adsabs/SciX_UAT_keywords huggingface dataset:
Warping Away Gravitational Instabilities in Protoplanetary Discs

We perform three-dimensional smoothed-particle hydrodynamics simulations of warped, non-coplanar gravitationally unstable discs to show that as the warp propagates through the self-gravitating disk, it heats up the disk rendering it gravitationally stable, thus losing their spiral structure and appearing completely axisymmetric. In their youth, protoplanetary discs are expected to be massive and self-gravitating, which results in nonaxisymmetric spiral structures. However recent observations of young protoplanetary discs with the Atacama Large Millimeter/submillimeter Array have revealed that discs with large-scale spiral structure are rarely observed in the midplane. Instead, axisymmetric discs, with some also having ring and gap structures, are more commonly observed. Our work invloving warps, non-coplanar disk structures that are expected to commonly occur in young discs, potentially resolves this discrepancy between observations and theoretical predictions. We demonstrate that they are able to suppress the large-scale spiral structure of self-gravitating protoplanetary discs.

Keywords: protoplanetary disks
Irregular Proton Injection to High Energies at Interplanetary Shocks

How thermal particles are accelerated to suprathermal energies is an unsolved issue, crucial for many astrophysical systems. We report novel observations of irregular, dispersive enhancements of the suprathermal particle population upstream of a high-Mach-number interplanetary shock. We interpret the observed behavior as irregular "injections" of suprathermal particles resulting from shock front irregularities. Our findings, directly compared to self-consistent simulation results, provide important insights for the study of remote astrophysical systems where shock structuring is often neglected.

Keywords: interplanetary particle acceleration; space plasmas; interplanetary shocks; shocks; heliosphere
Parker Solar Probe Observations of Magnetic Reconnection Exhausts in Quiescent Plasmas near the Sun

Parker Solar Probe observations are analyzed for the presence of reconnection exhausts across current sheets (CSs) within R < 0.26 au during encounters 4–11. Exhausts are observed with nearly equal probability at all radial distances with a preference for quiescent Tp < 0.80 MK plasmas typical of a slow-wind regime. High Tp > 0.80 MK plasmas of a fast wind characterized by significant transverse fluctuations rarely support exhausts irrespective of the CS width. Exhaust observations demonstrate the presence of local temperature gradients across several CSs with a higher-Tp plasma on locally closed fields and a lower-Tp plasma on locally open field lines for an interchange-type reconnection. A CS geometry analysis directly supports the property that X-lines bisect the magnetic field rotation θ-angle, whether the fields and plasmas are asymmetric or not, to maximize reconnection rates and available magnetic energy. The CS normal width d cs distributions suggest that a multiscale reconnection process through nested layers of bifurcated CSs may be responsible for observed power-law distributions beyond the median d cs ∼ 1000 km with an exponential d cs distribution present for ion kinetic dissipation scales below this median. Magnetic field shear θ-angles are essentially identical at R < 0.26 and 1 au with medians at θ ∼ 55° near the Sun and θ ∼ 65° at 1 au. In contrast, the tangential flow shear distributions are different near and far from the Sun. A bimodal flow shear angle distribution is present near the Sun with strong shear flow magnitudes. This distribution is modified with radial distance toward a relatively flat distribution of weaker flow shear magnitudes.

Keywords: solar wind; solar magnetic reconnection
Light Curves of the Explosion of ONe White Dwarf + CO White Dwarf Merger Remnant and Type Icn Supernovae

Type Icn supernovae (SNe Icn) are a newly detected, rare subtype of interacting stripped-envelope supernovae that show narrow P Cygni lines of highly ionized carbon, oxygen, and neon in their early spectra due to the interactions of the SNe ejecta with dense hydrogen- and helium-deficient circumstellar material (CSM). It has been suggested that SNe Icn may have multiple progenitor channels, such as the explosion of carbon-rich Wolf–Rayet stars or the explosion of stripped-envelope SNe, which undergo binary interactions. Among the SNe Icn, SN 2019jc shows unique properties, and previous work inferred that it may stem from the ultrastripped supernova, but other possibilities still exist. In this work, we aim to simulate the light curves from the explosions of oxygen-neon and carbon-oxygen double white dwarf (WD) merger remnants and to further investigate whether the corresponding explosions can appear as some particular SNe Icn. We generate the light curves from the explosive remnants and analyze the influence of different parameters on the light curves, such as the ejecta mass, explosion energy, mass of 56Ni, and CSM properties. Comparing our results with some SNe Icn, we found that the light curves from the explosions of double WD merger remnants can explain the observable properties of SN 2019jc, from which we infer that this special SN Icn may have a different progenitor. Our results indicate that double WD merger may be an alternative model in producing at least one of the SNe Icn.

Keywords: white dwarf stars; stellar mergers; supernovae; core-collapse supernovae
A Population Study of the Radio Emission of Fast Blue Optical Transients

Despite the fact that the progenitor of fast blue optical transients (FBOTs) is still a subject of debate, FBOTs are sometimes suggested to originate from the core collapse of ultra-stripped stars and be powered by a spinning-down neutron star. Following this consideration, it is expected that the late-time evolution of the progenitor stars can leave important imprints in the circumstellar material (CSM) of FBOTs, due to the strong mass loss of the stars. The interaction of the FBOT ejecta with the CSM can drive a long-lasting shock to generate radio emission, which thus enables us to probe the CSM properties through radio observation although such observations are still rare. Within the framework of the magnetar-powered model, Liu et al. fitted the multi-band optical light curves of 40 FBOTs, and hence, the statistical distributions of the FBOT magnetar and ejecta parameters were obtained. Based on these FBOT population results, we investigate the dependence of the radio emission on the mass-loss rate of the progenitors and evaluate the detectability of radio emission from FBOTs with current and future telescopes. It is found that the distribution of the peak time and peak luminosity of the emission at 8.4 GHz are primarily in the regions of t peak,ν = 102.12±0.63 days and L peak,ν = 1028.73±0.83 erg s-1 Hz-1, respectively. A joint detection of the Zwicky Transient Facility and Very Large Array could achieve success in about 8.7% FBOTs of z ≤ 1. Furthermore, if considering a joint detection of the Chinese Space Station Telescope and the Square Kilometer Array, this rate of success could be increased to about 23.9%.

Keywords: supernovae; radio transient sources; transient sources
The Buildup of the Intracluster Light of A85 as Seen by Subaru's Hyper Suprime-Cam

The study of low surface brightness light in large, deep imaging surveys is still uncharted territory as automated data reduction pipelines over-subtract or eliminate this light. Using archival data of the A85 cluster of galaxies taken with the Hyper Suprime-Cam on the Subaru Telescope, we show that using careful data processing can unveil the diffuse light within the cluster, the intracluster light. We reach surface brightness limits of ${\mu }_{g}^{\mathrm{limit}}$ (3σ, 10″ × 10″) = 30.9 and ${\mu }_{i}^{\mathrm{limit}}$ (3σ, 10″ × 10″) = 29.7 mag arcsec-2. We measured the radial surface brightness profiles of the brightest cluster galaxy out to the intracluster light (radius ∼215 kpc) for the g and i bands. We found that both the surface brightness and the color profiles become shallower beyond ∼75 kpc suggesting that a distinct component, the intracluster light, starts to dominate at that radius. The color of the profile at ∼100 kpc suggests that the buildup of the intracluster light of A85 occurs by the stripping of massive (∼1010M⊙) satellites. The measured fraction of this light ranges from 8%-30% in g, depending on the definition of intracluster light chosen.

Keywords: galaxy clusters; abell clusters; galactic and extragalactic astronomy; galaxy stellar halos; photometry; stellar populations
Nonequilibrium Ionization Plasma during a Large Solar Limb Flare Observed by Hinode/EIS

This study on plasma heating considers the time-dependent ionization process during a large solar flare on 2017 September 10, observed by Hinode/EUV Imaging Spectrometer (EIS). The observed Fe XXIV/Fe XXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electron temperature Te 25 MK. Moreover, this study also shows that the nonthermal velocity, which can be related to the turbulent velocity, reduces significantly along the downstream of the reconnection outflow, even when considering the time-dependent ionization process.

Keywords: solar flares
Dynamical Equilibrium in the Molecular ISM in 28 Nearby Star-forming Galaxies

We compare the observed turbulent pressure in molecular gas, Pturb, to the required pressure for the interstellar gas to stay in equilibrium in the gravitational potential of a galaxy, PDE. To do this, we combine arcsecond resolution CO data from PHANGS-ALMA with multiwavelength data that trace the atomic gas, stellar structure, and star formation rate (SFR) for 28 nearby star-forming galaxies. We find that Pturb correlates with - but almost always exceeds - the estimated PDE on kiloparsec scales. This indicates that the molecular gas is overpressurized relative to the large-scale environment. We show that this overpressurization can be explained by the clumpy nature of molecular gas; a revised estimate of PDE on cloud scales, which accounts for molecular gas self-gravity, external gravity, and ambient pressure, agrees well with the observed Pturb in galaxy disks. We also find that molecular gas with cloud-scale Pturb ≈ PDE ≳ 105 kB K cm-3 in our sample is more likely to be self-gravitating, whereas gas at lower pressure it appears more influenced by ambient pressure and/or external gravity. Furthermore, we show that the ratio between Pturb and the observed SFR surface density, ΣSFR, is compatible with stellar feedback-driven momentum injection in most cases, while a subset of the regions may show evidence of turbulence driven by additional sources. The correlation between ΣSFR and kpc-scale PDE in galaxy disks is consistent with the expectation from self-regulated star formation models. Finally, we confirm the empirical correlation between molecular-to-atomic gas ratio and kpc-scale PDE reported in previous works.

Keywords: interstellar molecules; star formation; interstellar dynamics
CLIMBER: Galaxy-Halo Connection Constraints from Next-generation Surveys

In the coming decade, a new generation of massively multiplexed spectroscopic surveys, such as the Prime Focus Spectrograph Galaxy Evolution Survey (PFS), Wide Area Vista Extragalactic Survey-Deep (WAVES), and Multi-Object Optical and Near-infrared Spectrograph (MOONS) for the Very Large Telescope, will probe galaxies in the distant universe in vastly greater numbers than was previously possible. In this work, we generate mock catalogs for each of these three planned surveys to help quantify and optimize their scientific output. To assign photometry into the UniverseMachine empirical model, we develop the Calibrating Light: Illuminating Mocks By Empirical Relations procedure using Ultra Deep Survey with the Visible and Infrared Survey Telescope for Astronomy (UltraVISTA) photometry. Using the published empirical selection functions for each aforementioned survey, we quantify the mass completeness of each survey. We compare different targeting strategies by varying the area and targeting completeness, and quantify how these survey parameters affect the uncertainty of the two-point correlation function. We demonstrate that the PFS and MOONS measurements will be primarily dominated by cosmic variance, not shot noise, motivating the need for increasingly large survey areas. On the other hand, the WAVES survey, which covers a much larger area, will strike a good balance between cosmic variance and shot noise. For a fixed number of targets, a 5% increased survey area (and ~5% decreased completeness) would decrease the uncertainty of the correlation function at intermediate scales by 0.15%, 1.2%, and 1.1% for our WAVES, PFS, and MOONS samples, respectively. Meanwhile, for a fixed survey area, 5% increased targeting completeness improves the same constraints by 0.7%, 0.25%, and 0.1%. All of the utilities used to construct our mock catalogs and many of the catalogs themselves are publicly available.

Keywords: galaxy dark matter halos; galaxy spectroscopy; galactic and extragalactic astronomy; galaxy photometry; redshift surveys; sky surveys; galaxy evolution; galaxy counts; galaxy cluster counts; two-point correlation function; stellar mass functions; star formation
The GN-z11-Flash Event can be a Satellite Glint

Recently Jiang et al. reported the discovery of a possible short duration transient, detected in a single image, spatially associated with a z ∼ 11 galaxy. Jiang et al. and Kann et al. suggested the transient originates from a γ-Ray Burst (GRB), while Padmanabhan & Loeb argued the flash is consistent with a supernova shock breakout event of a 300 M⊙ Population III star. Jiang et al. argued against the possibility that this event originated from light reflected off a satellite. Here we show that reflection of sunlight from a high-orbit satellite or a piece of space debris is a valid and reasonable explanation. As shown in recent works, the rate of point-like satellite reflections, brighter than 11th magnitude, is >10 deg-2 day-1 near the equatorial plane. At higher declinations the rate is 5-50 times lower, but still significant: about four orders of magnitudes higher than the rate estimated for GRBs.

Keywords: gamma-ray bursts; artificial satellites; high-redshift galaxies
Early Results from GLASS-JWST. XXI. Rapid Asembly of a Galaxy at z = 6.23 Revealed by Its C/O Abundance

The abundance of carbon relative to oxygen (C/O) is a promising probe of star formation history in the early universe, as the ratio changes with time due to production of these elements by different nucleosynthesis pathways. We present a measurement of $\mathrm{log}({\rm{C}}/{\rm{O}})=-1.01\pm 0.12$ (stat) ±0.15 (sys) in a z = 6.23 galaxy observed as part of the GLASS-JWST Early Release Science Program. Notably, we achieve good precision thanks to the detection of the rest-frame ultraviolet O III], C III], and C IV emission lines delivered by JWST/NIRSpec. The C/O abundance is ~0.8 dex lower than the solar value and is consistent with the expected yield from core-collapse supernovae, indicating that longer-lived intermediate-mass stars have not fully contributed to carbon enrichment. This in turn implies rapid buildup of a young stellar population with age ≲100 Myr in a galaxy seen ~900 Myr after the big bang. Our chemical abundance analysis is consistent with spectral energy distribution modeling of JWST/NIRCam photometric data, which indicates a current stellar mass $\mathrm{log}\,{M}_{* }/{M}_{\odot }={8.4}_{-0.2}^{+0.4}$ and specific star formation rate ≃20 Gyr-1. These results showcase the value of chemical abundances and C/O in particular to study the earliest stages of galaxy assembly.

Keywords: high-redshift galaxies; galaxy abundances; abundance ratios; emission line galaxies
Gaussian Processes and Nested Sampling Applied to Kepler's Small Long-period Exoplanet Candidates

There are more than 5000 confirmed and validated planets beyond the solar system to date, more than half of which were discovered by NASA's Kepler mission. The catalog of Kepler's exoplanet candidates has only been extensively analyzed under the assumption of white noise (i.i.d. Gaussian), which breaks down on timescales longer than a day due to correlated noise (point-to-point correlation) from stellar variability and instrumental effects. Statistical validation of candidate transit events becomes increasingly difficult when they are contaminated by this form of correlated noise, especially in the low-signal-to-noise (S/N) regimes occupied by Earth-Sun and Venus-Sun analogs. To diagnose small long-period, low-S/N putative transit signatures with few (roughly 3-9) observed transit-like events (e.g., Earth-Sun analogs), we model Kepler's photometric data as noise, treated as a Gaussian process, with and without the inclusion of a transit model. Nested sampling algorithms from the Python UltraNest package recover model evidences and maximum a posteriori parameter sets, allowing us to disposition transit signatures as either planet candidates or false alarms within a Bayesian framework.

Keywords: exoplanet detection methods; exoplanets; transit photometry; nested sampling; bayesian statistics; gaussian processes regression
An Optically Discovered Outburst from XTE J1859+226

Using the Zwicky Transient Facility, in 2021 February we identified the first known outburst of the black hole X-ray transient XTE J1859+226 since its discovery in 1999. The outburst was visible at X-ray, UV, and optical wavelengths for less than 20 days, substantially shorter than its full outburst of 320 days in 1999, and the observed peak luminosity was 2 orders of magnitude lower. Its peak bolometric luminosity was only 2 × 1035 erg s-1, implying an Eddington fraction of about 3 × 10-4. The source remained in the hard spectral state throughout the outburst. From optical spectroscopy measurements we estimate an outer disk radius of 1011 cm. The low observed X-ray luminosity is not sufficient to irradiate the entire disk, but we observe a surprising exponential decline in the X-ray light curve. These observations highlight the potential of optical and infrared synoptic surveys to discover low-luminosity activity from X-ray transients.

Keywords: low-mass x-ray binary stars; x-ray binary stars
Unusual Martian Foreshock Waves Triggered by a Solar Wind Stream Interaction Region

Planetary bow shocks noncollisionally dissipate the incident bulk flow energy of solar wind into some other forms. To what extent and how solar wind disturbances affect the energy dissipation processes at the bow shocks on different planets remain unclear. With the Chinese Tianwen-1 and American Mars Atmosphere and Volatile EvolutioN missions, we present the first observation of significant modifications by a solar wind stream interaction region to the Martian foreshock waves, which are an important energy dissipation product of the bow shock. After the stream interface hitting Mars, an unusual band of foreshock waves emerged, with a central frequency of ~0.4 Hz and frequency width of ~0.2 Hz. These waves exhibited highly distorted waveforms, with peak-to-peak amplitudes of 10-25 nT in contrast to a background magnetic field of 6-9 nT. They were approximately elliptically polarized with respect to the wavevector and propagated highly obliquely to the background magnetic field. These waves reported here differed greatly from the commonly known Martian foreshock "30 s waves" and "1 Hz waves," but resembled, to some extent, the less frequently occurring terrestrial foreshock "3 s waves." Our present findings may imply an unexpected energy dissipation pattern of the Martian bow shock to the disturbed solar wind, which needs further observational, theoretical, and numerical investigations.

Keywords: planetary bow shocks; solar-planetary interactions; corotating streams; space weather; space plasmas; plasma physics
Searches for Neutrinos in the Direction of Radio-bright Blazars with the ANTARES Telescope

Active galaxies, especially blazars, are among the most promising extragalactic candidates for high-energy neutrino sources. To date, ANTARES searches included these objects and used GeV–TeV γ-ray flux to select blazars. Here, a statistically complete blazar sample selected by their bright radio emission is used as the target for searches of origins of neutrinos collected by the ANTARES neutrino telescope over 13 yr of operation. The hypothesis of a neutrino–blazar directional correlation is tested by pair counting and a complementary likelihood-based approach. The resulting posttrial p-value is 3.0% (2.2σ in the two-sided convention). Additionally, a time-dependent analysis is performed to search for temporal clustering of neutrino candidates as a means of detecting neutrino flares in blazars. None of the investigated sources alone reaches a significant flare detection level. However, the presence of 18 sources with a pretrial significance above 3σ indicates a p = 1.4% (2.5σ in the two-sided convention) detection of a time-variable neutrino flux. An a posteriori investigation reveals an intriguing temporal coincidence of neutrino, radio, and γ-ray flares of the J0242+1101 blazar at a p = 0.5% (2.9σ in the two-sided convention) level. Altogether, the results presented here suggest a possible connection of neutrino candidates detected by the ANTARES telescope with radio-bright blazars.

Keywords: neutrino astronomy; blazars
Statistical Properties of Habitable Zones in Stellar Binary Systems

Observations of exoplanets and protoplanetary disks show that binary stellar systems can host planets in stable orbits. Given the high binary fraction among stars, the contribution of binary systems to Galactic habitability should be quantified. Therefore, we have designed a suite of Monte Carlo experiments aimed at generating large (up to 106) samples of binary systems. For each system randomly extracted we calculate the intersection between the radiative habitable zones (HZs) and the regions of dynamical stability using published empirical formulations that account for the dynamical and radiative parameters of both stars of the system. We also consider constraints on planetary formation in binary systems. We find that the habitability properties of circumstellar and circumbinary regions are quite different and complementary with respect to the binary system parameters. Circumbinary HZs are, generally, rare (≃4%) in the global population of binary systems, even if they are common for stellar separations ≲0.2 au. Conversely, circumstellar HZs are frequent (≥80%) in the global population but are rare for stellar separations ≲1 au. These results are robust against variations of poorly constrained binary system parameters. We derive ranges of stellar separations and stellar masses for which HZs in binary systems can be wider than the HZs around single stars; the widening can be particularly strong (up to one order of magnitude) for circumstellar regions around M-type secondary stars. The comparison of our statistical predictions with observational surveys shows the impact of selection effects on the habitability properties of detected exoplanets in binary systems.

Keywords: binary stars; astrobiology; computational methods; habitable zone; habitable planets