Sazuna/UAT_keywords huggingface dataset:
A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating. III. 3D Simulations and Atmospheric Response. Inspired by recent observations suggesting that photospheric magnetic flux cancellation occurs much more frequently than previously thought, we analytically estimated the energy released from reconnection driven by photospheric flux cancellation, and propose that it can act as a mechanism for chromospheric and coronal heating. Using two-dimensional simulations we validated the analytical estimates and studied the resulting atmospheric response. In the present work, we set up 3D resistive MHD simulations of two canceling polarities in a stratified atmosphere with a horizontal external field to further validate and improve upon the analytical estimates. The computational evaluation of the parameters associated with the energy release are in good qualitative agreement with the analytical estimates. The computational Poynting energy flux into the current sheet is in good qualitative agreement with the analytical estimates, after correcting the analytical expression to better account for the horizontal extent of the current sheet. The atmospheric response to the cancellation is the formation of hot ejections, cool ejections, or a combination of both hot and cool ejections, which can appear with a time difference and/or be spatially offset, depending on the properties of the canceling region and the resulting height of the reconnection. Therefore, during the cancellation, a wide spectrum of ejections can be formed, which can account for the variety of multi-thermal ejections associated with Ellerman bombs, UV bursts, and IRIS bombs, and also other ejections associated with small-scale canceling regions and spicules.

Keywords: Magnetohydrodynamics, Solar coronal transients, Solar magnetic reconnection, Solar coronal heating, Solar activity, Magnetic fields, Magnetohydrodynamical simulations
Discovery of a Remarkably Powerful Broad Absorption-line Quasar Outflow in SDSS J135246.37+423923.5. Broad absorption-line (BAL) features in quasar spectra reveal an unambiguous signature of energetic outflows from central supermassive black holes, and thus, BAL quasars are prime targets for investigating the potential process of luminous quasar feedback on galaxies. We analyzed the rest-UV spectrum of an "overlapping trough" iron low-ionization broad absorption-line quasar (FeLoBAL) SDSS J135246.37+423923.5 using the novel spectral synthesis code SimBAL and discovered an extraordinarily fast and energetic BAL outflow. Our analysis revealed outflow velocities reaching ∼-38,000 km s-1 with a velocity width of ∼ 10,000 km s-1, which is the largest FeLoBAL outflow velocity measured to date. The column density of the outflow gas is log N_{H} ∼23.2 cm-1 with the log kinetic luminosity log L_{KE} ∼48.1 (erg s-1), which exceeds the bolometric luminosity of the quasar and is energetic enough to effectively drive quasar feedback. The energy estimate for the outflow is far greater than the estimates from any BAL object previously reported. The object also shows "anomalous reddening" and a significant scattered component that we were able to model with SimBAL. We found the first definitive case for radiation filtering in an additional zero-velocity absorption component that required an absorbed continuum to produce the particular absorption lines observed (Mg II, Al III, and Al II) without also producing the high-ionization lines such as C IV.

Keywords: Galaxies, High-luminosity active galactic nuclei, Spectroscopy, Broad-absorption line quasar
Peak Temperatures of Large Solar X-Ray Flares and Associated CME Speeds and Widths. We recently repeated an earlier analysis by Garcia showing that large (≥M3.0) solar X-ray flares associated with solar energetic particle (SEP) events have significantly lower peak X-ray flux ratios R = (0.04-0.5 nm)/(0.1-0.8 nm), proxies for flare peak temperatures, than those without SEP events. As we expect SEP events to be produced by shocks ahead of fast coronal mass ejections (CMEs), a smaller R for an X-ray flare of a given peak flux Fp should also be more likely to be accompanied by a fast (Vcme &gt; 1000 km s-1) CME. We confirm this expectation, examine the role played by the ratios R in correlations between Fp and CME speeds Vcme, and then compare CME widths W, Vcme, and R with each other. We consider an apparent conflict between a global scaling model of eruptive events showing Vcme scaling with higher R and our confirmation that the Garcia analysis implies that faster CMEs are associated with flares of lower R. The R values are examined for 16 large flares of the well-studied AR 12192, for which nearly all flares had no associated CMEs. Those flares share the same high values of R as other active region (AR) flares with no CMEs. We also find that small (&lt;M3.0) flares of filament eruptions leading to SEP events share the lower R values of larger flares with fast CMEs.

Keywords: Solar flares, Solar flare spectra, Solar coronal mass ejection shocks, Solar active regions, Solar coronal mass ejections, Solar x-ray flares
Distortion of Magnetic Fields in Barnard 335. In this study, the detailed magnetic field structure of the dense protostellar core Barnard 335 (B335) was revealed, based on near-infrared polarimetric observations of background stars to measure dichroically polarized light produced by magnetically aligned dust grains in the core. Magnetic fields pervading B335 were mapped using 24 stars after subtracting unrelated ambient polarization components, revealing that they have an axisymmetrically distorted hourglass-shaped structure toward the protostellar core. On the basis of simple two- and three-dimensional magnetic field modeling, magnetic inclination angles in the plane-of-sky and line-of-sight directions were determined to be 90° ± 7° and 50° ± 10°, respectively. The total magnetic field strength of B335 was determined to be 30.2 ± 17.7 μG. The critical mass of B335, evaluated using both magnetic and thermal/turbulent support against collapse, was determined to be Mcr = 3.37 ± 0.94 M⊙, which is identical to the observed core mass of Mcore = 3.67 M⊙. We thus concluded that B335 started its contraction from a condition near equilibrium. We found a linear relationship in the polarization versus extinction diagram, up to AV ∼ 15 mag toward the stars with the greatest obscuration, which verified that our observations and analysis provide an accurate depiction of the core.

Keywords: Interstellar dust, Dense interstellar clouds, Infrared astronomy, Starlight polarization, Magnetic fields
Response of Pickup Ions in the Very Local Interstellar Medium to Solar Variations: Implications for the Evolution of the IBEX Ribbon and Interstellar Helium. The Interstellar Boundary Explorer (IBEX) observes the "ribbon" of enhanced energetic neutral atom (ENA) fluxes from the outer heliosphere. The ribbon flux is likely formed from the neutralization of energetic pickup ions (PUIs) gyrating in the interstellar magnetic field outside the heliopause. Voyager 1 crossed the heliopause in 2012 and has observed several shocks in the very local interstellar medium (VLISM) that likely originate from merged interaction regions in the inner heliosphere that propagated outside the heliopause. We simulate the response of PUIs and the IBEX ribbon flux to solar disturbances propagating into the VLISM. First, we show that PUIs outside the heliopause respond significantly to the dynamic neutralized solar wind (SW) via charge exchange and to interactions with shocks via adiabatic heating/cooling. However, the evolution of ribbon fluxes at 1 au is primarily driven by changes in the neutralized SW and not PUI interactions with shocks outside the heliopause. Comparisons with IBEX observations of the ribbon at 1.1 keV show that an abrupt decrease in ENA fluxes observed in 2012 was caused by a drop in SW (and thus neutralized SW) speed by ∼100 km s-1. Our simulation predicts a recovery of 1.1 keV ribbon fluxes starting in 2019 to levels observed early in the mission owing to an increase in SW speed. We also estimate that the presence of interstellar helium in the VLISM reduces the effectiveness of charge-exchange sources for PUIs and reduces the model ribbon flux at 1 au by ∼40%, matching well with IBEX ribbon fluxes.

Keywords: Solar cycle, Heliosphere, Solar wind, Pickup ions, Heliosheath, Interstellar medium, Solar activity, Shocks
Calibration of the Tip of the Red Giant Branch. The tip of the red giant branch (TRGB) method provides one of the most accurate and precise means of measuring the distances to nearby galaxies. Here we present a multi-wavelength, VIJHK absolute calibration of the TRGB based on observations of TRGB stars in the Large Magellanic Cloud (LMC), grounded on a geometric distance, determined by detached eclipsing binaries (DEBs). This paper presents a more detailed description of the method first presented by Freedman et al. for measuring corrections for the total line-of-sight extinction and reddening to the LMC. In this method, we use a differential comparison of the red giant population in the LMC, first with red giants in the Local Group galaxy IC 1613, and then with those in the Small Magellanic Cloud (SMC). As a consistency check, we derive an independent calibration of the TRGB sequence using the SMC alone, invoking its geometric distance also calibrated by DEBs. An additional consistency check comes from near-infrared observations of Galactic globular clusters covering a wide range of metallicities. In all cases we find excellent agreement in the zero-point calibration. We then examine the recent claims by Yuan et al., demonstrating that, in the case of the SMC, they corrected for extinction alone while neglecting the essential correction for reddening. In the case of IC 1613, we show that their analysis contains an incorrect treatment of (over-correction for) metallicity. Using our revised (and direct) measurement of the LMC TRGB extinction, we find a value of H0 = 69.6 ± 0.8 (±1.1% stat) ± 1.7 (±2.4% sys) km s-1 Mpc-1.

Keywords: Hubble constant, Galaxy distances, Observational cosmology, Interstellar extinction
Dim Prospects for Transmission Spectra of Ocean Earths around M Stars. The search for water-rich Earth-sized exoplanets around low-mass stars is rapidly gaining attention because they represent the best opportunity to characterize habitable planets in the near future. Understanding the atmospheres of these planets and determining the optimal strategy for characterizing them through transmission spectroscopy with our upcoming instrumentation is essential in order to constrain their environments. For this study, we present simulated transmission spectra of tidally locked Earth-sized ocean-covered planets around late-M to mid-K stellar spectral types, utilizing the results of general circulation models previously published by Kopparapu et al. as inputs for our radiative transfer calculations performed using NASA's Planetary Spectrum Generator (psg.gsfc.nasa.gov). We identify trends in the depth of H2O spectral features as a function of planet surface temperature and rotation rate. These trends allow us to calculate the exposure times necessary to detect water vapor in the atmospheres of aquaplanets through transmission spectroscopy with the upcoming James Webb Space Telescope as well as several future flagship space telescope concepts under consideration (the Large UV Optical Infrared Surveyor and the Origins Space Telescope) for a target list constructed from the Transiting Exoplanet Survey Satellite (TESS) Input Catalog (TIC). Our calculations reveal that transmission spectra for water-rich Earth-sized planets around low-mass stars will be dominated by clouds, with spectral features &lt;20 ppm, and only a small subset of TIC stars would allow for the characterization of an ocean planet in the habitable zone. We thus present a careful prioritization of targets that are most amenable to follow-up characterizations with next-generation instrumentation, in order to assist the community in efficiently utilizing precious telescope time.

Keywords: Ocean planets, Low mass stars, Exoplanet detection methods, Transit photometry, Habitable planets, Exoplanet atmospheres
Estimating the Jet Power of Mrk 231 during the 2017-2018 Flare. Long-term 17.6 GHz radio monitoring of the broad absorption-line quasar, Mrk 231, detected a strong flare in late 2017. This triggered four epochs of Very Long Baseline Array (VLBA) observations from 8.4 to 43 GHz over a 10 week period as well as an X-ray observation with NuSTAR. This was the third campaign of VLBA monitoring that we have obtained. The 43 GHz VLBA was degraded in all epochs, with only 7 of 10 antennas available in three epochs and 8 in the first epoch. However, useful results were obtained due to a fortuitous capturing of a complete, short 100 mJy flare at 17.6 GHz, both growth and decay. This provided useful constraints on the physical model of the ejected plasma that were not available in previous campaigns. We consider four classes of models: discrete ejections (both protonic and positronic) and jetted (protonic and positronic). The most viable model is a "dissipative bright knot" in a faint background leptonic jet with an energy flux ∼1043 erg s-1. Inverse Compton scattering calculations (based on these models) in the ambient quasar photon field explains the lack of a detectable increase in X-ray luminosity measured by NuSTAR. We show that the core (the bright knot) moves toward a nearby secondary at ≈0.97c. The background jet is much fainter. Evidently, the high-frequency VLBA core does not represent the point of origin of blazar jets, in general, and optical depth "core shift" estimates of jet points of origin can be misleading.

Keywords: Black hole physics, Quasars, Galaxy accretion disks, Radio quiet quasars, Radio loud quasars
Theoretical Study of the State-resolved Thermal Rate Constants for the Astrophysical Reaction Li + HD<SUP>+</SUP> (V = 0, 1). In the present study, we use the time-dependent wave packet (TDWP) method to calculate the thermal rate constants for the reaction Li + HD+(V = 0, 1) → LiH/LiD + H+/D+ in the temperature range of 200-5000 K on the potential energy surface constructed by Martinazzo et al. Total rate constants for both the V = 0 and V = 1 reactions exhibit simple Arrhenius behavior and are compared with previous isotope reactions. Total rate constants for V = 1 are several times larger than those of V = 0, particularly in the low-temperature region. For the two channels of the reaction, the vibrational excitation of HD+ greatly promotes the formation rate of the products LiH and LiD. For V = 0, the rate constants of LiH and LiD are comparable, while for V = 1, the rate constants of LiH are more than two times larger than those of LiD. The state-resolved rate constants show that the products LiH and LiD molecules can be excited to higher vibrational states and are preferably formed with hotter rotational states when the reactant HD+ is vibrationally excited. Applications of these rate constants in the modeling of the astrophysical sources are discussed.

Keywords: Early universe, Theoretical models, Abundance ratios, Recombination (cosmology), Galaxies
Constraining the Infalling Envelope Models of Embedded Protostars: BHR 71 and Its Hot Corino. The collapse of a protostellar envelope results in the growth of a protostar and the development of a protoplanetary disk, playing a critical role during the early stages of star formation. Characterizing the gas infall in the envelope constrains the dynamical models of star formation. We present unambiguous signatures of infall, probed by optically thick molecular lines, toward an isolated embedded protostar, BHR 71 IRS1. The three-dimensional radiative transfer calculations indicate that a slowly rotating infalling envelope model following the "inside-out" collapse reproduces the observations of both HCO + J = 4 → 3 and CS J = 7 → 6 lines, as well as the low-velocity emission of the HCN J = 4 → 3 line. The envelope has a model-derived age of 12,000 ± 3000 yr after the initial collapse. The envelope model underestimates the high-velocity emission at the HCN J = 4 → 3 and H13CN J = 4 → 3 lines, where outflows or a Keplerian disk may contribute. The ALMA observations serendipitously discover the emission of complex organic molecules (COMs) concentrated within a radius of 100 au, indicating that BHR 71 IRS1 harbors a hot corino. Eight species of COMs are identified, including CH3OH and CH3OCHO, along with H2CS, SO2 and HCN V2 = 1. The emission of methyl formate and 13C-methanol shows a clear velocity gradient within a radius of 50 au, hinting at an unresolved Keplerian rotating disk.

Keywords: Bok globules, Astrochemistry, Star formation, Radiative transfer, Gravitational collapse, Protostars
The Onset of 3D Magnetic Reconnection and Heating in the Solar Corona. Magnetic reconnection, a fundamentally important process in astrophysics, is believed to be initiated by the tearing instability of an electric current sheet, a region where magnetic field abruptly changes direction. Recent studies have suggested that the amount of magnetic shear in these structures is a critical parameter for the switch-on nature of magnetic reconnection in the solar atmosphere, at large spatial scales. We present results of visco-resistive magnetohydrodynamic simulations of magnetic reconnection in 3D current sheets with conditions appropriate to the solar corona. We follow the evolution of the linear and nonlinear 3D tearing instability. We find that, depending on the parameter space, magnetic shear can play a vital role in the onset of significant energy release and plasma heating. Two regimes in our study exist, dependent on whether the current sheet is longer or shorter than the wavelength of the fastest growing mode, thus determining whether subharmonics are present in the actual system. In one parameter regime, where the fastest growing parallel mode has subharmonics, the subsequent coalescence of 3D plasmoids dominates the nonlinear evolution, with magnetic shear playing only a weak role in the amount of energy released. In the second parameter regime, where the fastest growing parallel mode has no subharmonics, only strongly sheared current sheets, where 3D effects are strong enough, show any significant energy release. We expect both regimes to exist on the Sun, and so our results have important consequences for the question of reconnection onset in various solar physics applications.

Keywords: Solar atmosphere, Solar magnetic reconnection, Solar coronal heating, Solar physics, Solar corona, Solar magnetic fields
The Structure of Radiatively Inefficient Black Hole Accretion Flows. We run three long-timescale general-relativistic magnetohydrodynamic simulations of radiatively inefficient accretion flows (RIAFs) onto non-rotating black holes. Our aim is to achieve steady-state behavior out to large radii and understand the resulting flow structure. A simulation with adiabatic index Γ = 4/3 and small initial alternating poloidal magnetic field loops is run to a time of 440,000 GM/c3, reaching inflow equilibrium inside a radius of 370 GM/c2. Variations with larger alternating field loops and with Γ = 5/3 are run to 220,000 GM/c3, attaining equilibrium out to 170 GM/c2 and 440 GM/c2. There is no universal self-similar behavior obtained at radii in inflow equilibrium: the Γ = 5/3 simulation shows a radial density profile with a power-law index ranging from -1 in the inner regions to -1/2 in the outer regions, while the others have a power-law slope ranging from -1/2 to close to -2. Both simulations with small field loops reach a state with polar inflow of matter, while the more ordered initial field has polar outflows. However, unbound outflows remove only a factor of order unity of the inflowing material over a factor of ∼300 in radius. Our results suggest that the dynamics of RIAFs are sensitive to how the flow is fed from larger radii, and may differ appreciably in different astrophysical systems. Millimeter images appropriate for Sgr A* are qualitatively (but not quantitatively) similar in all simulations, with a prominent asymmetric image due to Doppler boosting.

Keywords: Accretion, Magnetohydrodynamics, Low-luminosity active galactic nuclei, General relativity, Relativistic fluid dynamics, Relativistic disks, Magnetohydrodynamical simulations
Truth or Delusion? A Possible Gravitational Lensing Interpretation of the Ultraluminous Quasar SDSS J010013.02+280225.8 at z = 6.30. Gravitational lensing sometimes dominates the observed properties of apparently very bright objects. We present morphological properties in the high-resolution (FWHM ∼ 0"15) Atacama Large Millimeter/submillimeter Array (ALMA) 1 mm map for an ultraluminous quasar at z = 6.30, SDSS J010013.02+280225.8 (hereafter J0100+2802), whose black hole (BH) mass MBH is the most massive (∼1.2 × 1010M☉) at z &gt; 6 ever known. We find that the continuum emission of J0100+2802 is resolved into a quadruple system within a radius of 0"2, which can be interpreted as either multiple dusty star-forming regions in the host galaxy or multiple images due to strong gravitational lensing. The Mg II absorption and the potential Lyα line features have been identified at z = 2.33 in the near-infrared spectroscopy toward J0100+2802, and a simple mass model fitting well reproduces the positions and flux densities of the quadruple system, both of which are consistent with the latter interpretation. Although a high-resolution map taken in the Advanced Camera for Survey on board Hubble Space Telescope (HST) shows a morphology with an apparently single component, in our fiducial lens mass model it can simply be explained by a ∼50 pc scale offset between the ALMA and HST emission regions. In this case, the magnification factor for the observed HST emission is obtained to ∼450, reducing the intrinsic MBH estimate to below 109 M☉. The confirmation or the rejection of the gravitational lensing scenario is important for our understanding of the supermassive BHs in the early universe.

Keywords: Supermassive black holes, Gravitational lensing, Early universe, Quasars
The MASSIVE Survey XIV—Stellar Velocity Profiles and Kinematic Misalignments from 200 pc to 20 kpc in Massive Early-type Galaxies. We use high spatial resolution stellar velocity maps from the Gemini integral-field spectrograph (IFS) and wide-field velocity maps from the McDonald Mitchell IFS to study the stellar velocity profiles and kinematic misalignments from ∼200 pc to ∼20 kpc in 20 early-type galaxies (ETGs) with stellar mass M* &gt; 1011.7M☉ in the MASSIVE survey. While 80% of the galaxies have low spins (λ &lt; 0.1) and low rotational velocities (&lt;50 km s-1) in both the central region and the main body, we find a diverse range of velocity features and misalignment angles. For the 18 galaxies with measurable central kinematic axes, 10 have well aligned kinematic axis and photometric major axis, and the other eight galaxies have misalignment angles that are distributed quite evenly from 15° to the maximal value of 90°. There is a strong correlation between central kinematic misalignment and galaxy spin, where all four galaxies with significant spins have well aligned kinematic and photometric axes, but only 43% of the low-spin galaxies are well aligned. The central and main-body kinematic axes within a galaxy are not always aligned. When the two kinematic axes are aligned (∼60% of the cases), they are either also aligned with the photometric major axis or orthogonal to it. We find 13 galaxies to also exhibit noticeable local kinematic twists, and one galaxy to have a counterrotating core. A diverse assembly history consisting of multiple gas-poor mergers of a variety of progenitor mass ratios and orbits is likely to be needed to account for the predominance of low spins and the wide range of central and main-body velocity features reported here for local massive ETGs.

Keywords: Galaxy formation, Elliptical galaxies, Galaxy evolution, Galaxy kinematics