Sazuna/UAT_keywords huggingface dataset:
An Accreting, Anomalously Low-mass Black Hole at the Center of Low-mass Galaxy IC 750. We present a multiwavelength study of the active galactic nucleus in the nearby (D = 14.1 Mpc) low-mass galaxy IC 750, which has circumnuclear 22 GHz water maser emission. The masers trace a nearly edge-on, warped disk ∼0.2 pc in diameter, coincident with the compact nuclear X-ray source that lies at the base of the ∼kiloparsec-scale extended X-ray emission. The position-velocity structure of the maser emission indicates that the central black hole (BH) has a mass less than 1.4 × 105 M☉. Keplerian rotation curves fitted to these data yield enclosed masses between 4.1 × 104 M☉ and 1.4 × 105 M☉, with a mode of 7.2 × 104 M☉. Fitting the optical spectrum, we measure a nuclear stellar velocity dispersion ${\sigma }_{* }={110.7}_{-13.4}^{+12.1}$ km s-1. From near-infrared photometry, we fit a bulge mass of (7.3 ± 2.7) × 108 M☉ and a stellar mass of 1.4 × 1010 M☉. The mass upper limit of the intermediate-mass BH in IC 750 falls roughly two orders of magnitude below the MBH-σ* relation and roughly one order of magnitude below the MBH-MBulge and MBH-M* relations—larger than the relations' intrinsic scatters of 0.58 ± 0.09 dex, 0.69 dex, and 0.65 ± 0.09 dex, respectively. These offsets could be due to larger scatter at the low-mass end of these relations. Alternatively, BH growth is intrinsically inefficient in galaxies with low bulge and/or stellar masses, which causes the BHs to be undermassive relative to their hosts, as predicted by some galaxy evolution simulations.

Keywords: Water masers, Dwarf galaxies, Active galactic nuclei
Hot Dust-obscured Galaxies with Excess Blue Light. Hot dust-obscured galaxies (Hot DOGs) are among the most luminous galaxies in the universe. Powered by highly obscured, possibly Compton-thick, active galactic nuclei (AGNs), Hot DOGs are characterized by spectral energy distributions that are very red in the mid-infrared yet dominated by the host galaxy stellar emission in the UV and optical. An earlier study identified a subsample of Hot DOGs with significantly enhanced UV emission. One target, W0204-0506, was studied in detail and, based on Chandra observations, it was concluded that the enhanced emission was most likely due to either extreme unobscured star formation (star formation rate &gt; 1000 M☉ yr-1) or to light from the highly obscured AGN scattered by gas or dust into our line of sight. Here, we present a follow-up study of W0204-0506 as well as two more Hot DOGs with excess UV emission. For the two new objects we obtained Chandra/ACIS-S observations, and for all three targets we obtained Hubble Space Telescope/WFC3 F555W and F160W imaging. The analysis of these observations, combined with multiwavelength photometry and UV/optical spectroscopy suggests that UV emission is most likely dominated by light from the central highly obscured, hyperluminous AGN that has been scattered into our line of sight, by either gas or dust. We cannot decisively rule out, however, that star formation or a second AGN in the system may significantly contribute to the UV excess of these targets.

Keywords: Quasars, Active galaxies, Infrared galaxies, Galaxy evolution, High-redshift galaxies
Heating at the Remote Footpoints as a Brake on Jet Flows along Loops in the Solar Atmosphere. We report on observations of a solar jet propagating along coronal loops taken by the Solar Dynamics Observatory, the Interface Region Imaging Spectrograph, and the 1 m New Vacuum Solar Telescope. The ejecta of the jet consist of multithermal components and propagate with a speed greater than 100 km s-1. Brightenings are found in the remote footpoints of the coronal loops having compact and round shape in the Hα images. The emission peak of the remote brightening in the Atmospheric Imaging Assembly (AIA) 94 Å passband lags 60 s behind that in the jet base. The brightenings in the remote footpoints are believed to be consequences of heating by nonthermal electrons, MHD waves, and/or a conduction front generated by the magnetic reconnection processes of the jet. The heating in the remote footpoints leads to extension of the brightening along the loops toward the jet base, which is believed to be the chromospheric evaporation. This apparently acts as a brake on the ejecta, leading to a deceleration in the range from 1.5 to 3 km s-2 with an error of ∼1.0 km s-2 when the chromospheric evaporation and the ejecta meet at locations near the loop apexes. The dynamics of this jet allows for a unique opportunity to diagnose the chromospheric evaporation from the remote footpoints, from which we deduce a velocity in the range of 330-880 km s-1.

Keywords: Solar atmosphere, Solar coronal transients, Plasma jets, Solar coronal loops, Solar corona, Solar chromosphere
The Pre-explosion Mass Distribution of Hydrogen-poor Superluminous Supernova Progenitors and New Evidence for a Mass-Spin Correlation. Despite indications that superluminous supernovae (SLSNe) originate from massive progenitors, the lack of a uniformly analyzed statistical sample has so far prevented a detailed view of the progenitor mass distribution. Here we present and analyze the pre-explosion mass distribution of hydrogen-poor SLSN progenitors as determined from uniformly modeled light curves of 62 events. We construct the distribution by summing the ejecta mass posteriors of each event, using magnetar light-curve models presented in our previous works (and using a nominal neutron star remnant mass). The resulting distribution spans 3.6-40 M⊙, with a sharp decline at lower masses, and is best fit by a broken power law described by ${dN}/d\mathrm{log}M\propto {M}^{-0.41\pm 0.06}$ at 3.6-8.6 M⊙ and $\propto {M}^{-1.26\pm 0.06}$ at 8.6-40 M⊙. We find that observational selection effects cannot account for the shape of the distribution. Relative to Type Ib/c SNe, the SLSN mass distribution extends to much larger masses and has a different power-law shape, likely indicating that the formation of a magnetar allows more massive stars to explode as some of the rotational energy accelerates the ejecta. Comparing the SLSN distribution with predictions from single and binary star evolution models, we find that binary models for a metallicity of Z ≲ 1/3 Z⊙ are best able to reproduce its broad shape, in agreement with the preference of SLSNe for low metallicity environments. Finally, we uncover a correlation between the pre-explosion mass and the magnetar initial spin period, where SLSNe with low masses have slower spins, a trend broadly consistent with the effects of angular momentum transport evident in models of rapidly rotating carbon-oxygen stars.

Keywords: Type Ic supernovae, Supernovae, Core-collapse supernovae
Reenergization of Radio Halo Electrons in the Merging Galaxy Cluster A2163. Radio halos in galaxy clusters are among the largest known radio-emitting objects in the universe. Their faint and amorphous structure and lack of emission elsewhere in the electromagnetic spectrum have yielded few clues to their origin. The strong association of halos with X-ray-luminous merging clusters has sustained the belief that mergers kindle halos. We report the detection of a sharply defined, central Ridge of halo emission in the galaxy cluster A2163, which is undergoing a merger. This "shock front"-like Ridge lies in between and is oriented perpendicular to the two merging subclusters, and is not associated with any active radio galaxy. This Ridge has the flattest spectrum and the brightest emission in the entire halo, suggesting that it is the principal site of energization, and appears to be a direct link between the merger geometry and halo energization. We also discuss the possibility that the Ridge is a relic seen in projection against the center of tthe halo. However, the configuration of the Ridge relative to the merging subclusters suggests that it is at the center of the halo. Based on our observations we suggest that a halo may simply be the merger-induced collective reincarnation of a large number of dead radio lobes.

Keywords: Galaxy clusters, Extragalactic radio sources, Non-thermal radiation sources, Radio continuum emission, Abell clusters, Intracluster medium
Fast Particle Acceleration at Perpendicular Shocks with Uniform Upstream Magnetic Field and Strong Downstream Turbulence. Shock waves produce relativistic particles via the diffusive shock acceleration (DSA) mechanism. Among various circumstances, fast acceleration has been expected for perpendicular shocks. We investigate the acceleration time and the energy spectrum of particles accelerated at a perpendicular shock. In our model, the upstream perpendicular magnetic field has no fluctuation, and the downstream region is highly turbulent. Then, the particle motion is the gyration in the upstream region and Bohm-like diffusion downstream. Under this situation, we derive an analytical form of the acceleration time. Using test particle simulations, the validity of our formula is verified. In addition, the energy spectrum of particles is the same as those predicted by standard DSA. Therefore, the presently proposed mechanism simultaneously realizes the rapid acceleration and the canonical spectrum, dN/dp ∝ p-2, even if there is no upstream magnetic amplification.

Keywords: Interplanetary shocks, Supernova remnants, Interplanetary particle acceleration, Computational methods, Cosmic rays
Black Hole Masses of Weak Emission Line Quasars Based on the Continuum Fit Method. We studied optical-ultraviolet spectral energy distribution of 10 weak emission-line quasars (WLQs) that lie at redshifts z = 0.19 and 1.43 &lt; z &lt; 3.48. The theoretical models of their accretion disk continua are created based on the Novikov-Thorne equations. It allows us to estimate masses of their supermassive black holes ( ${M}_{\mathrm{BH}}$ ) and accretion rates. We determined the virial factor for WLQs and note its anticorrelation with the FWHM of the Hβ emission line $(f\propto {\mathrm{FWHM}}^{\alpha },\alpha =-1.34\pm 0.37$ ). By comparison with the previously estimated BH masses, the underestimation of ${M}_{\mathrm{BH}}$ is noticed with a mean factor of 4-5, which depends on the measured full width. We proposed a new formula to estimate ${M}_{\mathrm{BH}}$ in WLQs based on their observed $\mathrm{FWHM}$ (Hβ) and luminosities at 5100 Å. In our opinion, WLQs are also normal quasars visible in a reactivation stage.

Keywords: Active galactic nuclei, Black holes, Quasars
Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations. We present the analysis of narrowband whistler wave signatures observed in the inner heliosphere (0.3-1 au). These signatures are bumps in the spectral density in the 10-200 Hz frequency range of the AC magnetic field as measured by the search coil magnetometer on board the Helios 1 spacecraft. We show that the majority of whistler signatures are observed in the slow solar wind (&lt;500 km s-1) and their occurrence increases with the radial distance (R), from ∼3% at 0.3 au to ∼10% at 0.9 au. In the fast solar wind (&gt;600 km s-1), whistler activity is significantly lower; whistler signatures start to appear for R &gt; 0.6 au and their number increases from ∼0.03% at 0.65 au to ∼1% at 0.9 au. We have studied the variation of the electron core and halo anisotropy (Te⊥/Te∥), as well as the electron normalized heat flux as a function of R and of the solar wind speed. We find that, in the slow wind electron core and halo anisotropy is higher than in fast one, and also that these anisotropies increase radially in both types of winds, which is in line with the occurrence of whistler signatures. We hypothesize the existence of a feedback mechanism to explain the observed radial variations of the occurrence of whistlers in relation with the halo anisotropy.

Keywords: Solar wind, Interplanetary magnetic fields
Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. VI. Evidence for the Long-lived Nonsteady Warp of Nongravitational Scenarios. By combining LAMOST DR4 and Gaia DR2 common red clump stars with age and proper motion, we analyze the amplitude evolution of the stellar warp independently of any assumption with a simple model. The greatest height of the warp disk increases with galactocentric distance in different populations and is dependent on age: the younger stellar populations exhibit stronger warp features than the old ones, accompanied by the warp amplitude γ (age) decreasing with age, and its first derivative $\dot{\gamma }(\mathrm{age})$ is different from zero. The azimuth of the line of nodes φw is stable at -5° without clear time evolution, which perfectly confirms some previous works. All of this self-consistent evidence supports that our Galactic warp should most likely be a long-lived but nonsteady structure and not a transient one, which is supporting that the warp originated from gas infall onto the disk or other hypotheses that suppose that the warp mainly affects the gas, and consequently, younger populations tracing the gas are stronger than older ones. In other words, the Galactic warp is induced by the nongravitational interaction over the disk models.

Keywords: Milky Way disk, Milky Way dynamics, Milky Way Galaxy
Effect of Electrical Resistivity on the Damping of Slow Sausage Modes. Recent observations of slow surface sausage modes in a photospheric magnetic pore have been shown to be heavily damped. Numerical calculations have shown that electrical resistivity plays a significant role in this damping process. The aim of the present paper is to make an independent analytical derivation that would confirm the importance of electrical resistivity in the damping of these modes. An analytical dispersion relation in the framework of resistive magnetohydrodynamics is derived for sausage modes in a straight cylinder with a circular cross section and a discontinuous boundary. The effect of electrical resistivity on the damping of slow sausage modes in photospheric pore conditions is then studied, by solving the obtained dispersion relation numerically. The obtained results agree with those from the numerical calculations.

Keywords: Solar magnetic fields, Magnetohydrodynamics, Solar coronal waves, Solar photosphere
Dependence of the Fundamental Plane of Early-type Galaxies on Age and Internal Structure. We investigate the scatter in the fundamental plane (FP) of early-type galaxies (ETGs) and its dependence on age and internal structure of ETGs, using 16,283 ETGs with Mr ≤ -19.5 and 0.025 ≤ z &lt; 0.055 in Sloan Digital Sky Survey data. We use the relation between the age of ETGs and photometric parameters such as color, absolute magnitude, and central velocity dispersion of ETGs and find that the scatter in the FP depends on age. The FP of old ETGs with age ≳9 Gyr has a smaller scatter of ∼0.06 dex (∼14%), while that of young ETGs with age ≲6 Gyr has a larger scatter of ∼0.075 dex (∼17%). In the case of young ETGs, less compact ETGs have a smaller scatter in the FP (∼0.065 dex; ∼15%) than more compact ones (∼0.10 dex; ∼23%). On the other hand, the scatter in the FP of old ETGs does not depend on the compactness of galaxy structure. Thus, among the subpopulations of ETGs, compact young ETGs have the largest scatter in the FP. This large scatter in compact young ETGs is caused by ETGs that have low dynamical mass-to-light ratio (Mdyn/L) and blue color in the central regions. By comparing with a simple model of the galaxy that has experienced a gas-rich major merger, we find that the scenario of recent gas-rich major merger can reasonably explain the properties of the compact young ETGs with excessive light for a given mass (low Mdyn/L) and blue central color.

Keywords: Galaxy properties, Galaxy colors, Galaxy structure, Galaxy ages, Galaxy mergers, Galaxy evolution, Red sequence galaxies, Early-type galaxies
PHANGS CO Kinematics: Disk Orientations and Rotation Curves at 150 pc Resolution. We present kinematic orientations and high-resolution (150 pc) rotation curves for 67 main-sequence star-forming galaxies surveyed in CO (2-1) emission by PHANGS-ALMA. Our measurements are based on the application of a new fitting method tailored to CO velocity fields. Our approach identifies an optimal global orientation as a way to reduce the impact of nonaxisymmetric (bar and spiral) features and the uneven spatial sampling characteristic of CO emission in the inner regions of nearby galaxies. The method performs especially well when applied to the large number of independent lines of sight contained in the PHANGS CO velocity fields mapped at 1″ resolution. The high-resolution rotation curves fitted to these data are sensitive probes of mass distribution in the inner regions of these galaxies. We use the inner slope as well as the amplitude of our fitted rotation curves to demonstrate that CO is a reliable global dynamical mass tracer. From the consistency between photometric orientations from the literature and kinematic orientations determined with our method, we infer that the shapes of stellar disks in the mass range of log( ${M}_{\star }({M}_{\odot })$ ) = 9.0-10.9 probed by our sample are very close to circular and have uniform thickness.

Keywords: Galaxy dynamics, Molecular clouds, Interstellar medium
Velocity Gradient in the Presence of Self-gravity: Identifying Gravity-induced Inflow and Determining Collapsing Stage. Understanding how star formation is regulated requires studying the energy balance between turbulence, magnetic fields, stellar feedback, and gravity within molecular clouds. However, identifying the transition region where the gravity takes over remains elusive. Recent studies of the Velocity Gradient Technique (VGT), which is an advanced tool for magnetic field studies, reveal that the gradients of spectroscopic observables change their directions by 90° with respect to the magnetic fields in the regions of gravitational collapse. In this study, we perform 3D MHD numerical simulations. We observe that star formation successfully proceeds in strongly magnetized and fully ionized media. We confirm that the self-gravity induces the change of gradients' orientation and gradients' high amplitude. We explore two ways of identifying collapsing self-gravitating regions through the double-peak feature in the histogram of gradients' orientation and the curvature of gradients. We show that velocity gradients' morphology and amplitude can be synthetically used to trace the convergent inflows. By comparing with the column density Probability Density Functions method, we show that VGT is a powerful new tool for studying the gas dynamics and tracing magnetic field in star-forming regions. By analogy with VGT, we extend the Intensity Gradient Technique (IGT) to locate the gravitational collapsing region and shocks. We demonstrate that the synergy of VGT and IGT can determine the collapsing stages in a star-forming region.

Keywords: Interstellar magnetic fields, Star forming regions, Star formation, Interstellar medium
Electron Density Structure of the Local Galactic Disk. Pulsar dispersion measures (DMs) have been used to model the electron density of the interstellar medium (ISM) in the Galactic disk as a plane-parallel medium, despite significant scatter in the DM-distance distribution and strong evidence for inhomogeneities in the ISM. We use a sample of pulsars with independent distance measurements to evaluate a model of the local ISM in the thick disk of the Galaxy that incorporates turbulent fluctuations, clumps, and voids in the electron density. The latter two components are required because about one-third of the lines of sight are discrepant from a strictly plane-parallel model. A likelihood analysis for smooth components of the model yields a scale height ${z}_{0}={1.57}_{-0.14}^{+0.15}$ kpc and a mid-plane density n0 = 0.015 ± 0.001 cm-3. The scatter in the DM-distance distribution is dominated by clumps and voids but receives significant contributions from a broad spectrum of density fluctuations, such as a Kolmogorov spectrum. The model is used to identify lines of sight with outlier values of DM. Three of these pulsars, J1614-2230, J1623-0908, and J1643-1224, lie behind known H II regions, and the electron density model is combined with Hα intensity data to constrain the filling factors and other substructure properties of the H II regions (Sh 2-7 and Sh 2-27). Several pulsars also exhibit enhanced DM fluctuations that are likely caused by an intersection of their lines of sight with the superbubble GSH 238+00+09.

Keywords: Galaxy structure, Pulsars, Milky Way disk, Interstellar medium, H II regions, Superbubbles
Persistent Starspot Signals on M Dwarfs: Multiwavelength Doppler Observations with the Habitable-zone Planet Finder and Keck/HIRES. Young, rapidly rotating M dwarfs exhibit prominent starspots, which create quasiperiodic signals in their photometric and Doppler spectroscopic measurements. The periodic Doppler signals can mimic radial velocity (RV) changes expected from orbiting exoplanets. Exoplanets can be distinguished from activity-induced false positives by the chromaticity and long-term incoherence of starspot signals, but these qualities are poorly constrained for fully convective M stars. Coherent photometric starspot signals on M dwarfs may persist for hundreds of rotations, and the wavelength dependence of starspot RV signals may not be consistent between stars due to differences in their magnetic fields and active regions. We obtained precise multiwavelength RVs of four rapidly rotating M dwarfs (AD Leo, G227-22, GJ 1245B, GJ 3959) using the near-infrared (NIR) Habitable-zone Planet Finder and the optical Keck/HIRES spectrometer. Our RVs are complemented by photometry from Kepler, TESS, and the Las Cumbres Observatory network of telescopes. We found that all four stars exhibit large spot-induced Doppler signals at their rotation periods, and investigated the longevity and optical-to-NIR chromaticity for these signals. The phase curves remain coherent much longer than is typical for Sunlike stars. Their chromaticity varies, and one star (GJ 3959) exhibits optical and NIR RV modulation consistent in both phase and amplitude. In general, though, we find that the NIR amplitudes are lower than their optical counterparts. We conclude that starspot modulation for rapidly rotating M stars frequently remains coherent for hundreds of stellar rotations and gives rise to Doppler signals that, due to this coherence, may be mistaken for exoplanets.

Keywords: M dwarf stars, Starspots, Stellar photometry, High resolution spectroscopy, Exoplanets, Gaussian Processes regression, Radial velocity, Time series analysis