Sazuna/UAT_keywords huggingface dataset:
On the Origin of the Photospheric Magnetic Field. This article presents results that challenge the paradigms that (1) the convection zone is the source of the radial magnetic field in the photosphere and (2) that coronal currents are neutralized from the perspective of the photosphere. We demonstrate, using a new analysis tool applied to simulations and observations, that bare or partially dressed current channels are supported by the solar corona and that fingerprints of these coronal current systems can be detected in the photosphere. These coronal current channels can be a significant source of the radial component of the magnetic field in the photosphere. The roots of these coronal current channels in the photosphere are the source of the magnetic field component parallel to the polarity inversion line in active region NOAA 12673. These analyses and observations transform our theoretical understanding of coronal evolution and argue for a reexamination of the present paradigm in which the convection zone is the sole source of the photospheric magnetic field.

Keywords: Solar active region magnetic fields, Solar magnetic flux emergence, Solar active regions, Solar corona, Solar magnetic fields
NuSTAR Observations of Intrinsically X-Ray Weak Quasar Candidates: An Obscuration-only Scenario. We utilize recent NuSTAR observations (co-added depth ≍55-120 ks) of PG 1001+054, PG 1254+047, and PHL 1811 to constrain their hard X-ray (≳5 keV) weakness and spectral shapes and thus to investigate the nature of their extreme X-ray weakness. These quasars showed very weak soft X-ray emission, and they were proposed to be intrinsically X-ray weak, with the X-ray coronae producing weak continuum emission relative to their optical/UV emission. However, the new observations suggest an alternative explanation. The NuSTAR 3-24 keV spectral shapes for PG 1001+054 and PHL 1811 are likely flat (effective power-law photon indices ${{\rm{\Gamma }}}_{\mathrm{eff}}={1.0}_{-0.6}^{+0.5}$ and ${{\rm{\Gamma }}}_{\mathrm{eff}}={1.4}_{-0.7}^{+0.8}$ , respectively), while the shape is nominal for PG 1254+047 (Γeff = 1.8 ± 0.3). PG 1001+054 and PHL 1811 are significantly weak at hard X-ray energies (by factors of ≍26-74 at rest-frame 8 keV) compared to the expectations from their optical/UV emission, while PG 1254+047 is only hard X-ray weak by a factor of ≍3. We suggest that X-ray obscuration is present in all three quasars. We propose that, as an alternative to the intrinsic X-ray weakness + X-ray obscuration scenario, the soft and hard X-ray weakness of these quasars can be uniformly explained under an obscuration-only scenario. This model provides adequate descriptions of the multiepoch soft and hard X-ray data of these quasars, with variable column density and leaked fraction of the partial covering absorber. We suggest that the absorber is the clumpy dust-free wind launched from the accretion disk. These quasars probably have super-Eddington accretion rates that drive powerful and high-density winds.

Keywords: Accretion, Quasars, Broad-absorption line quasar, X-ray active galactic nuclei, X-ray quasars
Accretion Disk Luminosity for Black Holes Surrounded by Dark Matter with Tangential Pressure. We study the motion of test particles in the gravitational field of a Schwarzschild black hole surrounded by a spherical dark matter cloud with nonzero tangential pressure, and compute the luminosity of the accretion disk. The presence of nonvanishing tangential pressure allows us to mimic the dark matter's angular momentum, while still considering a static model, which simplifies the mathematical framework. We compare the numerical results of the influence of dark matter on the luminosity of the accretion disks around static supermassive black holes with the previously studied cases of isotropic and anisotropic pressures. We show that the flux and luminosity of the accretion disk in the presence of dark matter are different from the case of a Schwarzschild black hole in a vacuum, and highlight the impact of the presence of tangential pressures.

Keywords: Dark matter distribution, Black holes, Schwarzschild black holes, Stellar accretion disks, Dark matter
Low-J Transitions in {\tilde{A}}(2) {\Pi }(0,0,0)-{\tilde{X}}(2) {{\Sigma }}(+) (0,0,0) Band of Buffer-gas-cooled CaOH. Calcium monohydroxide radical (CaOH) is receiving an increasing amount of attention from the astrophysics community as it is expected to be present in the atmospheres of hot rocky super-Earth exoplanets as well as interstellar and circumstellar environments. Here, we report the high-resolution laboratory absorption spectroscopy on low-J transitions in ${\tilde{A}}^{2}{\rm{\Pi }}(0,0,0)-{\tilde{X}}^{2}{{\rm{\Sigma }}}^{+}(0,0,0)$ band of buffer-gas-cooled CaOH. In total, 40 transitions out of the low-J states were assigned, including 27 transitions that have not been reported in previous literature. The determined rotational constants for both ground and excited states are in excellent agreement with previous literature, and the measurement uncertainty for the absolute transition frequencies was improved by more than a factor of 3. This will aid future interstellar, circumstellar, and atmospheric identifications of CaOH. The buffer-gas-cooling method employed here is a particularly powerful method to probe low-J transitions and is easily applicable to other astrophysical molecules.

Keywords: High resolution spectroscopy, Spectral line lists, Line positions, Molecular spectroscopy, Laboratory astrophysics, Experimental techniques
Radio Spectra of SN 2020oi: Effects of Radiative Cooling on the Deduced Source Properties. Observations of radiative cooling in a synchrotron source offer a possibility to further constrain its properties. Inverse Compton cooling is indicated in the radio spectra during the early phases of SN 2020oi. It is shown that contrary to previous claims, observations are consistent with equipartition between relativistic electrons and magnetic field as well as a constant mass-loss rate of the progenitor star prior to the supernova explosion. The reason for this difference is the need to include cooling directly in the fitting procedure rather than estimating its effects afterward. It is emphasized that the inferred properties of the supernova ejecta are sensitive to the time evolution of the synchrotron self-absorption frequency; hence, great care should be taken when modeling spectra for which cooling and/or inhomogeneities are indicated. Furthermore, it is noted that the energies of the relativistic electrons in the radio emission regions in supernovae are likely too low for first-order Fermi acceleration to be effective.

Keywords: Non-thermal radiation sources, Radio continuum emission, Shocks, Magnetic fields, Supernovae
Three-dimensional Magnetothermal Simulations of Magnetar Outbursts. The defining trait of magnetars, the most strongly magnetized neutron stars (NSs), is their transient activity in the X/γ-bands. In particular, many of them undergo phases of enhanced emission, the so-called outbursts, during which the luminosity rises by a factor ~10-1000 in a few hours to then decay over months/years. Outbursts often exhibit a thermal spectrum, associated with the appearance of hotter regions on the surface of the star, which subsequently change in shape and cool down. Here we simulate the unfolding of a sudden, localized heat injection in the external crust of an NS with a 3D magnetothermal evolution code, finding that this can reproduce the main features of magnetar outbursts. A full 3D treatment allows us to study for the first time the inherently asymmetric hot spots that appear on the surface of the star as the result of the injection and to follow the evolution of their temperature and shape. We investigate the effects produced by different physical conditions in the heated region, highlighting in particular how the geometry of the magnetic field plays a key role in determining the properties of the event.

Keywords: Neutron stars, Stellar magnetic fields, X-ray transient sources, Magnetars, Magnetohydrodynamical simulations
Is [Y/Mg] a Reliable Age Diagnostic for FGK Stars?. Current spectroscopic surveys are producing large catalogs of chemical abundances for stars of all types. The yttrium-to-magnesium ratio, [Y/Mg], has emerged as a candidate age indicator for solar twins in the local stellar neighborhood. However, it is unclear whether it is a viable age diagnostic for more diverse stellar types, so we investigate [Y/Mg] as an age indicator for the FGK-type planet host stars observed by Kepler. We find that the [Y/Mg] "Clock" is most precise for solar twins, with a [Y/Mg]/age slope of m = -0.0370 ±0.0071 dex Gyr-1 and σ Age = 2.6 Gyr. We attribute the lower precision compared to literature results to nonsolar twins contaminating our solar twin sample and recommend a 1.5 Gyr systematic uncertainty for stellar ages derived with any [Y/Mg]-Age relation. We also analyzed the [Y/Mg] Clock as a function of T eff, $\mathrm{log}g$ , and metallicity individually and find no strong trends, but we compute statistically significant [Y/Mg]-Age relations for subsamples defined by ranges in T eff, $\mathrm{log}g$ , and metallicity. Finally, we compare [Y/Mg] and rotation ages and find statistically similar trends as for isochrone ages, although we find that rotation ages perform better for GK dwarfs while isochrones perform better for FG subgiants. We conclude that the [Y/Mg] Clock is most precise for solar twins and analogs but is also a useful age diagnostic for FGK stars.

Keywords: Stellar properties, Stellar ages, Abundance ratios, Stellar evolutionary models, Chemical abundances, Planet hosting stars, Stellar rotation
Modeling Extinction and Reddening Effects by Circumstellar Dust in the Betelgeuse Envelope in the Presence of Radiative Torque Disruption. Circumstellar dust forms and evolves within the envelope of evolved stars, including asymptotic giant branch (AGB) and red supergiant (RSG) stars. The extinction of stellar light by circumstellar dust is vital for interpreting RSG/AGB observations and determining high-mass RSG progenitors of core-collapse supernovae. However, circumstellar dust properties are not well understood. Modern understanding of dust evolution suggests that intense stellar radiation can radically change dust properties across the circumstellar envelope through the RAdiative Torque Disruption (RAT-D) mechanism. In this paper, we study the impacts of RAT-D on the grain size distribution (GSD) of circumstellar dust and model its effects on photometric observations of α Orionis (Betelgeuse). Due to the RAT-D effects, large grains formed in the dust formation zone are disrupted into smaller species of size a &lt; 0.5 μm. Using the GSD constrained by the RAT-D effects, we model the visual extinction of background stars and Betelgeuse. We find that the extinction decreases at near-UV, optical, and IR wavelengths while increasing at far-UV wavelengths. The resulting flux potentially reproduces the observation from the near-UV to the near-IR range. Our results can be used to explain dust extinction and photometric observations of other RSG/AGB stars.

Keywords: Circumstellar envelopes, Red supergiant stars, Extinction, Circumstellar matter, Circumstellar dust
Bernstein-Greene-Kruskal Ion Modes in Dusty Space Plasmas Application in Saturn's Magnetosphere. Frequent observations of ion beams moving out from Saturn's plasma environment hints at the generation of ion Bernstein-Greene-Kruskal (BGK) modes. As the plasma environments of Saturn and its moon Enceladus are characterized by the ubiquitous presence of massive negatively charged dust particles, the existing BGK theory for electron-ion plasma models cannot address this scenario. This manuscript develops a theoretical model for studying ion BGK modes in dusty plasmas. The analysis reveals that the presence of dust in the plasma enhances the stability of BGK modes. As the dust density increases, the effect of other parameters on stability, such as the electron temperature, becomes negligible. The model is developed by assuming that electrons and ions follow a kappa distribution, featuring a long tail trend in the superthermal component, in agreement with observations. Different scenarios with either electrons or ions obeying a Maxwell or kappa distribution function have been considered. A thorough analysis of the trapped ion distribution function considering various combinations indicates that a plasma where electrons are in thermal equilibrium and ions follow kappa distribution is the least favorable system for the generation of BGK modes.

Keywords: Saturn
The North/South Asymmetry of the Galaxy: Possible Connection to the Vertical Phase-space Snail. The galaxy is found to be in disequilibrium based on recent findings of the north/south (N/S) asymmetry and the phase mixing signatures, such as a phase spiral (snail) structure in the vertical phase space (z - V  z ). We show that the N/S asymmetry in a tracer population of dwarfs may be quantitatively modeled with a simple phase snail model superimposed on a smooth equilibrium background. As the phase snail intersects with the z-axis, the number density is enhanced, and the velocity dispersion (σ  z ) is decreased relative to the other side of the Galactic plane. Fitting only to the observed asymmetric N/S σ  z  profiles, we obtain reasonable parameters for the phase-space snail and the potential utilized in modeling the background, despite the complex dependence of the model on the potential parameters and the significant selection effects of the data. Both the snail shape and the N/S number density difference given by our best-fit model are consistent with previous observations. The equilibrium background implies a local dark matter density of ${0.0151}_{-0.0051}^{+0.0050}$ M ⊙ pc-3. The vertical bulk motion of our model is similar to the observation, but with a ~1.2 km s-1 shift. Our work demonstrates the strong correlation between the phase-space snail and the N/S asymmetry. Future observational constraints will facilitate more comprehensive snail models to unravel the Milky Way potential and the perturbation history encoded in the snail feature.

Keywords: Stellar kinematics, Galaxy structure, Milky Way dynamics, Stellar dynamics, Milky Way disk
Variability-selected Intermediate-mass Black Hole Candidates in Dwarf Galaxies from ZTF and WISE. While it is difficult to observe the first black hole seeds in the early universe, we can study intermediate-mass black holes (IMBHs) in local dwarf galaxies for clues about their origins. In this paper we present a sample of variability-selected active galactic nuclei (AGN) in dwarf galaxies using optical photometry from the Zwicky Transient Facility (ZTF) and forward-modeled mid-IR photometry of time-resolved Wide-field Infrared Survey Explorer (WISE) co-added images. We found that 44 out of 25,714 dwarf galaxies had optically variable AGN candidates and 148 out of 79,879 dwarf galaxies had mid-IR variable AGN candidates, corresponding to active fractions of 0.17% ± 0.03% and 0.19% ± 0.02%, respectively. We found that spectroscopic approaches to AGN identification would have missed 81% of our ZTF IMBH candidates and 69% of our WISE IMBH candidates. Only nine candidates have been detected previously in radio, X-ray, and variability searches for dwarf galaxy AGN. The ZTF and WISE dwarf galaxy AGN with broad Balmer lines have virial masses of 105 M ⊙ &lt; M BH &lt; 107 M ⊙, but for the rest of the sample, BH masses predicted from host galaxy mass range between 105.2 M ⊙ &lt; M BH &lt; 107.25 M ⊙. We found that only 5 of 152 previously reported variability-selected AGN candidates from the Palomar Transient Factory in common with our parent sample were variable in ZTF. We also determined a nuclear supernova fraction of 0.05% ± 0.01% yr-1 for dwarf galaxies in ZTF. Our ZTF and WISE IMBH candidates show the promise of variability searches for the discovery of otherwise hidden low-mass AGN.

Keywords: Intermediate-mass black holes, Dwarf galaxies, Active galactic nuclei
A Systematic Study of the Short-term X-Ray Variability of Seyfert Galaxies. I. Diversity of the X-Ray rms Spectra. The X-ray variability of active galactic nuclei (AGN) carries crucial information about the X-ray radiation mechanism. We performed a systematic study of the X-ray short-term (1-100 ks timescale) variability for a large sample of 78 Seyferts with 426 deep XMM-Newton observations. In this paper, we present the time-averaged spectra and rms spectra for the entire sample, which show a variety of properties. Based on the spectral shape, we divide the rms spectra into five subtypes and the time-averaged spectra into four subtypes. The most common shape of the rms spectra is concave-down where the rms peaks at ~1 keV. We find that different sources can show similar time-averaged spectra and rms spectra. However, there is no one-to-one mapping between the subtypes of the time-averaged spectra and rms spectra, as similar time-averaged spectra can be accompanied by different rms spectra, and vice versa. This is likely because different physical mechanisms can produce similar rms spectra. For every subtype of the time-averaged spectra, we report its preferred subtypes of the rms spectra in both low- and high-frequency bands. We also compare the statistical properties for different subtypes, such as the black hole mass and Eddington ratio. Finally, we investigate the rms in the Fe Kα line regime and find that those with a broad and extended red-wing profile tend to show stronger variability than those showing a narrow or relatively symmetric profile. Our results demonstrate the necessity of performing joint spectral and variability modeling in order to understand the mechanism of the X-ray emission in AGN. All of the rms spectra have been made publicly available.

Keywords: X-ray active galactic nuclei
A Partial-sky Gibbs ILC Approach for the Estimation of CMB Posterior over Large Angular Scales of the Sky. In this article we present a formalism for incorporating the partial-sky maps into the Gibbs ILC algorithm to estimate the joint posterior density of the cosmic microwave background (CMB) signal and the theoretical CMB angular power spectrum given the observed CMB maps. In order to generate the partial-sky maps, we mask all the observed CMB maps provided by the WMAP and Planck satellite full-sky mission using a mask that removes 22% of the entire sky. The mask we use is based on the strength of the thermal dust emissions in the Planck 353 GHz map. While implementing the Gibbs ILC method on the partial-sky maps, we convert the partial-sky-cleaned angular power spectrum into the full-sky angular power spectrum using the mode-mode coupling matrix estimated from the smoothed mask. The main products of our analysis are a partial-sky cleaned best-fit CMB map and an estimate of the underlying full-sky theoretical CMB angular power spectrum in the multipole range 2 ≤ ℓ ≤ 32 along with their error estimates. We validate the method by performing detailed Monte Carlo simulations after using realistic models of foregrounds and detector noise consistent with the WMAP and Planck frequency channels used in our analysis. We can estimate the posterior density and full-sky theoretical CMB angular power spectrum without any need to explicitly model the foreground components from partial-sky maps using our method. Another important feature of this method is that the power spectrum results along with the error estimates can be directly used for cosmological parameter estimations.

Keywords: Cosmic microwave background radiation
Measuring the β-decay Properties of Neutron-rich Exotic Pm, Sm, Eu, and Gd Isotopes to Constrain the Nucleosynthesis Yields in the Rare-earth Region. The β-delayed neutron-emission probabilities of 28 exotic neutron-rich isotopes of Pm, Sm, Eu, and Gd were measured for the first time at RIKEN Nishina Center using the Advanced Implantation Detector Array (AIDA) and the BRIKEN neutron detector array. The existing β-decay half-life (T 1/2) database was significantly increased toward more neutron-rich isotopes, and uncertainties for previously measured values were decreased. The new data not only constrain the theoretical predictions of half-lives and β-delayed neutron-emission probabilities, but also allow for probing the mechanisms of formation of the high-mass wing of the rare-earth peak located at A ≈ 160 in the r-process abundance distribution through astrophysical reaction network calculations. An uncertainty quantification of the calculated abundance patterns with the new data shows a reduction of the uncertainty in the rare-earth peak region. The newly introduced variance-based sensitivity analysis method offers valuable insight into the influence of important nuclear physics inputs on the calculated abundance patterns. The analysis has identified the half-lives of 168Sm and of several gadolinium isotopes as some of the key variables among the current experimental data to understand the remaining abundance uncertainty at A = 167-172.

Keywords: R-process, Nucleosynthesis, Nuclear physics
On Planet Formation around Supermassive Black Holes and Grain Disruption Barriers by Radiative Torques. It has recently been suggested that planets can form by dust coagulation in the tori of active galactic nuclei (AGN) with low luminosities of L bol ≲ 1042 erg s-1, constituting a new class of exoplanets orbiting supermassive black holes called blanets. However, large dust grains in the AGN torus may be rotationally disrupted by the radiative torque disruption (RATD) mechanism due to AGN radiation feedback, which would prevent blanet formation. To test this scenario, we adopt a simple smooth and a clumpy dust/gas distribution inside the torus region to study the effect of RATD on the evolution of composite dust grains in the midplane of the torus. We found that grain growth and then blanet formation are possible in the smooth torus model. However, in the clumpy torus model, grain growth will be strongly constrained by RATD, assuming the gas density distribution as adopted by Wada et al. We also found that icy grain mantles inside clumps are quickly detached from the grain cores by rotational desorption, reducing the sticking coefficient between icy grains and the coagulation efficiency. The grain rotational disruption and ice desorption occur on timescales much shorter than the growth time up to a factor of ~104, which are the new barriers that grain growth must overcome to form blanets. Further studies with more realistic AGN models are required to constrain better the effect of RATD on grain growth and blanet formation hypothesis around low-luminosity AGN.

Keywords: Astrophysical dust processes, Interstellar dust, Exoplanet formation, Active galactic nuclei