adsabs/SciX_UAT_keywords huggingface dataset:
On the "Loose" Constraint from IceCube Neutrino Nondetection of GRB 230307A

The recent extremely bright gamma-ray burst (GRB) from a binary neutron star merger, GRB 230307A, may offer a good probe for the production of GRB neutrinos. Within the constraint from IceCube neutrino nondetection, the limits for key physical parameters of this burst are extracted in different scenarios, including the fireball, Poynting-flux-dominated, and hybrid jet. Different from the former nearby "monsters" and due to its smaller isotropic equivalent radiated energy (E γ,iso ~ 4 × 1052 erg), the constraint seems loose if nonthermal neutrinos produced from photomeson interactions are the only consideration. However, a quasi-thermal neutrino emission from hadronuclear processes is constrained in this neutron-rich postmerger environment, and the upper limit of the allowed nucleon loading factor is ~a few. Based on this, a discussion is presented on the possible prompt emission mechanism and jet composition for GRB 230307A in the context of multimessenger astrophysics. It is worth noting that until now, no GRB neutrinos have been ever detected, even for the two brightest nearby GRBs ever observed (GRB 221009A and GRB 230307A), which have different dissipation mechanisms.

Keywords: gamma-ray bursts; neutrino astronomy
Radio/X-Ray Correlation in the Mini-outbursts of Black Hole X-Ray Transient GRS 1739-278

We present quasi-simultaneous radio and X-ray observations of the black hole X-ray binary GRS 1739-278 during the 2015-2016 mini-outbursts, I.e., between 2015 June 10 and 2016 October 31, with the X-ray-to-radio time interval being less than one day. The monitor campaign was run by Swift in the X-rays and by VLA in the radio (at both 5 and 8 GHz). We find that the brightest radio emission is actually achieved during the soft sate, and the spectrum is marginally optically thick with the spectral index α ≈ -0.28 ± 0.17 (flux Fν ∝ να). For the radio emission in the hard state, we find a large diversity in the spectral index, I.e., a majority of radio spectra are optically thick with -0.5 ≲ α ≲ 0.5, while a few are optically thin, with α being lower than -1 in certain cases. We then investigate the correlation between the luminosities in radio (monochromatic at 5 GHz, L_{R}) and 1-10 keV X-rays (L_{X}) during the hard state. We find that for more than two orders of magnitude variation in the X-ray luminosity, this source exhibits a flat correlation with p ≈ 0.16 (in the form of L_{R} ∝ L_{X}^{p}), I.e., it belongs to the "outlier" (to the standard correlation with p ≈ 0.6) category that may follow a hybrid correlation. Both the slope and the corresponding luminosity range agree well with those in H1743-322, the prototype of the hybrid correlation. Theoretical implications of our results are discussed.

Keywords: stellar accretion disks; black hole physics; x-ray binary stars; low-mass x-ray binary stars
The Extraordinary Passage of Comet C/2020 F3 NEOWISE: Evidence for Heterogeneous Chemical Inventory in Its Nucleus

Upon its discovery in 2020 March, we requested Director Discretionary Time (DDT) at the NASA/IRTF facility to observe comet C/2020 F3 (NEOWISE), with the high-resolution spectrograph iSHELL. The comet approached the Sun, down to 0.3 au, in early 2020 July, providing a spectacular perihelion passage and revealing itself as one of the brightest comets that have appeared in the northern hemisphere in recent decades. Daytime observations with iSHELL/IRTF were performed to study the comet immediately after its perihelion passage, from 9 July to 1 August. In early August, a DDT at Keck Observatory was requested to continue following the comet with NIRSPEC 2.0. We acquired comprehensive high-resolution spectra of the comet as it progressively retreated from perihelion. We detected many cometary emission lines in the (2.8-5.3) μm range, identifying 12 molecular species: 9 primary volatiles (H2O, HCN, NH3, CO, C2H2, C2H6, CH4, CH3OH, and H2CO) and 3 product species (CN, NH2, OH). In this paper, we present the analysis and discussion of the molecular abundances found in this comet, and we compare them to reference median values for Oort Cloud Comets. Measured molecular mixing ratios showed drastic changes during our observing campaign, which spanned nearly one month from 2020 July 9 to August 6. Here, we provide a detailed discussion of the molecular spatial distributions and their role in identifying the presence of extended sources in the coma. Our investigations provided evidence for the heterogeneous chemical composition of the comet's nucleus.

Keywords: comet volatiles; high resolution spectroscopy; astrobiology
Proper-motion Membership Tests for Four Planetary Nebulae in Galactic Globular Clusters

Four planetary nebulae (PNe) are considered to be probable or possible members of Galactic globular clusters (GCs). These are Ps 1 = K648 in M15, GJJC 1 = IRAS 18333-2357 in M22, JaFu 1 in Palomar 6, and JaFu 2 in NGC 6441. In addition to lying close to the host GCs on the sky, these PNe have radial velocities that are consistent, within the errors and stellar velocity dispersions, with cluster membership. The remaining membership criterion is whether the proper motions (PMs) of the central stars are in agreement with those of the host clusters. We have carried out the PM test for all four PNe. Two of the central stars—those of Ps 1 and GJJC 1—have PMs listed in the recent Gaia Data Release 2 (DR2). We updated the PM of the Ps 1 central star to a more precise value using archival Hubble Space Telescope (HST) frames. Both PMs are statistically consistent with cluster membership. For the other two PNe, we used archival HST images to derive the PMs of their nuclei. For JaFu 2, there are HST images at several epochs, and the measured PM of the nucleus is in excellent agreement with that of the host cluster. For JaFu 1 the available archival HST images are less optimal and the results are less conclusive; the measured PM for the central star is marginally consistent with cluster membership, but additional astrometric observations are desirable for a more robust membership test. * Some of the data presented in this paper were obtained from the Mikulski Archive for Space Telescopes (MAST) at the Space Telescope Science Institute, operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

Keywords: globular star clusters; planetary nebulae; planetary nebulae nuclei; binary stars; space astrometry
A Decade of Multiwavelength Observations of the TeV Blazar 1ES 1215+303: Extreme Shift of the Synchrotron Peak Frequency and Long-term Optical-Gamma-Ray Flux Increase

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multiwavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z = 0.130), with a focus on its gamma-ray emission from 100 MeV to 30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline, and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by Very Long Baseline Array at 43.1, 22.2, and 15.3 GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed.

Keywords: active galaxies; jets; gamma-rays; blazars; bl lacertae objects
Validating Gaia DR3 Pulsating Variable Classifications with TESS: Building Reliable δ Scuti and γ Doradus Stars Catalogs (In Progress)

Gaia DR3 revealed 748,058 pulsating variable stars of mixed DSCT∣GDOR∣SXPHE types. This project undertakes a comprehensive examination to validate and distinguish these stars using Transiting Exoplanet Survey Satellite data. Aiming for reliable catalogs of bona fide δ Scuti and γ Doradus stars, I have validated 1715 δ Scuti stars, 1403 γ Doradus stars, and identified 260 eclipsing binaries, one RR Lyrae star, and 460+ rotating variables from an initial sample of 16,690 objects. Notably, 15 of the newfound eclipsing binaries harbor pulsating γ Doradus components. *Dedicated to my wife Jingyun Zhang.

Keywords: pulsating variable stars; delta scuti variable stars; gamma doradus variable stars; rr lyrae variable stars; eclipsing binary stars
Determining the Ionization Rates of Interstellar Neutral Species Using Direct-sampling Observations of Their Direct and Indirect Beams

A good understanding of the ionization rates of neutral species in the heliosphere is important for studies of the heliosphere and planetary atmospheres. So far, the intensities of the ionization reactions have been studied based on observations of the contributing phenomena, such as the solar spectral flux in the EUV band and the flux of the solar wind protons, alpha particles, and electrons. The results strongly depend on absolute calibration of these measurements, which, especially for the EUV measurements, is challenging. Here, we propose a novel method of determining the ionization rate of neutral species based on direct sampling of interstellar neutral gas from two locations in space distant to each other. In particular, we suggest performing observations from the vicinity of Earth's orbit and using ratios of fluxes of interstellar neutral He for the direct and indirect orbits of interstellar atoms. We identify the most favorable conditions and observations geometries, suitable for implementation on the forthcoming NASA Interstellar Mapping and Acceleration Probe mission.

Keywords: solar activity; solar extreme ultraviolet emission; solar wind; interstellar atomic gas; interstellar medium wind; interstellar medium; heliosphere
2D and 3D Analysis of a Torus-unstable Quiet-Sun Prominence Eruption

The role of ideal-MHD instabilities in a prominence eruption is explored through 2D and 3D kinematic analysis of an event observed with the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory between 22:06 UT on 2013 February 26 and 04:06 UT on 2013 February 27. A series of 3D radial slits are used to extract height-time profiles ranging from the midpoint of the prominence leading edge to the southeastern footpoint. These height-time profiles are fit with a kinematic model combining linear and nonlinear rise phases, returning the nonlinear onset time (tnl) as a free parameter. A range (1.5-4.0) of temporal power indices (I.e., β in the nonlinear term ${(t-{t}_{\mathrm{nl}})}^{\beta }$ ) are considered to prevent prescribing any particular form of nonlinear kinematics. The decay index experienced by the leading edge is explored using a radial profile of the transverse magnetic field from a PFSS extrapolation above the prominence region. Critical decay indices are extracted for each slit at their own specific values of height at the nonlinear phase onset (h(tnl)) and filtered to focus on instances resulting from kinematic fits with ${\chi }_{\mathrm{red}}^{2}\lt 2$ (restricting β to 1.9-3.9). Based on this measure of the critical decay index along the prominence structure, we find strong evidence that the torus instability is the mechanism driving this prominence eruption. Defining any single decay index as being "critical" is not that critical because there is no single canonical or critical value of decay index through which all eruptions must succeed.

Keywords: the sun; solar magnetic fields; solar atmosphere; solar prominences
Transmission Spectroscopy of WASP-79b from 0.6 to 5.0 μm

As part of the Panchromatic Exoplanet Treasury program, we have conducted a spectroscopic study of WASP-79b, an inflated hot Jupiter orbiting an F-type star in Eridanus with a period of 3.66 days. Building on the original WASP and TRAPPIST photometry of Smalley et al., we examine Hubble Space Telescope (HST)/Wide Field Camera 3 (WFC3) (1.125-1.650 μm), Magellan/Low Dispersion Survey Spectrograph (LDSS)-3C (0.6-1 μm) data, and Spitzer data (3.6 and 4.5 μm). Using data from all three instruments, we constrain the water abundance to be -2.20 ≤ log(H2O) ≤ -1.55. We present these results along with the results of an atmospheric retrieval analysis, which favor inclusion of FeH and H- in the atmospheric model. We also provide an updated ephemeris based on the Smalley, HST/WFC3, LDSS-3C, Spitzer, and Transiting Exoplanet Survey Satellite (TESS) transit times. With the detectable water feature and its occupation of the clear/cloudy transition region of the temperature/gravity phase space, WASP-79b is a target of interest for the approved James Webb Space Telescope (JWST) Director’s Discretionary Early Release Science (ERS) program, with ERS observations planned to be the first to execute in Cycle 1. Transiting exoplanets have been approved for 78.1 hr of data collection, and with the delay in the JWST launch, WASP-79b is now a target for the Panchromatic Transmission program. This program will observe WASP-79b for 42 hr in four different instrument modes, providing substantially more data by which to investigate this hot Jupiter.

Keywords: exoplanet atmospheres; observational astronomy; spectroscopy
The GeMS/GSAOI Galactic Globular Cluster Survey (G4CS). II. Characterization of 47 Tuc with Bayesian Statistics

We present a photometric analysis of globular cluster 47 Tuc (NGC 104) using near-IR imaging data from the GeMS/GSAOI Galactic Globular Cluster Survey (G4CS), which is in operation at Gemini-South telescope. Our survey is designed to obtain AO-assisted deep imaging with near diffraction-limited spatial resolution of the central fields of Milky Way globular clusters. The G4CS near-IR photometry was combined with an optical photometry catalog that was obtained from Hubble Space Telescope survey data to produce a high-quality color-magnitude diagram that reaches down to K s ≈ 21 Vega mag. We used the software suite BASE-9, which uses an adaptive Metropolis sampling algorithm to perform a Markov chain Monte Carlo Bayesian analysis, and obtained probability distributions and precise estimates for the age, distance, and extinction cluster parameters. Our best estimate for the age of 47 Tuc is ${12.42}_{-0.05}^{+0.05}$ ± 0.08 Gyr and our true distance modulus estimate is (m-M)0 = 13.250 ${}_{-0.003}^{+0.003}$ ± 0.028 mag, which are in tight agreement with previous studies using Gaia DR2 parallax and detached eclipsing binaries.

Keywords: globular star clusters
The AREPO Public Code Release

We introduce the public version of the cosmological magnetohydrodynamical moving-mesh simulation code AREPO. This version contains a finite-volume magnetohydrodynamics algorithm on an unstructured, dynamic Voronoi tessellation coupled to a tree-particle-mesh algorithm for the Poisson equation either on a Newtonian or cosmologically expanding spacetime. Time integration is performed adopting local time step constraints for each cell individually, solving the fluxes only across active interfaces, and calculating gravitational forces only between active particles, using an operator-splitting approach. This allows simulations with high dynamic range to be performed efficiently. AREPO is a massively distributed-memory parallel code, using the message passing interface (MPI) communication standard and employing a dynamical workload and memory balancing scheme to allow for optimal use of multi-node parallel computers. The employed parallelization algorithms of AREPO are deterministic and produce binary-identical results when rerun on the same machine and with the same number of MPI ranks. A simple primordial cooling and star formation model is included as an example of sub-resolution models commonly used in simulations of galaxy formation. AREPO also contains a suite of computationally inexpensive test problems, ranging from idealized tests for automated code verification to scaled-down versions of cosmological galaxy formation simulations, and is extensively documented in order to assist adoption of the code by new scientific users.

Keywords: computational methods; computational astronomy; magnetohydrodynamics; astrophysical fluid dynamics; gravitation; galaxy formation; large-scale structure of the universe
WASP Lightcurves: Red Noise and a Cautionary Tale

A recent RNAAS, analyzing data from the WASP survey, claimed that the star TYC 2623-1439-1 underwent a 1% dimming that lasted for 11 days, and interpreted this as a transit of a wide-orbiting planet. However, WASP survey data is prone to red noise. I show that the same dip is seen on a nearby star, and conclude that it is a pipeline artifact rather than being real.

Keywords: observational astronomy
TESS Stellar Rotation up to 80 Days in the Southern Continuous Viewing Zone

The Transiting Exoplanet Survey Satellite (TESS) mission delivers time-series photometry for millions of stars across the sky, offering a probe into stellar astrophysics, including rotation, on a population scale. However, light-curve systematics related to the satellite's 13.7 day orbit have prevented stellar rotation searches for periods longer than 13 days, putting the majority of stars beyond reach. Machine-learning methods have the ability to identify systematics and recover robust signals, enabling us to recover rotation periods up to 35 days for GK dwarfs and 80 days for M dwarfs. We present a catalog of 7245 rotation periods for cool dwarfs in the Southern Continuous Viewing Zone, estimated using convolutional neural networks. We find evidence for structure in the period distribution consistent with prior Kepler and K2 results, including a gap in 10–20 day cool-star periods thought to arise from a change in stellar spin-down or activity. Using a combination of spectroscopic and gyrochronologic constraints, we fit stellar evolution models to estimate masses and ages for stars with rotation periods. We find strong correlations between the detectability of rotation in TESS and the effective temperature, age, and metallicity of the stars. Finally, we investigate the relationships between rotation and newly obtained spot filling fractions estimated from Apache Point Observatory Galactic Evolution Experiment spectra. Field starspot filling fractions are elevated in the same temperature and period regime where open clusters' magnetic braking stalls, lending support to an internal shear mechanism that can produce both phenomena.

Keywords: stellar populations; computational astronomy; stellar evolution; stellar physics; starspots; light curves; convolutional neural networks; stellar activity; stellar rotation; stellar properties
Being Careful with the Field Formation Interpretation of GW190412

The LIGO/Virgo Scientific Collaboration recently announced the detection of a compact object binary merger, GW190412, as the first asymmetric binary black hole (BBH) merger with mass ratio q ≈ 0.25. Other than the mass ratio, this BBH has been shown to have a positive effective spin of around χeff ≈ 0.28. Assuming a field formation channel, associating this effective spin to either the primary or the secondary black hole (BH) each have implications: if the spin of the BBH comes from the primary BH, it has consequences for the efficiency of angular momentum transport in the formation of the BH. If, on the other hand, the spin is due to the secondary BH through tidal spin-up processes, it should be noted that (I) such processes have very short delay times, and (II) subsequently, their local merger rate is determined by local star formation rate at the assumed formation metallicity of the BBH. We show that the predicted merger rate density from this channel is $\lesssim 0.3\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ , and is in tension with the rather high local merger rate of such systems, which we estimate from this single event to be $\sim {1.7}_{-1.4}^{+2.5}\,{\mathrm{Gpc}}^{-3}\,{\mathrm{yr}}^{-1}$ (90% confidence interval, and assuming 50 days of observing time). Large natal kicks (V ≳ 500 km s-1) would be required to get such an BBHs with an in-plane spin component to account for the marginal detection of precession in GW190412. However, this would only exacerbate the tension as the estimated local merger rate would be further decreased. Similarly, the formation of such systems through the dynamical assembly is exceedingly rare; consequently, it is difficult to account for this system with the currently accepted paradigms of BBH formation.

Keywords: stellar populations; binary stars; ligo; black hole physics; close binary stars
Beamed Emission from a Neutron-star ULX in a GRRMHD Simulation

We perform a global 2.5D general-relativistic radiation magnetohydrodynamic simulation of supercritical accretion onto a neutron star with a 2 × 1010 G dipolar magnetic field, as a model of a neutron-star-powered ultraluminous X-ray source (ULX). We compute a lower limit on the total luminosity of ~2.5 LEdd, and find the radiation to be highly beamed by the accretion disk outflows. The apparent isotropic luminosity, which is a function of the viewing angle, reaches a maximum above 100 LEdd, consistent with the luminosities observed in ULXs.

Keywords: ultraluminous x-ray sources; magnetohydrodynamical simulations; neutron stars
Tests of Loop Quantum Gravity from the Event Horizon Telescope Results of Sgr A*

The Event Horizon Telescope (EHT) collaboration's image of the compact object at the Galactic center is the first direct evidence of the supermassive black hole (BH) Sgr A*. The shadow of Sgr A* has an angular diameter d sh = 48.7 ± 7 μas with fractional deviation from the Schwarzschild BH shadow diameter $\delta =-{0.08}_{-0.09}^{+0.09},-{0.04}_{-0.10}^{+0.09}$ (for the VLTI and Keck mass-to-distance ratios). Sgr A*'s shadow size is within 10% of Kerr predictions, equipping us with yet another tool to analyze gravity in the strong-field regime, including testing loop quantum gravity (LQG). We use Sgr A*'s shadow to constrain the metrics of two well-motivated LQG-inspired rotating BH (LIRBH) models characterized by an additional deviation parameter L q , which recover the Kerr spacetime in the absence of quantum effects (L q → 0). When increasing the quantum effects through L q , the shadow size increases monotonically, while the shape gets more distorted, allowing us to constrain the fundamental parameter L q . We use the astrophysical observables shadow area A and oblateness D to estimate the BH parameters. It may be useful in extracting additional information about LIRBHs. While the EHT observational results completely rule out the wormhole region in LIRBH-2, a substantial parameter region of the generic BHs in both models agrees with the EHT results. We find that the upper bounds on L q obtained from the shadow of Sgr A*-L q ≲ 0.0423 and L q ≲ 0.0821 for the two LIRBHs, respectively-are more stringent than those obtained from the EHT image of M87*.

Keywords: astrophysical black holes; black hole physics; galactic center; gravitation; gravitational lensing