Sazuna/UAT_keywords huggingface dataset:
A Low-mass Pre-main-sequence Eclipsing Binary in Lower Centaurus Crux Discovered with TESS. We report the discovery of 2M1222-57 as a low-mass, pre-main-sequence (PMS) eclipsing binary (EB) in the Lower Centaurus Crux (LCC) association for which, using Gaia parallaxes and proper motions with a neural net age estimator, we determine an age of 16.2 ± 2.2 Myr. The broadband spectral energy distribution (SED) shows clear excess at ≳10 μm indicative of a circumbinary disk, and new speckle imaging observations reveal a faint, tertiary companion separated by ~100 au. Hα emission is modulated on the orbital period, consistent with theoretical models of orbitally pulsed accretion streams reaching from the inner disk edge to the central stars. From a joint analysis of spectroscopically determined radial velocities and TESS light curves, together with additional tight constraints provided by the SED and the Gaia parallax, we measure masses for the eclipsing stars of 0.74 M ☉ and 0.67 M ☉; radii of 0.98 R ☉ and 0.94 R ☉; and effective temperatures of 3750 K and 3645 K. The masses and radii of both stars are measured to an accuracy of ~1%. The measured radii are inflated, and the temperatures suppressed, relative to predictions of standard PMS evolutionary models at the age of LCC; also, the Li abundances are ~2 dex less depleted than predicted by those models. However, models that account for the global and internal effects of surface magnetic fields are able to simultaneously reproduce the measured radii, temperatures, and Li abundances at an age of 17.0 ± 0.5 Myr. Altogether, the 2M1222-57 system presents very strong evidence that magnetic activity in young stars alters both their global properties and the physics of their interiors.

Keywords: Stellar ages, Fundamental parameters of stars, Stellar effective temperatures, Stellar magnetic fields, Stellar radii, Stellar activity, Pre-main sequence stars, Low mass stars, Stellar accretion, Stellar masses, Eclipsing binary stars
Monte Carlo Simulations on Possible Collimation Effects of Outflows to Fan Beam Emission of Ultraluminous Accreting X-Ray Pulsars. Pulsating ultraluminous X-ray sources (PULXs) are accreting pulsars with apparent X-ray luminosity exceeding 1039 erg s-1. We perform Monte Carlo simulations to investigate whether a high collimation effect (or strong beaming effect) is dominant in the presence of accretion outflows, for the fan beam emission of the accretion column of the neutron stars in PULXs. We show that the three nearby PULXs (RX J0209.6-7427, Swift J0243.6+6124, and SMC X-3), namely, the Three Musketeers here, have their main pulsed emission not strongly collimated even if strong outflows exist. This conclusion can be extended to the current sample of extragalactic PULXs, if accretion outflows are commonly produced from them. This means that the observed high luminosity of PULXs is indeed intrinsic, which can be used to infer the existence of very strong surface magnetic fields of ~1013-14 G, possibly multipole fields. However, if strong outflows are launched from the accretion disks in PULXs as a consequence of disk spherization by radiation pressure, regular dipole magnetic fields of ~1012 G may be required, comparable to that of the Three Musketeers, which have experienced large luminosity changes from well below their Eddington limit (2 × 1038 erg s-1 for an NS) to super-Eddington and whose maximum luminosity fills the luminosity gap between Galactic pulsars and extragalactic PULXs.

Keywords: Accretion, Ultraluminous x-ray sources, Binary pulsars
Confining Burst Energy Function and Spectral Fringe Pattern of FRB 20121102A with Multifrequency Observations. The observed spectral shapes variation and tentative bimodal burst energy distribution (E-distribution) of fast radio burst (FRB) 20121102A with the FAST telescope are great puzzles. Adopting the published multifrequency data observed with the FAST and Arecibo telescopes at L band and the Green Bank Telescope (GBT) at C band, we investigate these puzzles through Monte Carlo simulations. The intrinsic energy function (E-function) is modeled as ${dp}/{dE}\propto {E}^{-{\alpha }_{{\rm{E}}}}$ , and the spectral profile is described as a Gaussian function. A fringe pattern of its spectral peak frequency (ν  p ) in 0.5-8 GHz is inferred from the ν  p  distribution of the GBT sample. We estimate the likelihood of α E and the standard deviation of the spectral profile (σ s) by utilizing the Kolmogorov-Smirnov test probability for the observed and simulated specific E-distributions. Our simulations yield ${\alpha }_{{\rm{E}}}={1.82}_{-0.30}^{+0.10}$ , and ${\sigma }_{{\rm{s}}}={0.18}_{-0.06}^{+0.28}$ (3σ confidence level) with the FAST sample. These results suggest that a single power-law function is adequate to model the E-function of FRB 20121102A. The variations of its observed spectral indices and E-distributions with telescopes in different frequency ranges are due to both physical and observational reasons, i.e., narrow spectral width for a single burst and discrete ν  p  fringe pattern in a broad frequency range among bursts, and the selection effects of the telescope bandpass and sensitivity. The putative ν  p  fringe pattern cannot be explained with the current radiation physics models of FRBs. Some caveats of possible artificial effects that may introduce such a feature are discussed.

Keywords: Radio transient sources
Central Star Formation in Early-type Galaxy I Zw 81 in the Bootes Void. The origin of star formation in customarily passively evolving early-type massive galaxies is poorly understood. We present a case study of a massive galaxy, I Zw 81, inside the Bootes void. The void galaxy is known to host active galactic nuclei (AGN). Our detailed 2D decomposition of the surface brightness distribution in the Canada France Hawaii Telescope (CFHT) g and r bands revealed multiple structural components such as a nuclear point source, a bar, a ring, and an inner exponential disk followed by an outer low surface brightness disk. I Zw 81 turns out to be a disk-dominated galaxy with lenticular morphology. The modeling of the multiwavelength spectral energy distribution shows that the galaxy is star-forming (SF), and belongs to the blue cloud. We find that the optical (g-r) color of the bar is bluer than the disks, and the far- and near-ultraviolet emission inside the galaxy observed with Imaging Telescope onboard AstroSat is concentrated in the central few kpc region enclosing the bar. The strong bar might be playing a pivotal role in driving the gas inflow and causing SF activity in tandem with the minor merger-like interactions as evident from the deep CFHT data. The low-luminosity AGN is insufficient to quench the central SF. The results are peculiar from the standpoint of a massive barred lenticular galaxy.

Keywords: Ultraviolet astronomy, Lenticular galaxies, Galaxy evolution, Star formation
Probability of Forming Gaps in the GD-1 Stream by Close Encounters of Globular Clusters. One of the most intriguing properties of the GD-1 stellar stream is the existence of three gaps. If these gaps were formed by close encounters with dark matter subhalos, the GD-1 stream opens an exciting window through which we can see the size, mass, and velocity distributions of the dark matter subhalos in the Milky Way. However, in order to use the GD-1 stream as a probe of the dark matter substructure, we need to disprove that these gaps are not due to the perturbations from baryonic components of the Milky Way. Here we ran a large number of test-particle simulations to investigate the probability that each of the known globular clusters (GCs) can form a GD-1-like gap, by using the kinematical data of the GD-1 stream and GCs from Gaia early data release 3 and by fully taking the observational uncertainty into account. We found that the probability that all of the three gaps were formed by GCs is as low as 1.7 × 10-5, and the expected number of gaps formed by GCs is only 0.057 in our fiducial model. Our result highly disfavors a scenario in which GCs form the gaps. Given that other baryonic perturbers (e.g., giant molecular clouds) are even less likely to form a gap in the retrograde-moving GD-1 stream, we conclude that at least one of the gaps in the GD-1 stream was formed by dark matter subhalos if the gaps were formed by flyby perturbations.

Keywords: Globular star clusters, Milky Way dark matter halo, Stellar streams, Milky Way dynamics, Stellar dynamics
Quantifying the Evidence Against a Mass Gap between Black Holes and Neutron Stars. The lack of objects between 2 and 5 M ⊙ in the joint mass distribution of compact objects has been termed the "mass gap," and attributed mainly to the characteristics of the supernova mechanism precluding their birth. However, recent observations show that a number of candidates reported to lie inside the "gap" may fill it, suggesting instead a paucity that may be real or largely a result of small number statistics. We quantify in this work the individual candidates and evaluate the joint probability of a mass gap. Our results show that an absolute mass gap is not present, to a very high confidence level. It remains to be seen if a relative paucity of objects stands in the future, and how this population can be related to the formation processes, which may include neutron star mergers, the collapse of a neutron star to a black hole, and others.

Keywords: Neutron stars, Black holes, Stellar mass black holes, Compact objects, Astrophysical black holes
Vertical Equilibrium Model for Accretion Flow: An Exact General Relativistic Self-consistent Analysis. We provide a complete general relativistic and fluid dynamical treatment to derive an expression for the relativistic accretion rate in curved spacetime. We exploit the Killing symmetry of stationary axisymmetric spacetime to obtain the conserved current, using which we find an integral relation between mass flux and height of the accretion disk. In comparison with the existing different models of thin- and slim-disk approaches our analysis is self-consistent and mathematically rigorous. We reviewed the previous work and surveyed the recent status in this field. Our formula is different from the existing expression in the literature. The difference arises solely due to the rotation parameter of the compact star. The effect becomes important for slim/thick disks and for rapidly spinning compact stars. Thus one needs to alter the formula $\dot{M}=2\pi {rH}\rho {u}^{r}$ for Newtonian or spherically symmetric spacetime while studying the accretion flows around a Kerr black hole. Our formula can also be used to connect the variability of the vertical structure of the accretion disk through the luminosity variation of X-ray binaries, and can thereby explain the origin of the hysteresis loop of the spectral states.

Keywords: Accretion, Black hole physics, Hydrodynamics, Relativity, Relativistic fluid dynamics
Inpainting Hydrodynamical Maps with Deep Learning. From 1000 hydrodynamic simulations of the CAMELS project, each with a different value of the cosmological and astrophysical parameters, we generate 15,000 gas temperature maps. We use a state-of-the-art deep convolutional neural network to recover missing data from those maps. We mimic the missing data by applying regular and irregular binary masks that cover either 15% or 30% of the area. We quantify the reliability of our results using two summary statistics: (1) the distance between the probability density functions, estimated using the Kolmogorov-Smirnov (K-S) test, and (2) the 2D power spectrum. We find an excellent agreement between the model prediction and the unmasked maps when using the power spectrum: better than 1% for k &lt; 20 h Mpc-1 for any irregular mask. For regular masks, we observe a systematic offset of ~5% when covering 15% of the maps, while the results become unreliable when 30% of the data is missing. The observed K-S test p-values favor the null hypothesis that the reconstructed and the ground-truth maps are drawn from the same underlying distribution when irregular masks are used. For regular-shaped masks, on the other hand, we find a strong evidence that the two distributions do not match each other. Finally, we use the model, trained on gas temperature maps, to inpaint maps from fields not used during model training. We find that, visually, our model is able to reconstruct the missing pixels from the maps of those fields with great accuracy, although its performance using summary statistics depends strongly on the considered field.

Keywords: Computational methods, Astrostatistics, Large-scale structure of the universe
Turbulent Magnetic Field Amplification by the Interaction of a Shock Wave and Inhomogeneous Medium. Magnetic fields of the order of 100 μG observed in young supernova remnants cannot be amplified by shock compression alone. To investigate the amplification caused by a turbulent dynamo, we perform three-dimensional MHD simulations of the interaction between a shock wave and an inhomogeneous density distribution with a shallow spectrum in the preshock medium. The postshock turbulence is mainly driven by the strongest preshock density contrast and follows the Kolmogorov scaling. The resulting turbulence amplifies the postshock magnetic field. The time evolution of the magnetic fields agrees with the prediction of the nonlinear turbulent dynamo theory of Xu &amp; Lazarian. When the initially weak magnetic field is perpendicular to the shock normal, the maximum amplification of the field's strength reaches a factor of ≈200, which is twice as large as that for a parallel shock. We find that the perpendicular shock exhibits a smaller turbulent Alfvén Mach number in the vicinity of the shock front than the parallel shock. However, the strongest magnetic field has a low volume filling factor and is limited by the turbulent energy due to the reconnection diffusion taking place in a turbulent and magnetized fluid. The magnetic field strength averaged along the z-axis is reduced by a factor ≳10. We decompose the turbulent velocity and magnetic field into solenoidal and compressive modes. The solenoidal mode is dominant and evolves to follow the Kolmogorov scaling, even though the preshock density distribution has a shallow spectrum. When the preshock density distribution has a Kolmogorov spectrum, the turbulent velocity's compressive component increases.

Keywords: Magnetohydrodynamics, Interstellar dynamics, Interstellar magnetic fields, Supernova remnants, Interstellar medium
Evaluating Lyα Emission as a Tracer of the Largest Cosmic Structure at z   2.47. The discovery and spectroscopic confirmation of Hyperion, a protosupercluster at z ~ 2.47, provides an unprecedented opportunity to study distant galaxies in the context of their large-scale environment. We carry out deep narrowband imaging of a ≈1° × 1° region around Hyperion and select 157 Lyα emitters (LAEs). The inferred LAE overdensity is δ  g  ≈ 40 within an effective volume of 30 × 20 × 15 cMpc3, consistent with the fact that Hyperion is composed of multiple protoclusters and will evolve into a supercluster with a total mass of M tot ≈ 1.4 × 1015 M ⊙ at z = 0. The distribution of LAEs closely mirrors that of known spectroscopic members, tracing the protocluster cores and extended filamentary arms connected to them, suggesting that they trace the same large-scale structure. By cross-correlating the LAE positions with H I tomography data, we find weak evidence that LAEs may be less abundant in the highest H I regions, perhaps because Lyα is suppressed in such regions. The Hyperion region hosts a large population of active galactic nuclei (AGNs) ≈ 12 times more abundant than that in the field. The prevalence of AGNs in protocluster regions hints at the possibility that they may be triggered by physical processes that occur more frequently in dense environments, such as galaxy mergers. Our study demonstrates LAEs as reliable markers of the largest cosmic structures. When combined with ongoing and upcoming imaging and spectroscopic surveys, wide-field narrowband imaging has the potential to advance our knowledge in the formation and evolution of cosmic structures and of their galaxy inhabitants.

Keywords: Galaxy formation, Galaxy evolution, High-redshift galaxy clusters
Herschel Optimized Tau and Temperature (HOTT) Maps: Uncertainty Analysis and Robust Parameter Extraction. We introduce the HOTT dust optical depth and temperature maps parameterizing thermal dust emission. Such maps have revolutionized studies of the distribution of matter in molecular clouds and processes relevant to star formation, including virial stability. HOTT maps for a suite of fields, including the Herschel Gould Belt Survey, are available online. The standardization of our robust pipeline for modified blackbody fitting of the spectral energy distribution (SED) of high-quality archival submillimeter data from the Herschel Space Observatory is based on a thorough analysis and quantification of the uncertainties of the data. This enables proper weighting in the SED fits. The uncertainties assessed fall into four main categories: instrument noise; the cosmic infrared background anisotropy, a contaminating sky signal; gradient-related noise arising because of dust signal morphology; and calibration uncertainty, scaling with the signal strength. Zero-level adjustments are important too. An analysis of residuals from the SED fits across many fields supports the overall appropriateness of the assumed modified blackbody model and points to where it breaks down. Finding χ 2 distributions close to the theoretical expectation boosts confidence in the pipeline and the optimized quality of the parameter maps and their estimated uncertainties. We compared our HOTT parameter maps to those from earlier studies to understand and quantify the potential for systematic differences.

Keywords: Interstellar dust, Astronomy data analysis, Molecular clouds, Interstellar medium
The Host Galaxies of Hybrid Morphology Radio Sources. Based on their differing radio morphologies, powerful radio galaxies can be separated into the Fanaroff-Riley I (FR I) and II (FR II) classes. Hybrid morphology radio sources (HyMoRS) contain morphologies consistent with each type of jet on either side: a powerful, highly relativistic FR I-like jet terminating in a hotspot on one side and an FR I-like plume on the other. HyMoRS present a unique opportunity to study the conditions that give rise to the dichotomy. Using host galaxy properties, we conduct the first multiwavelength investigation into whether orientation can explain HyMoRS morphology. Through optical spectroscopy and mid-infrared photometry, we analyze the emission characteristics, and evaluate the broad characteristics of five HyMoRS host galaxies at intermediate redshifts (0.4 &lt; z &lt; 1.5). The HyMoRS host galaxies in our sample have properties consistent with typical host galaxies of FR II sources, suggesting that the observed hybrid morphologies may be caused by a dense, cluster-like environment bending FR II jets combined with a favorable orientation that can make one side appear similar to an FR I jet. Our results thus support the hypothesis that HyMoRS are mainly caused by environment and orientation.

Keywords: Galaxy clusters, Galaxy environments, Active galaxies, Emission line galaxies, Radio galaxies, Fanaroff-Riley radio galaxies, Galaxy evolution, Ionization, Spectroscopy, Early-type galaxies
Turbulent Energy Transfer and Proton-Electron Heating in Collisionless Plasmas. Despite decades of study of high-temperature weakly collisional plasmas, a complete understanding of how energy is transferred between particles and fields in turbulent plasmas remains elusive. Two major questions in this regard are how fluid-scale energy transfer rates, associated with turbulence, connect with kinetic-scale dissipation, and what controls the fraction of dissipation on different charged species. Although the rate of cascade has long been recognized as a limiting factor in the heating rate at kinetic scales, there has not been direct evidence correlating the heating rate with MHD-scale cascade rates. Using kinetic simulations and in situ spacecraft data, we show that the fluid-scale energy flux indeed accounts for the total energy dissipated at kinetic scales. A phenomenology, based on disruption of proton gyromotion by fluctuating electric fields that are produced in turbulence at proton scales, argues that the proton versus electron heating is controlled by the ratio of the nonlinear timescale to the proton cyclotron time and by the plasma beta. The proposed scalings are supported by the simulations and observations.

Keywords: Space plasmas, Magnetohydrodynamics, Plasma astrophysics, Plasma physics
V5856 Sagittarii/2016: Broad Multiepoch Spectral Coverage of a Sustained High-luminosity Nova. Nova V5856 Sagittarii is unique for having remained more than nine magnitudes above its pre-outburst brightness for more than 6 yr. Extensive visible and infrared (IR) spectra from the time of outburst to the present epoch reveal separate emitting regions with distinct spectral characteristics. Permitted emission lines have both broad and narrow components, whereas the forbidden line profiles are almost entirely broad. The permitted line components frequently display P Cygni profiles indicating high optical depth, whereas the broad components do not show detectable absorption. The densities and velocities deduced from the spectra, including differences in the O I λ7773 and λ8446 lines, are not consistent with an ongoing wind. Instead, the prolonged high luminosity and spectral characteristics are indicative of a post-outburst common envelope that enshrouds the binary, and is likely the primary source of the visible and IR emission.

Keywords: Cataclysmic variable stars, Novae
Successive Interacting Coronal Mass Ejections: How to Create a Perfect Storm. Coronal mass ejections (CMEs) are the largest type of eruptions on the Sun and the main driver of severe space weather at the Earth. In this study, we implement a force-free spheromak CME description within 3D magnetohydrodynamic simulations to parametrically evaluate successive interacting CMEs within a representative heliosphere. We explore CME-CME interactions for a range of orientations, launch time variations, and CME handedness and quantify their geo-effectiveness via the primary solar wind variables and empirical measures of the disturbance storm time index and subsolar magnetopause standoff distance. We show how the interaction of two moderate CMEs between the Sun and the Earth can translate into extreme conditions at the Earth and how CME-CME interactions at different radial distances can maximize different solar wind variables that induce different geophysical impacts. In particular, we demonstrate how the orientation and handedness of a given CME can have a significant impact on the conservation and loss of magnetic flux, and consequently B  z , due to magnetic reconnection with the interplanetary magnetic field. This study thus implicates the identification of CME chirality in the solar corona as an early diagnostic for forecasting geomagnetic storms involving multiple CMEs.

Keywords: Space plasmas, Interplanetary shocks, Heliosphere, Space weather, Solar wind, Solar coronal mass ejections, Solar storm, Habitable planets, Magnetic storms, Magnetohydrodynamical simulations