adsabs/SciX_UAT_keywords huggingface dataset:
Implications of Symmetry and Pressure in Friedmann Cosmology. II. Stellar Remnant Black Hole Mass Function

We consider some observational consequences of replacing all black holes (BHs) with a class of non-singular solutions that mimic BHs but with dark energy (DE) interiors; GEneric Objects of DE (GEODEs). We focus on the BH mass function and chirp-mass redshift distribution of mergers visible to gravitational-wave observatories. We incorporate the GEODE blueshift into an initially Salpeter stellar remnant distribution, and model the binary population by evolving synthesized binary remnant distributions, published before LIGO's first measurements. We find that a GEODE produced between 20 ≲ z ≲ 40, and observed at z ∼ 7, will have its initial mass amplified by ∼20-140×. This can relieve tension between accretion-only growth models and the inferred masses of BHs in quasars at z ≳ 6. Moreover, we find that merger rates of GEODE binaries increase by a factor of ∼2× relative to classical BHs. The resulting GEODE mass function is consistent with the most recent LIGO constraints at <0.5σ. In contrast, a Salpeter stellar distribution that evolves into classical remnants is in tension at ≳2σ. This agreement occurs without low-metallicity regions, abnormally massive progenitor stars, novel formation channels, or primordial object formation at extreme rates. In particular, we find that solar metallicity progenitors, which produce 1.1-1.8M⊙ remnants, overlap with many LIGO observations when evolved as GEODEs.

Keywords: intermediate-mass black holes; dark energy; astrophysical black holes; stellar mass black holes; compact binary stars; quasars
Dusty-wind-clear JWST Super-early Galaxies

The JWST discovery of a number of super-early (redshift z > 10) blue galaxies requires these systems to be essentially dust free in spite of their large stellar masses. A possible explanation is that dust is evacuated by radiatively driven outflows. We test this hypothesis by deriving the Eddington ratio λ E = L bol/L E , where L bol is the bolometric luminosity produced by star formation and possible black hole accretion, for 134 galaxies at 6.5 < z < 16. We find a strong anticorrelation between λ E and dust UV optical depth, ${\tau }_{1500}\propto {\lambda }_{E}^{-0.63};$ also, λ E increases with redshift. We confirm that galaxies exceeding a specific star formation rate sSFR > 13 Gyr-1 develop powerful outflows clearing the galaxy from its dust. This result is supported by ALMA dust continuum nondetections in three super-early systems.

Keywords: high-redshift galaxies; galaxy evolution; galaxy formation
Long-term Evolution of Postexplosion Helium-star Companions of Type Iax Supernovae

Supernovae of Type Iax (SNe Iax) are an accepted faint subclass of hydrogen-free supernovae. Their origin, the nature of the progenitor systems, however, is an open question. Recent studies suggest that the weak deflagration explosion of a near-Chandrasekhar-mass white dwarf in a binary system with a helium-star donor could be the origin of SNe Iax. In this scenario, the helium-star donor is expected to survive the explosion. We use the one-dimensional stellar evolution codes MESA and Kepler to follow the postimpact evolution of the surviving helium companion stars. The stellar models are based on our previous hydrodynamical simulations of ejecta-donor interaction, and we explore the observational characteristics of these surviving helium companions. We find that the luminosities of the surviving helium companions increase significantly after the impact: they could vary from 2500 L ⊙ to 16,000 L ⊙ for a Kelvin-Helmholtz timescale of about 104 yr. After the star reaches thermal equilibrium, it evolves as an O-type hot subdwarf (sdO) star and continues its evolution along the evolutionary track of a normal sdO star with the same mass. Our results will help to identify the surviving helium companions of SNe Iax in future observations and to place new constraints on their progenitor models.

Keywords: close binary stars; supernovae; type ia supernovae
Asteroid Lightcurves and Detection, Shape, and Size Biases in Large-scale Surveys

Most asteroids are somewhat elongated and have non-zero lightcurve amplitudes. Such asteroids can be detected in large-scale sky surveys even if their mean magnitudes are fainter than the stated sensitivity limits. We explore the detection of elongated asteroids under a set of idealized but useful approximations. We find that objects up to 1 mag fainter than a survey's sensitivity limit are likely to be detected, and that the effect is most pronounced for asteroids with lightcurve amplitudes 0.1-0.4 mag. This imposes a bias on the derived size and shape distributions of the population that must be properly accounted for.

Keywords: surveys; asteroids
GRB 110213A: A Study of Afterglow Electromagnetic Cascade Radiation

We obtained well-sampled optical photometry of GRB 110213A, including Swift/UVOT and XRT. Combining our data from those of other ground-based telescopes, we present 15 optical multicolor light curves showing similar shapes with two peaks. In contrast, in the X-ray band, only a single peak is observed between the two optical peaks. Temporal and spectral analysis of GRB 110213A shows that the X-rays differ from the optical for Phases I-III (before the second peak of the optical band at ~5.6 ks). Moreover, they have the same spectral behavior at late times (Phases IV-VI). These data indicate that the optical and X-ray emission are dominated by different components. The synchrotron-supported pair cascade emission is included in the standard external forward-shock model, which is dominated by synchrotron radiation and synchrotron self-Compton (SSC). We find that the optical bands of GRB 110213A are dominated by the cascade emission from synchrotron radiation + SSC at the early stage, while the primary synchrotron + SSC radiation dominates the X-ray band. At late stages, both the X-ray and optical bands are dominated by emission from primary synchrotron + SSC radiation. The cascade component can reasonably explain the first optical peak. In contrast, the primary synchrotron + SSC emission mainly contributes to the second peak.

Keywords: gamma-ray bursts
Bayesian Analysis for Remote Biosignature Identification on exoEarths (BARBIE). I. Using Grid-based Nested Sampling in Coronagraphy Observation Simulations for H2O

Detecting H2O in exoplanet atmospheres is the first step on the path to determining planet habitability. Coronagraphic design currently limits the observing strategy used to detect H2O, requiring the choice of specific bandpasses to optimize abundance constraints. In order to examine the optimal observing strategy for initial characterization of habitable planets using coronagraph-based direct imaging, we quantify the detectability of H2O as a function of signal-to-noise ratio (S/N) and molecular abundance across 25 bandpasses in the visible wavelength range (0.5-1 μm). We use a preconstructed grid consisting of 1.4 million geometric albedo spectra across a range of abundance and pressure, and interpolate to produce forward models for an efficient nested sampling routine, PSGnest. We first test the detectability of H2O in atmospheres that mimic a modern-Earth twin, and then expand to examine a wider range of H2O abundances; for each abundance value, we constrain the optimal 20% bandpasses based on the effective S/N of the data. We present our findings of H2O detectability as functions of S/N, wavelength, and abundance, and discuss how to use these results for optimizing future coronographic instrument design. We find that there are specific points in wavelength where H2O can be detected down to 0.74 μm with moderate-S/N data for abundances at the upper end of Earth's presumed historical values, while at 0.9 μm, detectability is possible with low-S/N data at modern Earth abundances of H2O.

Keywords: exoplanets; exoplanet atmospheres
The Atacama Cosmology Telescope: Galactic Dust Structure and the Cosmic PAH Background in Cross-correlation with WISE

We present a cross-correlation analysis between $1^{\prime} $ resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15″ mid-infrared photometry from the Wide-field Infrared Survey Explorer (WISE) over 107 12.°5 × 12.°5 patches of sky. We detect a spatially isotropic signal in the WISE×ACT TT cross-power spectrum at 30σ significance that we interpret as the correlation between the cosmic infrared background at ACT frequencies and polycyclic aromatic hydrocarbon (PAH) emission from galaxies in WISE, i.e., the cosmic PAH background. Within the Milky Way, the Galactic dust TT spectra are generally well described by power laws in ℓ over the range 103 < ℓ < 104, but there is evidence both for variability in the power-law index and for non-power-law behavior in some regions. We measure a positive correlation between WISE total intensity and ACT E-mode polarization at 1000 < ℓ ≲ 6000 at >3σ in each of 35 distinct ~100 deg2 regions of the sky, suggesting that alignment between Galactic density structures and the local magnetic field persists to subparsec physical scales in these regions. The distribution of TE amplitudes in this ℓ range across all 107 regions is biased to positive values, while there is no evidence for such a bias in the TB spectra. This work constitutes the highest-ℓ measurements of the Galactic dust TE spectrum to date and indicates that cross-correlation with high-resolution mid-infrared measurements of dust emission is a promising tool for constraining the spatial statistics of dust emission at millimeter wavelengths.

Keywords: interstellar dust; dust continuum emission; interstellar magnetic fields; cosmic background radiation; interstellar medium; polycyclic aromatic hydrocarbons
Radiative Magnetohydrodynamic Simulation of the Confined Eruption of a Magnetic Flux Rope: Magnetic Structure and Plasma Thermodynamics

It is widely believed that magnetic flux ropes are the key structure of solar eruptions; however, their observable counterparts are not clear yet. We study a flare associated with flux rope eruption in a comprehensive radiative magnetohydrodynamic simulation of flare-productive active regions, especially focusing on the thermodynamic properties of the plasma involved in the eruption and their relation to the magnetic flux rope. The preexisting flux rope, which carries cold and dense plasma, rises quasi-statically before the onset of eruptions. During this stage, the flux rope does not show obvious signatures in extreme ultraviolet (EUV) emission. After the flare onset, a thin "current shell" is generated around the erupting flux rope. Moreover, a current sheet is formed under the flux rope, where two groups of magnetic arcades reconnect and create a group of postflare loops. The plasma within the "current shell," current sheet, and postflare loops are heated to more than 10 MK. The postflare loops give rise to abundant soft X-ray emission. Meanwhile, a majority of the plasma hosted in the flux rope is heated to around 1 MK, and the main body of the flux rope is manifested as a bright arch in cooler EUV passbands such as the AIA 171 Å channel.

Keywords: radiative magnetohydrodynamics; solar extreme ultraviolet emission; solar magnetic fields; solar activity
Excalibur: A Nonparametric, Hierarchical Wavelength Calibration Method for a Precision Spectrograph

Excalibur is a nonparametric, hierarchical framework for precision wavelength calibration of spectrographs. It is designed with the needs of extreme-precision radial-velocity (EPRV) instruments in mind, which require calibration or stabilization to better than 10-4 pixels. Instruments vary along only a few dominant degrees of freedom, especially EPRV instruments that feature highly stabilized optical systems and detectors. Excalibur takes advantage of this property by using all calibration data to construct a low-dimensional representation of all accessible calibration states for an instrument. Excalibur also takes advantage of laser-frequency combs or etalons, which generate a dense set of stable calibration points. This density permits the use of a nonparametric wavelength solution that can adapt to any instrument or detector oddities better than parametric models, such as a polynomial. We demonstrate the success of this method with data from the Extreme Precision Spectrograph (EXPRES), which uses a laser-frequency comb. When wavelengths are assigned to laser comb lines using excalibur, the rms of the residuals is about one-fifth that of wavelengths assigned using polynomial fits to individual exposures. Radial-velocity measurements of HD 34411 show a reduction in rms scatter over a 10 month time baseline from 1.17 to 1.05 m s-1.

Keywords: exoplanet detection methods; radial velocity; astronomical techniques; astronomical instrumentation; spectrometers; computational methods
Numerical Modeling of Suprathermal Electron Transport in the Solar Wind: Effects of Whistler Turbulence

The solar wind electron velocity distribution function deviates significantly from an equilibrium Maxwellian distribution and is composed of a Maxwellian core, a suprathermal halo, a field-aligned component strahl, and a higher-energy superhalo. Wave-particle interactions associated with whistler wave turbulence are introduced into the kinetic transport equation to describe the interaction between the suprathermal electrons and the whistler waves and to explain the observation that the halo and the strahl relative densities vary in an opposite sense. An efficient numerical method has been developed to solve the Fokker-Planck kinetic transport equation. Application of the numerical method to suprathermal electrons in the solar wind in the presence of whistler waves is presented. Comparison and analysis between the numerical results and observations are made.

Keywords: solar wind
Comprehensive High-resolution Chemical Spectroscopy of Barnard's Star with SPIRou

Determination of fundamental parameters of stars impacts all fields of astrophysics, from galaxy evolution to constraining the internal structure of exoplanets. This paper presents a detailed spectroscopic analysis of Barnard's star (otherwise known as Gl 699) that compares an exceptionally high-quality (an average signal-to-noise ratio of ∼1000 in the entire domain), high-resolution near-infrared (NIR) spectrum taken with Canada-France-Hawaii Telescope/SPIRou to PHOENIX-ACES stellar atmosphere models. The observed spectrum shows thousands of lines not identified in the models with a similarly large number of lines present in the model but not in the observed data. We also identify several other caveats, such as continuum mismatch, unresolved contamination, and spectral lines significantly shifted from their expected wavelengths; all of these can be a source of bias for the determination of abundance. Out of >104 observed lines in the NIR that could be used for chemical spectroscopy, we identify a short list of a few hundred lines that are reliable. We present a novel method for determining the effective temperature (T eff) and overall metallicity of slowly rotating M dwarfs that uses several groups of lines as opposed to bulk spectral fitting methods. With this method, we infer T eff = 3231 ± 21 K for Barnard's star, consistent with the value of 3238 ± 11 K inferred from the interferometric method. We also provide measurements of the abundance of 15 different elements for Barnard's star, including the abundances of four elements (K, O, Y, Th) never reported before for this star. This work emphasizes the need to improve current atmosphere models to fully exploit the NIR domain for chemical spectroscopy analysis.

Keywords: m dwarf stars; low mass stars; stellar atmospheres; chemical abundances; abundance ratios; metallicity; stellar abundances; astronomical techniques; atomic spectroscopy; molecular spectroscopy
Monitoring AGNs with Hβ Asymmetry. III. Long-term Reverberation Mapping Results of 15 Palomar-Green Quasars

In this third paper of the series reporting on the reverberation mapping campaign of active galactic nuclei with asymmetric Hβ emission-line profiles, we present results for 15 Palomar-Green quasars using spectra obtained between the end of 2016-2021 May. This campaign combines long time spans with relatively high cadence. For eight objects, both the time lags obtained from the entire light curves and the measurements from individual observing seasons are provided. Reverberation mapping of nine of our targets has been attempted for the first time, while the results for six others can be compared with previous campaigns. We measure the Hβ time lags over periods of years and estimate their black hole masses. The long duration of the campaign enables us to investigate their broad-line region (BLR) geometry and kinematics for different years by using velocity-resolved lags, which demonstrate signatures of diverse BLR geometry and kinematics. The BLR geometry and kinematics of individual objects are discussed. In this sample, the BLR kinematics of Keplerian/virialized motion and inflow is more common than that of outflow.

Keywords: reverberation mapping; active galactic nuclei; active galaxies; supermassive black holes; quasars
Modeling Electron Acceleration and Transport in the Early Impulsive Phase of the 2017 September 10th Solar Flare

The X8.2-class limb flare on 2017 September 10 is among the best studied solar flare events owing to its great similarity to the standard flare model and the broad coverage by multiple spacecraft and ground-based observations. These multiwavelength observations indicate that electron acceleration and transport are efficient in the reconnection and flare looptop regions. However, there lacks a comprehensive model for explaining and interpreting the multi-faceted observations. In this work, we model the electron acceleration and transport in the early impulsive phase of this flare. We solve the Parker transport equation that includes the primary acceleration mechanism during magnetic reconnection in the large-scale flare region modeled by MHD simulations. We find that electrons are accelerated up to several MeV and fill a large volume of the reconnection region, similar to the observations shown in microwaves. The electron spatial distribution and spectral shape in the looptop region agree well with those derived from the microwave and hard X-ray emissions before magnetic islands grow large and dominate the acceleration. Future emission modelings using the electron maps will enable direct comparison with microwave and hard X-ray observations. These results shed new light on the electron acceleration and transport in a broad region of solar flares within a data-constrained realistic flare geometry.

Keywords: interplanetary particle acceleration; solar magnetic reconnection; solar flares; solar corona; space plasmas
Morpheus: A Deep Learning Framework for the Pixel-level Analysis of Astronomical Image Data

We present Morpheus, a new model for generating pixel-level morphological classifications of astronomical sources. Morpheus leverages advances in deep learning to perform source detection, source segmentation, and morphological classification pixel-by-pixel via a semantic segmentation algorithm adopted from the field of computer vision. By utilizing morphological information about the flux of real astronomical sources during object detection, Morpheus shows resiliency to false-positive identifications of sources. We evaluate Morpheus by performing source detection, source segmentation, morphological classification on the Hubble Space Telescope data in the five CANDELS fields with a focus on the GOODS South field, and demonstrate a high completeness in recovering known GOODS South 3D-HST sources with H < 26 AB. We release the code publicly, provide online demonstrations, and present an interactive visualization of the Morpheus results in GOODS South.

Keywords: galaxy classification systems; galaxies; extragalactic astronomy; convolutional neural networks; computational methods; gpu computing
Evidence for Nitrogen-bearing Species on Umbriel: Sourced from a Subsurface Ocean, Undifferentiated Crust, or Impactors?

Near-infrared spectra of Umbriel and the other classical Uranian moons exhibit 2.2 μm absorption bands that could result from ammonia (NH3) bearing species, possibly exposed in the geologically recent past. However, Umbriel has an ancient surface with minimal evidence for recent endogenic activity, raising the possibility that more refractory species are present, and/or that NH3 is retained over long timescales. We analyzed 33 spectra of Umbriel to investigate its 2.2 μm band, along with three other absorption features we identified near 2.14, 2.22, and 2.24 μm. We assessed the subobserver longitudinal distributions of these four bands, finding that they are present across Umbriel and may be spatially associated with geologic features such as craters and large basins. We compared the bands to 15 candidate constituents. We found that Umbriel's 2.14 μm and 2.22 μm bands are most consistent with the spectral signature of organics, its 2.24 μm band is best matched by NH3 ice, and its 2.2 μm band is consistent with the signatures of NH3-H2O mixtures, aluminum-bearing phyllosilicates, and sodium-bearing carbonates. However, some of these candidate constituents do not match Umbriel's spectral properties in other wavelength regions, highlighting the gaps in our understanding of the Uranian moons' surface compositions. Umbriel's 2.14 μm band may alternatively result from a 2 ν 3 overtone mode of CO2 ice. If present on Umbriel, these candidate constituents could have formed in contact with an internal ocean and were subsequently exposed during Umbriel's early history. Alternatively, these constituents might have originated in an undifferentiated crust or were delivered by impactors.

Keywords: surface ices; surface processes; planetary surfaces; surface composition; uranian satellites
The Two Hot Corinos of the SVS13-A Protostellar Binary System: Counterposed Siblings

We present ALMA high-angular-resolution (~50 au) observations of the Class I binary system SVS13-A. We report images of SVS13-A in numerous interstellar complex organic molecules: CH3OH, 13CH3OH, CH3CHO, CH3OCH3, and NH2CHO. Two hot corinos at different velocities are imaged in VLA4A (V sys = +7.7 km s-1) and VLA4B (V sys = +8.5 km s-1). From a non-LTE analysis of methanol lines, we derive a gas density of 3 × 108 cm-3 and gas temperatures of 140 and 170 K for VLA4A and VLA4B, respectively. For the other species, the column densities are derived from an LTE analysis. Formamide, which is the only N-bearing species detected in our observations, is more prominent around VLA4A, while dimethyl ether, methanol, and acetaldehyde are associated with both VLA4A and VLA4B. We derive in the two hot corinos abundance ratios of ~1 for CH3OH, 13CH3OH, and CH3OCH3; ~2 for CH3CHO; and ~4 for NH2CHO. The present data set supports chemical segregation between the different species inside the binary system. The emerging picture is that of an onion-like structure of the two SVS13-A hot corinos, caused by the different binding energies of the species, also supported by ad hoc quantum chemistry calculations. In addition, the comparison between molecular and dust maps suggests that the interstellar complex organic molecules emission originates from slow shocks produced by accretion streamers impacting the VLA4A and VLA4B disks and enriching the gas-phase component.

Keywords: astrochemistry