adsabs/SciX_UAT_keywords huggingface dataset:
A Comprehensive Observational Study of the FRB 121102 Persistent Radio Source

FRB 121102 is the first fast radio burst to be spatially associated with a persistent radio source (QRS 121102), the nature of which remains unknown. We constrain the physical size of QRS 121102 by measuring its flux-density variability with the VLA from 12 to 26 GHz. Any such variability would likely be due to Galactic refractive scintillation and would require the source radius to be ≲1017 cm at the host-galaxy redshift. We found the radio variability to be lower than the scintillation theory predictions for such a small source, leaving open the possibility for non-AGN models for QRS 121102. In addition, we roughly estimated the mass of any potential supermassive black hole (BH) associated with QRS 121102 from the line width of the host-galaxy Hα emission using a new optical spectrum from the Keck Observatory. The line width indicates a supermassive BH mass of ≲104~5 M ⊙, too low for the observed radio luminosity and X-ray luminosity constraints, if QRS 121102 were an AGN. Finally, some dwarf galaxies that host supermassive BHs may be the stripped cores of massive galaxies during tidal interactions with companion systems. We find no nearby galaxy at the same redshift as the QRS 121102 host from low-resolution Keck spectra or the PanSTARRS catalog. In conclusion, we find no evidence supporting the hypothesis that QRS 121102 is an AGN. We instead argue that the inferred size and flat radio spectrum favor a plerion interpretation. We urge continued broadband radio monitoring of QRS 121102 to search for long-term evolution.

Keywords: radio transient sources; high energy astrophysics; radio bursts; extragalactic radio sources
Using Rover-analogous Methodology to Discriminate between Volcanic and Sedimentary Origins in Successions Dominated by Igneous Composition

We tested rover science operations strategies to determine best practices for interrogating geologic sections where the bulk composition is igneous but depositional/emplacement processes range from sedimentary to volcanic. This scenario may mirror locations on Mars interrogated by mobile vehicles (e.g., Perseverance rover in Jezero crater). Two field teams studied a 60 m vertical outcrop on Iceland's Tjörnes peninsula as an analog for a Martian site containing interleaved layers of sedimentary and volcanic units. A Rover team commanded a human rover to execute observations based on common Mars rover sequences; the resulting data were used to characterize the geologic history of the location. Results were compared to that of a Tiger team using traditional terrestrial field methods to interrogate the same site. The goal was to understand which instruments, at what resolution, are required to assess the provenance of volcanic or sedimentary layers of similar chemical composition. Results suggest that, in a succession dominated by rocks having basaltic composition, current rover-driven decision-making protocols are sufficient to support a first-order interpretation of a sequence of sedimentary and volcanic layers. Two crucial data sets in maximizing science return in this scenario are (1) handlens-scale images revealing grain morphology and relationships and (2) data sets that allow comparison between surface and bulk geochemistry. Certain sedimentary features can be difficult to confidently identify if not viewed at a specific angle and resolution, and confident interpretations appear to require lateral scanning of beds at meter scales. This work illuminates the need for strategic planning, particularly of resource-intensive observations.

Keywords: rovers; mars
The Wolf-Rayet + Black Hole Binary NGC 300 X-1: What is the Mass of the Black Hole?

We present new X-ray and UV observations of the Wolf-Rayet + black hole (BH) binary system NGC 300 X-1 with the Chandra X-ray Observatory and the Hubble Space Telescope Cosmic Origins Spectrograph. When combined with archival X-ray observations, our X-ray and UV observations sample the entire binary orbit, providing clues to the system geometry and interaction between the BH accretion disk and the donor star wind. We measure a binary orbital period of 32.7921 ± 0.0003 hr, in agreement with previous studies, and perform phase-resolved spectroscopy using the X-ray data. The X-ray light curve reveals a deep eclipse, consistent with inclination angles of i = 60°-75°, and a pre-eclipse excess consistent with an accretion stream impacting the disk edge. We further measure radial velocity variations for several prominent far-UV spectral lines, most notably H II λ1640 and C IV λ1550. We find that the He II emission lines systematically lag the expected Wolf-Rayet star orbital motion by a phase difference of Δφ ∼ 0.3, while C IV λ1550 matches the phase of the anticipated radial velocity curve of the Wolf-Rayet donor. We assume the C IV λ1550 emission line follows a sinusoidal radial velocity curve (semi-amplitude = 250 km s-1) and infer a BH mass of 17 ± 4 M⊙. Our observations are consistent with the presence of a wind-Roche lobe overflow accretion disk, where an accretion stream forms from gravitationally focused wind material and impacts the edge of the BH accretion disk.

Keywords: high mass x-ray binary stars; x-ray binary stars; astrophysical black holes; stellar mass black holes; wolf-rayet stars
Inferring Fundamental Properties of the Flare Current Sheet Using Flare Ribbons: Oscillations in the Reconnection Flux Rates

Magnetic reconnection is understood to be the main physical process that facilitates the transformation of magnetic energy into heat, motion, and particle acceleration during solar eruptions. Yet, observational constraints on reconnection region properties and dynamics are limited due to a lack of high-cadence and high-spatial-resolution observations. By studying the evolution and morphology of postreconnected field-lines footpoints, or flare ribbons and vector photospheric magnetic field, we estimate the magnetic reconnection flux and its rate of change with time to study the flare reconnection process and dynamics of the current sheet above. We compare high-resolution imaging data to study the evolution of the fine structure in flare ribbons as ribbons spread away from the polarity inversion line. Using data from two illustrative events (one M- and X-class flare), we explore the relationship between the ribbon-front fine structure and the temporal development of bursts in the reconnection region. Additionally, we use the RibbonDB database to perform statistical analysis of 73 (C- to X-class) flares and identify quasiperiodic pulsation (QPP) properties using the Wavelet Transform. Our main finding is the discovery of QPP signatures in the derived magnetic reconnection rates in both example events and the large flare sample. We find that the oscillation periods range from 1 to 4 minutes. Furthermore, we find nearly cotemporal bursts in Hard X-ray (HXR) emission profiles. We discuss how dynamical processes in the current sheet involving plasmoids can explain the nearly cotemporal signatures of quasiperiodicity in the reconnection rates and HXR emission.

Keywords: solar flares; solar x-ray flares; solar magnetic reconnection; solar magnetic fields; solar physics; solar active region magnetic fields
One Channel to Rule Them All? Constraining the Origins of Binary Black Holes Using Multiple Formation Pathways

The second LIGO-Virgo catalog of gravitational-wave (GW) transients has more than quadrupled the observational sample of binary black holes. We analyze this catalog using a suite of five state-of-the-art binary black hole population models covering a range of isolated and dynamical formation channels and infer branching fractions between channels as well as constraints on uncertain physical processes that impact the observational properties of mergers. Given our set of formation models, we find significant differences between the branching fractions of the underlying and detectable populations, and the diversity of detections suggests that multiple formation channels are at play. A mixture of channels is strongly preferred over any single channel dominating the detected population: an individual channel does not contribute to more than ≃70% of the observational sample of binary black holes. We calculate the preference between the natal spin assumptions and common-envelope efficiencies in our models, favoring natal spins of isolated black holes of ≲0.1 and marginally preferring common-envelope efficiencies of ≳2.0 while strongly disfavoring highly inefficient common envelopes. We show that it is essential to consider multiple channels when interpreting GW catalogs, as inference on branching fractions and physical prescriptions becomes biased when contributing formation scenarios are not considered or incorrect physical prescriptions are assumed. Although our quantitative results can be affected by uncertain assumptions in model predictions, our methodology is capable of including models with updated theoretical considerations and additional formation channels.

Keywords: gravitational wave sources; gravitational wave astronomy; stellar mass black holes; ligo; stellar evolution; compact objects; bayesian statistics
Volumetric Rates of Luminous Red Novae and Intermediate-luminosity Red Transients with the Zwicky Transient Facility

Luminous red novae (LRNe) are transients characterized by low luminosities and expansion velocities, and they are associated with mergers or common-envelope ejections in stellar binaries. Intermediate-luminosity red transients (ILRTs) are an observationally similar class with unknown origins, but they are generally believed to be either electron-capture supernovae in super-asymptotic giant branch stars or outbursts in dusty luminous blue variables (LBVs). In this paper, we present a systematic sample of eight LRNe and eight ILRTs detected as part of the Census of the Local Universe (CLU) experiment on the Zwicky Transient Facility (ZTF). The CLU experiment spectroscopically classifies ZTF transients associated with nearby (<150 Mpc) galaxies, achieving 80% completeness for m r < 20 mag. Using the ZTF-CLU sample, we derive the first systematic LRNe volumetric rate of ${7.8}_{-3.7}^{+6.5}\times {10}^{-5}$ Mpc-3 yr-1 in the luminosity range -16 ≤ M r ≤ -11 mag. We find that, in this luminosity range, the LRN rate scales as ${dN}/{dL}\propto {L}^{-2.5\pm 0.3}$ -significantly steeper than the previously derived scaling of L -1.4±0.3 for lower-luminosity LRNe (M V ≥ -10 mag). The steeper power law for LRNe at high luminosities is consistent with the massive merger rates predicted by binary population synthesis models. We find that the rates of the brightest LRNe (M r ≤ -13 mag) are consistent with a significant fraction of them being progenitors of double compact objects that merge within a Hubble time. For ILRTs, we derive a volumetric rate of ${2.6}_{-1.4}^{+1.8}\times {10}^{-6}$ Mpc-3 yr-1 for M r ≤ -13.5 mag, which scales as ${dN}/{dL}\propto {L}^{-2.5\pm 0.5}$ . This rate is ~1%-5% of the local core-collapse supernova rate and is consistent with theoretical ECSN rate estimates.

Keywords: binary stars; common envelope evolution; time domain astronomy; transient sources; core-collapse supernovae; luminous blue variable stars
Polarization Constraints on the Geometry of the Magnetic Field in the External Shock of Gamma-Ray Bursts

We study the ensemble of linear polarization measurements in the optical afterglows of long-duration gamma-ray bursts. We assume a non-sideways-expanding top-hat jet geometry and use the relatively large number of measurements under the assumption that they represent a statistically unbiased sample. This allows us to constrain the ratio between the maximum predicted polarization and the measured one, which is an indicator of the geometry of the magnetic field in the downstream region of the external shock. We find that the measured polarization is substantially suppressed with respect to the maximum possible for either a completely ordered magnetic field parallel to the shock normal or to a field that is entirely contained in the shock plane. The measured polarization is limited, on average, to between 25% and 30% of the maximum theoretically possible value. This reduction requires the perpendicular component of the magnetic field to be dominant in energy with respect to the component parallel to the shock front, as expected for a shock-generated and/or shock-compressed field. We find, however, that the data only marginally support the assumption of a simple top-hat jet, pointing toward a more complex geometry for the outflow.

Keywords: gamma-ray bursts; polarimetry; non-thermal radiation sources
Detection of a 2.85 μm Feature on Five Spinel-rich Asteroids from JWST

Ground-based observations of "Barbarian" L-type asteroids at 1–2.5 μm indicate that their near-infrared spectra are dominated by the mineral spinel, which has been attributed to a high abundance of calcium-aluminum inclusions (CAIs)—the first solids to condense out of the protoplanetary disk during the formation of the solar system. However, the spectral properties of these asteroids from 2.5–5 μm, a wavelength region that covers signatures of hydrated minerals, water, and organics, have not yet been explored. Here, we present 2–5 μm reflectance spectra of five spinel-rich asteroids obtained with the NIRSpec instrument on the James Webb Space Telescope. All five targets exhibit a ∼2.85 μm absorption feature with a band depth of 3%–6% that appears correlated in strength with that of the 2 μm spinel absorption feature. The shape and position of the 2.85 μm feature are not a good match to the 2.7 μm feature commonly seen in carbonaceous CM meteorites or C-type asteroids. The closest spectral matches are to the Moon and Vesta, suggesting commonalities in aqueous alteration across silicate bodies, infall of hydrated material, and/or space weathering by solar wind H implantation. Lab spectra of CO/CV chondrites, CAIs, as well as the minerals cronstedtite and spinel, also show a similar feature, providing clues into the origin of the 2.85 μm feature.

Keywords: infrared spectroscopy; spectroscopy; asteroids; asteroid surfaces
Sensitivity of Cosmological Parameter Estimation to Nonlinear Prescription from Galaxy Clustering

Next-generation large-scale surveys will probe the nonlinear regime with high resolution. Making viable cosmological inferences based on these observations requires accurate theoretical modeling of the mildly nonlinear regime. In this work we investigate the sensitivity of cosmological parameter measurements from future probes of galaxy clustering to the choice of nonlinear prescription up to ${k}_{\max }=0.3\,h\,{\mathrm{Mpc}}^{-1}$ . In particular, we calculate the induced parameter bias when the mildly nonlinear regime is modeled by the Halofit fitting scheme. We find significant (~5σ) bias for some parameters with a future Euclid-like survey. We also explore the contribution of different scales to the parameter estimation for different observational setups and cosmological scenarios, compared for the two nonlinear prescriptions of Halofit and EFTofLSS. We include in the analysis the free parameters of the nonlinear theory and a blind parameterization for the galaxy bias. We find that marginalization over these nuisance parameters significantly boosts the errors of the standard cosmological parameters. This renders the differences in the predictions of the various nonlinear prescriptions less effective when transferred to the parameter space. More accurate modeling of these nuisance parameters would therefore greatly enhance the cosmological gain from the mildly nonlinear regime.

Keywords: dark energy; cosmological parameters from large-scale structure; large-scale structure of the universe; astronomy data analysis; fisher's information
On Radiative Dissipation in Stellar Turbulent Flows

The purpose of this paper is to study the exchange of momentum between photons and material particles in a stellar turbulent flow located far away from the outer boundary of the star. The flow is assumed to possess a wide interval of characteristic scales, such that the largest turbulent eddies are optically thick while the smallest ones are optically thin. An asymptotic analysis of the radiation hydrodynamics transport equations is performed in the limit of small velocities. All of the angular information carried by the radiative intensity is kept, and an exact expression for its perturbed state is derived. From it, an expression for the radiative force exerted by photons on matter is deduced. This force reverts to the standard radiative viscous stress in the optically thick regime and takes the form of a return-to-the-mean term in the opposite regime. The transition between the two is controlled by a local average of the velocity field taken on a domain of the size of a photon mean free path. Besides, the radiative force is found to always dissipate kinetic energy. But, as opposed to a purely viscous situation, the corresponding dissipation has an upper bound that is reached in the optically thin regime. All of these results are valid not only in the gray case but also for frequency-dependent opacities, including when true and scattering components are present. To validate these results, Monte Carlo simulations are performed on a simplified configuration.

Keywords: radiative transfer; hydrodynamics; stellar physics
Molecules with ALMA at Planet-forming Scales (MAPS). VIII. CO Gap in AS 209-Gas Depletion or Chemical Processing?

Emission substructures in gas and dust are common in protoplanetary disks. Such substructures can be linked to planet formation or planets themselves. We explore the observed gas substructures in AS 209 using thermochemical modeling with RAC2D and high-spatial-resolution data from the Molecules with ALMA at Planet-forming Scales (MAPS) program. The observations of C18O J = 2-1 emission exhibit a strong depression at 88 au overlapping with the positions of multiple gaps in millimeter dust continuum emission. We find that the observed CO column density is consistent with either gas surface-density perturbations or chemical processing, while C2H column density traces changes in the C/O ratio rather than the H2 gas surface density. However, the presence of a massive planet (>0.2 MJup) would be required to account for this level of gas depression, which conflicts with constraints set by the dust emission and the pressure profile measured by gas kinematics. Based on our models, we infer that a local decrease of CO abundance is required to explain the observed structure in CO, dominating over a possible gap-carving planet present and its effect on the H2 surface density. This paper is part of the MAPS special issue of the Astrophysical Journal Supplement.

Keywords: protoplanetary disks; astrochemistry
The Complex Space Weather Events of 2017 September

Interplanetary coronal mass ejections (ICMEs), magnetic clouds (MCs), sheaths, corotating interaction regions (CIRs), solar wind high-speed streams (HSSs), fast forward shocks (FSs), reverse waves (RWs), stream interfaces, and heliospheric current sheet crossings detected upstream of the Earth and their geoeffectiveness are studied during 2017 September. The most intense geomagnetic storm (SYM-H peak = -146 nT) starting on September 7 had a three-step main phase. A compound interplanetary structure resulting from an FS encountering and compressing the upstream MC southward interplanetary magnetic fields (IMFs) caused the first two steps of the storm. A magnetospheric supersubstorm (SSS; SML peak = -3712 nT) led to the third and most intense step. An MC portion of an ICME created an intense storm (SYM-H peak = -115 nT) on September 8. A second SSS (SML peak = -2642 nT) occurred during the main phase of this storm. Intense geomagnetically induced currents (GICs) occurred during the SSSs. Two moderate magnetic storms with peak SYM-H indices of -65 and -74 nT occurring on September 13 and 27 were caused by sheath and CIR southward IMFs, respectively. Six FSs and their associated sheaths caused sudden impulses (SI+s) of magnitude ranging from +11 to +56 nT. The shocks/sheaths led to magnetospheric relativistic electron flux decreases. The RWs caused SI-s and substorm recoveries by reducing southward IMFs. The high-intensity long-duration continuous AE activities (HILDCAAs) caused by the HSSs were related to the increase/acceleration of relativistic electron fluxes.

Keywords: solar flares; solar coronal mass ejections; corotating streams; interplanetary shocks
The Binary-Host Connection: Astrophysics of Gravitational-Wave Binaries from Host Galaxy Properties

Gravitational waves from the merger of binary neutron stars (BNSs) are accompanied by electromagnetic counterparts, making it possible to identify the associated host galaxy. In this work, we explore how properties of the hosts relate to the astrophysical processes leading to the mergers. It is thought that the BNS merger rate within a galaxy at a given epoch depends primarily on the galaxy's star formation history, as well as the underlying merger time-delay distribution of the binary systems. The stellar history of a galaxy, meanwhile, depends on the cosmological evolution of the galaxy through time, and is tied to the growth of structure in the universe. We study the hosts of BNS mergers in the context of structure formation by populating the UniverseMachine simulations with gravitational wave (GW) events, based on a simple time-delay model. We find that different time-delay distributions predict different properties of the associated host galaxies, including the distributions of stellar mass, star formation rate, halo mass, and local and large-scale clustering of hosts. Moreover, BNSs merging today with short delay times occur preferentially in hosts with high star formation rates, while those with long delay times live in dense regions within massive halos that have low star formation. We show that with ${ \mathcal O }(10)$ events from current GW detector networks, it is possible to make preliminary distinctions between formation channels which trace stellar mass, halo mass, or star formation rate. We also find that strategies to follow-up GW events with electromagnetic telescopes can be significantly optimized using the clustering properties of their hosts.

Keywords: gravitational wave sources; galaxy evolution; cosmological evolution; compact binary stars
Constraining Black Hole Natal Kicks with Astrometric Microlensing

Multiple pieces of evidence suggest that neutron stars receive large kicks when formed from the remnant of a collapsing star. However, the evidence for whether black holes (BHs) receive natal kicks is less clear, reliant on weak constraints from the analysis of BH X-ray binaries and massive runaway and walkaway stars. Here we show, for the first time, that recent microlensing detections offer a new method for measuring the kicks BHs receive at birth. When a BH is identified through both photometric and astrometric microlensing and when the lensed star has a known distance and proper motion, the mass, distance, and proper motion of the BH can be determined. We study the runaway velocities for components of eccentric binaries disrupted during a supernova (SN), finding the peculiar velocity correlates strongly with the kick a BH received at birth, typically within 20%, even when the natal kick is smaller than the orbital velocity. Therefore, by measuring the peculiar velocity of a BH or other compact object that formed from a binary which disrupted during core collapse, we are in effect measuring the natal kick that object received. We focus on MOA-2011-BLG-191/OGLE-2011-BLG-0462, an isolated, single BH detected by microlensing, and consider a range of possible formation scenarios, including its formation from the disruption of a binary during a SN event. We determine that MOA-2011-BLG-191/OGLE-2011-BLG-0462 has a Milky Way orbit consistent with a thick-disk population, but if it was formed within the kinematic thin disk it received a natal kick ≲100 km s-1.

Keywords: black hole physics; binary stars