Sazuna/UAT_keywords huggingface dataset:
Asteroseismology Applied to Constrain Structure Parameters of δ Scuti Stars. Asteroseismology is a powerful tool to probe stellar structure. Spaceborne instruments like CoRoT, Kepler, and TESS have observed the oscillations of numerous stars, among which δ Scutis are particularly interesting, owing to their fast rotation and complex pulsation mechanisms. In this work, we inferred model-dependent masses, metallicities, and ages of 60 δ Scuti stars from photometric, spectroscopic, and asteroseismic observations using least-squares minimization. These statistics have the potential to explain why only a tiny fraction of δ Scuti stars pulsate in a very clean manner. We find most of these stars with masses around 1.6 M ⊙ and metallicities below Z = 0.010. We observed a bimodality in age for these stars, with more than half the sample younger than 30 Myr, while the remaining ones were inferred to be older, i.e., hundreds of Myrs. This work emphasizes the importance of the large-frequency separation (Δν) in studies of δ Scutis. We also designed three machine-learning (ML) models that hold the potential for inferring these parameters at lower computational cost and much more rapidly. These models further revealed that constraining dipole modes can help in significantly improving age estimation and that radial modes succinctly encode information regarding luminosity and temperature. Using the ML models, we also gained qualitative insight into the importance of stellar observables in estimating mass, metallicity, and age. The effective temperature T eff strongly affects the inference of all structure parameters, and the asteroseismic offset parameter ϵ plays an essential role in the inference of age.

Keywords: Delta Scuti variable stars
The Decay of Two Adjacent Sunspots Associated with Moving Magnetic Features. The relationship between the decay of sunspots and moving magnetic features (MMFs) plays an important role in understanding the evolution of active regions. We present observations of two adjacent sunspots, the gap between them, and a lot of MMFs propagating from the gap and the sunspots' outer edges in NOAA Active Region 13023. The MMFs are divided into two types based on their magnetic field inclination angle: vertical (0° &lt; γ &lt; 45°) and horizontal (45° ≤ γ &lt; 90°) MMFs (V-MMFs and H-MMFs, respectively). The main results are as follows: (1) the mean magnetic flux decay rates of the two sunspots are -1.7 × 1020 and -1.4 × 1020 Mx day-1; (2) the magnetic flux generation rate of all MMFs is calculated to be -1.9 × 1021 Mx day-1, which is on average 5.6 times higher than the total magnetic flux loss rate of the sunspots; (3) the magnetic flux of V-MMFs (including a pore separated from the sunspots) is 1.4 times larger than the total lost magnetic flux of the two sunspots, and in a later stage when the pore has passed through the reference ellipse, the magnetic flux generation rate of the V-MMFs is almost the same as the magnetic flux loss rate of the sunspots; and (4) within the gap, the magnetic flux of V-MMFs is one-third of the total magnetic flux. Few V-MMFs stream out from the sunspots at the nongap region. All observations suggest that MMFs with vertical magnetic fields are closely related to the disintegration of the sunspot, and most of the MMFs from the gap may originate directly from the sunspot umbra.

Keywords: Solar photosphere, Sunspots, Solar magnetic fields
The Atacama Cosmology Telescope: Galactic Dust Structure and the Cosmic PAH Background in Cross-correlation with WISE. We present a cross-correlation analysis between $1^{\prime} $ resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15″ mid-infrared photometry from the Wide-field Infrared Survey Explorer (WISE) over 107 12.°5 × 12.°5 patches of sky. We detect a spatially isotropic signal in the WISE×ACT TT cross-power spectrum at 30σ significance that we interpret as the correlation between the cosmic infrared background at ACT frequencies and polycyclic aromatic hydrocarbon (PAH) emission from galaxies in WISE, i.e., the cosmic PAH background. Within the Milky Way, the Galactic dust TT spectra are generally well described by power laws in ℓ over the range 103 &lt; ℓ &lt; 104, but there is evidence both for variability in the power-law index and for non-power-law behavior in some regions. We measure a positive correlation between WISE total intensity and ACT E-mode polarization at 1000 &lt; ℓ ≲ 6000 at &gt;3σ in each of 35 distinct ~100 deg2 regions of the sky, suggesting that alignment between Galactic density structures and the local magnetic field persists to subparsec physical scales in these regions. The distribution of TE amplitudes in this ℓ range across all 107 regions is biased to positive values, while there is no evidence for such a bias in the TB spectra. This work constitutes the highest-ℓ measurements of the Galactic dust TE spectrum to date and indicates that cross-correlation with high-resolution mid-infrared measurements of dust emission is a promising tool for constraining the spatial statistics of dust emission at millimeter wavelengths.

Keywords: Interstellar dust, Polycyclic aromatic hydrocarbons, Interstellar magnetic fields, Dust continuum emission, Interstellar medium, Cosmic background radiation
Evolution of the Magnetic Field in High- and Low-β Disks with Initially Toroidal Fields. We present the results from a pair of high-resolution, long-timescale (~105 GM/c 3), global, three-dimensional magnetohydrodynamical accretion disk simulations with differing initial magnetic plasma β in order to study the effects of the initial toroidal field strength on the production of a large-scale poloidal field. We initialize our disks in approximate equilibrium with purely toroidal magnetic fields of strength β 0 = 5 and 200. We also perform a limited resolution study. We find that simulations of differing field strengths diverge early in their evolution and remain distinct over the time studied, indicating that the initial magnetic conditions leave a persistent imprint in our simulations. Neither simulation enters the magnetically arrested disk regime. Both simulations are able to produce poloidal fields from initially toroidal fields, with the β 0 = 5 simulation evolving clear signs of a large-scale poloidal field. We make a cautionary note that computational artifacts in the form of large-scale vortices may be introduced in the combination of initially weak field and disk-internal mesh refinement boundaries, as evidenced by the production of an m = 1 mode overdensity in the weak field simulation. Our results demonstrate that the initial toroidal field strength plays a vital role in the simulated disk evolution for the models studied.

Keywords: Accretion, Black hole physics, Magnetic fields
Indirect Detection of Decaying Dark Matter with High Angular Resolution: The Case for Axion Search by IRCS on the Subaru Telescope. Recent advances in photon detectors have provided exceptional sensitivities to dark matter with high angular resolution. Motivated by this, we present a detailed study of photon flux from dark matter decay in dwarf spheroidal galaxies (dSphs) by focusing on the detectors with arcsecond-level field of view and/or angular resolution. We propose to use differential D-factors since such detectors are sensitive to their dark matter distributions. We carefully estimate the differential D-factors of 35 dSphs. By using the differential D-factors, it turns out that the resulting signal flux can have a more than ${ \mathcal O }$ (1-10) enhancement compared to conventional estimations. Based on this analysis, we find that the Infrared Camera and Spectrograph (IRCS) installed on the 8.2 m Subaru Telescope can be an excellent dark matter detector for the mass in the eV range, particularly axion-like particles (ALPs). Observing the Draco or Ursa Major II dSphs with the IRCS for ${ \mathcal O }(1)$ night will enable us to place the most stringent bound for the ALP dark matter in the mass range of 1 eV ≲ m  a  ≲ 2 eV.

Keywords: Dark matter distribution, Cold dark matter, Infrared spectroscopy
On the Seasonal Variations of the Ion Precipitation Down to the Upper Atmosphere of Mars. We investigate the seasonal variations of ion precipitation, utilizing observations from the Mars Atmosphere and Volatile Evolution mission spanning from 2014 January 4 to 2023 February 14. Our analysis reveals that a diminishing pattern characterizes the transition from Mars season L  s  0°-180° to Mars season L  s  180°-360°, manifesting as a reduction in precipitating ion fluxes. Additionally, we discern a significant influence of the crustal magnetic field on the seasonal variations in precipitating ion fluxes. Intriguingly, within regions where the crustal magnetic field exhibits a strong quasi-horizontal orientation, opposite seasonal trends become evident. The underlying physical mechanism driving these seasonal variations in ion precipitation is probably attributed to the mass loading effect that may decelerate the solar wind and influence the magnetic pileup. A detailed investigation is further demanded in the future.

Keywords: Mars, Planetary ionospheres, Planetary atmospheres
The Structure and Composition of Multiphase Galactic Winds in a Large Magellanic Cloud Mass Simulated Galaxy. We present the first results from a high-resolution simulation with a focus on galactic wind driving for an isolated galaxy with a halo mass of ~1011 M ⊙ (similar to the Large Magellanic Cloud) and a total gas mass of ~6 × 108 M ⊙, resulting in ~108 gas cells at ~4 M ⊙ mass resolution. We adopt a resolved stellar feedback model with nonequilibrium cooling and heating, including photoelectric heating and photoionizing radiation, as well as supernovae, coupled to the second-order meshless finite-mass method for hydrodynamics. These features make this the largest resolved interstellar medium (ISM) galaxy model run to date. We find mean star formation rates around 0.05 M ⊙ yr-1 and evaluate typical time-averaged loading factors for mass (η  M  ~ 1.0, in good agreement with recent observations) and energy (η  E  ~ 0.01). The bulk of the mass of the wind is transported by the warm (T &lt; 5 × 105 K) phase, while there is a similar amount of energy transported in the warm and the hot phases (T &gt; 5 × 105 K). We find an average opening angle of 30° for the wind, decreasing with higher altitude above the midplane. The wind mass loading is decreasing (flat) for the warm (hot) phase as a function of the star formation surface rate density ΣSFR, while the energy loading shows inverted trends with ΣSFR, decreasing for the warm wind and increasing for the hot wind, although with very shallow slopes. These scalings are in good agreement with previous simulations of resolved wind driving in the multiphase ISM.

Keywords: Galactic winds, Hydrodynamical simulations, Stellar feedback, Galaxy evolution, Interstellar medium
Enhancing Triangulation of Interplanetary Type III Bursts through Wavevector Correction. Interplanetary Type III bursts, generated by relativistic electron beams at solar flare reconnection sites, are explored through an investigation of 152 instances observed by the Solar Terrestrial Relations Observatory mission. This study reveals that the absolute values of the wavevector deviations from the Sun-spacecraft line are statistically 3.72 and 2.10 larger than predicted by the density model, assuming fundamental and harmonic emission, respectively. Through Monte Carlo simulations, we examine the impact of scattering by density inhomogeneities on the apparent locations of radio emissions in the interplanetary medium. The findings indicate that relative density fluctuations of 0.40 can account for the observed angular shift, a conclusion supported by the multiple flux-tube solar wind model, which confirms the presence of such magnitude of relative perpendicular density fluctuations in the solar wind. We propose a wavevector correction that incorporates this effect to enhance the triangulation of interplanetary Type III bursts, demonstrating that radio triangulation, with this correction, can reliably track electron beams in the interplanetary medium.

Keywords: Radio bursts, Radio astronomy
Are Electric-field-driven Magnetohydrodynamic Simulations of the Solar Corona Sensitive to the Initial Condition?. Magnetohydrodynamic (MHD) simulations of the solar corona are often started from a potential field initial condition, which may be far from the true state of the coronal magnetic field. To test the sensitivity of the simulations to the initial condition, an electric-field-driven MHD code was initiated from three different initial conditions: the commonly used potential field, a nonlinear force-free field (NLFFF) extrapolation, which is believed to be a better representation of the true coronal magnetic field, and a purely vertical field. After relaxation, the magnetic field in the MHD simulations was compared. It was found that there is a tendency for all of the initial conditions to converge to a similar connectivity, particularly in areas of strong fields that are not close to the boundary, suggesting that the final state of the simulation is not particularly sensitive to the initial condition. The relaxed solution more closely resembles the NLFFF initial condition than the other initial conditions, but still exhibits substantial differences from it.

Keywords: Solar magnetic fields, Solar corona, Magnetohydrodynamical simulations
A Model-independent Method to Determine H <SUB>0</SUB> Using Time-delay Lensing, Quasars, and Type Ia Supernovae. Absolute distances from strong lensing can anchor Type Ia Supernovae (SNe Ia) at cosmological distances giving a model-independent inference of the Hubble constant (H 0). Future observations could provide strong lensing time-delay distances with source redshifts up to z ≃ 4, which are much higher than the maximum redshift of SNe Ia observed so far. In order to make full use of time-delay distances measured at higher redshifts, we use quasars as a complementary cosmic probe to measure cosmological distances at redshifts beyond those of SNe Ia and provide a model-independent method to determine H 0. In this work, we demonstrate a model-independent, joint constraint of SNe Ia, quasars, and time-delay distances from strong lensed quasars. We first generate mock data sets of SNe Ia, quasar, and time-delay distances based on a fiducial cosmological model. Then, we calibrate the quasar parameters model independently using Gaussian process (GP) regression with mock SNe Ia data. Finally, we determine the value of H 0 model-independently using GP regression from mock quasars and time-delay distances from strong lensing systems. As a comparison, we also show the H 0 results obtained from mock SNe Ia in combination with time-delay lensing systems whose redshifts overlap with SNe Ia. Our results show that quasars at higher redshifts show great potential to extend the redshift coverage of SNe Ia and thus enable the full use of strong lens time-delay distance measurements from ongoing cosmic surveys and improve the accuracy of the estimation of H 0 from 2.1% to 1.3% when the uncertainties of the time-delay distances are 5% of the distance values.

Keywords: Hubble constant, Strong gravitational lensing, Observational cosmology, Hubble diagram
The Structure and Morphology of Galaxies during the Epoch of Reionization Revealed by JWST. We analyze 347 galaxies at redshift 4 &lt; z &lt; 9.5 using JWST observations from the Cosmic Evolution Early Release Science (CEERS) program by simultaneously fitting a two-dimensional parametric model to the seven-filter Near Infrared Camera images to measure the overall structural parameters and quantify the global properties of the galaxies in the rest-frame optical band. Particular attention is devoted to deriving robust uncertainties that include, among other factors, the influence of cosmological surface brightness dimming and resolution effects. Using the global Sérsic index (n &lt; 1.5) and observed axial ratio (q &lt; 0.6) as a guide, we place a conservative lower limit of ~45% on the incidence of galactic disks. Galaxies follow a relation between the rest-frame optical luminosity and effective radius in the redshift range 4 &lt; z &lt; 9.5, as well as separately over the intervals 4 &lt; z &lt; 5 and 5 ≤ z &lt; 9.5, with a very similar slope but a marginally lower zero-point in the higher-redshift bin (R  e  = 0.69 ± 0.05 kpc) compared to the lower-redshift bin (R  e  = 0.91 ± 0.04 kpc). Within the limitations of the current sample size, we find no significant redshift evolution of n or R  e  at these early epochs.

Keywords: Early universe, Galaxy formation, High-redshift galaxies, Galaxy evolution
A Possible Correlation between Metallicity and Near-IR Color for Late-M and L Dwarfs. We examine the relationship between metallicity and J - K color for 64 benchmark late-M and L dwarfs, all of which are wide companions to higher-mass stars, and six of which are new discoveries. We assess the correlation between the Δ(J - K) color anomaly (the difference in an object's J - K color from the median color for field objects of the same spectral type) and the metallicity of the host star to investigate how metallicity affects ultracool photospheres. Using Spearman's rank correlation test and Student's t-test, the late-M dwarf (L dwarf) sample's Δ(J - K) and metallicity show a positive correlation at the 95% (90%) confidence level. A linear fit to color anomaly as a function of metallicity finds a slope of 0.17 ± 0.07 for the late-M dwarfs and a slope of ${0.20}_{-0.08}^{+0.07}$ for the L dwarfs. We also computed the Δ(J - K) versus metallicity relationship predicted by multi-metallicity model spectra generated using Drift-Phoenix. The modeled late-M dwarfs show a slope of 0.202 ± 0.03, which is close to our observational results, but the modeled L dwarfs show a slope of 0.493 ± 0.02, steeper than our observational results. Both our empirical results and the models indicate that more metal-rich objects should appear redder photometrically. We speculate that higher metallicity drives more condensate formation in these atmospheres, thus making these ultracool dwarfs appear redder.

Keywords: Metallicity, Brown dwarfs, L dwarfs, Photometry
Future Prospects for Constraining Black Hole Spacetime: Horizon-scale Variability of Astrophysical Jets. The Event Horizon Telescope (EHT) Collaboration has recently published the first horizon-scale images of the supermassive black holes M87* and Sgr A* and provided some first information on the physical conditions in their vicinity. The comparison between the observations and the three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations has enabled the EHT to set initial constraints on the properties of these black hole spacetimes. However, accurately distinguishing the properties of the accretion flow from those of the spacetime, most notably, the black hole mass and spin, remains challenging because of the degeneracies the emitted radiation suffers when varying the properties of the plasma and those of the spacetime. The next-generation EHT (ngEHT) observations are expected to remove some of these degeneracies by exploring the complex interplay between the disk-jet dynamics, which represents one of the most promising tools for extracting information on the black hole spin. By using GRMHD simulations of magnetically arrested disks and general relativistic radiative transfer (GRRT) calculations of the emitted radiation, we have studied the properties of the jet and the accretion disk dynamics on spatial scales that are comparable with the horizon. In this way, we are able to highlight that the radial and azimuthal dynamics of the jet are well correlated with the black hole spin. Based on the resolution and image reconstruction capabilities of the ngEHT observations of M87*, we can assess the detectability and associated uncertainty of this correlation. Overall, our results serve to assess the prospects for constraining the black hole spin with future EHT observations.

Keywords: Black hole physics, Galaxies, Magnetohydrodynamics, Relativistic jets, Radiative transfer, High angular resolution, Astronomy image processing
Correcting Exoplanet Transmission Spectra for Stellar Activity with an Optimized Retrieval Framework. The chromatic contamination that arises from photospheric heterogeneities, e.g., spots and faculae on the host star presents a significant noise source for exoplanet transmission spectra. If this contamination is not corrected for, it can introduce substantial bias in our analysis of the planetary atmosphere. We utilize two stellar models of differing complexity, StARPA (Stellar Activity Removal for Planetary Atmospheres) and ASteRA (Active Stellar Retrieval Algorithm), to explore the biases introduced by stellar contamination in retrieval under differing degrees of stellar activity. We use the retrieval framework TauREx3 and a grid of 27 synthetic, spot-contaminated transmission spectra to investigate potential biases and to determine how complex our stellar models must be in order to accurately extract the planetary parameters from transmission spectra. The input observation is generated using the more complex model (StARPA), in which the spot latitude is an additional, fixable parameter. This observation is then fed into a combined stellar-planetary retrieval, which contains a simplified stellar model (ASteRA). Our results confirm that the inclusion of stellar activity parameters in retrieval minimizes bias under all activity regimes considered. ASteRA performs very well under low-to-moderate activity conditions, retrieving the planetary parameters with a high degree of accuracy. For the most active cases, characterized by larger, higher-temperature contrast spots, some minor residual bias remains due to ASteRA neglecting the interplay between the spot and the limb-darkening effect. As a result of this, we find larger errors in retrieved planetary parameters for central spots (0°) and those found close to the limb (60°) than those at intermediate latitudes (30°).

Keywords: Exoplanets, Transmission spectroscopy, Exoplanet atmospheres, Stellar activity
Are There Higher Electron Densities in Narrow Emission Line Regions of Type-1 AGNs than in Type-2 AGNs?. In the manuscript, we check properties of electron densities n  e  traced by flux ratio R sii of [S II]λ6716 Å to [S II]λ6731 Å in narrow emission line regions (NLRs) between Type-1 active galactic nucleus (AGN) and Type-2 AGN in SDSS Data Release 12 (DR12). Under the framework of unified model considering kiloparsec-scale structures, similar n  e  in NLRs should be expected between Type-1 AGN and Type-2 AGN. Based on reliable measurements of the [S II] doublet with measured parameters at least 5 times larger than corresponding uncertainties, there are 6039 Type-1 AGN and 8725 Type-2 AGN (excluding the Type-2 LINERs and the composite galaxies) collected from SDSS DR12. Then, lower R sii (higher n  e ) in NLRs can be well confirmed in Type-1 AGN than in Type-2 AGN, with the confidence level higher than 5σ, even after considering the necessary effects including effects of electron temperatures traced by [O III]λ4364,4959,5007 Å on estimating n  e  in NLRs. Two probable methods are proposed to explain the higher n  e  in NLRs in Type-1 AGN. First, the higher n  e  in NLRs of Type-1 AGN could indicate longer time durations of AGN activities in Type-1 AGN than in Type-2 AGN, if AGN activities triggering galactic-scale outflows leading to more electrons injecting into NLRs were accepted to explain the higher n  e  in NLRs of Type-2 AGN than H II galaxies. Second, the lower n  e  in NLRs of Type-2 AGN could be explained by stronger star-forming contributions in Type-2 AGN, considering lower n  e  in H II regions. The results provide interesting challenges to the commonly and widely accepted unified model of AGN.

Keywords: Seyfert galaxies, Active galaxies, Active galactic nuclei, Emission line galaxies