Sazuna/UAT_keywords huggingface dataset:
Small-scale Magnetic Flux Ropes with Field-aligned Flows via the PSP In Situ Observations. Magnetic flux rope, formed by the helical magnetic field lines, can sometimes maintain its shape while carrying significant plasma flow that is aligned with the local magnetic field. We report the existence of such structures and static flux ropes by applying the Grad-Shafranov-based algorithm to the Parker Solar Probe in situ measurements in the first five encounters. These structures are detected at heliocentric distances, ranging from 0.13 to 0.66 au, in a 4-month time period. We find that flux ropes with field-aligned flows, although they occur more frequently, have certain properties similar to those of static flux ropes, such as the decaying relations of the magnetic fields within structures with respect to heliocentric distances. Moreover, these events are more likely with magnetic pressure dominating over the thermal pressure. About one-third of events are detected in the relatively fast solar wind. Taking into account the high Alfvénicity, we also compare with switchback spikes identified during three encounters and interpret their interrelations. We find that some switchbacks can be detected when the spacecraft traverses flux-rope-like structures. The cross-section maps for selected events are presented via the new Grad-Shafranov-type reconstruction. Finally, the possible evolution of the magnetic flux rope structures in the inner heliosphere is discussed.

Keywords: Solar magnetic reconnection, Interplanetary turbulence, Solar wind, Astronomy data analysis, Solar magnetic fields
Influence of Irradiation-driven Winds on the Evolution of Intermediate-mass Black Hole X-ray Binaries. In young dense clusters, an intermediate-mass black hole (IMBH) may get a companion star via exchange encounters or tidal capture and then evolve toward the IMBH X-ray binary by the Roche lobe overflow. It is generally thought that IMBH X-ray binaries are potential ultraluminous X-ray sources (ULXs); hence, their evolution is very significant. However, the irradiation-driven winds by the strong X-ray flux from the accretion disks around the IMBHs play an important role in determining the evolution of IMBH X-ray binaries and should be considered in the detailed binary evolution simulation. Employing the models with the MESA code, we focus on the influence of irradiation-driven winds on the evolution of IMBH X-ray binaries. Our simulations indicate that a high wind-driving efficiency (f = 0.01 for Z = 0.02, and f = 0.002 for Z = 0.001) substantially shortens the duration in the ULX stage of IMBH X-ray binaries with an intermediate-mass (5 M⊙) donor star. However, this effect can be ignored for high-mass (10 M⊙) donor stars. The irradiation effect (f = 0.01 or 0.002) markedly shrinks the initial parameter space of IMBH binaries evolving toward ULXs with high luminosity (LX &gt; 1040 erg s-1) and hyperluminous X-ray sources in the donor-star mass versus orbital period diagram. Furthermore, the irradiation effect results in an efficient angular momentum loss, yielding to IMBH X-ray binaries with relatively close orbits. In our simulated parameter space, about 1% of IMBH binaries would evolve toward compact X-ray sources owing to short initial orbital periods, some of which might be detected as low-frequency gravitational-wave sources.

Keywords: Galaxy clusters, X-ray binary stars, Black holes, Gravitational waves, Stellar evolution
Diffusion of Cosmic Antiprotons Generated throughout the Dark Matter Halo-A Semianalytical Solution for a Linear Galactic Wind Model. The public GALPROP code gives a fully numerical solution for the spectrum of cosmic rays propagating through a linear Galactic wind directed outward from the Galactic plane in the framework of a cylindrical diffusion model. Alternatively, for the linear Galactic wind case, we present a semianalytical solution of the two-zone cylindrical model that describes the spectrum of cosmic-ray antiprotons produced from the primary sources throughout the dark matter (DM) halo. While the secondary antiprotons can be generated by, e.g., the GALPROP WebRun, consistently using this semianalytical solution for the primary ones would be helpful to build a suited DM model, which may be sophisticated, and then to perform a statistical analysis when comparing it with data. As an example, using the obtained formula, we study the possible DM signal through the channel $\mathrm{DM}\,\mathrm{DM}\to \bar{b}b$ and its constraint from the measurement of the AMS-02 antiproton-to-proton ratio. The indication of the DM signal is discussed. The advantages of the semianalytical approach and its comparison with the GALPROP model are presented.

Keywords: Galactic cosmic rays, Dark matter, Cosmic ray sources
Common Envelope Shaping of Planetary Nebulae. III. The Launching of Jets in Proto-Planetary Nebulae. We compute successfully the launching of two magnetic winds from two circumbinary disks formed after a common envelope event. The launching is produced by the increase of magnetic pressure due to the collapse of the disks. The collapse is due to internal torques produced by a weak poloidal magnetic field. The first wind can be described as a wide jet, with an average mass-loss rate of ~1.3 × 10-7 M⊙ yr-1 and a maximum radial velocity of ~230 km s-1. The outflow has a half-opening angle of ~20°. Narrow jets are also formed intermittently with velocities up to 3000 km s-1, with mass-loss rates of ~6 × 10-12 M⊙ yr-1 during short periods of time. The second wind can be described as a wide X-wind, with an average mass-loss rate of ~1.68 × 10-7 M⊙ yr-1 and a velocity of ~30 km s-1. A narrow jet is also formed with a velocity of 250 km s-1 and a mass-loss rate of ~10-12 M⊙ yr-1. The computed jets are used to provide inflow boundary conditions for simulations of proto-planetary nebulae. The wide jet evolves into a molecular collimated outflow within a few astronomical units, producing proto-planetary nebulae with bipolar, elongated shapes, whose kinetic energies reach ~4 × 1045 erg at 1000 yr. Similarities with observed features in W43A, OH 231.8+4.2, and Hen 3-1475 are discussed. The computed wide X-wind produces proto-planetary nebulae with slower expansion velocities, bipolar and elliptical shapes, and possible starfish-type and quadrupolar morphology.

Keywords: Post-asymptotic giant branch stars, Protoplanetary nebulae, Stellar evolution, Asymptotic giant branch stars, Planetary nebulae, Common envelope binary stars
Testing Einstein's Equivalence Principle and Its Cosmological Evolution from Quasar Gravitational Redshifts. We propose and apply a new test of Einstein's equivalence principle (EEP) based on the gravitational redshift induced by the central supermassive black hole of quasars in the surrounding accretion disk. Specifically, we compare the observed gravitational redshift of the Fe III λλ 2039-2113 emission line blend in quasars with the predicted values in a wide, uncharted, cosmic territory (0 ≲ zcosm ≲ 3). For the first time we measure, with statistical uncertainties comparable or better than those of other classical methods outside the solar system, the ratio between the observed gravitational redshifts and the theoretical predictions in 10 independent cosmological redshift bins in the 1 ≲ zcosm ≲ 3 range. The average of the measured over predicted gravitational redshifts ratio in this cosmological redshift interval is $\langle {z}_{g}^{m}/{z}_{g}^{p}\rangle =1.05\pm 0.06$ with scatter 0.13 ± 0.05 showing no cosmological evolution of EEP within these limits. This method can benefit from larger samples of measurements with better signal-to-noise ratios, paving the way for high-precision tests (below 1%) of EEP on cosmological scales.

Keywords: Cosmology, General relativity, Quasars
High Spatial Resolution Observations of Molecular Lines toward the Protoplanetary Disk around TW Hya with ALMA. We present molecular line observations of 13CO and C18O J = 3 - 2, CN N = 3 - 2, and CS J = 7 - 6 lines in the protoplanetary disk around TW Hya at a high spatial resolution of ~9 au (angular resolution of 0"15), using the Atacama Large Millimeter/Submillimeter Array. A possible gas gap is found in the deprojected radial intensity profile of the integrated C18O line around a disk radius of ~58 au, slightly beyond the location of the au-scale dust clump at ~52 au, which resembles predictions from hydrodynamic simulations of planet-disk interaction. In addition, we construct models for the physical and chemical structure of the TW Hya disk, taking account of the dust surface density profile obtained from high spatial resolution dust continuum observations. As a result, the observed flat radial profile of the CN line intensities is reproduced due to a high dust-to-gas surface density ratio inside ~20 au. Meanwhile, the CO isotopologue line intensities trace high temperature gas and increase rapidly inside a disk radius of ~30 au. A model with either CO gas depletion or depletion of gas-phase oxygen elemental abundance is required to reproduce the relatively weak CO isotopologue line intensities observed in the outer disk, consistent with previous atomic and molecular line observations toward the TW Hya disk. Further observations of line emission of carbon-bearing species, such as atomic carbon and HCN, with high spatial resolution would help to better constrain the distribution of elemental carbon abundance in the disk gas.

Keywords: Planetary system formation, Molecular gas, Submillimeter astronomy, Protoplanetary disks
On Synthetic Absorption Line Profiles of Thermally Driven Winds from Active Galactic Nuclei. The warm absorbers observed in more than half of all nearby active galactic nuclei are tracers of ionized outflows located at parsec-scale distances from the central engine. If the smallest inferred ionization parameters correspond to plasma at a few 104 K, then the gas undergoes a transition from being bound to unbound, provided it is further heated to ~106 K at larger radii. Dannen et al. recently discovered that, under these circumstances, thermally driven wind solutions are unsteady and even show very dense clumps due to thermal instability. To explore the observational consequences of these new wind solutions, we compute line profiles based on the one-dimensional simulations of Dannen et al. We show how the line profiles from even a simple steady-state wind solution depend on the ionization energy (IE) of absorbing ions, which is a reflection of the wind ionization stratification. To organize the diversity of the line shapes, we group them into four categories: weak Gaussians, saturated boxy profiles with and without an extended blue wing, and broad weak profiles. The lines with profiles in the last two categories are produced by ions with the highest IE that probe the fastest regions. Their maximum blueshifts agree with the highest flow velocities in thermally unstable models, both steady-state and clumpy versions. In contrast, the maximum blueshifts of the highest-IE lines in thermally stable models can be less than half of the actual solution velocities. Clumpy solutions can additionally imprint distinguishable absorption troughs at widely separated velocities.

Keywords: Hydrodynamical simulations, Photoionization, Active galactic nuclei
Spitzer Mid-infrared Study of Sh 2-208: Evolution of Protoplanetary Disks in Low-metallicity Environments. This study presents sensitive mid-infrared (MIR) photometry obtained with the Spitzer/IRAC for a young cluster in Sh 2-208 (S208) located in one of the lowest-metallicity H II regions in the Galaxy, $[{\rm{O}}/{\rm{H}}]=-0.8$ dex. Previous studies suggested that the cluster is ~0.5 Myr old and has a distance of D = 4 kpc, which is consistent with the astrometric distance from Gaia EDR3. In a ~ $3\buildrel{\,\prime}\over{.} 5\times 4^{\prime} $ field, 96 sources were detected in at least one MIR band at ≥10σ, covering intermediate-mass stars with a ~1.0 ${M}_{\odot }$ mass detection limit. A total of 41 probable cluster members were identified based on the spatial distributions of spectral energy distribution slopes derived from the near-infrared (NIR) KS and IRAC bands and extinctions of the sources. The cumulative distribution of the spectral energy distribution slopes for the S208 cluster was not significantly different from those of other clusters in solar-metallicity environments with approximately the same age for intermediate-mass stars, if one also considers nondetected MIR sources identified as S208 cluster members from NIR observations. This suggests that the degree of dust growth/settling does not significantly change with metallicities as different as ~1 dex. The fraction of stars with MIR disk emissions for the cluster members with ≥1 ${M}_{\odot }$ was 64%-93%, which is comparable to the results in solar-metallicity environments. Although this may suggest that dominant disk dispersal mechanisms for intermediate-mass stars have either no or very weak dependence on metallicity, it can be argued alternatively that this may suggest that the disk dispersal process does not work effectively at this young stage.

Keywords: Protostars, Galaxy abundances, Star formation, Protoplanetary disks, Infrared sources, Pre-main sequence, H II regions, Open star clusters, Metallicity
The Lithium Abundances from the Large Sky Area Multi-object Fiber Spectroscopic Telescope Medium-resolution Survey. I. The Method. One of the purposes of taking spectra for millions of stars through the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey (MRS) is to obtain the elemental abundances, so that one can trace the origin and evolution for the element of interests. Lithium is one of such elements of great importance, which exhibits many puzzling behaviors. Investigating the lithium abundances to a uniquely large sample of stars is essential to understand its origin and evolution. In this paper, we present the lithium abundances obtained from the LAMOST MRS spectra calculated by the template-matching method. Our data set consists of 294,857 spectra that corresponds to 165,479 stars with a resolution power of ∆λ/λ ~ 7500. We compared the lithium abundances derived from our work with those using the high-resolution spectra and found a good consistence. The errors of lithium abundances are discussed. Our results suggest that the distribution of lithium abundances show two clear peaks at +2.6 and +1.0 dex, respectively. This sample is potentially important for investigating physical mechanisms occurring inside stars that alter the surface lithium abundance.

Keywords: Stellar abundances, Chemically peculiar stars, Stellar evolution
SOFIA FEEDBACK Survey: Exploring the Dynamics of the Stellar Wind-Driven Shell of RCW 49. We unveil the stellar wind-driven shell of the luminous massive star-forming region of RCW 49 using SOFIA FEEDBACK observations of the [C II] 158 μm line. The complementary data set of the 12CO and 13CO J = 3 → 2 transitions is observed by the APEX telescope and probes the dense gas toward RCW 49. Using the spatial and spectral resolution provided by the SOFIA and APEX telescopes, we disentangle the shell from a complex set of individual components of gas centered around RCW 49. We find that the shell of radius ~6 pc is expanding at a velocity of 13 km s-1 toward the observer. Comparing our observed data with the ancillary data at X-ray, infrared, submillimeter, and radio wavelengths, we investigate the morphology of the region. The shell has a well-defined eastern arc, while the western side is blown open and venting plasma further into the west. Though the stellar cluster, which is ~2 Myr old, gave rise to the shell, it only gained momentum relatively recently, as we calculate the shell's expansion lifetime of ~0.27 Myr, making the Wolf-Rayet star WR 20a a likely candidate responsible for the shell's reacceleration.

Keywords: Star forming regions, Stellar feedback
X-Ray Emission from Isolated Neutron Stars Revisited: 3D Magnetothermal Simulations. X-ray emission from the surface of isolated neutron stars (NSs) has been now observed in a variety of sources. The ubiquitous presence of pulsations clearly indicates that thermal photons either come from a limited area, possibly heated by some external mechanism, or from the entire (cooling) surface but with an inhomogeneous temperature distribution. In an NS the thermal map is shaped by the magnetic field topology since heat flows in the crust mostly along the magnetic field lines. Self-consistent surface thermal maps can hence be produced by simulating the coupled magnetic and thermal evolution of the star. We compute the evolution of the NS crust in three dimensions for different initial configurations of the magnetic field and use the ensuing thermal surface maps to derive the spectrum and the pulse profile as seen by an observer at infinity, accounting for general-relativistic effects. In particular, we compare cases with a high degree of symmetry with inherently 3D ones, obtained by adding a quadrupole to the initial dipolar field. Axially symmetric fields result in rather small pulsed fractions (≲5%), while more complex configurations produce higher pulsed fractions, up to ~25%. We find that the spectral properties of our axisymmetric model are close to those of the bright isolated NS RX J1856.5-3754 at an evolutionary time comparable with the inferred dynamical age of the source.

Keywords: Neutron stars, Magnetars, Stellar magnetic fields, Magnetohydrodynamical simulations
A Bayesian ILC Method for CMB B-mode Posterior Estimation and Reconstruction of Primordial Gravity Wave Signal. The cosmic microwave background (CMB) radiation B-mode polarization signal contains the unique signature of primordial metric perturbations produced during the inflation. The separation of the weak CMB B-mode signal from strong foreground contamination in observed maps is a complex task, and proposed new-generation low-noise satellite missions compete with the weak signal level of this gravitational background. In this paper, for the first time, we employ a foreground model-independent internal linear combination (ILC) method to reconstruct the CMB B-mode signal using simulated observations over large angular scales of the sky of six frequency bands of the future-generation CMB mission Probe of Inflation and Cosmic Origins (PICO). We estimate the joint CMB B-mode posterior density following the interleaving Gibbs steps of the B-mode angular power spectrum and cleaned map samples using the ILC method. We extend and improve the earlier reported Bayesian ILC method to analyze weak CMB B-mode reconstruction by introducing noise-bias corrections at two stages during the ILC weight estimation. By performing 200 Monte Carlo simulations of the Bayesian ILC method, we find that our method can reconstruct the CMB signals and the joint posterior density accurately over large angular scales of the sky. We estimate the Blackwell-Rao statistics of the marginal density of the CMB B-mode angular power spectrum and use them to estimate the joint density of the tensor-to-scalar ratio r and a lensing power spectrum amplitude ${A}^{{\rm{lens}}}$ . Using 200 Monte Carlo simulations of the delensing approach, we find that our method can achieve an unbiased detection of the primordial gravitational-wave signal r with more than 8σ significance for levels of $r\geqslant 0.01$ for input frequency maps with realistic lensing and foregrounds with constant spectral indices.

Keywords: Extragalactic astronomy, Cosmic microwave background radiation, Principal component analysis, Cosmic inflation
Extreme HBL-like Behavior of Markarian 421 and Its Two-zone Photohadronic Interpretation. Markarian 421 is the nearest high-energy peaked blazar and is also the first extragalactic source to be detected in multi-TeV γ-rays. It has been observed in multiwavelength for an exceptionally long period of time with dense monitoring and several major outbursts have been detected from this source. In 2010 March, the source was in a high state of activity and was observed in multiwavelength by various telescopes for 13 consecutive days. During this period the position of the synchrotron peak was found to be above 1017 Hz and also the position of the second peak was shifted toward higher energy, a signature of extreme HBL-like behavior. We observed that the standard photohadronic model is inadequate to explain the observed spectra. However, a recently proposed two-zone photohadronic model explains very well the GeV-TeV flaring events observed by both MAGIC and VERITAS telescopes. From the observation of the highest energy γ-ray event on MJD 55266 we also estimated the minimum bulk Lorentz factor.

Keywords: BL Lacertae objects, High energy astrophysics, Blazars, Relativistic jets, Gamma-rays
The NANOGrav 11 yr Data Set: Limits on Supermassive Black Hole Binaries in Galaxies within 500 Mpc. Supermassive black hole binaries (SMBHBs) should form frequently in galactic nuclei as a result of galaxy mergers. At subparsec separations, binaries become strong sources of low-frequency gravitational waves (GWs), targeted by Pulsar Timing Arrays. We used recent upper limits on continuous GWs from the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 11 yr data set to place constraints on putative SMBHBs in nearby massive galaxies. We compiled a comprehensive catalog of ~44,000 galaxies in the local universe (up to redshift ~0.05) and populated them with hypothetical binaries, assuming that the total mass of the binary is equal to the SMBH mass derived from global scaling relations. Assuming circular equal-mass binaries emitting at NANOGrav's most sensitive frequency of 8 nHz, we found that 216 galaxies are within NANOGrav's sensitivity volume. We ranked the potential SMBHBs based on GW detectability by calculating the total signal-to-noise ratio such binaries would induce within the NANOGrav array. We placed constraints on the chirp mass and mass ratio of the 216 hypothetical binaries. For 19 galaxies, only very unequal-mass binaries are allowed, with the mass of the secondary less than 10% that of the primary, roughly comparable to constraints on an SMBHB in the Milky Way. However, we demonstrated that the (typically large) uncertainties in the mass measurements can weaken the upper limits on the chirp mass. Additionally, we were able to exclude binaries delivered by major mergers (mass ratio of at least 1/4) for several of these galaxies. We also derived the first limit on the density of binaries delivered by major mergers purely based on GW data.

Keywords: Supermassive black holes, Gravitational waves, Galaxies
Two-component Magnetic Field along the Line of Sight to the Perseus Molecular Cloud: Contribution of the Foreground Taurus Molecular Cloud. Optical stellar polarimetry in the Perseus molecular cloud direction is known to show a fully mixed bimodal distribution of position angles across the cloud. We study the Gaia trigonometric distances to each of these stars and reveal that the two components in position angles trace two different dust clouds along the line of sight. One component, which shows a polarization angle of -37°6 ± 35°2 and a higher polarization fraction of 2.0 ± 1.7 %, primarily traces the Perseus molecular cloud at a distance of 300 pc. The other component, which shows a polarization angle of +66°8 ± 19°1 and a lower polarization fraction of 0.8 ± 0.6 %, traces a foreground cloud at a distance of 150 pc. The foreground cloud is faint, with a maximum visual extinction of ≤1 mag. We identify that foreground cloud as the outer edge of the Taurus molecular cloud. Between the Perseus and Taurus molecular clouds, we identify a lower-density ellipsoidal dust cavity with a size of 100-160 pc. This dust cavity is located at l = 170°, b = -20°, and d = 240 pc, which corresponds to an HI shell generally associated with the Per OB2 association. The two-component polarization signature observed toward the Perseus molecular cloud can therefore be explained by a combination of the plane-of-sky orientations of the magnetic field both at the front and at the back of this dust cavity.

Keywords: Interstellar magnetic fields, Starlight polarization, Interstellar clouds, Polarimetry