Sazuna/UAT_keywords huggingface dataset:
A Detailed Temperature Map of the Archetypal Protostellar Shocks in L1157. We present sensitive NH3 (1,1)-(7,7) line images from the Karl G. Jansky Very Large Array toward successive shocks, which are associated with the blueshifted outflow lobe driven by the compact protobinary system L1157. Within a projection distance of 0.1 pc, our observations not only trace the quiescent and cold gas in the flattened envelope, but also illustrate the complex physical and chemical processes that take place where the high-velocity jet impinges on its surrounding medium. Specifically, the NH3 ortho-to-para ratio is enhanced by a factor of 2-2.5 along the jet path, where the velocity offset between the line peak and the blueshifted wing reaches values as high as 10 km s-1; it also shows a strong spatial correlation with the NH3 column density, which is enhanced to &gt;1016 cm-2 toward the shock cavities. At a linear resolution of 1500 au, our refined temperature map from the seven NH3 lines shows a gradient from the warm B0 eastern cavity wall (&gt;120 K) to the cool cavity B1 and the earlier shock B2 (&lt;80 K), indicating shock heating.

Keywords: Low mass stars, Stellar bow shocks, Astrochemistry
MUSSES2020J: The Earliest Discovery of a Fast Blue Ultraluminous Transient at Redshift 1.063. In this Letter, we report the discovery of an ultraluminous fast-evolving transient in rest-frame UV wavelengths, MUSSES2020J, soon after its occurrence by using the Hyper Suprime-Cam (HSC) mounted on the 8.2 m Subaru telescope. The rise time of about 5 days with an extremely high UV peak luminosity shares similarities to a handful of fast blue optical transients whose peak luminosities are comparable with the most luminous supernovae while their timescales are significantly shorter (hereafter "fast blue ultraluminous transient," FBUT). In addition, MUSSES2020J is located near the center of a normal low-mass galaxy at a redshift of 1.063, suggesting a possible connection between the energy source of MUSSES2020J and the central part of the host galaxy. Possible physical mechanisms powering this extreme transient such as a wind-driven tidal disruption event and an interaction between supernova and circumstellar material are qualitatively discussed based on the first multiband early-phase light curve of FBUTs, although whether the scenarios can quantitatively explain the early photometric behavior of MUSSES2020J requires systematical theoretical investigations. Thanks to the ultrahigh luminosity in UV and blue optical wavelengths of these extreme transients, a promising number of FBUTs from the local to the high-z universe can be discovered through deep wide-field optical surveys in the near future.

Keywords: Optical observation, Wide-field telescopes, Transient sources, Time domain astronomy, Transient detection, Compact objects, Ultraviolet transient sources
Electric Field Screening in Pair Discharges and Generation of Pulsar Radio Emission. Pulsar radio emission may be generated in pair discharges that fill the pulsar magnetosphere with plasma as an accelerating electric field is screened by freshly created pairs. In this Letter, we develop a simplified analytic theory for the screening of the electric field in these pair discharges and use it to estimate total radio luminosity and spectrum. The discharge has three stages. First, the electric field is screened for the first time and starts to oscillate. Next, a nonlinear phase occurs. In this phase, the amplitude of the electric field experiences strong damping because the field dramatically changes the momenta of newly created pairs. This strong damping ceases, and the system enters a final linear phase, when the electric field can no longer dramatically change pair momenta. Applied to pulsars, this theory may explain several aspects of radio emission, including the observed luminosity, L rad ~ 1028 erg s-1, and the observed spectrum, S  ω  ~ ω -1.4±1.0.

Keywords: Neutron stars, High energy astrophysics, Plasma physics, Plasma astrophysics, Pulsars, Radio pulsars
Are the Magnetic Field Directions of Surrounding Loops a Key Parameter for Confining a Solar Filament Eruption?. Using high-resolution Hα data from the 1 m New Vacuum Solar Telescope, combined with multiband Atmospheric Imaging Assembly extreme ultraviolet observations and Helioseismic and Magnetic Imager light-of-sight magnetograms from the Solar Dynamical Observatory, we study a quiet-Sun filament eruption on 2019 November 1. During the erupting process, the filament was blocked by at least three sets of surrounding loops (L1-L3). The magnetic field direction of L2 is opposite to that of the top segment of the erupting filament. While the top segment contacted L2, a current sheet formed between L2 and the top segment. Then, magnetic reconnection took place, resulting in the destruction of L2 and the filament. On the other hand, the magnetic field direction of L1 is the same as that of the left leg of the erupting filament, and that of L3 is the same as that of the right leg. The left leg expanded eastward and met L1, then it stopped. The right leg expanded westward and collided with L3. It rebounded and finally stopped at the interaction region. These observations imply that the magnetic field directions of the surrounding magnetic structures are a key parameter for confining a filament eruption. While the field direction of a surrounding structure is the same as that of an eruptive filament, the filament is confined.

Keywords: Solar prominences, Solar magnetic reconnection, Solar filaments, Solar magnetic fields, Solar activity
Characterizing the Breakdown of Quasi-universality in Postmerger Gravitational Waves from Binary Neutron Star Mergers. The postmerger gravitational wave (GW) emission from a binary neutron star merger is expected to provide exciting new constraints on the dense-matter equation of state (EoS). Such constraints rely, by and large, on the existence of quasi-universal relations, which relate the peak frequencies of the postmerger GW spectrum to properties of the neutron star structure in a model-independent way. In this work, we report on violations of existing quasi-universal relations between the peak spectral frequency, f 2, and the stellar radius, for EoS models with backwards-bending slopes in their mass-radius relations (such that the radius increases at high masses). The violations are extreme, with variations in f 2 of up to ~600 Hz between EoSs that predict the same radius for a 1.4 M ⊙ neutron star but that have significantly different radii at higher masses. Quasi-universality can be restored by adding in a second parameter to the fitting formulae that depends on the slope of the mass-radius curve. We further find strong evidence that quasi-universality is better maintained for the radii of very massive stars (with masses 2 M ⊙). Both statements imply that f 2 is mainly sensitive to the high-density EoS. Combined with observations of the binary neutron star inspiral, these generalized quasi-universal relations can be used to simultaneously infer the characteristic radius and slope of the neutron star mass-radius relation.

Keywords: Neutron stars, Gravitational waves
Water UV-shielding in the Terrestrial Planet-forming Zone: Implications for Carbon Dioxide Emission. Carbon dioxide is an important tracer of the chemistry and physics in the terrestrial planet-forming zone. Using a thermochemical model that has been tested against the mid-infrared water emission, we reinterpret the CO2 emission as observed with Spitzer. We find that both water UV-shielding and extra chemical heating significantly reduce the total CO2 column in the emitting layer. Water UV-shielding is the more efficient effect, reducing the CO2 column by ~2 orders of magnitude. These lower CO2 abundances lead to CO2-to-H2O flux ratios that are closer to the observed values, but CO2 emission is still too bright, especially in relative terms. Invoking the depletion of elemental oxygen outside of the water midplane ice line more strongly impacts the CO2 emission than it does the H2O emission, bringing the CO2-to-H2O emission in line with the observed values. We conclude that the CO2 emission observed with Spitzer-IRS is coming from a thin layer in the photosphere of the disk, similar to the strong water lines. Below this layer, we expect CO2 not to be present except when replenished by a physical process. This would be visible in the 13CO2 spectrum as well as certain 12CO2 features that can be observed by JWST-MIRI.

Keywords: Protoplanetary disks, Astrochemistry
Constraining High-redshift Stellar-mass Primordial Black Holes with Next-generation Ground-based Gravitational-wave Detectors. The possible existence of primordial black holes in the stellar-mass window has received considerable attention because their mergers may contribute to current and future gravitational-wave detections. Primordial black hole mergers, together with mergers of black holes originating from Population III stars, are expected to dominate at high redshifts (z ≳ 10). However, the primordial black hole merger rate density is expected to rise monotonically with redshift, while Population III mergers can only occur after the birth of the first stars. Next-generation gravitational-wave detectors such as the Cosmic Explorer (CE) and Einstein Telescope (ET) can access this distinctive feature in the merger rates as functions of redshift, allowing for direct measurement of the abundance of the two populations and hence for robust constraints on the abundance of primordial black holes. We simulate four months' worth of data observed by a CE-ET detector network and perform hierarchical Bayesian analysis to recover the merger rate densities. We find that if the universe has no primordial black holes with masses of ${ \mathcal O }(10{M}_{\odot })$ , the projected upper limit on their abundance f PBH as a fraction of dark matter energy density may be as low as ${f}_{\mathrm{PBH}}\sim { \mathcal O }({10}^{-5})$ , about two orders of magnitude lower than the current upper limits in this mass range. If instead f PBH ≳ 10-4, future gravitational-wave observations would exclude f PBH = 0 at the 95% credible interval.

Keywords: Gravitational wave sources, Gravitational waves, Primordial black holes, Gravitational wave astronomy
Jansky Very Large Array Detections of CO(1-0) Emission in H I-absorption-selected Galaxies at z ≳ 2. We report a Karl G. Jansky Very Large Array search for redshifted CO(1-0) emission from three H I-absorption-selected galaxies at z ≈ 2, identified earlier in their CO(3-2) or CO(4-3) emission. We detect CO(1-0) emission from DLA B1228-113 at z ≈ 2.1933 and DLA J0918+1636 at z ≈ 2.5848; these are the first detections of CO(1-0) emission in high-z H I-selected galaxies. We obtain high molecular gas masses, M mol ≈ 1011 × (α CO/4.36) M ⊙, for the two objects with CO(1-0) detections, which are a factor of ≈1.5-2 lower than earlier estimates. We determine the excitation of the mid-J CO rotational levels relative to the J = 1 level, r  J1, in H I-selected galaxies for the first time, obtaining r 31 = 1.00 ± 0.20 and r 41 = 1.03 ± 0.23 for DLA J0918+1636, and r 31 = 0.86 ± 0.21 for DLA B1228-113. These values are consistent with thermal excitation of the J = 3 and J = 4 levels. The excitation of the J = 3 level in the H I-selected galaxies is similar to that seen in massive main-sequence and submillimeter galaxies at z≳2, but higher than that in main-sequence galaxies at z ≈ 1.5; the higher excitation of the galaxies at z ≳ 2 is likely to be due to their higher star formation rate (SFR) surface density. We use Hubble Space Telescope Wide Field Camera 3 imaging to detect the rest-frame near-ultraviolet (NUV) emission of DLA B1228-113, obtaining an NUV SFR of 4.44 ± 0.47 M ⊙ yr-1, significantly lower than that obtained from the total infrared luminosity, indicating significant dust extinction in the z ≈ 2.1933 galaxy.

Keywords: Damped Lyman-alpha systems, High-redshift galaxies, CO line emission
Beginning a Journey Across the Universe: The Discovery of Extragalactic Neutrino Factories. Neutrinos are the most elusive particles in the universe, capable of traveling nearly unimpeded across it. Despite the vast amount of data collected, a long-standing and unsolved issue is still the association of high-energy neutrinos with the astrophysical sources that originate them. Among the candidate sources of neutrinos, there are blazars, a class of extragalactic sources powered by supermassive black holes that feed highly relativistic jets, pointed toward Earth. Previous studies appear controversial, with several efforts claiming a tentative link between high-energy neutrino events and individual blazars, and others putting into question such relation. In this work, we show that blazars are unambiguously associated with high-energy astrophysical neutrinos at an unprecedented level of confidence, i.e., a chance probability of 6 × 10-7. Our statistical analysis provides the observational evidence that blazars are astrophysical neutrino factories and hence, extragalactic cosmic-ray accelerators.

Keywords: Supermassive black holes, Neutrino telescopes, Blazars, Neutrino astronomy, Relativistic jets, Cosmic ray astronomy
A Look at Outbursts of Comet C/2014 UN<SUB>271</SUB> (Bernardinelli-Bernstein) near 20 au. Cometary activity may be driven by ices with very low sublimation temperatures, such as carbon monoxide ice, which can sublimate at distances well beyond 20 au. This point is emphasized by the discovery of the Oort cloud comet C/2014 UN271 (Bernardinelli-Bernstein) and its observed activity out to ~26 au. Through observations of this comet's optical brightness and behavior, we can potentially discern the drivers of activity in the outer solar system. We present a study of the activity of comet Bernardinelli-Bernstein with broad-band optical photometry taken at 19-20 au from the Sun (2021 June to 2022 February) as part of the LCO Outbursting Objects Key (LOOK) Project. Our analysis shows that the comet's optical brightness during this period was initially dominated by cometary outbursts, stochastic events that ejected ~107 to ~108 kg of material on short (&lt;1 day) timescales. We present evidence for three such outbursts occurring in 2021 June and September. The nominal nuclear volumes excavated by these events are similar to the 10-100 m pit-shaped voids on the surfaces of short-period comet nuclei, as imaged by spacecraft. Two out of three Oort cloud comets observed at large pre-perihelion distances exhibit outburst behavior near 20 au, suggesting such events may be common in this population. In addition, quiescent CO-driven activity may account for the brightness of the comet in 2022 January to February, but that variations in the cometary active area (i.e., the amount of sublimating ice) with heliocentric distance are also possible.

Keywords: Optical astronomy, Long period comets, Comet surfaces, Broad band photometry, Coma dust
Constraining the Progenitor System of the Type Ia Supernova 2021aefx. We present high-cadence optical and ultraviolet light curves of the normal Type Ia supernova (SN) 2021aefx, which shows an early bump during the first two days of observation. This bump may be a signature of interaction between the exploding white dwarf and a nondegenerate binary companion, or it may be intrinsic to the white dwarf explosion mechanism. In the case of the former, the short duration of the bump implies a relatively compact main-sequence companion star, although this conclusion is viewing-angle dependent. Our best-fit companion-shocking and double-detonation models both overpredict the UV luminosity during the bump, and existing nickel-shell models do not match the strength and timescale of the bump. We also present nebular spectra of SN 2021aefx, which do not show the hydrogen or helium emission expected from a nondegenerate companion, as well as a radio nondetection that rules out all symbiotic progenitor systems and most accretion disk winds. Our analysis places strong but conflicting constraints on the progenitor of SN 2021aefx; no current model can explain all of our observations.

Keywords: White dwarf stars, Type Ia supernovae, Binary stars, Supernovae
The Low-redshift Lyα Forest as a Constraint for Models of AGN Feedback. We study the sensitivity of the z = 0.1 Lyα forest observables, such as the column density distribution function (CDD), flux PDF, flux power spectrum, and line-width distribution, to subgrid models of active galactic nucleus (AGN) feedback using the Illustris and IllustrisTNG (TNG) cosmological simulations. The two simulations share an identical ultraviolet background (UVB) prescription and similar cosmological parameters, but TNG features an entirely reworked AGN feedback model. Due to changes in the AGN radio-mode model, the original Illustris simulations have a factor of 2-3 fewer Lyα absorbers than TNG at column densities N H I  &lt; 1015.5 cm-2. We compare the simulated forest statistics to UV data from the Cosmic Origins Spectrograph (COS) and find that neither simulation can reproduce the slope of the absorber distribution. Both Illustris and TNG also produce significantly smaller line-width distributions than observed in the COS data. We show that TNG is in much better agreement with the observed z = 0.1 flux power spectrum than Illustris. We explore which statistics can disentangle the effects of AGN feedback from alternative UVB models by rescaling the UVB of Illustris to produce a CDD match to TNG. While this UVB rescaling is degenerate with the effect of AGN feedback on the CDD, the amplitude and shape of the flux PDF and 1D flux power spectrum change in a way distinct from the scaling of the UVB. Our study suggests that the z = 0.1 Lyα forest observables can be used as a diagnostic of AGN feedback models.

Keywords: Intergalactic gas, Lyman alpha forest, Intergalactic medium
Nucleosynthesis Contribution of Neutrino-dominated Accretion Flows to the Chemical Evolution of Active Galactic Nuclei. Recent observations of quasars show high line-flux ratios in their broad emission lines and the ratios appear to be independent of redshift up to z ≳ 6, which indicates that the broad-line regions of these early quasars are surprisingly metal-rich. Here, we revisit the chemical evolution of high-redshift quasars by adding a new ingredient, i.e., the neutrino-dominated accretion flows (NDAFs) with outflows, on top of the conventional core-collapse supernovae (CCSNe). In the presence of the chemical contribution from NDAFs with outflows, the total metal mass (i.e., the summation of the conventional CCSN and NDAFs with outflows) per CCSN depends weakly upon the mass of the progenitor star if the mass is in the range of ~25-55 M ⊙. We model the chemical evolution by adopting a improved open-box model with three typical initial mass functions (IMFs). We find that, with the additional chemical contribution from NDAFs with outflows, the quasar metallicity can be enriched more rapidly in the very early universe (z ~ 10) and reaches a higher saturation than the no-NDAF case at z ~ 8, after which they evolve slowly with redshift. The quasar metallicity can reach ~20 Z ⊙ (Z ⊙ denotes the metallicity of the Sun, ~20% of which is produced by NDAF outflows) at z ~ 8 for the "top-heavy" IMF model in Toyouchi et al., which readily explains the quasar observations on the supersolar metal abundance and redshift-independent evolution.

Keywords: Accretion, AGN host galaxies, Black holes, Core-collapse supernovae, Nuclear abundances
Unraveling the Observational Signatures of Cloud-Cloud Collision and Hub-filament Systems in W31. To understand the formation process of massive stars, we present a multiscale and multiwavelength study of the W31 complex hosting two extended H II regions (i.e., G10.30-0.15 (hereafter, W31-N) and G10.15-0.34 (hereafter, W31-S)) powered by a cluster of O-type stars. Several Class I protostars and a total of 49 ATLASGAL 870 μm dust clumps (at d = 3.55 kpc) are found toward the H II regions where some of the clumps are associated with the molecular outflow activity. These results confirm the existence of a single physical system hosting the early phases of star formation. The Herschel 250 μm continuum map shows the presence of a hub-filament system (HFS) toward both W31-N and W31-S. The central hubs harbor H II regions and they are depicted with extended structures (with T  d  ~ 25-32 K) in the Herschel temperature map. In the direction of W31-S, an analysis of the NANTEN2 12CO(J = 1-0) and SEDIGISM 13CO(J = 2-1) line data supports the presence of two cloud components around 8 and 16 km s-1, and their connection in velocity space. A spatial complementary distribution between the two cloud components is also investigated toward W31-S, where the signposts of star formation, including massive O-type stars, are concentrated. These findings favor the applicability of cloud-cloud collision (CCC) around ~2 Myr ago in W31-S. Overall, our observational findings support the theoretical scenario of CCC in W31, which explains the formation of massive stars and the existence of HFSs.

Keywords: Star forming regions, Molecular clouds, Interstellar emissions, Pre-main sequence stars, Star formation, Dust continuum emission, Interstellar medium, Young stellar objects, H II regions
Polarized Optical Emission of the Blazar PKS 1222+216: Discovery of a 420 day Quasiperiodic Signal. We report our search for quasiperiodic signals in long-term optical and γ-ray data for the blazar PKS 1222+216, where the data are from the Steward Observatory blazar monitoring program and the all-sky survey with the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, respectively. A quasiperiodic signal, with a period of ≃420 days and a significance of &gt;5σ, is found in the measurements of the optical linear polarization degree for the source, while no similar signals are found in the optical and γ-ray light curves covering approximately the same time period of ~10 yr. We study the quasiperiodic variations by applying a helical jet model and find that the model can provide a good explanation. This work shows that polarimetry can be a powerful tool for revealing the physical properties, in particular the configuration of the magnetic fields of jets from galactic supermassive black holes.

Keywords: Active galactic nuclei, Radio jets, Polarimetry
New Constraints on the Spin of the Black Hole Cygnus X-1 and the Physical Properties of its Accretion Disk Corona. We present a new analysis of NuSTAR and Suzaku observations of the black hole Cygnus X-1 in the intermediate state. The analysis is performed using kerrC, a new model for analyzing spectral and spectropolarimetric X-ray observations of black holes. kerrC builds on a large library of simulated black holes in X-ray binaries. The model accounts for the X-ray emission from a geometrically thin, optically thick accretion disk, the propagation of the X-rays through the curved black hole spacetime, the reflection off the accretion disk, and the Comptonization of photons in coronae of different 3D shapes and physical properties before and after the reflection. We present the results from using kerrC for the analysis of archival NuSTAR and Suzaku observations taken on 2015 May 27-28. The best wedge-shaped corona gives a better fit than the cone-shaped corona. Although we included cone-shaped coronae in the funnel regions above and below the black hole to resemble to some degree the common assumption of a compact lamppost corona hovering above and/or below the black hole, the fit chooses a very large version of this corona that makes it possible to Comptonize a sufficiently large fraction of the accretion disk photons to explain the observed power-law emission. The analysis indicates a black hole spin parameter a (-1 ≤ a ≤ 1) between 0.861 and 0.921. The kerrC model provides new insights into the radial distribution of the energy flux of returning and coronal emission irradiating the accretion disk. kerrC furthermore predicts small polarization fractions around 1% in the 2-8 keV energy range of the recently launched Imaging X-ray Polarimetry Explorer.

Keywords: Black hole physics, Black holes, Kerr black holes, High mass x-ray binary stars, Stellar mass black holes