Sazuna/UAT_keywords huggingface dataset:
Fast-rotating Blue Straggler Stars in the Globular Cluster NGC 3201. We used high-resolution spectra acquired with the Magellan Telescope to measure radial and rotational velocities of approximately 200 stars in the Galactic globular cluster NGC 3201. The surveyed sample includes blue straggler stars (BSSs) and reference stars in different evolutionary stages (main-sequence turnoff, subgiant, red giant, and asymptotic giant branches). The average radial velocity value (&lt;V  r &gt; = 494.5 ± 0.5 km s-1) confirms a large systemic velocity for this cluster and was used to distinguish 33 residual field interlopers. The final sample of member stars has 67 BSSs and 114 reference stars. Similarly to what is found in other clusters, the totality of the reference stars has negligible rotation (&lt; 20 km s-1), while the BSS rotational velocity distribution shows a long tail extending up to ~200 km s-1, with 19 BSSs (out of 67) spinning faster than 40 km s-1. This sets the percentage of fast-rotating BSSs to ~28%. Such a percentage is roughly comparable to that measured in other loose systems (ω Centauri, M4, and M55) and significantly larger than that measured in high-density clusters (as 47 Tucanae, NGC 6397, NGC 6752, and M30). This evidence supports a scenario where recent BSS formation (mainly from the evolution of binary systems) is occurring in low-density environments. We also find that the BSS rotational velocity tends to decrease for decreasing luminosity and surface temperature, similarly to what is observed in main-sequence stars. Hence, further investigations are needed to understand the impact of BSS internal structure on the observed rotational velocities. *Based on observations collected at the Clay Magellan Telescope, located at Las Campanas Observatory (Chile).

Keywords: Globular star clusters, Blue straggler stars, Spectroscopy
Nitrogen as a Tracer of Giant Planet Formation. II. Comprehensive Study of Nitrogen Photochemistry and Implications for Observing NH<SUB>3</SUB> and HCN in Transmission and Emission Spectra. Atmospheric nitrogen may provide important constraints on giant planet formation. Following our semianalytical work, we further pursue the relation between observable NH3 and an atmosphere's bulk nitrogen abundance by applying the photochemical kinetics model VULCAN across planetary equilibrium temperature, mass, age, eddy diffusion coefficient, atmospheric composition, and stellar spectral type. We confirm that the quenched NH3 abundance coincides with the bulk nitrogen abundance only at sub-Jupiter-mass (≲1M J) planets and old ages (≳1 Gyr) for solar composition atmospheres, highlighting important caveats for inferring atmospheric nitrogen abundances. Our semianalytical model reproduces the quenched NH3 abundance computed by VULCAN and thus helps to infer the bulk nitrogen abundance from a retrieved NH3 abundance. By computing transmission and emission spectra, we predict that the equilibrium temperature range of 400-1000 K is optimal for detecting NH3 because NH3 depletion by thermochemistry and photochemistry is significant at hotter planets whereas entire spectral features become weak at colder planets. For Jupiter-mass planets around Sun-like stars in this temperature range, NH3 leaves observable signatures of ~50 ppm at 1.5, 2.1, and 11 μm in transmission spectra and &gt;300-100 ppm at 6 and 11 μm in emission spectra. The photodissociation of NH3 leads HCN to replace NH3 at low pressures. However, the low HCN column densities lead to much weaker absorption features than for NH3. The NH3 features are readily accessible to JWST observations to constrain atmospheric nitrogen abundances, which may open a new avenue to understanding the formation processes of giant exoplanets.

Keywords: Exoplanet atmospheric composition , Exoplanets, Astrochemistry, Exoplanet formation, Exoplanet atmospheres, Exoplanet atmospheric structure
The Disk Reverberation Mapping of X-Ray Weak Quasars: A Case Study of SDSS J153913.47+395423.4. The widely adopted "lamppost" thermal reprocessing model, in which the variable UV/optical emission is a result of the accretion-disk reprocessing of the highly fluctuating X-ray emission, can be tested by measuring interband time lags in quasars spanning a range of X-ray power. This work reports the interband time lag in an apparent X-ray-weak quasar, SDSS J153913.47+395423.4. A significant cross correlation with a time delay of ~33 days (observed frame) is detected in the Zwicky Transient Facility g and r light curves of SDSS J153913.47+395423.4. The observed X-ray power seems to be too weak to account for the observed interband cross correlation with time delay. Hence the X-ray-weak quasar SDSS J153913.47+395423.4 is either intrinsically X-ray normal (but observationally X-ray weak), or the X-ray emission is not the only mechanism to drive UV/optical variability. In the former case, the required X-ray power is at least 19 times stronger than observed, which requires either an exceptionally anisotropic corona or Compton-thick obscuration. Alternatively, the corona-heated accretion-disk reprocessing or the EUV torus models may account for the observed time lags.

Keywords: Accretion, Supermassive black holes, Active galactic nuclei, Quasars
ALMA 300 pc Resolution Imaging of a z = 6.79 Quasar: No Evidence for Supermassive Black Hole Influence on the C II Kinematics. We present Atacama Large Millimeter/submillimeter Array (ALMA) [C II] 158 μm and dust continuum observations of the z = 6.79 quasar J0109-3047 at a resolution of 0.″045 (~300 pc). The dust and [C II] emission are enclosed within a ~500 pc radius, with the central beam (r &lt; 144 pc) accounting for ~25% (8%) of the total continuum ([C II]) emission. The far-infrared (FIR) luminosity density increases radially from ~5 × 1011  L ☉ kpc-2 to a central value of ~70 × 1011 L ☉ kpc-2 (SFRD ~50-700 M ☉yr-1 kpc-2). The [C II] kinematics are dispersion dominated with a constant velocity dispersion of 137 ± 6 km s-1. The constant dispersion implies that the underlying mass distribution is not centrally peaked, consistent with the expectations of a flat gas mass profile. The lack of an upturn in velocity dispersion within the central beam is inconsistent with a black hole mass greater than M BH &lt; 6.5 × 108  M ☉ (2σ level), unless highly fine-tuned changes in the interstellar medium properties conspire to produce a decrease of the gas mass in the central beam comparable to the black hole mass. Our observations therefore imply either that (a) the black hole is less massive than previously measured, or (b) the central peak of the FIR and [C II] emission are not tracing the location of the black hole, as suggested by the tentative offset between the near-infrared position of the quasar and the ALMA continuum emission.

Keywords: Supermassive black holes, Quasars, Galaxy dynamics, Interstellar medium, Submillimeter astronomy, High-redshift galaxies
Can Cosmologically Coupled Mass Growth of Black Holes Solve the Mass Gap Problem?. Observations of elliptical galaxies suggest that black holes (BHs) might serve as dark energy candidates, coupled to the expansion of the Universe. According to this hypothesis, the mass of a BH could increase as the Universe expands. BH low-mass X-ray binaries (LMXBs) in the Galactic disk were born several gigayears ago, making the coupling effect potentially significant. In this work, we calculate the evolution of BH binaries with a binary population synthesis method to examine the possible influence of cosmologically coupled growth of BHs, if it really exists. The measured masses of the compact objects in LMXBs show a gap around ~2.5-5 M ⊙, separating the most-massive neutron stars from the least-massive BHs. Our calculated results indicate that considering the mass growth seems to (partially) account for the mass gap and the formation of compact BH LMXBs, alleviating the challenges in modeling the formation and evolution of BH LMXBs with traditional theory. However, critical observational evidence like the detection of intermediate-mass BH binaries is required to test this hypothesis.

Keywords: Low-mass x-ray binary stars, Dark energy, Stellar mass black holes, Expanding universe
The Contribution and FIP Bias of Three Types of Materials inside ICMEs Associated with Different Flare Intensities. The relationship between coronal mass ejections (CMEs) and flares is an important issue in solar and stellar physics. The studies on the origination and generation mechanisms of interplanetary CME (ICME) materials are crucial for understanding the connection between CMEs and flares. The materials inside ICMEs can be classified into three types, coming from corona directly (corona materials), heated by magnetic reconnection in corona (heated corona materials), and generated by chromospheric evaporation (chromospheric evaporation materials). Here the contribution and first ionization potential (FIP) bias of three types of materials inside ICMEs associated with different flare intensities are analyzed and compared. We find that the speeds and scales of near-Earth ICMEs both increase with flare intensities. The proportions of heated corona materials are nearly constant with flare intensities. The contributions of corona materials (chromospheric evaporation materials) are significantly decreased (increased) with flare intensities. More than two-thirds of materials are chromospheric evaporation materials for ICMEs associated with strong flares. The FIP bias of corona materials and heated corona materials is almost the same. The FIP bias of chromospheric evaporation materials is significantly higher than that of corona materials and heated corona materials, and it is increased with flare intensities. The above characteristics of FIP bias can be explained reasonably by the origination and generation mechanisms of three types of ICME materials. The present study demonstrates that the origination and generation mechanisms of ICME materials are significantly influenced by flare intensities. The reasons for the elevation of FIP bias, if ICMEs are regarded as a whole, are that the FIP bias of chromospheric evaporation materials is much higher, and the chromospheric evaporation materials contributed significantly to the ICMEs that are associated with strong flares.

Keywords: Solar abundances, Solar flares, Solar coronal mass ejections
A 3D Numerical Study of Anisotropies in Supernova Remnants. We develop a suite of 3D hydrodynamic models of supernova remnants (SNRs) expanding against the circumstellar medium (CSM). We study the Rayleigh-Taylor instability forming at the expansion interface by calculating an angular power spectrum for each of these models. The power spectra of young SNRs are seen to exhibit a dominant angular mode, which is a diagnostic of their ejecta density profile as found by previous studies. The steep scaling of power at smaller modes and the time evolution of the spectra are indicative of the absence of a turbulent cascade. Instead, as the time evolution of the spectra suggests, they may be governed by an angular mode-dependent net growth rate. We also study the impact of anisotropies in the ejecta and in the CSM on the power spectra of velocity and density. We confirm that perturbations in the density field (whether imposed on the ejecta or the CSM) do not influence the anisotropy of the remnant significantly unless they have a very large amplitude and form large-scale coherent structures. In any case, these clumps can only affect structures on large angular scales. The power spectrum on small angular scales is completely independent of the initial clumpiness and governed only by the growth and saturation of the Rayleigh-Taylor instability.

Keywords: Supernova remnants, Shocks, Hydrodynamical simulations, Hydrodynamics
Multipoint Observations of the Dynamics at an ICME Sheath-Ejecta Boundary. The radial evolution of interplanetary coronal mass ejections (ICMEs) is dependent on their interaction with the ambient medium, which causes ICME erosion and affects their geoefficiency. Here, an ICME front boundary, which separates the confined ejecta from the mixed, interacted sheath-ejecta plasma upstream, is analyzed in a multipoint study examining the ICME at 1 au on 2020 April 20. A bifurcated current sheet, highly filamented currents, and a two-sided jet were observed at the boundary. The two-sided jet, which was recorded for the first time for a magnetic shear angle &lt;40°, implies multiple (patchy) reconnection sites associated with the ICME erosion. The reconnection exhaust exhibited fine structure, including multistep magnetic field rotation and localized structures that were measured only by separate Cluster spacecraft with the mission inter-spacecraft separation of 0.4-1.6 R E. The mixed plasma upstream of the boundary with a precursor at 0.8 au lacked coherency at 1 au and exhibited substantial variations of southward magnetic fields over radial (transverse) distances of 41-237 R E (114 R E). This incoherence demonstrates the need for continuous (sub)second-resolution plasma and field measurements at multiple locations in the solar wind to adequately address the spatiotemporal structure of ICMEs and to produce accurate space weather predictions.

Keywords: Solar wind, Interplanetary magnetic fields, Solar coronal mass ejections, Solar magnetic reconnection
Discovery and Timing of Millisecond Pulsars with the Arecibo 327 MHz Drift-scan Survey. We present the discovery and timing solutions of four millisecond pulsars (MSPs) discovered in the Arecibo 327 MHz Drift-Scan Pulsar Survey. Three of these pulsars are in binary systems, consisting of a redback (PSR J2055+1545), a black widow (PSR J1630+3550), and a neutron star-white dwarf binary (PSR J2116+1345). The fourth MSP, PSR J2212+2450, is isolated. We present the multiyear timing solutions as well as polarization properties across a range of radio frequencies for each pulsar. We perform a multiwavelength search for emission from these systems and find an optical counterpart for PSR J2055+1545 in Gaia DR3, as well as a gamma-ray counterpart for PSR J2116+1345 with the Fermi-LAT telescope. Despite the close colocation of PSR J2055+1545 with a Fermi source, we are unable to detect gamma-ray pulsations, likely due to the large orbital variability of the system. This work presents the first two binaries found by this survey with orbital periods shorter than a day; we expect to find more in the 40% of the survey data that have yet to be searched.

Keywords: Gamma-ray sources, Binary pulsars, Millisecond pulsars
Radio Emission From a z = 10.1 Black Hole in UHZ1. The recent discovery of a 4 × 107 M ⊙ black hole (BH) in UHZ1 at z = 10.3, just 450 Myr after the Big Bang, suggests that the seeds of the first quasars may have been direct-collapse BHs from the collapse of supermassive primordial stars at z ~ 20. This object was identified in James Webb Space Telescope NIRcam and Chandra X-ray data, but recent studies suggest that radio emission from such a BH should also be visible to the Square Kilometer Array (SKA) and the next-generation Very Large Array (ngVLA). Here, we present estimates of radio flux densities for UHZ1 from 0.1 to 10 GHz, and find that SKA and ngVLA could detect it with integration times of 10-100 hr and just 1-10 hr, respectively. It may be possible to see this object with VLA now with longer integration times. The detection of radio emission from UHZ1 would be a first test of exciting new synergies between near-infrared and radio observatories that could open the era of z ~ 5-15 quasar astronomy in the coming decade.

Keywords: Astrophysical black holes
Experimental Investigation of the Photochemical Production of Hydrocarbons in Warm Gas Giant Exoplanet Atmospheres. In warm (equilibrium temperature &lt;1000 K) gas giant exoplanet atmospheres, the observation of trace species in abundances deviating from thermochemical equilibrium predictions could be used as an indicator of disequilibrium chemical processes, such as photochemistry. To predict which compounds could be used as such tracers, it is therefore essential to study how photochemical processes affect their abundances. For this purpose, we investigated experimentally the efficiency of the photochemical formation of hydrocarbons in gas mixtures representative of warm gas giant atmospheres as a function of the gas temperature at millibar pressures. We find that, compared to thermal reactions alone, photochemistry efficiently promotes, under the studied conditions, the formation of hydrocarbons, with the detection of acetylene, ethane, and propane, as well as carbon monoxide. Therefore, our results confirm the importance of photochemistry in exoplanet atmospheres as a disequilibrium process. Ethane is the major hydrocarbon formed in our experiments, in apparent contradiction with the prediction by thermo-photochemical models that acetylene should be the main hydrocarbon product. We also observe an evolution of the hydrocarbon production efficiency as a function of the temperature, a behavior not reproduced by a 0D thermo-photochemical model. Additional studies are necessary to definitively understand the origin of the differences between the experimental and modeling results and to infer the importance of our results for understanding hydrocarbon formation in warm gas giant exoplanet atmospheres. Finally, our work demonstrates the importance of experimental studies together with modeling studies to accurately interpret, understand, and predict observations of exoplanet atmospheres.

Keywords: Exoplanet atmospheric composition , Hot Jupiters, Laboratory astrophysics, Planetary atmospheres, Exoplanet atmospheres
Deep Search for Molecular Oxygen in TW Hya. The dominant form of oxygen in cold molecular clouds is gas-phase carbon monoxide (CO) and ice-phase water (H2O). Yet, in planet-forming disks around young stars, gas-phase CO and H2O are less abundant relative to their interstellar medium values, and no other major oxygen-carrying molecules have been detected. Some astrochemical models predict that gas-phase molecular oxygen (O2) should be a major carrier of volatile oxygen in disks. We report a deep search for emission from the isotopologue 16O18O (N  J  = 21 - 01 line at 233.946 GHz) in the nearby protoplanetary disk around TW Hya. We used imaging techniques and matched filtering to search for weak emission but do not detect 16O18O. Based on our results, we calculate upper limits on the gas-phase O2 abundance in TW Hya of (6.4-70) × 10-7 relative to H, which is 2-3 orders of magnitude below solar oxygen abundance. We conclude that gas-phase O2 is not a major oxygen carrier in TW Hya. Two other potential oxygen-carrying molecules, SO and SO2, were covered in our observations, which we also do not detect. Additionally, we report a serendipitous detection of the C15N N  J  = 25/2 - 13/2 hyperfine transitions, F = 3 - 2 and F = 2 - 1, at 219.9 GHz, which we found via matched filtering and confirm through imaging.

Keywords: Protoplanetary disks, Astrochemistry
Early Results from GLASS-JWST. XXIII. The Transmission of Lyα from UV-faint z   3-6 Galaxies. Lyα emission from galaxies can be used to trace neutral hydrogen in the epoch of reionization, however, there is a degeneracy between the attenuation of Lyα in the intergalactic medium (IGM) and the line profile emitted by the galaxy. Large shifts of Lyα redward of systemic due to scattering in the interstellar medium can boost Lyα transmission in the IGM during reionization. The relationship between the Lyα velocity offset from systemic and other galaxy properties is not well established at high redshift or low luminosities, due to the difficulty of observing emission lines which trace the systemic redshift. Rest-frame optical spectroscopy with JWST/NIRSpec has opened a new window into understanding Lyα at z &gt; 3. We present a sample of 12 UV-faint galaxies (-20 ≲ M UV ≲ -16) at 3 ≲ z ≲ 6, with Lyα velocity offsets, ∆v Lyα , measured from the Very Large Telescope/MUSE and JWST/NIRSpec from the GLASS-JWST Early Release Program. We find a median ∆v Lyα  of 205 km s-1 and standard deviation of 75 km s-1, compared to 320 and 170 km s-1, respectively, for M UV &lt; -20 galaxies in the literature. Our new sample demonstrates the previously observed trend of decreasing Lyα velocity offset with decreasing UV luminosity and optical line velocity dispersion, which extends to M UV ≳ -20, consistent with a picture where the Lyα profile is shaped by gas close to the systemic redshift. Our results imply that during reionization Lyα from UV-faint galaxies will be preferentially attenuated, but that detecting Lyα with low ∆v Lyα  can be an indicator of large ionized bubbles.

Keywords: Emission line galaxies, Galaxy evolution, Lyman-alpha galaxies, High-redshift galaxies, Galaxies
Are "Changing-look" Active Galactic Nuclei Special in the Coevolution of Supermassive Black Holes and Their Hosts? I.. The nature of the so-called "changing-look" (CL) active galactic nucleus (AGN), which is characterized by spectral-type transitions within ~10 yr, remains an open question. As the first in our series of studies, we attempt here to understand the CL phenomenon from the view of the coevolution of AGNs and their host galaxies (i.e., if CL-AGNs are at a specific evolutionary stage) by focusing on the SDSS local "partially obscured" AGNs in which the stellar population of the host galaxy can be easily measured in the integrated spectra. A spectroscopic follow-up program using the Xinglong 2.16 m, Lick/Shane 3 m, and Keck 10 m telescopes enables us to identify in total nine CL-AGNs from a sample of 59 candidates selected by their mid-infrared variability. Detailed analysis of these spectra shows that the host galaxies of the CL-AGNs are biased against young stellar populations and tend to be dominated by intermediate-age stellar populations. This motivates us to propose that CL-AGNs are probably particular AGNs at a specific evolutionary stage, such as a transition stage from "feast" to "famine" fueling of the supermassive black hole. In addition, we reinforce the previous claim that CL-AGNs tend to be biased against both a high Eddington ratio and a high bolometric luminosity, suggesting that the disk-wind broad-line-region model is a plausible explanation of the CL phenomenon.

Keywords: Supermassive black holes, Active galaxies, Active galactic nuclei, Galaxy evolution, Spectroscopy, X-ray active galactic nuclei
Atmospheric Effects on Neutron Star Parameter Constraints with NICER. We present an analysis of the effects of uncertainties in the atmosphere models on the radius, mass, and other neutron star parameter constraints for the NICER observations of rotation-powered millisecond pulsars. To date, NICER has applied the X-ray pulse profile modeling technique to two millisecond-period pulsars: PSR J0030+0451 and the high-mass pulsar PSR J0740+6620. These studies have commonly assumed a deep-heated, fully ionized hydrogen atmosphere model, although they have explored the effects of partial ionization and helium composition in some cases. Here, we extend that exploration and also include new models with partially ionized carbon composition, externally heated hydrogen, and an empirical atmospheric beaming parameterization to explore deviations in the expected anisotropy of the emitted radiation. None of the studied atmosphere cases have any significant influence on the inferred radius of PSR J0740+6620, possibly due to its X-ray faintness, tighter external constraints, and/or viewing geometry. In the case of PSR J0030+0451, both the composition and ionization state could significantly alter the inferred radius. However, based on the evidence (prior predictive probability of the data), partially ionized hydrogen and carbon atmospheres are disfavored. The difference in the evidence for ionized hydrogen and helium atmospheres is too small to be decisive for most cases, but the inferred radius for helium models trends to larger sizes around or above 14-15 km. External heating or deviations in the beaming that are less than 5% at emission angles smaller than 60°, on the other hand, have no significant effect on the inferred radius.

Keywords: Neutron stars, X-ray astronomy