Sazuna/UAT_keywords huggingface dataset:
Do Current X-Ray Observations Capture Most of the Black-hole Accretion at High Redshifts?. The cosmic black hole accretion density (BHAD) is critical for our understanding of the formation and evolution of supermassive black holes (BHs). However, at high redshifts (z &gt; 3), X-ray observations report BHADs significantly (~10 times) lower than those predicted by cosmological simulations. It is therefore paramount to constrain the high-z BHAD using independent methods other than direct X-ray detections. The recently established relation between star formation rate and BH accretion rate among bulge-dominated galaxies provides such a chance, as it enables an estimate of the BHAD from the star formation histories (SFHs) of lower-redshift objects. Using the CANDELS Lyα Emission At Reionization (CLEAR) survey, we model the SFHs for a sample of 108 bulge-dominated galaxies at z = 0.7-1.5, and further estimate the BHAD contributed by their high-z progenitors. The predicted BHAD at z ≈ 4-5 is consistent with the simulation-predicted values, but higher than the X-ray measurements (by ≈3-10 times at z = 4-5). Our result suggests that the current X-ray surveys could be missing many heavily obscured Compton-thick active galactic nuclei (AGNs) at high redshifts. However, this BHAD estimation assumes that the high-z progenitors of our z = 0.7-1.5 sample remain bulge-dominated where star formation is correlated with BH cold-gas accretion. Alternatively, our prediction could signify a stark decline in the fraction of bulges in high-z galaxies (with an associated drop in BH accretion). JWST and Origins will resolve the discrepancy between our predicted BHAD and the X-ray results by constraining Compton-thick AGN and bulge evolution at high redshifts.

Keywords: AGN host galaxies, Supermassive black holes, Star formation, X-ray active galactic nuclei, Active galactic nuclei, Galaxy evolution, High-redshift galaxies
Multiple Stellar Populations at Less-evolved Stages-II: No Evidence of Significant Helium Spread among NGC 1846 Dwarfs. The detection of star-to-star chemical variations in star clusters older than 2 Gyr has changed the traditional view of star clusters as canonical examples of "simple stellar populations" into the so-called "multiple stellar populations" (MPs). Although the significance of MPs seems to correlate with cluster total mass, it seems that the presence of MPs is determined by cluster age. In this article, we use deep photometry from the Hubble Space Telescope to investigate whether the FG-type dwarfs in the ~1.7 Gyr old cluster NGC 1846, have helium spread. By comparing the observation with the synthetic stellar populations, we estimate a helium spread of ΔY ~ 0.01 ± 0.01 among the main-sequence stars in NGC 1846. The maximum helium spread would not exceed ΔY ~ 0.02, depending on the adopted fraction of helium-enriched stars. To mask the color variation caused by such a helium enrichment, a nitrogen enrichment of at least Δ[N/Fe] = 0.8 dex is required, which is excluded by previous analyses of the red-giant branch in this cluster. We find that our result is consistent with the ΔY-mass relationship for Galactic globular clusters. To examine whether or not NGC 1846 harbors MPs, higher photometric accuracy is required. We conclude that under the adopted photometric quality, there is no extreme helium variation among NGC 1846 dwarfs.

Keywords: Stellar populations, Hertzsprung Russell diagram, Large Magellanic Cloud, Star clusters
Confined and Eruptive Catastrophes of Solar Magnetic Flux Ropes Caused by Mass Loading and Unloading. It is widely accepted that coronal magnetic flux ropes are the core structures of large-scale solar eruptive activities, which have a dramatic impact on the solar-terrestrial system. Previous studies have demonstrated that varying magnetic properties of a coronal flux rope system could result in a catastrophe of the rope, which may trigger solar eruptive activities. Since the total mass of a flux rope also plays an important role in stabilizing the rope, we use 2.5 dimensional magnetohydrodynamic numerical simulations in this article to investigate how a flux rope evolves as its total mass varies. It is found that an unloading process that decreases the total mass of the rope could result in an upward (eruptive) catastrophe in the flux rope system, during which the rope jumps upward and the magnetic energy is released. This indicates that mass unloading processes could initiate the eruption of the flux rope. Moreover, when the system is not too diffusive, there is also a downward (confined) catastrophe that could be caused by mass loading processes via which the total mass accumulates. The magnetic energy, however, is increased during the downward catastrophe, indicating that mass loading processes could cause confined activities that may contribute to the storage of energy before the onset of coronal eruptions.

Keywords: Solar flares, Solar prominences, Quiescent solar prominence, Solar filaments, Solar coronal mass ejections, Solar filament eruptions, Solar activity
The Water-ice Feature in Near-infrared Disk-scattered Light around HD 142527: Micron-sized Icy Grains Lifted up to the Disk Surface?. We study the 3 μm scattering feature of water ice detected in the outer disk of HD 142527 by performing radiative transfer simulations. We show that an ice mass abundance at the outer disk surface of HD 142527 is much lower than estimated in a previous study. It is even lower than inferred from far-infrared ice observations, implying ice disruption at the disk surface. Next, we demonstrate that a polarization fraction of disk-scattered light varies across the ice-band wavelengths depending on ice grain properties; hence, polarimetric spectra would be another tool for characterizing water-ice properties. Finally, we argue that the observed reddish disk-scattered light is due to grains a few microns in size. To explain the presence of such grains at the disk surface, we need a mechanism that can efficiently oppose dust settling. If we assume turbulent mixing, our estimate requires α ≳ 2 × 10-3, where α is a nondimensional parameter describing the vertical diffusion coefficient of grains. Future observations probing gas kinematics would be helpful to elucidate vertical grain dynamics in the outer disk of HD 142527.

Keywords: Spectropolarimetry, Protoplanetary disks, Near infrared astronomy
Radiative-dynamical Simulation of Jupiter's Stratosphere and Upper Troposphere. We present a two-dimensional radiative-dynamical model of the combined stratosphere and upper troposphere of Jupiter to understand its temperature distribution and meridional circulation pattern. Our study highlights the importance of radiative and mechanical forcing for driving the middle atmospheric circulation on Jupiter. Our model adopts a state-of-the-art radiative transfer scheme with recent observations of Jovian gas abundances and haze distribution. Assuming local radiative equilibrium, latitudinal variation of hydrocarbon abundances is not able to explain the observed latitudinal temperature variations in the mid-latitudes. With mechanical forcing parameterized as a frictional drag on zonal wind, our model produces ~2 K latitudinal temperature variations observed in low to mid-latitudes in the troposphere and lower stratosphere, but cannot reproduce the observed 5 K temperature variations in the middle stratosphere. In the high latitudes, temperature and meridional circulation depend strongly on polar haze radiation. The simulated residual mean circulation shows either two broad equator-to-pole cells or multi-cell patterns, depending on the frictional drag timescale and polar haze properties. A more realistic wave parameterization and a better observational characterization of haze distribution and optical properties are needed to better understand latitudinal temperature distributions and circulation patterns in the middle atmosphere of Jupiter.

Keywords: Atmospheric circulation, Planetary atmospheres, Solar system gas giant planets, Jupiter, Radiative transfer, Planetary science
Limits on Polarized Dust Spectral Index Variations for CMB Foreground Analysis. Using Planck polarization data, we search for and constrain spatial variations of the polarized dust foreground for cosmic microwave background (CMB) observations, specifically in its spectral index, βd. Failure to account for such variations will cause errors in the foreground cleaning that propagate into errors on cosmological parameter recovery from the cleaned CMB map. It is unclear how robust prior studies of the Planck data that constrained βd variations are due to challenges with noise modeling, residual systematics, and priors. To clarify constraints on βd and its variation, we employ two pixel space analyses of the polarized dust foreground at &gt;3°7 scales on ≈60% of the sky at high Galactic latitudes. A template fitting method, which measures βd over three regions of ≈20% of the sky, does not find significant deviations from a uniform βd = 1.55, consistent with prior Planck determinations. An additional analysis in these regions, based on multifrequency fits to a dust and CMB model per pixel, puts limits on ${\sigma }_{{\beta }_{d}}$ , the Gaussian spatial variation in βd. The data support ${\sigma }_{{\beta }_{d}}$ up to 0.45 at the highest latitudes, 0.30 at midlatitudes, and 0.15 at low latitudes. We also demonstrate that care must be taken when interpreting the current Planck constraints, βd maps, and noise simulations. Due to residual systematics and low dust signal-to-noise ratios at high latitudes, forecasts for ongoing and future missions should include the possibility of large values of ${\sigma }_{{\beta }_{d}}$ as estimated in this paper, based on current polarization data.

Keywords: Cosmic microwave background radiation
Discovery of a New Population of Galactic H II Regions with Ionized Gas Velocity Gradients. We investigate the kinematic properties of Galactic H II regions using radio recombination line (RRL) emission detected by the Australia Telescope Compact Array at 4-10 GHz and the Jansky Very Large Array at 8-10 GHz. Our H II region sample consists of 425 independent observations of 374 nebulae that are relatively well isolated from other, potentially confusing sources and have a single RRL component with a high signal-to-noise ratio. We perform Gaussian fits to the RRL emission in position-position-velocity data cubes and discover velocity gradients in 178 (42%) of the nebulae with magnitudes between 5 and 200 ${\rm{m}}\,{{\rm{s}}}^{-1}\,{\mathrm{arcsec}}^{-1}$ . About 15% of the sources also have an RRL width spatial distribution that peaks toward the center of the nebula. The velocity gradient position angles appear to be random on the sky with no favored orientation with respect to the Galactic plane. We craft H II region simulations that include bipolar outflows or solid body rotational motions to explain the observed velocity gradients. The simulations favor solid body rotation since, unlike the bipolar outflow kinematic models, they are able to produce both the large, &gt;40 ${\rm{m}}\,{{\rm{s}}}^{-1}\,{\mathrm{arcsec}}^{-1}$ , velocity gradients and also the RRL width structure that we observe in some sources. The bipolar outflow model, however, cannot be ruled out as a possible explanation for the observed velocity gradients for many sources in our sample. We nevertheless suggest that most H II region complexes are rotating and may have inherited angular momentum from their parent molecular clouds.

Keywords: Radio spectroscopy, Radio astronomy, H II regions, Interstellar medium
Capturing the Physics of MaNGA Galaxies with Self-supervised Machine Learning. As available data sets grow in size and complexity, advanced visualization tools enabling their exploration and analysis become more important. In modern astronomy, integral field spectroscopic galaxy surveys are a clear example of increasing high dimensionality and complex data sets, which challenges the traditional methods used to extract the physical information they contain. We present the use of a novel self-supervised machine-learning method to visualize the multidimensional information on stellar population and kinematics in the MaNGA survey in a 2D plane. Our framework is insensitive to nonphysical properties such as the size of the integral field unit and is therefore able to order galaxies according to their resolved physical properties. Using the extracted representations, we study how galaxies distribute based on their resolved and global physical properties. We show that even when exclusively using information about the internal structure, galaxies naturally cluster into two well-known categories, rotating main-sequence disks and massive slow rotators, from a purely data-driven perspective, hence confirming distinct assembly channels. Low-mass rotation-dominated quenched galaxies appear as a third cluster only if information about the integrated physical properties is preserved, suggesting a mixture of assembly processes for these galaxies without any particular signature in their internal kinematics that distinguishes them from the two main groups. The framework for data exploration is publicly released with this publication, ready to be used with the MaNGA or other integral field data sets.

Keywords: Galaxies, Neural networks
Multi-messenger Approaches to Supermassive Black Hole Binary Detection and Parameter Estimation: Implications for Nanohertz Gravitational Wave Searches with Pulsar Timing Arrays. Pulsar timing array (PTA) experiments are becoming increasingly sensitive to gravitational waves (GWs) in the nanohertz frequency range, where the main astrophysical sources are supermassive black hole binaries (SMBHBs), which are expected to form following galaxy mergers. Some of these individual SMBHBs may power active galactic nuclei, and thus their binary parameters could be obtained electromagnetically, which makes it possible to apply electromagnetic (EM) information to aid the search for a GW signal in PTA data. In this work, we investigate the effects of such an EM-informed search on binary detection and parameter estimation by performing mock data analyses on simulated PTA data sets. We find that by applying EM priors, the Bayes factor of some injected signals with originally marginal or sub-threshold detectability (i.e., Bayes factor ~1) can increase by a factor of a few to an order of magnitude, and thus an EM-informed targeted search is able to find hints of a signal when an uninformed search fails to find any. Additionally, by combining EM and GW data, one can achieve an overall improvement in parameter estimation, regardless of the source's sky location or GW frequency. We discuss the implications for the multi-messenger studies of SMBHBs with PTAs.

Keywords: Supermassive black holes, Active galaxies, Gravitational waves
Detection of Flare Multiperiodic Pulsations in Mid-ultraviolet Balmer Continuum, Lyα, Hard X-Ray, and Radio Emissions Simultaneously. Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of nonstationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 6, which were simultaneously measured by the Hard X-ray Modulation Telescope (Insight-HXMT), as well as the ground-based BLENSW. The multiple periods, detected by applying a wavelet transform and Lomb-Scargle periodogram to the detrended light curves, are found to be ~20-55 s in the Lyα and mid-ultraviolet Balmer continuum emissions during the flare impulsive phase. Similar QPPs with multiple periods are also found in the hard X-ray emission and low-frequency radio emission. Our observations suggest that the flare QPPs could be related to nonthermal electrons accelerated by the repeated energy release process, i.e., triggering of repetitive magnetic reconnection, while the multiple periods might be modulated by the sausage oscillation of hot plasma loops. For the multiperiodic pulsations, other generation mechanisms could not be completely ruled out.

Keywords: Solar flares, Solar ultraviolet emission, Solar x-ray emission, Solar radio emission, Solar oscillations
Magnetar Models of Superluminous Supernovae from the Dark Energy Survey: Exploring Redshift Evolution. Superluminous supernovae (SLSNe) are luminous transients that can be detected to high redshifts with upcoming optical time-domain surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time. An interesting open question is whether the properties of SLSNe evolve through cosmic time. To address this question, in this paper we model the multicolor light curves of all 21 Type I SLSNe from the Dark Energy Survey (DES) with a magnetar spin-down engine, implemented in the Modular Open-Source Fitter for Transients (MOSFiT). With redshifts up to z ≈ 2, this sample includes some of the highest-redshift SLSNe. We find that the DES SLSNe span a similar range of ejecta and magnetar engine parameters as previous samples of mostly lower-redshift SLSNe (spin period P ≈ 0.79-13.61 ms, magnetic field B ≈ (0.03-7.33) × 1014 G, ejecta mass Mej ≈ 1.54-30.32 M⊙, and ejecta velocity vej ≈ (0.55-1.45) × 104 km s-1). The DES SLSN sample by itself exhibits the previously found negative correlation between Mej and P, with a pronounced absence of SLSNe with low ejecta mass and rapid spin. Combining our results for the DES SLSNe with 60 previous SLSNe modeled in the same way, we find no evidence for redshift evolution in any of the key physical parameters.

Keywords: Supernovae
Probing Protoplanetary Disk Winds with C II Absorption. We present an analysis of wind absorption in the C II λ1335 doublet toward 40 classical T Tauri stars with archival far-ultraviolet (FUV) spectra obtained by the Hubble Space Telescope. Absorption features produced by fast or slow winds are commonly detected (36 out of 40 targets) in our sample. The wind velocity of the fast wind decreases with disk inclination, which is consistent with expectations for a collimated jet. Slow wind absorption is mostly detected in disks with intermediate or high inclination, without a significant dependence of wind velocity on disk inclination. Both the fast and slow wind absorption are preferentially detected in FUV lines of neutral or singly ionized atoms. The Mg II λλ2796, 2804 lines show wind absorption consistent with the absorption in the C II lines. We develop simplified semi-analytical disk/wind models to interpret the observational disk wind absorption. Both fast and slow winds are consistent with expectations from a thermal-magnetized disk wind model and are generally inconsistent with a purely thermal wind. Both the models and the observational analysis indicate that wind absorption occurs preferentially from the inner disk, which offers a wind diagnostic in complement to optical forbidden line emission that traces the wind in larger volumes.

Keywords: Classical T Tauri stars, Ultraviolet astronomy, Stellar winds, Protoplanetary disks, Stellar accretion
Disk Masses and Dust Evolution of Protoplanetary Disks around Brown Dwarfs. We present the largest sample of brown dwarf (BD) protoplanetary disk spectral energy distributions modeled to date. We compile 49 objects with ALMA observations from four star-forming regions: ρ Ophiuchus, Taurus, Lupus, and Upper Scorpius. Studying multiple regions with various ages enables us to probe disk evolution over time. Specifically, from our models, we obtain values for dust grain sizes, dust settling, and disk mass; we compare how each of these parameters vary between the regions. We find that disk mass decreases with age. We also find evidence of disk evolution (i.e., grain growth and significant dust settling) in all four regions, indicating that planet formation and disk evolution may begin to occur at earlier stages. We generally find that these disks contain too little mass to form planetary companions, though we cannot rule out that planet formation may have already occurred. Finally, we examine the disk mass-host mass relationship and find that BD disks are largely consistent with previously determined relationships for disks around T Tauri stars.

Keywords: Exoplanet formation, Brown dwarfs, Star formation, Protoplanetary disks
GRB 101225A as Orphan Dipole Radiation of a Newborn Magnetar with Precession Rotation in an Off-axis Gamma-ray Burst. The unusual multiwavelength lightcurves of GRB 101225A are revisited by assuming that they are from an off-axis GRB powered by a newborn magnetar. We show that GRB 101225A's optical afterglow lightcurve is fitted with the forward shock model by parameterizing its jet structure as a Gaussian function with a half-opening angle of the jet core as 1°67. The derived initial Lorentz factor (Γ0) is 120, and the viewing angle to the jet axis is θv = 3°7. Tentative QPO signatures of P = 488 s and P = 250 ~ 300 s are found with a confidence level of 90% by analyzing its X-ray flares observed in the time interval of [4900, 7500] s. Its global gamma-ray/X-ray lightcurve and the QPO signatures are represented with the magnetar dipole radiation (DR) model by considering the magnetar precession motion, assuming that the magnetar spindown is dominated by GW emission. The bulk Lorentz factor of the DR ejecta is limited to 8, being much lower than Γ0. Comparing GRB 101225A with the extremely off-axis GRB 170817A, we suspect that the nature of the two-component jet in GRB 170817A is a combination of a co-axial GRB jet and a DR ejecta. GRB 101225A would be among the brightest ones of the CDF-S XT2-like X-ray transient population driven by newborn magnetars. A discussion of the detectability of its gravitational wave emission is also presented.

Keywords: Magnetars, Gamma-ray bursts
The Implications of High Black Hole Spins for the Origin of Binary Black Hole Mergers. The LIGO-Virgo collaboration has reported 50 black hole-black hole (BH-BH) mergers and 8 candidates recovered from digging deeper into the detector noise. The majority of these mergers have low effective spins pointing toward low BH spins and efficient angular momentum (AM) transport in massive stars as proposed by several models (e.g., the Tayler-Spruit dynamo). However, out of these 58 mergers, 7 are consistent with having high effective-spin parameter (χ eff &gt; 0.3). Additionally, two events seem to have high effective spins sourced from the spin of the primary (more massive) BH. These particular observations could be used to discriminate between the isolated binary and dynamical formation channels. It might seem that high BH spins point to a dynamical origin if AM in stars is efficient and forms low-spinning BHs. In such a case dynamical formation is required to produce second and third generations of BH-BH mergers with typically high spinning BHs. Here we show, however, that isolated binary BH-BH formation naturally reproduces such highly spinning BHs. Our models start with efficient AM in massive stars that is needed to reproduce the majority of BH-BH mergers with low effective spins. Later, some of the binaries are subject to a tidal spin-up allowing the formation of a moderate fraction (~10%) of BH-BH mergers with high effective spins (χ eff ≳ 0.4-0.5). In addition, isolated binary evolution can produce a small fraction of BH-BH mergers with almost maximally spinning primary BHs. Therefore, the formation scenario of these atypical BH-BH mergers remains to be found.

Keywords: Massive stars, Black holes, Compact objects