Sazuna/UAT_keywords huggingface dataset:
Metal-THINGS: On the Metallicity and Ionization of ULX Sources in NGC 925. We present an analysis of the optical properties of three Ultra Luminous X-ray (ULX) sources identified in NGC 925. We use Integral field unit data from the George Mitchel spectrograph in the context of the Metal-THINGS survey. The optical properties for ULX-1 and ULX-3 are presented, while the spaxel associated with ULX-2 had a low S/N, which prevented its analysis. We also report the kinematics and dimensions of the optical nebula associated with each ULX using ancillary data from the PUMA Fabry-Perot spectrograph. A BPT analysis demonstrates that most spaxels in NGC 925 are dominated by star-forming regions, including those associated with ULX-1 and ULX-3. Using the resolved gas-phase metallicities, a negative metallicity gradient is found, consistent with previous results for spiral galaxies, while the ionization parameter tends to increase radially throughout the galaxy. Interestingly, ULX-1 shows a very low gas metallicity for its galactocentric distance, identified by two independent methods, while exhibiting a typical ionization. We find that such low gas metallicity is best explained in the context of the high-mass X-ray binary population, where the low-metallicity environment favors active Roche lobe overflows that can drive much higher accretion rates. An alternative scenario invoking accretion of a low-mass galaxy is not supported by the data in this region. Finally, ULX-3 shows both a high metallicity and ionization parameter, which is consistent with the progenitor being a highly accreting neutron star within an evolved stellar population region.

Keywords: Abundance ratios, Chemical abundances, Emission line galaxies, Ionization, Spectroscopy, X-ray sources
The SAMI Galaxy Survey: Stellar Populations of Passive Spiral Galaxies in Different Environments. We investigate the stellar populations of passive spiral galaxies as a function of mass and environment, using integral field spectroscopy data from the Sydney-AAO Multi-object Integral field spectrograph Galaxy Survey. Our sample consists of 52 cluster passive spirals and 18 group/field passive spirals, as well as a set of S0s used as a control sample. The age and [Z/H] estimated by measuring Lick absorption line strength indices both at the center and within 1Re do not show a significant difference between the cluster and the field/group passive spirals. However, the field/group passive spirals with log(M⋆/M⊙) ≳ 10.5 show decreasing [α/Fe] along with stellar mass, which is ∼0.1 dex smaller than that of the cluster passive spirals. We also compare the stellar populations of passive spirals with S0s. In the clusters, we find that passive spirals show slightly younger age and lower [α/Fe] than the S0s over the whole mass range. In the field/group, stellar populations show a similar trend between passive spirals and S0s. In particular, [α/Fe] of the field/group S0s tend to be flattening with increasing mass above log(M⋆/M⊙) ≳ 10.5, similar to the field/group passive spirals. We relate the age and [α/Fe] of passive spirals to their mean infall time in phase space; we find a positive correlation, in agreement with the prediction of numerical simulations. We discuss the environmental processes that can explain the observed trends. The results lead us to conclude that the formation of the passive spirals and their transformation into S0s may significantly depend on their environments.

Keywords: Galaxy environments, Galaxy ages, Galaxy abundances, Galaxy evolution, Extragalactic astronomy
Silicon and Hydrogen Chemistry under Laboratory Conditions Mimicking the Atmosphere of Evolved Stars. Silicon is present in interstellar dust grains, meteorites and asteroids, and to date 13 silicon-bearing molecules have been detected in the gas phase toward late-type stars or molecular clouds, including silane and silane derivatives. In this work, we have experimentally studied the interaction between atomic silicon and hydrogen under physical conditions mimicking those in the atmosphere of evolved stars. We have found that the chemistry of Si, H, and H2 efficiently produces silane (SiH4), disilane (Si2H6) and amorphous hydrogenated silicon (a-Si:H) grains. Silane has been definitely detected toward the carbon-rich star IRC +10216, while disilane has not been detected in space yet. Thus, based on our results, we propose that gas-phase reactions of atomic Si with H and H2 are a plausible source of silane in C-rich asymptotic giant branch stars, although its contribution to the total SiH4 abundance may be low in comparison with the suggested formation route by catalytic reactions on the surface of dust grains. In addition, the produced a-Si:H dust analogs decompose into SiH4 and Si2H6 at temperatures above 500 K, suggesting an additional mechanism of formation of these species in envelopes around evolved stars. We have also found that the exposure of these dust analogs to water vapor leads to the incorporation of oxygen into Si-O-Si and Si-OH groups at the expense of SiH moieties, which implies that if this kind of grain is present in the interstellar medium, it will probably be processed into silicates through the interaction with water ices covering the surface of dust grains.

Keywords: Interstellar dust, Silicate grains, Laboratory astrophysics, Astrochemistry, Interstellar dust processes
Structure and Evolution of an Inter-Active Region Large-scale Magnetic Flux Rope. Magnetic flux rope (MFR) has been recognized as the key magnetic configuration of solar eruptions. While pre-eruption MFRs within the core of solar active regions (ARs) have been widely studied, those existing between two ARs, i.e., the intermediate ones in weak-field regions, were rarely studied. There are also major eruptions that occurred in such intermediate regions and study of the MFR there will help us understand the physics mechanism underlying the eruptions. Here, with a nonlinear force-free field reconstruction of solar coronal magnetic fields, we tracked the five-day evolution covering the full life of a large-scale inter-AR MFR forming between ARs NOAA 11943 and 11944, which is closely cospatial with a long sigmoidal filament channel and an eruptive X1.2 flare occurring on 2014 January 7. Through topological analysis of the reconstructed 3D magnetic field, it is found that the MFR begins to form early on 2014 January 6; then with its magnetic twist degree continuously increasing for over 30 hr, it becomes highly twisted with field lines winding numbers approaching six turns, which might be the highest twisting degree in extrapolated MFRs that have been reported in the literature. The formation and strength of the MFR are attributed to a continuous sunspot rotation of AR 11944 and flux cancellation between the two ARs. The MFR and its associated filaments exhibit no significant change across the flare time, indicating it is not responsible for the flare eruption. After the flare, the MFR slowly disappears, possibly due to the disturbance by the eruption.

Keywords: Solar active region magnetic fields, Magnetohydrodynamics, Solar flares, Solar prominences, Solar coronal mass ejections, Solar magnetic fields, Solar filament eruptions
A New Method to Estimate Halo CME Mass Using Synthetic CMEs Based on a Full Ice Cream Cone Model. In this study, we suggest a new method to estimate the mass of a halo coronal mass ejection (CME) using synthetic CMEs. For this, we generate synthetic CMEs based on two assumptions: (1) the CME structure is a full ice cream cone, and (2) the CME electron number density follows a power-law distribution (ρcme = ρ0r-n). The power-law exponent n is obtained by minimizing the rms error between the electron number density distributions of an observed CME and the corresponding synthetic CME at a position angle of the CME leading edge. By applying this methodology to 56 halo CMEs, we estimate two kinds of synthetic CME masses. One is a synthetic CME mass that considers only the observed CME region (Mcme1), the other is a synthetic CME mass that includes both the observed CME region and the occulted area (Mcme2). From these two cases, we derive conversion factors that are the ratio of a synthetic CME mass to an observed CME mass. The conversion factor for Mcme1 ranges from 1.4 to 3.0 and its average is 2.0. For Mcme2, the factor ranges from 1.8 to 5.0 with an average of 3.0. These results imply that the observed halo CME mass can be underestimated by about 2 times when we consider the observed CME region, and about 3 times when we consider the region including the occulted area. Interestingly these conversion factors have a very strong negative correlation with angular widths of halo CMEs.

Keywords: Solar corona, Solar coronal mass ejections
Three-dimensional Distribution of the Interstellar Dust in the Milky Way. We present a three-dimensional (3D) extinction map of the southern sky. The map covers the SkyMapper Southern Survey (SMSS) area of ∼14,000 deg2 and has spatial resolutions between 6'9 and 27'. Based on the multi-band photometry of SMSS, the Two Micron All Sky Survey, the Wide-Field Infrared Survey Explorer Survey, and the Gaia mission, we have estimated values of the r-band extinction for ∼19 million stars with the spectral energy distribution analysis. Together with the distances calculated from the Gaia data release 2 (DR2) parallaxes, we have constructed a 3D extinction map of the southern sky. By combining our 3D extinction map with those from the literature, we present an all-sky 3D extinction map, and use it to explore the 3D distribution of the Galactic dust grains. We use two different models, one consisting of a single disk and another of two disks, to fit the 3D distribution of the Galactic dust grains. The data is better fitted by a two-disk model, yielding smaller values of the Bayesian Information Criterion. The best-fit model has scale heights of 73 and 225 pc for the "thin" and "thick" dust disks, respectively.

Keywords: Interstellar dust, Galaxy structure, Milky Way Galaxy, Interstellar dust extinction
Chandra Observations of Abell 2261 Brightest Cluster Galaxy, a Candidate Host to a Recoiling Black Hole. We use Chandra X-ray observations to look for evidence of a recoiling black hole from the brightest cluster galaxy in Abell 2261 (A2261-BCG). A2261-BCG is a strong candidate for a recoiling black hole because of its large, flat stellar core, revealed by Hubble Space Telescope imaging observations. We took 100 ks observations with Chandra and combined it with 35 ks of archival observations to look for low-level accretion onto a black hole of expected mass $M\sim {10}^{10}\,{M}_{\odot }$ that could possibly be located in one of four off-center stellar knots near the galaxy's center or else in the optical center of the galaxy or in the location of radio emission. We found no X-ray emission arising from a point source in excess of the cluster gas and can place limits on the accretion of any black hole in the central region to a 2-7 keV flux below $4.3\times {10}^{-16}\ \mathrm{erg}\ {{\rm{s}}}^{-1}\ {\mathrm{cm}}^{-2}$ , corresponding to a bolometric Eddington fraction of about 10-6. Thus there is either no 1010 ${M}_{\odot }$ black hole in the core of A2261-BCG, or it is accreting at a low level. We also discuss the morphology of the X-ray emitting gas in the cluster and how its asymmetry is consistent with a large dynamic event.

Keywords: X-ray astronomy, Supermassive black holes, Black hole physics, Galaxy clusters, Low-luminosity active galactic nuclei, X-ray active galactic nuclei, Gravitational waves, Brightest cluster galaxies, Intracluster medium, Abell clusters
Intergalactic Medium Dispersion Measures of Fast Radio Bursts Estimated from IllustrisTNG Simulation and Their Cosmological Applications. Fast radio bursts (FRBs) are millisecond-duration radio transients and can be used as a cosmological probe. However, the dispersion measure (DM) contributed by the intergalactic medium (IGM) is hard to distinguish from other components. In this paper, we use the IllustrisTNG simulation to realistically estimate DMIGM up to z ∼ 9. We find ${\mathrm{DM}}_{\mathrm{IGM}}={892}_{-270}^{+721}$ pc cm-3 at z = 1. The probability distribution of DMIGM can be well fitted by a quasi-Gaussian function with a long tail. The tail is caused by structures along the line of sight in the IGM. Subtracting DM contributions from the Milky Way and host galaxy for localized FRBs, the DMIGM value is close to that given by the derived DMIGM-z relation. We also show the ability to constrain the cosmic reionization history with DMIGM of high-redshift FRBs in the IllustrisTNG universe. The derived DMIGM-z relation at high redshifts can be well fitted by a tanh reionization model with the reionization redshift z = 5.95, which is compatible with the reionization model used by the IllustrisTNG simulation. DMIGM of high-redshift FRBs also provides an independent way to measure the optical depth of the cosmic microwave background. Our result can be used to derive the pseudo-redshifts of nonlocalized FRBs for DMIGM &lt; 4000 pc cm-3.

Keywords: Intergalactic medium, Reionization, Radio bursts, Radio transient sources
Robotic Reverberation Mapping of the Southern Seyfert NGC 3783. We present spectroscopic and photometric monitoring of NGC 3783 conducted throughout the first half of 2020. Time delays between the continuum variations and the response of the broad optical emission lines were clearly detected, and we report reverberation measurements for Hβ, He II λ4686, Hγ, and Hδ. From the time delay in the broad Hβ emission line and the line width in the variable portion of the spectrum, we derive a black hole mass of ${M}_{\mathrm{BH}}={2.34}_{-0.43}^{+0.43}\times {10}^{7}$ M⊙. This is slightly smaller than, but consistent with, previous determinations. However, our significantly improved time sampling (Tmed = 1.7 days compared to Tmed = 4.0 days) has reduced the uncertainties on both the time delay and the derived mass by ∼50%. We also detect clear velocity-resolved time delays across the broad Hβ profile, with shorter lags in the line wings and a longer lag in the line core. Future modeling of the full velocity-resolved time-delay response will further improve the reverberation-based mass for NGC 3783, adding it to the small but growing sample of active galactic nuclei for which we have constrained the black hole mass as well as the geometry and kinematics of the broad-ine region. Upcoming MUSE observations at the Very Large Telescope will also allow NGC 3783 to join the smaller sample of black holes where reverberation masses and masses from stellar dynamical modeling may be directly compared.

Keywords: Supermassive black holes, Reverberation mapping, Seyfert galaxies
A Two-zone Blazar Radiation Model for "Orphan" Neutrino Flares. In this work, we investigate the 2014-2015 neutrino flare associated with the blazar TXS 0506+056 and a recently discovered muon neutrino event IceCube-200107A in spatial coincidence with the blazar 4FGL J0955.1+3551, under the framework of a two-zone radiation model of blazars where an inner/outer blob close to/far from the supermassive black hole is invoked. An interesting feature that the two sources have in common is that no evidence of GeV gamma-ray activity is found during the neutrino detection period, probably implying a large opacity for GeV gamma rays in the neutrino production region. In our model, continuous particle acceleration/injection takes place in the inner blob at the jet base, where the hot X-ray corona of the supermassive black hole provides target photon fields for efficient neutrino production and strong GeV gamma-ray absorption. We show that this model can self-consistently interpret the neutrino emission from both blazars in a large parameter space. In the meantime, the dissipation processes in outer blob are responsible for the simultaneous multiwavelength emission of both sources. In agreement with previous studies of TXS 0506+056, an intense MeV emission from the induced electromagnetic cascade in the inner blob is robustly expected to accompany the neutrino flare in our model and could be used to test the model using the next-generation MeV gamma-ray detector in the future.

Keywords: High energy astrophysics, High-energy cosmic radiation, Gamma-ray sources, Blazars, Neutrino astronomy, Active galactic nuclei
Accretion of Gas Giants Constrained by the Tidal Barrier. After protoplanets have acquired sufficient mass to open partial gaps in their natal protostellar disks, residual gas continues to diffuse onto horseshoe streamlines under the effect of viscous dissipation, and to meander in and out of the planets' Hill sphere. Within the Hill sphere, the horseshoe streamlines intercept gas flow in circumplanetary disks. The host star's tidal perturbation induces a barrier across the converging streamlines' interface. Viscous transfer of angular momentum across this tidal barrier determines the rate of mass diffusion from the horseshoe streamlines onto the circumplanetary disks, and eventually the accretion rate onto the protoplanets. We carry out a series of numerical simulations to test the influence of this tidal barrier on superthermal planets. In weakly viscous disks, the protoplanets' accretion rate steeply decreases with their masses above the thermal limit. As their growth timescale exceeds the gas depletion timescale, their masses reach asymptotic values comparable to that of Jupiter. In relatively thick and strongly viscous disks, protoplanets' asymptotic masses exceed several times that of Jupiter. Two-dimensional numerical simulations show that such massive protoplanets strongly excite the eccentricity of nearby horseshoe streamlines, destabilize orderly flow, substantially enhance the diffusion rate across the tidal barrier, and elevate their growth rate until their natal disk is severely depleted. In contrast, eccentric streamlines remain stable in three-dimensional simulations. Based on the upper falloff in the observed mass distribution of known exoplanets, we suggest that their natal disks had relatively low viscosity (α ∼ 10-3) and modest thickness (H/R ∼ 0.03-0.05).

Keywords: Accretion, Tidal interaction, Extrasolar gaseous giant planets, Protoplanetary disks
Evolutionary Models for the Remnant of the Merger of Two Carbon-Oxygen Core White Dwarfs. We construct evolutionary models of the remnant of the merger of two carbon-oxygen (CO) core white dwarfs (WDs). With total masses in the range 1-2 M⊙, these remnants may either leave behind a single massive WD or undergo a merger-induced collapse to a neutron star (NS). On the way to their final fate, these objects generally experience a ∼10 kyr luminous giant phase, which may be extended if sufficient helium remains to set up a stable shell-burning configuration. The uncertain, but likely significant, mass-loss rate during this phase influences the final remnant mass and fate (WD or NS). We find that the initial CO core composition of the WD is converted to oxygen-neon (ONe) in remnants with final masses ≳1.05 M⊙. This implies that the CO core/ONe core transition in single WDs formed via mergers occurs at a similar mass as in WDs descended from single stars and thus that WD-WD mergers do not naturally provide a route to producing ultramassive CO-core WDs. As the remnant contracts toward a compact configuration, it experiences a "bottleneck" that sets the characteristic total angular momentum that can be retained. This limit predicts that single WDs formed from WD-WD mergers have rotational periods of ≈10-20 minutes on the WD cooling track. Similarly, it predicts remnants that collapse can form NSs with rotational periods ∼10 ms.

Keywords: Neutron stars, White dwarf stars, Supernovae, Stellar mergers
Differential Modeling Systematics across the HR Diagram from Asteroseismic Surface Corrections. Localized modeling error in the near-surface layers of evolutionary stellar models causes the frequencies of their normal modes of oscillation to differ from those of actual stars with matching interior structures. These frequency differences are referred to as the asteroseismic surface term. Global stellar properties estimated via detailed constraints on individual mode frequencies have previously been shown to be robust with respect to different parameterizations of this surface term. It has also been suggested that this may be true of a broader class of nonparametric treatments. We examine systematic differences in inferred stellar properties with respect to different surface-term treatments, both for a statistically large sample of main-sequence stars, as well as for a sample of red giants, for which no such characterization has previously been done. For main-sequence stars, we demonstrate that while masses and radii, and hence ages, are indeed robust to the choice of surface term, the inferred initial helium abundance Y0 is sensitive to the choice of surface correction. This implies that helium-abundance estimates returned from detailed asteroseismology are methodology dependent. On the other hand, for our red giant sample, nonparametric surface corrections return dramatically different inferred stellar properties than parametric ones do. The nature of these differences suggests that such nonparametric methods should be preferred for evolved stars; this should be verified on a larger sample.

Keywords: Stellar oscillations, Computational methods, Asteroseismology
Detection of PO in Orion-KL: Phosphorus Chemistry in the Plateau Outflow. The PO molecule (X2Πr) has been detected toward Orion-KL via its J = 2.5 → 1.5 transition near 109 GHz using the 12 m telescope of the Arizona Radio Observatory. This transition consists of a quartet of lines, generated by lambda-doubling and phosphorus hyperfine interactions, creating a distinct pattern of doublets of doublets. All four features (F = 3 → 2, e, f and 2 → 1, e, f ) were detected. The line profiles measured were relatively broad, with ΔV1/2 ∼ 21-25 km s-1, and VLSR ∼ 10 km s-1, clearly identifying the molecule as arising from the Orion "plateau" region. The J = 2 → 1 transition of PN (X1Σ) at 94 GHz was also measured, and its line profile indicates a plateau origin in Orion, as found previously by Ziurys. Therefore, PO and PN arise from the same gas. There was no evidence of a "hot core" or "ridge" component in either molecule. The column densities determined for PO and PN in the Orion plateau are Ntot ≈ 5.4(0.2) × 1013 and 2.0(0.4) × 1013 cm-2, respectively, with corresponding abundances, relative to H2, of f ∼ 1.6(0.1) × 10-10 and 6.1(0.6) × 10-11, resulting in PO/PN ∼ 3. The PO and PN line profiles also resemble those of SiO and SiS, suggesting that the phosphorus molecules are produced by shocks in the plateau outflow. The observed PO/PN ratio in Orion-KL is very close in value to that measured in other warm molecular clouds, indicating a common synthesis pathway for these two molecules in outflows caused by star formation.

Keywords: Interstellar molecules, Interstellar abundances, Molecular clouds, Astrochemistry, Astrobiology, Star formation