet population. In the ESO DESTINYS large program, we study these disks within the first 10 Myr of their development with near-infrared scattered-light imaging. Here we present VLT/SPHERE polarimetric observations of the nearby class II system SU Aur in which we resolve the disk down to scales of ∼7 au. In addition to the new SPHERE observations, we utilize VLT/NACO, HST/STIS, and ALMA archival data. The new SPHERE data show the disk around SU Aur and extended dust structures in unprecedented detail. We resolve several dust tails connected to the Keplerian disk. By comparison with ALMA data, we show that these dust tails represent material falling onto the disk. The disk itself shows an intricate spiral structure and a shadow lane, cast by an inner, misaligned disk component. Our observations suggest that SU Aur is undergoing late infall of material, which can explain the observed disk structures. SU Aur is the clearest observational example of this mechanism at work and demonstrates that late accretion events can still occur in the class II phase, thereby significantly affecting the evolution of circumstellar disks. Constraining the frequency of such events with additional observations will help determine whether this process is responsible for the spin-orbit misalignment in evolved exoplanet systems. * Based on observations performed with VLT/SPHERE under program ID 1104.C-0415(E).

Keywords: Exoplanets, Direct imaging, Circumstellar disks, Circumstellar dust, Polarimetry
A Self-consistent Simulation of Proton Acceleration and Transport Near a High-speed Solar Wind Stream. Solar wind stream interaction regions (SIRs) are often characterized by energetic ion enhancements. The mechanisms accelerating these particles, as well as the locations where the acceleration occurs, remain debated. Here, we report the findings of a simulation of a SIR event observed by Parker Solar Probe at ∼0.56 au and the Solar Terrestrial Relations Observatory-Ahead at ∼0.95 au in 2019 September when both spacecraft were approximately radially aligned with the Sun. The simulation reproduces the solar wind configuration and the energetic particle enhancements observed by both spacecraft. Our results show that the energetic particles are produced at the compression waves associated with the SIR and that the suprathermal tail of the solar wind is a good candidate to provide the seed population for particle acceleration. The simulation confirms that the acceleration process does not require shock waves and can already commence within Earth's orbit, with an energy dependence on the precise location where particles are accelerated. The three-dimensional configuration of the solar wind streams strongly modulates the energetic particle distributions, illustrating the necessity of advanced models to understand these particle events.

Keywords: Interplanetary particle acceleration, Solar wind, Corotating streams
Evolution of Retrograde Orbiters in an Active Galactic Nucleus Disk. Active galactic nucleus (AGN) disks have been proposed as promising locations for the mergers of stellar-mass black hole binaries (BBHs). Much recent work has been done on this merger channel, but the majority focuses on stellar-mass black holes (BHs) orbiting in the prograde direction. Little work has been done to examine the impact of retrograde orbiters (ROs) on the formation and mergers of BBHs in AGN disks. Quantifying the retrograde contribution is important, as roughly half of all orbiters should initially be on retrograde orbits when the disk forms. We perform an analytic calculation of the evolution of ROs in an AGN disk. Because this evolution could cause the orbits of ROs to cross those of prograde BBHs, we derive the collision rate between a given RO and a given BBH orbiting in the prograde direction. In the examples given here, ROs in the inner region of the disk experience a rapid decrease in the semimajor axis of their orbits while also becoming highly eccentric in less than a million years. This rapid orbital evolution could lead to extreme mass ratio inspirals detectable by the Laser Interferometer Space Antenna. The collision rates of our example ROs with prograde BBHs in the migration trap depend strongly on the volume of the inner radiation-pressure-dominated region, which depends on the mass of the supermassive black hole (SMBH). Rates are lowest for larger-mass SMBHs, which dominate the AGN merger channel, suggesting that merger rates for this channel may not be significantly altered by ROs.

Keywords: Black hole physics, Supermassive black holes, Stellar dynamics, Stellar mass black holes, Active galactic nuclei, Gravitational waves, LIGO
GW170817 and GW190814: Tension on the Maximum Mass. The detection of the binary events GW170817 and GW190814 has provided invaluable constraints on the maximum mass of nonrotating configurations of neutron stars, MTOV. However, the large differences in the neutron-star masses measured in GW170817 and GW190814 has also lead to significant tension between the predictions for such maximum masses, with GW170817 suggesting that MTOV ≲ 2.3 M⊙, and GW190814 requiring MTOV ≳ 2.5 M⊙ if the secondary was a (non- or slowly rotating) neutron star at merger. Using a genetic algorithm, we sample the multidimensional space of parameters spanned by gravitational-wave and astronomical observations associated with GW170817. Consistent with previous estimates, we find that all of the physical quantities are in agreement with the observations if the maximum mass is in the range of ${M}_{\mathrm{TOV}}={2.210}_{-0.123}^{+0.116}\,{M}_{\odot }$ within a 2σ confidence level. By contrast, maximum masses with MTOV ≳ 2.5 M⊙, not only require efficiencies in the gravitational-wave emission that are well above the numerical-relativity estimates, but they also lead to a significant underproduction of the ejected mass. Hence, the tension can be released by assuming that the secondary in GW190814 was a black hole at merger, although it could have been a rotating neutron star before.

Keywords: Neutron stars, Analytical mathematics, Nuclear astrophysics, Gravitational waves
Intermediate-mass Black Holes from High Massive-star Binary Fractions in Young Star Clusters. Black holes formed in dense star clusters, where dynamical interactions are frequent, may have fundamentally different properties than those formed through isolated stellar evolution. Theoretical models for single-star evolution predict a gap in the black hole mass spectrum from roughly 40-120 M⊙ caused by (pulsational) pair-instability supernovae. Motivated by the recent LIGO/Virgo event GW190521, we investigate whether black holes with masses within or in excess of this "upper-mass gap" can be formed dynamically in young star clusters through strong interactions of massive stars in binaries. We perform a set of N-body simulations using the CMC cluster-dynamics code to study the effects of the high-mass binary fraction on the formation and collision histories of the most massive stars and their remnants. We find that typical young star clusters with low metallicities and high binary fractions in massive stars can form several black holes in the upper-mass gap and often form at least one intermediate-mass black hole. These results provide strong evidence that dynamical interactions in young star clusters naturally lead to the formation of more massive black hole remnants.

Keywords: Intermediate-mass black holes, Binary stars, Stellar mergers, Young star clusters, N-body simulations
RELICS-DP7: Spectroscopic Confirmation of a Dichromatic Primeval Galaxy at z ∼ 7. We report the discovery of a spectroscopically confirmed strong Lyα emitter at z = 7.0281 ± 0.0003, observed as part of the Reionization Lensing Cluster Survey (RELICS). This galaxy, dubbed "Dichromatic Primeval Galaxy" at z ∼ 7 (DP7), shows two distinct components. While fairly unremarkable in terms of its ultraviolet (UV) luminosity ( $\sim 0.3{L}_{\mathrm{UV}}^{* }$ , where ${L}_{\mathrm{UV}}^{* }$ is the characteristic luminosity), DP7 has one of the highest observed Lyα equivalent widths (EWs) among Lyα emitters at z &gt; 6 (&gt;200 Å in the rest frame). The strong Lyα emission generally suggests a young metal-poor, low-dust galaxy; however, we find that the UV slope β of the galaxy as a whole is redder than typical star-forming galaxies at these redshifts, -1.13 ± 0.84, likely indicating, on average, a considerable amount of dust obscuration, or an older stellar population. When we measure β for the two components separately, however, we find evidence of differing UV colors, suggesting two separate stellar populations. Also, we find that Lyα is spatially extended and likely larger than the galaxy size, hinting to the possible existence of a Lyα halo. Rejuvenation or merging events could explain these results. Either scenario requires an extreme stellar population, possibly including a component of Population III stars, or an obscured active galactic nucleus. DP7, with its low UV luminosity and high Lyα EW, represents the typical galaxies that are thought to be the major contribution to the reionization of the universe, and for this reason DP7 is an excellent target for follow-up with the James Webb Space Telescope.

Keywords: Galaxy formation, Galaxy evolution, Reionization, High-redshift galaxies, Galaxies
Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations. We present an analysis of the R ≲ 1.5 kpc core regions of seven simulated Milky Way-mass galaxies, from the FIRE-2 (Feedback in Realistic Environments) cosmological zoom-in simulation suite, for a finely sampled period (Δt = 2.2 Myr) of 22 Myr at z ≈ 0, and compare them with star formation rate (SFR) and gas surface density observations of the Milky Way's Central Molecular Zone (CMZ). Despite not being tuned to reproduce the detailed structure of the CMZ, we find that four of these galaxies are consistent with CMZ observations at some point during this 22 Myr period. The galaxies presented here are not homogeneous in their central structures, roughly dividing into two morphological classes; (a) several of the galaxies have very asymmetric gas and SFR distributions, with intense (compact) starbursts occurring over a period of roughly 10 Myr, and structures on highly eccentric orbits through the CMZ, whereas (b) others have smoother gas and SFR distributions, with only slowly varying SFRs over the period analyzed. In class (a) centers, the orbital motion of gas and star-forming complexes across small apertures (R ≲ 150 pc, analogously ∣l∣ &lt; 1° in the CMZ observations) contributes as much to tracers of star formation/dense gas appearing in those apertures, as the internal evolution of those structures does. These asymmetric/bursty galactic centers can simultaneously match CMZ gas and SFR observations, demonstrating that time-varying star formation can explain the CMZ's low star formation efficiency.

Keywords: Galactic center, Stellar feedback, Spiral galaxies, Star formation, Galaxy kinematics, Interstellar medium
Late-time Observations of Calcium-rich Transient SN 2019ehk Reveal a Pure Radioactive Decay Power Source. We present multiband Hubble Space Telescope imaging of the calcium-rich supernova (SN) SN 2019ehk at 276-389 days after explosion. These observations represent the latest B-band to near-IR photometric measurements of a calcium-rich transient to date and allow for the first opportunity to analyze the late-time bolometric evolution of an object in this observational SN class. We find that the late-time bolometric light curve of SN 2019ehk can be described predominantly through the radioactive decay of 56Co for which we derive a mass of M(56Co) = (2.8 ± 0.1) × 10-2 M⊙. Furthermore, the rate of decline in bolometric luminosity requires the leakage of γ-rays on timescale tγ = 53.9 ± 1.30 days, but we find no statistical evidence for incomplete positron trapping in the SN ejecta. While our observations cannot constrain the exact masses of other radioactive isotopes synthesized in SN 2019ehk, we estimate a mass ratio limit of M(57Co)/M(56Co) ≤ 0.030. This limit is consistent with the explosive nucleosynthesis produced in the merger of low-mass white dwarfs, which is one of the favored progenitor scenarios in early-time studies of SN 2019ehk.

Keywords: Nucleosynthesis, Type Ib supernovae, White dwarf stars, Nuclear abundances, Supernovae
Eclipsing the X-Ray Emitting Region in the Active Galaxy NGC 6814. We report the detection of a rapid occultation event in the nearby Seyfert galaxy NGC 6814, simultaneously captured in a transient light curve and spectral variability. The intensity and hardness ratio curves capture distinct ingress and egress periods that are symmetric in duration. Independent of the selected continuum model, the changes can be simply described by varying the fraction of the central engine that is covered by transiting obscuring gas. Together, the spectral and timing analyses self-consistently reveal the properties of the obscuring gas, its location to be in the broad-line region, and the size of the X-ray source to be ∼ 25 rg. Our results demonstrate that obscuration close to massive black holes can shape their appearance, and can be harnessed to measure the active region that surrounds the event horizon.

Keywords: X-ray astronomy, Supermassive black holes, Eclipses, Accretion, Seyfert galaxies, X-ray active galactic nuclei, Partial eclipses, Astrophysical black holes
Measuring the Hubble Constant with GW190521 as an Eccentric black hole Merger and Its Potential Electromagnetic Counterpart. Gravitational-wave observations can be used to accurately measure the Hubble constant H0 and could help understand the present discrepancy between constraints from Type Ia supernovae and the cosmic microwave background. Neutron star mergers are primarily used for this purpose as their electromagnetic emission can be used to greatly reduce measurement uncertainties. Here we quantify the implied H0 using the recently observed black hole merger GW190521 and its candidate electromagnetic counterpart found by ZTF using a highly eccentric explanation of the properties of GW190521. As the electromagnetic association is currently uncertain, our main goal here is to determine the effect of eccentricity on the estimated H0. We obtain ${H}_{0}={68.8}_{-25.5}^{+45.7}$ km s-1 Mpc-1. Our results indicate that future H0 computations using black hole mergers will need to account for possible eccentricity. For extreme cases, the orbital velocity of binaries in active galactic nucleus disks can represent a significant systematic uncertainty.

Keywords: Gravitational wave astronomy, Cosmology
Consistent Dynamical and Stellar Masses with Potential Light IMF in Massive Quiescent Galaxies at 3 &lt; z &lt; 4 Using Velocity Dispersions Measurements with MOSFIRE. We present the velocity dispersion measurements of four massive ∼1011M☉ quiescent galaxies at 3.2 &lt; z &lt; 3.7 based on deep H and K-band spectra using the Keck/MOSFIRE near-infrared spectrograph. We find high velocity dispersions of order σe ∼250 km s-1 based on strong Balmer absorption lines, and we combine these with size measurements based on HST/WFC3 F160W imaging to infer dynamical masses. The velocity dispersions are broadly consistent with the high stellar masses and small sizes. Together with evidence for quiescent stellar populations, the spectra confirm the existence of a population of massive galaxies that formed rapidly and quenched in the early universe z &gt; 4. Investigating the evolution at constant velocity dispersion between z ∼3.5 and z ∼2, we find a large increase in effective radius 0.35 ± 0.12 dex and in dynamical-to-stellar mass ratio $\langle \mathrm{log}({M}_{\mathrm{dyn}}/M* )\rangle $ of 0.33 ± 0.08 dex, with low expected contribution from dark matter. The dynamical masses for our z ∼3.5 sample are consistent with the stellar masses for a Chabrier initial mass function (IMF), with the ratio $\langle \mathrm{log}({M}_{\mathrm{dyn}}/{M}_{\mathrm{Ch}}^{* })\rangle =-0.13\pm 0.10$ dex suggesting an IMF lighter than Salpeter may be common for massive quiescent galaxies at z &gt; 3. This is surprising in light of the Salpeter or heavier IMFs found for high velocity dispersion galaxies at z ∼2 and cores of present-day ellipticals, which these galaxies are thought to evolve into. Future imaging and spectroscopic observations with resolved kinematics using the upcoming James Webb Space Telescope could rule out potential systematics from rotation and confirm these results.

Keywords: High-redshift galaxies, Galaxy kinematics, Galaxy evolution
External Inverse-Compton Emission Associated with Extended and Plateau Emission of Short Gamma-Ray Bursts: Application to GRB 160821B. The recent detection of TeV photons from two gamma-ray bursts (GRBs), GRB 190114C and GRB 180720B, has opened a new window for multimessenger and multiwavelength astrophysics of high-energy transients. We study the origin of very high energy (VHE) γ-rays from the short GRB 160821B, for which the MAGIC Collaboration reported a ∼3σ statistical significance. Short GRBs are often accompanied by extended and plateau emission, which is attributed to internal dissipation resulting from activities of a long-lasting central engine, and Murase et al. (2018) recently suggested the external inverse-Compton (EIC) scenario for VHE counterparts of short GRBs and neutron star mergers. Applying this scenario to GRB 160821B, we show that the EIC flux can reach ∼10-12 erg cm-2 s-1 within a time period of ∼103-104 s, which is consistent with the MAGIC observations. EIC γ-rays expected during the extended and plateau emission will be detectable with greater significance by future detectors such as the Cerenkov Telescope Array. The resulting light curve has a distinguishable feature, where the VHE emission is predicted to reach the peak around the end of the seed photon emission.

Keywords: Gamma-ray bursts, High energy astrophysics, Gamma-ray sources, Relativistic jets, Gravitational wave astronomy, Non-thermal radiation sources, Gamma-ray astronomy
Diagnosing a Solar Flaring Core with Bidirectional Quasi-periodic Fast Propagating Magnetoacoustic Waves. Quasi-periodic fast propagating (QFP) waves are often excited by solar flares, and could be trapped in the coronal structure with low Alfvén speed, so they could be used as a tool for diagnosing both the flaring core and magnetic waveguide. As the periodicity of a QFP wave could originate from a periodic source or be dispersively waveguided, it is a key parameter for diagnosing the flaring core and waveguide. In this paper, we study two QFP waves excited by a Geostationary Operational Environmental Satellite-class C1.3 solar flare occurring at active region NOAA 12734 on 2019 March 8. Two QFP waves were guided by two oppositely oriented coronal funnels. The periods of two QFP waves were identical and were roughly equal to the period of the oscillatory signal in the X-ray and 17 GHz radio emission released by the flaring core. It is very likely that the two QFP waves could be periodically excited by the flaring core. Many features of this QFP wave event are consistent with the magnetic tuning fork model. We also investigated the seismological application with QFP waves, and found that the magnetic field inferred with magnetohydrodynamic seismology was consistent with that obtained in the magnetic extrapolation model. Our study suggests that the QFP wave is a good tool for diagnosing both the flaring core and the magnetic waveguide.

Keywords: Solar coronal seismology, Magnetohydrodynamics, Solar flares, Solar coronal heating, Solar coronal waves, Solar oscillations, Active solar corona
Dynamical Formation of the GW190814 Merger. We investigate the possible dynamical origin of GW190814, a gravitational wave (GW) source discovered by the LIGO-Virgo-Kagra collaboration (LVC) associated with a merger between a stellar black hole (BH) with mass 23.2 M⊙ and a compact object, either a BH or a neutron star (NS), with mass 2.59 M⊙. Using a database of 240,000 N-body simulations modeling the formation of NS-BH mergers via dynamical encounters in dense clusters, we find that systems like GW190814 are likely to form in young, metal-rich clusters. Our model suggests that a little excess (∼2%-4%) of objects with masses in the range of 2.3-3 M⊙ in the compact remnants' mass spectrum leads to a detection rate for dynamically formed "GW190814 -like" mergers of ΓGW190814 ≃ 1-6 yr-1 Gpc-3, i.e., within the observational constraints set by the GW190814 discovery, ΓLVC ∼ 1-23 yr-1 Gpc-3. Additionally, our model suggests that ∼1.8%-4.8% of dynamical NS-BH mergers are compatible with GW190426_152155, the only confirmed NS-BH merger detected by the LVC. We show that the relative amount of light and heavy NS-BH mergers can provide clues about the environments in which they developed.

Keywords: Neutron stars, Compact radiation sources, Stellar astronomy, Gravitational waves, Compact objects, Astrophysical black holes
Heavy Elements Unveil the Non-primordial Origin of the Giant H I Ring in Leo. The origin and fate of the most extended extragalactic neutral cloud known in the local universe, the Leo ring, is still debated 38 yr after its discovery. Its existence is alternatively attributed to leftover primordial gas with some low level of metal pollution versus enriched gas stripped during a galaxy-galaxy encounter. Taking advantage of Multi Unit Spectroscopic Explorer operating at the Very Large Telescope, we performed optical integral field spectroscopy of three H I clumps in the Leo ring where ultraviolet continuum emission has been found. We detected, for the first time, ionized hydrogen in the ring and identify four nebular regions powered by massive stars. These nebulae show several metal lines ([O III], [N II], [S II]) that allowed reliable measures of metallicities, found to be close to or above the solar value (0.8 ≤ Z/Z☉ ≤ 1.4). Given the faintness of the diffuse stellar counterparts, less than 3% of the observed heavy elements could have been produced locally in the main body of the ring and not much more than 15% in the H I clump toward M96. This inference, and the chemical homogeneity among the regions, convincingly demonstrates that the gas in the ring is not primordial, but has been pre-enriched in a galaxy disk, then later removed and shaped by tidal forces and it is forming a sparse population of stars.

Keywords: Interacting galaxies, Intergalactic clouds, Chemical abundances, H II regions