Sazuna/UAT_keywords huggingface dataset:
A Reliable Calibration of H II Galaxies Hubble Diagram with Cosmic Chronometers and Artificial Neural Network. The L-σ relation of H II galaxies (HIIGx) calibrated by a distance indicator is a reliable standard candle for measuring the Hubble constant H 0. The most straightforward calibration technique anchors them with the first tier of distance ladders from the same galaxies. Recently another promising method that uses the cosmological model-independent cosmic chronometers as a calibrator has been proposed. We promote this technique by removing the assumptions about the cosmic flatness and using a nonparametric artificial neural network for the data reconstruction process. We observe a correlation between the cosmic curvature density parameter and the slope of the L-σ relation, thereby improving the reliability of the calibration. Using the calibrated HIIGx Hubble diagram, we obtain a Type Ia supernovae Hubble diagram free of the conventional assumption about H 0. Finally we get a value of ${H}_{0}={65.9}_{-2.9}^{+3.0}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}$ , which is compatible with the latest Planck 18 measurement.

Keywords: Hubble diagram, Neural networks, Standard candles, Astronomy data analysis, Hubble constant, Type Ia supernovae, H II regions
The Fundamental Plane Is Not a Plane: Warped Nature of the Fundamental Plane of Early-type Galaxies and Its Implication for Galaxy Formation. Based on 16,283 early-type galaxies (ETGs) in 0.025 ≤ z spec &lt; 0.055 from Sloan Digital Sky Survey data, we show that the fundamental plane (FP) of ETGs is not a plane in the strict sense but is a curved surface with a twisted shape whose orthogonal direction to the surface is shifted as the central velocity dispersion (σ 0) or mean surface brightness within the half-light radius (μ  e ) changes. When ETGs are divided into subsamples according to σ 0, the coefficient of μ  e  of the FP increases, whereas the zero-point of the FP decreases at higher σ 0. Taking the z band as an example, the coefficient of μ  e  rises from 0.28 to 0.36 as σ 0 increases from ~100 to ~300 km s-1. At the same time, the zero-point of the FP falls from -7.5 to -9.0 in the same σ 0 range. The consistent picture on the curved nature of the FP is also reached by inspecting changes in the FP coefficients for ETG subsamples with different μ  e . By examining scaling relations that are projections of the FP, we suggest that the warped nature of the FP may originate from dry merger effects that are imprinted more prominently in ETGs with higher masses.

Keywords: Galaxy formation, Galaxy properties, Galaxy mergers, Galaxy evolution, Red sequence galaxies, Early-type galaxies
Distributed YSOs in the Perseus Molecular Cloud from the Gaia and LAMOST Surveys. Identifying the young optically visible population in a star-forming region is essential for fully understanding the star formation event. In this paper, we identify 211 candidate members of the Perseus molecular cloud based on Gaia astrometry. We use LAMOST spectra to confirm that 51 of these candidates are new members, bringing the total census of known members to 856. The newly confirmed members are less extincted than previously known members. Two new stellar aggregates are identified in our updated census. With the updated member list, we obtain a statistically significant distance gradient of 4.84 pc deg-1 from west to east. Distances and extinction corrected color-magnitude diagrams indicate that NGC 1333 is significantly younger than IC 348 and the remaining cloud regions. The disk fraction in NGC 1333 is higher than elsewhere, consistent with its youngest age. The star formation scenario in the Perseus molecular cloud is investigated and the bulk motion of the distributed population is consistent with the cloud being swept away by the Per-Tau Shell.

Keywords: Star forming regions, Statistical parallax, Two-color diagrams, Pre-main sequence stars, Proper motions, Spectroscopy, Hertzsprung Russell diagram
Polarized Synchrotron Foreground Assessment for CMB Experiments. Polarized Galactic synchrotron emission is an undesirable foreground for cosmic microwave background experiments observing at frequencies &lt;150 GHz. We perform a combined analysis of observational data at 1.4, 2.3, 23, 30, and 33 GHz to quantify the spatial variation of the polarized synchrotron spectral index, β pol, on ~3.°5 scales. We compare results from different data combinations to address limitations and inconsistencies present in these public data, and form a composite map of β pol. Data quality masking leaves 44% sky coverage (73% for ∣b∣ &gt; 45°). Generally -3.2 &lt; β pol ≲ -3 in the inner Galactic plane and spurs, but the Fan Region in the outer galaxy has a flatter index. We find a clear spectral index steepening with increasing latitude south of the Galactic plane with Δβ pol = 0.4, and a smaller steepening of 0.25 in the north. Near the south Galactic pole the polarized synchrotron spectral index is β pol ≈ -3.4. Longitudinal spectral index variations of Δβ pol ~ 0.1 about the latitudinal mean are also detected. Within the BICEP2/Keck survey footprint, we find consistency with a constant value, β pol = -3.25 ± 0.04 (statistical) ±0.02 (systematic). We compute a map of the frequency at which synchrotron and thermal dust emission contribute equally to the total polarized foreground. The limitations and inconsistencies among data sets encountered in this work make clear the value of additional independent surveys at multiple frequencies, especially between 10 and 20 GHz, provided these surveys have sufficient sensitivity and control of instrumental systematic errors.

Keywords: Diffuse radiation, Observational cosmology
Galaxy Alignments with Surrounding Structure in the Sloan Digital Sky Survey. Using data from the Sloan Digital Sky Survey Legacy Survey, we study the alignment of luminous galaxies with spectroscopic data with the surrounding larger-scale structure as defined by galaxies with only photometric data. We find that galaxies from the red sequence have a statistically significant tendency for their apparent long axes to align parallel to the projected surrounding structure. Red galaxies more luminous than the median of our sample (M  r  &lt; -21.78) have a mean alignment angle &lt;Φ&gt; &lt; 45°, indicating preferred parallel alignment, at a significance level &gt;4.5σ on projected scales 0.1 Mpc &lt; r  p  ≤ 7.5 Mpc. Fainter red galaxies have &lt;Φ&gt; &lt; 45° at a significance level &gt;4.3σ at scales 1 Mpc &lt; r  p  &lt; 3 Mpc. At a projected scale r  p  = 3.0 Mpc, the mean alignment angle decreases steadily with increasing luminosity for red galaxies with M  r  ≲ -22.5, reaching &lt;Φ&gt; = 40.°49 ± 0.°56 for the most luminous 1% (M  r  ~ -23.57). Galaxies from the blue sequence show no statistically significant tendency for their axes to align with larger-scale structure, regardless of galaxy luminosity. Galaxies in higher-density regions do not show a statistically significant difference in the mean alignment angle from galaxies in lower-density regions; this holds true for the faint blue, luminous blue, faint red, and luminous red subsets.

Keywords: Clustering, Cosmic web, Galaxy properties, Large-scale structure of the universe
Long-term Evolution of Nonthermal Emission from Type Ia and Core-collapse Supernova Remnants in a Diversified Circumstellar Medium. The contribution of galactic supernova remnants (SNRs) to the origin of cosmic rays (CRs) is an important open question in modern astrophysics. Broadband nonthermal emission is a useful proxy for probing the energy budget and production history of CRs in SNRs. We conduct hydrodynamic simulations to model the long-term SNR evolution from explosion all the way to the radiative phase (or 3 × 105 yr at maximum) and compute the time evolution of the broadband nonthermal spectrum to explore its potential applications on constraining the surrounding environments, as well as the natures and mass-loss histories, of the SNR progenitors. A parametric survey is performed on the ambient environments separated into two main groups, namely, a homogeneous medium with a uniform gas density and one with the presence of a circumstellar structure created by the stellar wind of a massive red supergiant progenitor star. Our results reveal a highly diverse evolution history of the nonthermal emission closely correlated to the environmental characteristics of an SNR. Up to the radiative phase, the roles of CR reacceleration and ion-neutral wave damping on the spectral evolution are investigated. Finally, we make an assessment of the future prospect of SNR observations by the next-generation hard X-ray space observatory FORCE and predict what we can learn from their comparison with our evolution models.

Keywords: Galactic cosmic rays, Circumstellar matter, Supernova remnants, Non-thermal radiation sources, Interstellar medium
Anisotropic Electron Heating in Turbulence-driven Magnetic Reconnection in the Near-Sun Solar Wind. We perform a high-resolution, 2D, fully kinetic numerical simulation of a turbulent plasma system with observation-driven conditions, in order to investigate the interplay between turbulence, magnetic reconnection, and particle heating from ion to subelectron scales in the near-Sun solar wind. We find that the power spectra of the turbulent plasma and electromagnetic fluctuations show multiple power-law intervals down to scales smaller than the electron gyroradius. Magnetic reconnection is observed to occur in correspondence of current sheets with a thickness of the order of the electron inertial length, which form and shrink owing to interacting ion-scale vortices. In some cases, both ion and electron outflows are observed (the classic reconnection scenario), while in others-typically for the shortest current sheets-only electron jets are present ("electron-only reconnection"). At the onset of reconnection, the electron temperature starts to increase and a strong parallel temperature anisotropy develops. This suggests that in strong turbulence electron-scale coherent structures may play a significant role for electron heating, as impulsive and localized phenomena such as magnetic reconnection can efficiently transfer energy from the electromagnetic fields to particles.

Keywords: Interplanetary turbulence, Space plasmas, Solar wind, Plasma astrophysics
3D Hydrodynamics of Pre-supernova Outbursts in Convective Red Supergiant Envelopes. Eruptive mass loss likely produces the energetic outbursts observed from some massive stars before they become core-collapse supernovae (SNe). The resulting dense circumstellar medium may also cause the subsequent SNe to be observed as Type IIn events. The leading hypothesis of the cause of these outbursts is the response of the envelope of the red supergiant (RSG) progenitor to energy deposition in the months to years prior to collapse. Early theoretical studies of this phenomenon were limited to 1D, leaving the 3D convective RSG structure unaddressed. Using FLASH's hydrodynamic capabilities, we explore the 3D outcomes by constructing convective RSG envelope models and depositing energies less than the envelope binding energies on timescales shorter than the envelope dynamical time deep within them. We confirm the 1D prediction of an outward-moving acoustic pulse steepening into a shock, unbinding the outermost parts of the envelope. However, we find that the initial 2-4 km s-1 convective motions seed the intrinsic convective instability associated with the high-entropy material deep in the envelope, enabling gas from deep within the envelope to escape and increasing the amount of ejected mass compared to an initially "quiescent" envelope. The 3D models reveal a rich density structure, with column densities varying by ≈10× along different lines of sight. Our work highlights that the 3D convective nature of RSG envelopes impacts our ability to reliably predict the outburst dynamics, the amount, and the spatial distribution of the ejected mass associated with deep energy deposition.

Keywords: Stellar-interstellar interactions, Stellar convection envelopes, Late stellar evolution, Time domain astronomy, Astrophysical fluid dynamics, Supernova dynamics
Synthetic Polarization Maps of an Outflow Zone from Magnetohydrodynamic Simulations. The canonical theory of star formation in a magnetized environment predicts the formation of hourglass-shaped magnetic fields during the prestellar collapse phase. In protostellar cores, recent observations reveal complex and strongly distorted magnetic fields in the inner regions that are sculpted by rotation and outflows. We conduct resistive, nonideal magnetohydrodynamic simulations of a protostellar core and employ the radiative transfer code POLARIS to produce synthetic polarization segment maps. A comparison of our mock-polarization maps based on the toroidal-dominated magnetic field in the outflow zone with the observed polarization vectors of SiO lines in Orion Source I shows a reasonable agreement when the magnetic axis is tilted at an angle θ = 15° with respect to the plane of the sky and if the SiO lines have a net polarization parallel to the local magnetic field. Although the observed polarization is from SiO lines and our synthetic maps are due to polarized dust emission, a comparison is useful and allows us to resolve the ambiguity of whether the line polarization is parallel or perpendicular to the local magnetic field direction.

Keywords: Magnetohydrodynamics, Star forming regions, Interstellar magnetic fields, Interstellar clouds, Radiative transfer, Interstellar dust processes
Exomoons as Sources of White Dwarf Pollution. Polluted white dwarfs (WDs) offer a unique way to study the bulk compositions of exoplanetary material, but it is not always clear if this material originates from comets, asteroids, moons, or planets. We combine N-body simulations with an analytical model to assess the prevalence of extrasolar moons as WD polluters. Using a sample of observed polluted WDs, we find that the extrapolated parent body masses of the polluters are often more consistent with those of many solar system moons, rather than solar-like asteroids. We provide a framework for estimating the fraction of WDs currently undergoing observable moon accretion based on results from simulated WD planetary and moon systems. Focusing on a three-planet WD system of super-Earth to Neptune-mass bodies, we find that we could expect about one percent of such systems to be currently undergoing moon accretions as opposed to asteroid accretion.

Keywords: White dwarf stars, Planetary dynamics
Mid-infrared and Maser Flux Variability Correlation in Massive Young Stellar Object G036.70+00.09. We present the discovery of the simultaneous flux variation of a massive young stellar object (MYSO) G036.70+00.09 (G036.70) both in the maser emission and mid-infrared (MIR; λ = 3-5 μm) bands. Using the ALLWISE and NEOWISE archival databases that cover a long time span of approximately 10 yr with a cadence of 6 months, we confirm that G036.70 indicates a stochastic year-long MIR variability with no signs of a WISE band color change of W1 (3.4 μm) -W2 (4.6 μm). Cross-matching the MIR data set with the high-cadence 6.7 GHz class II methanol maser flux using the Hitachi 32 m radio telescope that discovered its periodicity in the methanol maser of 53.0-53.2 days, we also determine the flux correlations between the two bands at two different timescales, year-long and day-long, both of which have never been reported in MYSOs, except when they are in the accretion burst phase. The results of our study support the scenario that a class II methanol maser is pumped up by infrared emission from accreting disks of MYSOs. We also discuss the possible origins of MIR and maser variability. To explain the two observed phenomena, a stochastic year-long MIR variability with no signs of significant color change and maser-MIR variability correlation or a change in mass accretion rate and line-of-sight extinction because of the nonaxisymmetric dust density distribution in a rotating accretion disk are possible origins. Observations through spectroscopic monitoring of accretion-related emission lines are essential for determining the origin of the observed variability in G036.70.

Keywords: Massive stars, Infrared astronomy, Young stellar objects, Circumstellar masers, Time domain astronomy, Variable stars
Investigation of the Broadband Emission of the Gamma-Ray Binary HESS J0632+057 Using an Intrabinary Shock Model. We investigated a wealth of X-ray and gamma-ray spectral energy distribution (SED) and multiband light-curve (LC) data of the gamma-ray binary HESS J0632+057 using a phenomenological intrabinary shock (IBS) model. Our baseline model assumes that the IBS is formed by colliding winds from a putative pulsar and its Be companion and that particles accelerated in the IBS emit broadband radiation via synchrotron (SY) and inverse Compton upscattering (ICS) processes. Adopting the latest orbital solution and system geometry, we reproduced the global X-ray and TeV LC features, two broad bumps at ϕ ~ 0.3 and ~0.7, with the SY and ICS model components. We found that these TeV LC peaks originate from ICS emission caused by the enhanced seed photon density near periastron and superior conjunction or Doppler-beamed emission of bulk-accelerated particles in the IBS at inferior conjunction. While our IBS model successfully explained most of the observed SED and LC data, we found that phase-resolved SED data in the TeV band require an additional component associated with ICS emission from preshock particles (produced by the pulsar wind). This finding indicates a possibility of delineating the IBS emission components and determining the bulk Lorentz factors of the pulsar wind at certain orbital phases.

Keywords: High energy astrophysics, Relativistic binary stars, Gamma-ray sources, High mass x-ray binary stars, Radiative processes
A White Dwarf-Main-sequence Binary Unveiled by Time-domain Observations from LAMOST and TESS. We report a single-lined white dwarf-main-sequence binary system, LAMOST J172900.17+652952.8, which is discovered by the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST)'s medium-resolution time-domain surveys. The radial-velocity semi-amplitude and orbital period of the optical visible star are measured by using follow-up observations with the Palomar 200 inch telescope and light curves from the Transiting Exoplanet Survey Satellite (TESS). Thus the mass function of the invisible candidate white dwarf is derived, f(M 2) = 0.120 ± 0.003 M ⊙. The mass of the visible star is measured based on a spectral energy distribution fitting, M 1 = ${0.81}_{-0.06}^{+0.07}\,{M}_{\odot }$ . Hence, the mass of its invisible companion is M 2 ≳ 0.63 M ⊙. The companion ought to be a compact object rather than a main-sequence star owing to the mass ratio q = M 2/M 1 ≳ 0.78 and the single-lined spectra. The compact object is likely to be a white dwarf if the inclination angle is not small, i ≳ 40°. By using the Galaxy Evolution Explorer (GALEX) near-UV flux, the effective temperature of the white dwarf candidate is constrained as ${T}_{\mathrm{eff}}^{\mathrm{WD}}$ ≲ 12,000-13,500 K. It is difficult to detect white dwarfs which are outshone by their bright companions via single-epoch optical spectroscopic surveys. Therefore, optical time-domain surveys can play an important role in unveiling invisible white dwarfs and other compact objects in binaries.

Keywords: Close binary stars, Radial velocity, White dwarf stars, Light curves
Energy Conversion and Partition in Plasma Turbulence Driven by Magnetotail Reconnection. A long-outstanding issue in fundamental plasma physics is how magnetic energy is finally dissipated in kinetic scale in the turbulent plasma. Based on the Magnetospheric Multiscale mission data in the plasma turbulence driven by magnetotail reconnection, we establish the quantitative relation between energy conversion ( J • E ; J is current density and E is electric field) and current density (J). The results show that the magnetic energy is primarily released in the perpendicular directions (up to 90%), in the region with current density less than 2.3 J rms, where J rms is the rms value of the total current density ∣ J ∣. In the relatively weak current region (&lt;1.0 J rms), the ions get most of the released energy while the largely negative energy conversion rate of the electrons means a dynamo action. In the strong currents (&gt;1.0 J rms), the ion energization was negligible and the electrons are significantly energized. Moreover, a linearly increasing relationship was established between ∣ J • E ∣ and $\left|{\boldsymbol{J}}\right|$ . The observations indicate that ions overall dominate energy conversion in turbulence, but the electron dynamics are crucial for energy conversion in intense currents and the turbulence evolution.

Keywords: Interplanetary turbulence, Space plasmas, Plasma astrophysics, Solar magnetic reconnection
Two-dimensional Configuration and Temporal Evolution of Spark Discharges in Pulsars. We report on our investigation of the evolution of a system of spark discharges in the inner acceleration region (IAR) above the pulsar polar cap. The surface of the polar cap is heated to temperatures of around 106 K and forms a partially screened gap (PSG), due to thermionic emission of positively charged ions from the stellar surface. The spark lags behind corotation speed during their lifetimes due to variable E × B drift. In a PSG, spark discharges arise in locations where the surface temperatures go below the critical level (T  i ) for ions to freely flow from the surface. The spark commences due to the large drop in potential developing along the magnetic field lines in these lower temperature regions and subsequently back-streaming particles heat the surface to T  i . Regulation of the temperature requires the polar cap to be tightly filled with sparks and a continuous presence of sparks is required around its boundary since no heating is possible from the closed field line region. We estimate the time evolution of the spark system in the IAR, which shows a gradual shift in the spark formation along two distinct directions resembling clockwise and anticlockwise motions in two halves of the polar cap. Due to the differential shift of the spark pattern in the two halves, a central spark develops representing the core emission. The temporal evolution of the spark process was simulated for different orientations of a non-dipolar polar cap and reproduced the diverse observational features associated with subpulse drifting.

Keywords: Pulsars, Radio pulsars