Sazuna/UAT_keywords huggingface dataset:
Observational Evidence Points at AGB Stars as Possible Progenitors of CEMP-s and CEMP-r/s Stars. The origin of enhanced abundance of heavy elements observed in the surface chemical composition of carbon-enhanced metal-poor (CEMP) stars still remains poorly understood. Here, we present detailed abundance analysis of seven CEMP stars based on high-resolution (R ~ 50,000) spectra that reveal enough evidence of asymptotic giant branch (AGB) stars being possible progenitors for these objects. For the objects HE 0110-0406, HE 1425-2052, and HE 1428-1950, we present for the first time a detailed abundance analysis. Our sample is found to consist of one metal-poor ([Fe/H] &lt; -1.0) and six very metal-poor ([Fe/H] &lt; -2.0) stars with enhanced carbon and neutron-capture elements. We have critically analyzed the observed abundance ratios of [O/Fe], [Sr/Ba], and [hs/ls] and examined the possibility of AGB stars being possible progenitors. The abundance of oxygen estimated in the program stars is characteristic of AGB progenitors except for HE 1429-0551 and HE 1447+0102. The estimated values of [Sr/Ba] and [hs/ls] ratios also support AGB stars as possible progenitors. The locations of the program stars in the absolute carbon abundance A(C) versus [Fe/H] diagram, along with the Group I objects, hint at the binary nature of the object. We have studied the chemical enrichment histories of the program stars based on abundance ratios [Mg/C], [Sc/Mn], and [C/Cr]. Using [C/N] and 12C/13C ratios, we have examined whether any internal mixing had modified their surface chemical compositions. Kinematic analysis shows that the objects HE 0110-0406 and HE 1447+0102 are thick-disk objects and the remaining five objects belong to the halo population of the Galaxy. * Based on data collected at Himalayan Chandra Telescope, IAO, Hanle, India, and at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. The Subaru data are retrieved from the JVO portal (http://jvo.nao.ac.jp/portal/v2/) operated by the NAOJ.

Keywords: Population II stars
Galaxy Stellar Mass Functions from z   10 to z   6 using the Deepest Spitzer/Infrared Array Camera Data: No Significant Evolution in the Stellar-to-halo Mass Ratio of Galaxies in the First Gigayear of Cosmic Time. We present new stellar mass functions at z ~ 6, z ~ 7, z ~ 8, z ~ 9 and, for the first time, z ~ 10, constructed from ~800 Lyman-break galaxies previously identified over the eXtreme Deep Field and Hubble Ultra-Deep Field parallel fields and the five Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields. Our study is distinctive due to (1) the much deeper (~200 hr) wide-area Spitzer/Infrared Array Camera (IRAC) imaging at 3.6 μm and 4.5 μm from the Great Observatories Origins Deep Survey Re-ionization Era Wide-area Treasury from Spitzer program (GREATS) and (2) consideration of z ~ 6-10 sources over a 3× larger area than those of previous Hubble Space Telescope+Spitzer studies. The Spitzer/IRAC data enable ≥2σ rest-frame optical detections for an unprecedented 50% of galaxies down to a stellar mass limit of $\sim {10}^{8}{{ \mathcal M }}_{\odot }$ across all redshifts. Schechter fits to our volume densities suggest a combined evolution in the characteristic mass ${{ \mathcal M }}^{* }$ and normalization factor φ* between z ~ 6 and z ~ 8. The stellar mass density (SMD) increases by ~1000× in the ~500 Myr between z ~ 10 and z ~ 6, with indications of a steeper evolution between z ~ 10 and z ~ 8, similar to the previously reported trend of the star formation rate density. Strikingly, abundance matching to the Bolshoi-Planck simulation indicates halo mass densities evolving at approximately the same rate as the SMD between z ~ 10 and z ~ 4. Our results show that the stellar-to-halo mass ratios, a proxy for the star formation efficiency, do not change significantly over the huge stellar mass buildup occurred from z ~ 10 to z ~ 6, indicating that the assembly of stellar mass closely mirrors the buildup in halo mass in the first ~1 Gyr of cosmic history. The James Webb Space Telescope is poised to extend these results into the "first galaxy" epoch at z ≳ 10.

Keywords: Stellar mass functions, Lyman-break galaxies, A giant stars
New Galactic β Lyrae-type Binaries Showing Superorbital Photometric Cycles. We present the discovery of 32 new double periodic variables (DPVs) located toward the Galactic bulge. We found these objects among the nearly half a million binary stars published by the Optical Gravitational Lensing Experiment project. With this discovery, we increase the number of known DPVs in the Milky Way by a factor of 2. The new set of DPVs contains 31 eclipsing binaries and one ellipsoidal variable star. The orbital periods cover the range from 1.6 to 26 days, while long periods are detected between 47 and 1144 days. Our analysis confirms a known correlation between orbital and long periods that is also observed in similar systems in the Magellanic Clouds.

Keywords: Eclipsing binary stars, Double periodic variable stars, Beta Lyrae stars
Simultaneous Multiwavelength Flare Observations of EV Lacertae. We present the first results of our ongoing project conducting simultaneous multiwavelength observations of flares on nearby active M dwarfs. We acquired data of the nearby dM3.5e star EV Lac using five different observatories: NASA's Transiting Exoplanet Survey Satellite (TESS), NASA's Neil Gehrels Swift Observatory (Swift), NASA's Neutron Interior Composition Explorer (NICER), the University of Hawaii 2.2-meter telescope (UH88), and the Las Cumbres Observatory Global Telescope (LCOGT) Network. During the ~25 days of TESS observations, we acquired three simultaneous UV/X-ray observations using Swift that total ~18 ks, 21 simultaneous epochs totaling ~98 ks of X-ray data using NICER, one observation (~3 hr) with UH88, and one observation (~3 hr) with LCOGT. We identified 56 flares in the TESS light curve with estimated energies in the range log ET (erg) = (30.5-33.2), nine flares in the Swift UVM2 light curve with estimated energies in the range log EUV (erg) = (29.3-31.1), 14 flares in the NICER light curve with estimated minimum energies in the range log EN (erg) = (30.5-32.3), and 1 flare in the LCOGT light curve with log EL (erg) = 31.6. We find that the flare frequency distributions (FFDs) of TESS and NICER flares have comparable slopes, βT = -0.67 ± 0.09 and βN = - 0.65 ± 0.19, and the FFD of UVOT flares has a shallower slope (βU = -0.38 ± 0.13). Furthermore, we do not find conclusive evidence for either the first ionization potential (FIP) or the inverse FIP effect during coronal flares on EV Lac.

Keywords: M dwarf stars, Stellar activity, Flare stars
Ultra-High-energy Cosmic Rays from beyond the Greisen-Zatsepin-Kuz'min Horizon. Ultra-high-energy (UHE) cosmic rays (CRs) of energies ~(1018-1020) eV, accelerated in violent astrophysical environments, interact with cosmic background radiation fields via photo-hadronic processes, leading to strong attenuation. Typically, the Universe would become "opaque" to UHE CRs after several tens of megaparsecs, setting the boundary of the Greisen-Zatsepin-Kuz'min (GZK) horizon. In this work, we investigate the contribution of sources beyond the conventional GZK horizon to the UHE CR flux observed on Earth, when photospallation of the heavy nuclear CRs is taken into account. We demonstrate that this contribution is substantial, despite the strong attenuation of UHE CRs. A significant consequence is the emergence of an isotropic background component in the observed flux of UHE CRs, coexisting with the anisotropic foreground component that is associated with nearby sources. Multi-particle CR horizons, which evolve over redshift, are determined by the CR nuclear composition. Thus, they are dependent on the source populations and source evolutionary histories.

Keywords: Secondary cosmic rays, Cosmic ray sources, Extragalactic astronomy, Ultra-high-energy cosmic radiation, Astronomical radiation sources
Unexpected Short-period Variability in Dwarf Carbon Stars from the Zwicky Transient Facility. Dwarf carbon (dC) stars, main-sequence stars showing carbon molecular bands, are enriched by mass transfer from a previous asymptotic-giant-branch (AGB) companion, which has since evolved to a white dwarf. While previous studies have found radial-velocity variations for large samples of dCs, there are still relatively few dC orbital periods in the literature and no dC eclipsing binaries have yet been found. Here, we analyze photometric light curves from DR5 of the Zwicky Transient Facility for a sample of 944 dC stars. From these light curves, we identify 34 periodically variable dC stars. Remarkably, of the periodic dCs, 82% have periods less than two days. We also provide spectroscopic follow-up for four of these periodic systems, measuring radial velocity variations in three of them. Short-period dCs are almost certainly post-common-envelope binary systems, because the periodicity is most likely related to the orbital period, with tidally locked rotation and photometric modulation on the dC either from spots or from ellipsoidal variations. We discuss evolutionary scenarios that these binaries may have taken to accrete sufficient C-rich material while avoiding truncation of the thermally pulsing AGB phase needed to provide such material in the first place. We compare these dCs to common-envelope models to show that dC stars probably cannot accrete enough C-rich material during the common-envelope phase, suggesting another mechanism like wind-Roche lobe overflow is necessary. The periodic dCs in this paper represent a prime sample for spectroscopic follow-up and for comparison to future models of wind-Roche lobe overflow mass transfer.

Keywords: Close binary stars, Carbon stars, Period search , Spectroscopy, Common envelope evolution, Chemically peculiar stars
A Comprehensive Study of Multiflare GRB Spectral Lag. We select 48 multiflare gamma-ray bursts (GRBs) (including 137 flares) from the Swift/XRT database and estimate the spectral lag with the discrete correlation function. It is found that 89.8% of the flares have positive lags and only 9.5% of the flares show negative lags when fluctuations are taken into account. The median lag of the multiflares (2.75 s) is much greater than that of GRB pulses (0.18 s), which can be explained by the fact that we confirm that multiflare GRBs and multipulse GRBs have similar positive lag-duration correlations. We investigate the origin of the lags by checking the Epeak evolution with the two brightest bursts and find the leading models cannot explain all of the multiflare lags and there may be other physical mechanisms. All of the results above reveal that X-ray flares have the same properties as GRB pulses, which further supports the observation that X-ray flares and GRB prompt-emission pulses have the same physical origin.

Keywords: Gamma-ray bursts
The Green Bank Northern Celestial Cap Pulsar Survey. VI. Discovery and Timing of PSR J1759+5036: A Double Neutron Star Binary Pulsar. The Green Bank North Celestial Cap survey is a 350 MHz all-sky survey for pulsars and fast radio transients using the Robert C. Byrd Green Bank Telescope. To date, the survey has discovered over 190 pulsars, including 33 millisecond pulsars and 24 rotating radio transients. Several exotic pulsars have been discovered in the survey, including PSR J1759+5036, a binary pulsar with a 176 ms spin period in an orbit with a period of 2.04 days, an eccentricity of 0.3, and a projected semi-major axis of 6.8 light seconds. Using seven years of timing data, we are able to measure one post-Keplerian parameter, advance of periastron, which has allowed us to constrain the total system mass to 2.62 ± 0.03 M⊙. This constraint, along with the spin period and orbital parameters, suggests that this is a double neutron star system, although we cannot entirely rule out a pulsar-white dwarf binary. This pulsar is only detectable in roughly 45% of observations, most likely due to scintillation. However, additional observations are required to determine whether there may be other contributing effects.

Keywords: Radio pulsars, Neutron stars, Binary pulsars, Pulsars
Universal Protoplanetary Disk Size under Complete Nonideal Magnetohydrodynamics: The Interplay between Ion-neutral Friction, Hall Effect, and Ohmic Dissipation. The role of nonideal magnetohydrodynamics has been proven critical during the formation of protoplanetary disks, particularly in regulating their sizes. We provide a simple model to predict the disk size under the interplay among ambipolar diffusion, the Hall effect, and ohmic dissipation. The model predicts a small disk size of around 20 au that depends only sublinearly on disk parameters, for a wide range of initial conditions of subsolar mass and moderate magnetization. It is able to explain phenomena manifested in existing numerical simulations, including the bimodal disk behavior under parallel and antiparallel alignment between the rotation and magnetic field. In the parallel configuration, the disk size decreases and eventually disappears. In the antiparallel configuration, the disk has an outer partition (or pseudodisk), which is flat, shrinking, and short-lived, as well as an inner partition, which grows slowly with mass and is long-lived. Even with significant initial magnetization, the vertical field in the disk can only dominate at the early stage when the mass is low, and the toroidal field eventually dominates in all disks.

Keywords: Interstellar magnetic fields, Magnetohydrodynamics, Protoplanetary disks, Gravitation
The Measurement of Dynamic Tidal Contribution to Apsidal Motion in Heartbeat Star KIC 4544587. Apsidal motion is a gradual shift in the position of periastron. The impact of dynamic tides on apsidal motion has long been debated, because the contribution could not be quantified due to the lack of high-quality observations. KIC 4544587 with tidally excited oscillations has been observed by Kepler high-precision photometric data based on long-time-baseline and short-cadence schema. In this paper, we compute the rate of apsidal motion that arises from the dynamic tides as 19.05 ± 1.70 mrad yr-1 via tracking the orbital phase shifts of tidally excited oscillations. We also calculate the procession rate of the orbit due to the Newtonian and general relativistic contribution as 21.49 ± 2.8 and 2.4 ± 0.06 mrad yr-1, respectively. The sum of these three factors is in excellent agreement with the total observational rate of apsidal motion 42.97 ± 0.18 mrad yr-1 measured by eclipse timing variations. The tidal effect accounts for about 44% of the overall observed apsidal motion and is comparable to that of the Newtonian term. Dynamic tides have a significant contribution to the apsidal motion. The analysis method mentioned in this paper presents an alternative approach to measuring the contribution of the dynamic tides quantitatively.

Keywords: Tidal interaction, Apsidal motion, Binary stars, Asteroseismology
The Simons Observatory Microwave SQUID Multiplexing Detector Module Design. Advances in cosmic microwave background (CMB) science depend on increasing the number of sensitive detectors observing the sky. New instruments deploy large arrays of superconducting transition-edge sensor (TES) bolometers tiled densely into ever larger focal planes. High multiplexing factors reduce the thermal loading on the cryogenic receivers and simplify their design. We present the design of focal-plane modules with an order of magnitude higher multiplexing factor than has previously been achieved with TES bolometers. We focus on the novel cold readout component, which employs microwave SQUID multiplexing (μmux). Simons Observatory will use 49 modules containing 70,000 bolometers to make exquisitely sensitive measurements of the CMB. We validate the focal-plane module design, presenting measurements of the readout component with and without a prototype detector array of 1728 polarization-sensitive bolometers coupled to feedhorns. The readout component achieves a 95% yield and a 910 multiplexing factor. The median white noise of each readout channel is 65 $\mathrm{pA}/\sqrt{\mathrm{Hz}}$ . This impacts the projected SO mapping speed by &lt;8%, which is less than is assumed in the sensitivity projections. The results validate the full functionality of the module. We discuss the measured performance in the context of SO science requirements, which are exceeded.

Keywords: Cosmology, CMBR detectors, Cosmic microwave background radiation, Astronomical instrumentation
Constraints on the Occurrence of 'Oumuamua-Like Objects. At present, there exists no consensus in the astronomical community regarding either the bulk composition or the formation mechanism for the interstellar object 1I/2017 U1 ('Oumuamua). With the goal of assessing the merits of the various scenarios that have been suggested to explain 'Oumuamua's appearance and observed properties, we report a number of new analyses and provide an up-to-date review of the current hypotheses. We consider the interpretations that can reconcile 'Oumuamua's observed non-Keplerian trajectory with the nondetection of traditional cometary volatiles. We examine the ability of these proposed formation pathways to populate the galaxy with sufficient interstellar objects such that the detection of 'Oumuamua by Pan-STARRS would be statistically favored. We consider two exotic ices, hydrogen and nitrogen, showing that the frigid temperature requirement for the former and the necessary formation efficiency of the latter pose serious difficulties for these interpretations. Via order-of-magnitude arguments and hydrodynamical cratering simulations, we show that impacts on extrasolar Kuiper Belt analogues are not expected to generate N2 ice fragments as large as 'Oumuamua. In addition, we discuss observational tests to confirm the presence of these ices in future interstellar objects. Next, we examine the explanations that attribute 'Oumuamua's properties to other compositions: ultraporous dust aggregates and thin membranes powered by solar radiation pressure, among others. While none of these hypotheses are perfectly satisfactory, we make predictions that will be testable by the Vera Rubin Observatory to resolve the tension introduced by 'Oumuamua.

Keywords: Small Solar System bodies, Interstellar objects
Galaxy Core Formation by Supermassive Black Hole Binaries: The Importance of Realistic Initial Conditions and Galaxy Morphology. The binding energy liberated by the coalescence of supermassive black hole (SMBH) binaries during galaxy mergers is thought to be responsible for the low density cores often found in bright elliptical galaxies. We use high-resolution N-body and Monte Carlo techniques to perform single and multistage galaxy merger simulations and systematically study the dependence of the central galaxy properties on the binary mass ratio, the slope of the initial density cusps, and the number of mergers experienced. We study both the amount of depleted stellar mass (or mass deficit), Mdef, and the radial extent of the depleted region, rb. We find that rb ≃ rSOI and that Mdef varies in the range of 0.5-4M•, with rSOI the influence radius of the remnant SMBH and M• its mass. The coefficients in these relations depend weakly on the binary mass ratio and remain remarkably constant through subsequent mergers. We conclude that the core size and mass deficit do not scale linearly with the number of mergers, making it hard to infer merger histories from observations. On the other hand, we show that both Mdef and rb are sensitive to the morphology of the galaxy merger remnant, and that adopting spherical initial conditions, as done in early work, leads to misleading results. Our models reproduce the range of values for Mdef found in most observational work, but span nearly an order-of magnitude range around the true ejected stellar mass.

Keywords: Supermassive black holes, Galaxy formation, Galaxy dynamics, Stellar cores, Galaxy nuclei, Giant elliptical galaxies, Galaxy kinematics, Galaxy evolution, Gravitational waves, Elliptical galaxies
Magnetic Helicity Estimations in Models and Observations of the Solar Magnetic Field. IV. Application to Solar Observations. In this ISSI-supported series of studies on magnetic helicity in the Sun, we systematically implement different magnetic helicity calculation methods on high-quality solar magnetogram observations. We apply finite-volume, discrete flux tube (in particular, connectivity-based) and flux-integration methods to data from Hinode's Solar Optical Telescope. The target is NOAA Active Region 10930 during a 1.5-day interval in 2006 December that included a major eruptive flare (SOL2006-12-13T02:14X3.4). Finite-volume and connectivity-based methods yield instantaneous budgets of the coronal magnetic helicity, while the flux-integration methods allow an estimate of the accumulated helicity injected through the photosphere. The objectives of our work are twofold: a cross-validation of methods, as well as an interpretation of the complex events leading to the eruption. To the first objective, we find (i) strong agreement among the finite-volume methods, (ii) a moderate agreement between the connectivity-based and finite-volume methods, (iii) an excellent agreement between the flux-integration methods, and (iv) an overall agreement between finite-volume- and flux-integration-based estimates regarding the predominant sign and magnitude of the helicity. To the second objective, we are confident that the photospheric helicity flux significantly contributed to the coronal helicity budget and that a right-handed structure erupted from a predominantly left-handed corona during the X-class flare. Overall, we find that the use of different methods to estimate the (accumulated) coronal helicity may be necessary in order to draw a complete picture of an active region corona, given the careful handling of identified data (preparation) issues, which otherwise would mislead the event analysis and interpretation.

Keywords: Astronomy data modeling, Solar flares, Astronomy data analysis, Solar coronal mass ejections, Solar magnetic fields
CHIME/FRB Catalog 1 Results: Statistical Cross-correlations with Large-scale Structure. The CHIME/FRB Project has recently released its first catalog of fast radio bursts (FRBs), containing 492 unique sources. We present results from angular cross-correlations of CHIME/FRB sources with galaxy catalogs. We find a statistically significant (p-value ~ 10-4, accounting for look-elsewhere factors) cross-correlation between CHIME FRBs and galaxies in the redshift range 0.3 ≲ z ≲ 0.5, in three photometric galaxy surveys: WISE × SCOS, DESI-BGS, and DESI-LRG. The level of cross-correlation is consistent with an order-one fraction of the CHIME FRBs being in the same dark matter halos as survey galaxies in this redshift range. We find statistical evidence for a population of FRBs with large host dispersion measure (~400 pc cm-3) and show that this can plausibly arise from gas in large halos (M ~ 1014 M⊙), for FRBs near the halo center (r ≲ 100 kpc). These results will improve in future CHIME/FRB catalogs, with more FRBs and better angular resolution.

Keywords: Large-scale structure of the universe, Cosmology, High energy astrophysics, Radio transient sources
First Discovery of New Pulsars and RRATs with CHIME/FRB. We report the discovery of seven new Galactic pulsars with the Canadian Hydrogen Intensity Mapping Experiment's Fast Radio Burst (CHIME/FRB) backend. These sources were first identified via single pulses in CHIME/FRB, then followed up with CHIME/Pulsar. Four sources appear to be rotating radio transients, pulsar-like sources with occasional single-pulse emission with an underlying periodicity. Of those four sources, three have detected periods ranging from 220 ms to 2.726 s. Three sources have more persistent but still intermittent emission and are likely intermittent or nulling pulsars. We have determined phase-coherent timing solutions for the latter two. These seven sources are the first discovery of previously unknown Galactic sources with CHIME/FRB and highlight the potential of fast radio burst detection instruments to search for intermittent Galactic radio sources.

Keywords: Radio pulsars, Pulsars