adsabs/SciX_UAT_keywords huggingface dataset:
SiO, 29SiO, and 30SiO Emission from 67 Oxygen-rich Stars: A Survey of 61 Maser Lines from 7 to 1 mm

Circumstellar environments of oxygen-rich stars are among the strongest SiO maser emitters. Physical processes such as collisions, infrared pumping, and overlaps favor the inversion of level population and produce maser emission at different vibrational states. Despite numerous observational and theoretical efforts, we still do not have a unified picture including all of the physical processes involved in SiO maser emission. The aim of this work is to provide homogeneous data in a large sample of oxygen-rich stars. We present a survey of 67 oxygen-rich stars from 7 to 1 mm, in their rotational transitions from J = 1 → 0 to J = 5 → 4, for vibrational numbers v from 0 to 6 in the three main SiO isotopologs. We have used one of the 34 m NASA antennas at Robledo and the IRAM 30 m radio telescope. The first tentative detection of a v = 6 line is reported, as well as the detection of new maser lines. The highest vibrational levels seem confined to small volumes, presumably close to the stars. The J = 1 → 0, v = 2 line flux is greater than the corresponding v = 1 in almost half of the sample, which may confirm a predicted dependence on the pulsation cycle. This database is potentially useful in models which should consider most of the physical agents, time dependency, and mass-loss rates. As a by-product, we report detections of 27 thermal rotational lines from other molecules, including isotopologs of SiS, H2S, SO, SO2, and NaCl.

Keywords: silicon monoxide masers; asymptotic giant branch; interstellar medium; interstellar molecules; circumstellar envelopes; stellar evolution; surveys; radio astronomy
Things That Might Go Bump in the Night: Assessing Structure in the Binary Black Hole Mass Spectrum

Several features in the mass spectrum of merging binary black holes (BBHs) have been identified using data from the Third Gravitational Wave Transient Catalog (GWTC-3). These features are of particular interest as they may encode the uncertain mechanism of BBH formation. We assess if the features are statistically significant or the result of Poisson noise due to the finite number of observed events. We simulate catalogs of BBHs whose underlying distribution does not have the features of interest, apply the analysis previously performed on GWTC-3, and determine how often such features are spuriously found. We find that one of the features found in GWTC-3, the peak at ~35 M ☉, cannot be explained by Poisson noise alone: peaks as significant occur in 1.7% of catalogs generated from a featureless population. This peak is therefore likely to be of astrophysical origin. The data is suggestive of an additional significant peak at ~10 M ☉, though the exact location of this feature is not resolvable with current observations. Additional structure beyond a power law, such as the purported dip at ~14 M ☉, can be explained by Poisson noise. We also provide a publicly available package, GWMockCat, that creates simulated catalogs of BBH events with correlated measurement uncertainty and selection effects according to user-specified underlying distributions and detector sensitivities.

Keywords: astrophysical black holes; stellar mass black holes; black holes; gravitational waves; gravitational wave sources; gravitational wave astronomy; bayesian statistics; hierarchical models
Find the Gap: Black Hole Population Analysis with an Astrophysically Motivated Mass Function

We introduce a novel black hole mass function that realistically models the physics of pair-instability supernovae with a minimal number of parameters. Applying this to all events in the LIGO-Virgo Gravitational-Wave Transient Catalog 2 (GWTC-2), we detect a peak at ${M}_{\mathrm{BHMG}}={46}_{-6}^{+17}\,{M}_{\odot }$. Repeating the analysis without the black holes from the event GW190521, we find this feature at MBHMG = 54 ± 6 M⊙. These results establish the edge of the anticipated "black hole mass gap" at a value compatible with the expectation from standard stellar structure theory. The mass gap manifests itself as a discontinuity in the mass function and is populated by a distinct, less-abundant population of higher-mass black holes. We find that the primary black hole population scales with power-law index -1.95 ± 0.51 (-1.97 ± 0.44) with (without) GW190521, consistent with models of star formation. Using Bayesian techniques, we establish that our mass function fits a new catalog of black hole masses approximately as well as pre-existing phenomenological mass functions. We also remark on the implications of these results for constraining or discovering new phenomena in nuclear and particle physics.

Keywords: astrophysical black holes; black holes; gravitational waves; particle astrophysics; gravitational wave astronomy; nuclear astrophysics; stellar evolution; stellar populations; population iii stars; helium burning
The Astronomy Commons Platform: A Deployable Cloud-based Analysis Platform for Astronomy

We present a scalable, cloud-based science platform solution designed to enable next-to-the-data analyses of terabyte-scale astronomical tabular data sets. The presented platform is built on Amazon Web Services (over Kubernetes and S3 abstraction layers), utilizes Apache Spark and the Astronomy eXtensions for Spark for parallel data analysis and manipulation, and provides the familiar JupyterHub web-accessible front end for user access. We outline the architecture of the analysis platform, provide implementation details and rationale for (and against) technology choices, verify scalability through strong and weak scaling tests, and demonstrate usability through an example science analysis of data from the Zwicky Transient Facility's 1Bn+ light-curve catalog. Furthermore, we show how this system enables an end user to iteratively build analyses (in Python) that transparently scale processing with no need for end-user interaction. The system is designed to be deployable by astronomers with moderate cloud engineering knowledge, or (ideally) IT groups. Over the past 3 yr, it has been utilized to build science platforms for the DiRAC Institute, the ZTF partnership, the LSST Solar System Science Collaboration, and the LSST Interdisciplinary Network for Collaboration and Computing, as well as for numerous short-term events (with over 100 simultaneous users). In a live demo instance, the deployment scripts, source code, and cost calculators are accessible. 4 4 http://hub.astronomycommons.org/

Keywords: astronomy databases; astronomy data analysis; cloud computing; light curves
Recurrent Strong Outbursts of an EXor-like Young Eruptive Star Gaia20eae

We present follow-up photometric and spectroscopic observations, and subsequent analysis of Gaia20eae. This source triggered photometric alerts during 2020 after showing a ~3 mag increase in its brightness. Its Gaia Alert light curve showed the shape of a typical eruptive young star. We carried out observations to confirm Gaia20eae as an eruptive young star and classify it. Its pre-outburst spectral energy distribution shows that Gaia20eae is a moderately embedded Class II object with L bol = 7.22 L ⊙. The color-color and color-magnitude diagrams indicate that the evolution in the light curve is mostly gray. Multiple epochs of the Hα line profile suggest an evolution of the accretion rate and winds. The near-infrared spectra display several emission lines, a feature typical of EX Lupi-type (EXor) eruptive young stars. We estimated the mass accretion rate during the dimming phase to be $\dot{M}$ = 3-8 × 10-7 M ⊙ yr-1, higher than typical T Tauri stars of similar mass and comparable to other EXors. We conclude Gaia20eae is a new EXor-type candidate.

Keywords: young stellar objects; t tauri stars; spectroscopy; broad band photometry
Time Domain Structures and Dust in the Solar Vicinity: Parker Solar Probe Observations

On 2019 April 5, while the Parker Solar Probe was at its 35 solar radius perihelion, the data set collected at 293 samples/s contained more than 10,000 examples of spiky electric-field-like structures with durations less than 200 milliseconds and amplitudes greater than 10 mV m-1. The vast majority of these events were caused by plasma turbulence. Defining dust events as those with similar, narrowly peaked, positive, and single-ended signatures resulted in finding 135 clear dust events, which, after correcting for the low detection efficiently, resulted in an estimate consistent with the 1000 dust events expected from other techniques. Defining time domain structures (TDS) as those with opposite polarity signals in the opposite antennas resulted in finding 238 clear TDS events which, after correcting for the detection efficiency, resulted in an estimated 500-1000 TDS events on this day. The TDS electric fields were bipolar, as expected for electron holes. Several events were found at times when the magnetic field was in the plane of the two measured components of the electric field such that the component of the electric field parallel to the magnetic field was measured. One example of significant parallel electric fields shows the negative potential that classified them as electron holes. Because the TDS observation rate was not uniform with time, it is likely that there were local regions below the spacecraft with field-aligned currents that generated the TDS.

Keywords: interplanetary dust; solar electromagnetic emission; solar coronal waves
The Impact of Realistic Foreground and Instrument Models on 21 cm Epoch of Reionization Experiments

Predictions for the ability of 21 cm interferometric experiments to discriminate Epoch of Reionization (EoR) signal models are typically limited by the simplicity of data models, whereby foreground signals and characteristics of the instrument are often simplified or neglected. To move toward more realistic scenarios, we explore the effects of applying more realistic foreground and instrument models to the 21 cm signal, as well as the ability to estimate astrophysical parameters with these additional complexities. We use a highly optimized version of 21cm FAST, integrated into 21cm MC, to generate lightcones of the brightness temperature fluctuation for Bayesian parameter estimation. We include a statistical point-source foreground model and an instrument model based on the Murchison Widefield Array scaled in observation time to have an effective sensitivity similar to the future Square Kilometre Array. We also extend the current likelihood prescription to account for the presence of beam convolution and foregrounds, the two-dimensional power spectrum (PS), and the correlation of PS modes. We use frequency bands between 150 and 180 MHz to constrain the ionizing efficiency (ζ), the minimum virial temperature of halos ( ${T}_{\mathrm{vir}}$ ), the soft X-ray emissivity per unit star formation rate (SFR) (LX/SFR), and the X-ray energy threshold (E0). We find that the inclusion of realistic foregrounds and instrumental components biases the parameter constraints, due to unaccounted for cross-power between the EoR signal, foregrounds, and thermal noise. This causes estimates of ζ to be biased by up to 5σ, but the estimates of Tvir, LX/SFR and E0 remain unaffected and are all within 1σ.

Keywords: reionization; cosmology; large-scale structure of the universe; astronomical instrumentation
Experimental Study of Micrometeoroids Impacts on an X-Ray Telescope Model using Micro-pore Optics and CMOS Detector with Micron-sized Particles

This laboratory study aimed to assess the potential damage caused by the impact of micrometeoroids or space debris on a novel X-ray focusing telescope composed of Micro-pore Optics (MPO) plates and Complementary Metal Oxide Semiconductor (CMOS) sensors. An impact experiment was conducted on a simplified model of an X-ray telescope composed of two MPO plates and one CMOS sensor. The diameters of the projectiles we used are 1 ~ 50 μm. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDS) are methods for investigating the morphology of the impact craters and analyzing the composition of residues. We described the impact crater morphology on both MPO plates and CMOS chips. Results of impact craters size and number show that one 1 μm particle produces a damaged area of 18 μm2 in aluminum (Al) film of the MPO plate on average (at a median speed of 2 km s-1), resulting in 10 light leak spots on the CMOS chip. Meanwhile, one particle with a diameter of 50 μm may damage 3 micropores (about 7 × 10-3 mm2) on the MPO plate at a median speed of 6 km s-1. About 1.5 particles could cause one bad pixel on the CMOS chip behind the MPO plates. Nevertheless, no failure of the CMOS sensor or severe damage to the MPO device was observed after the impact.

Keywords: micrometeoroids; x-ray telescopes; x-ray detectors; impact phenomena; astronomical instrumentation
Predicting Localized Primordial Star Formation with Deep Convolutional Neural Networks

We investigate applying 3D deep convolutional neural networks as fast surrogate models of the formation and feedback effects of primordial stars in hydrodynamic cosmological simulations of the first galaxies. Here, we present the surrogate model to predict localized primordial star formation; the feedback model will be presented in a subsequent paper. The star formation prediction model consists of two submodels: the first is a 3D volume classifier that predicts which (10 comoving kpc)3 volumes will host star formation, followed by a 3D Inception-based U-net voxel segmentation model that predicts which voxels will form primordial stars. We find that the combined model predicts primordial star-forming volumes with high skill, with F1 > 0.995 and true skill score (TSS) >0.994. The star formation is localized within the volume to ≲53 voxels (∼1.6 comoving kpc3) with F1 > 0.399 and TSS >0.857. Applied to simulations with low spatial resolution, the model predicts star-forming regions in the same locations and at similar redshifts as sites in resolved full-physics simulations that explicitly model primordial star formation and feedback. When applied to simulations with lower mass resolution, we find that the model predicts star-forming regions at later redshift due to delayed structure formation resulting from lower mass resolution. Our model predicts primordial star formation without halo finding, so it will be useful in spatially under-resolved simulations that cannot resolve primordial star-forming halos. To our knowledge, this is the first model that can predict primordial star-forming regions that match highly resolved cosmological simulations.

Keywords: convolutional neural networks; population iii stars
Superadiabaticity in Jupiter and Giant Planet Interiors

Interior models of giant planets traditionally assume that at a given radius (i.e., pressure) the density should be larger than or equal to the one corresponding to a homogeneous, adiabatic stratification throughout the planet (referred to as the "outer adiabat"). The observations of Jupiter's gravity field by Juno combined with the constraints on its atmospheric composition appear to be incompatible with such a profile. In this Letter, we show that the above assumption stems from an incorrect understanding of the Schwarzschild-Ledoux criterion, which is only valid on a local scale. In order to fulfill the buoyancy stability condition, the density gradient with pressure in a nonadiabatic region must indeed rise more steeply than the local adiabatic density gradient. However, the density gradient can be smaller than the one corresponding to the outer adiabat at the same pressure because of the higher temperature in an inhomogeneously stratified medium. Deep enough, the density can therefore be lower than the one corresponding to the outer adiabat. We show that this is permitted only if the slope of the local adiabat becomes shallower than the slope of the outer adiabat at the same pressure, as found in recent Jupiter models due to the increase of both specific entropy and adiabatic index with depth. We examine the dynamical stability of this structure and show that it is stable against nonadiabatic perturbations. The possibility of such an unconventional density profile in Jupiter further complicates our understanding of the internal structure and evolution of (extrasolar) giant planets.

Keywords: planetary interior; exoplanet structure
Predictions for Sparse Photometry of Jupiter-family Comet Nuclei in the LSST Era

The Legacy Survey of Space and Time (LSST) at Vera C. Rubin Observatory will deliver high-quality, temporally sparse observations of millions of solar system objects on an unprecedented scale. Such data sets will likely enable the precise estimation of small-body properties on a population-wide basis. In this work, we consider the possible applications of photometric data points from LSST to the characterization of Jupiter-family comet (JFC) nuclei. We simulate sparse-in-time lightcurve points with an LSST-like cadence for the orbit of a JFC between 2024 and 2033. Convex lightcurve inversion is used to assess whether the simulation input parameters can be accurately reproduced for a sample of nucleus rotation periods, pole orientations, activity onsets, shapes, and sizes. We find that the rotation period and pole direction can be reliably constrained across all nucleus variants tested, and that the convex shape models, while limited in their ability to describe complex or bilobed nuclei, are effective for correcting sparse photometry for rotational modulation to improve estimates of nucleus phase functions. Based on this analysis, we anticipate that LSST photometry will significantly enhance our present understanding of the spin state and phase function distributions of JFC nuclei.

Keywords: light curves; comet nuclei; short period comets; sky surveys
An Overview of Sunspot Observations in 1727-1748

Solar activity generally exhibits cyclic behavior in terms of sunspot group number and sunspot positions every ≈11 yr. These sunspot data have therefore played key roles in numerous analyses of solar-terrestrial physics. However, their reconstructions prior to the 1830s have remained controversial and included significant data gaps, especially from the 1720s to the 1740s. Therefore, this study reviewed contemporary sunspot observations for 1727-1748 to add several forgotten records by Van Coesfelt in 1728-1729, Dûclos in 1736, Martin in 1737, and Cassini and Maraldi in 1748. On the basis of these records, this study revised the sunspot group number and newly derived the sunspot positions in this interval. The results show clearer solar cycles in sunspot group number than those of previous studies and indicate regular solar cycles with limited hemispheric asymmetry over Solar Cycles 0 to -2. The sunspot positions also show sunspot groups mostly at heliographic latitude φ fulfilling ∣φ∣ < 35° in both solar hemispheres, with slight equatorward motions. Furthermore, the solar minima between Solar Cycles -2 and -1 and between Solar Cycles -1 and 0 have been located around 1733.5 ± 0.5 and 1743 ± 0.5, indicating cycle lengths of 11.7 ± 0.5 yr and 10.0 ± 1.0 yr, respectively. Our results provide a chronological missing link between the Maunder Minimum and the regular solar cycles observed since Staudach's observations from 1749 onward. This lets us better understand the transition of solar activity from the grand minimum to the regular solar cycles.

Keywords: sunspot cycle; sunspot groups; sunspot number; sunspots; solar cycle; solar-terrestrial interactions
Toward the Detection of Relativistic Image Doubling in Water Cerenkov Detectors

When a gamma or cosmic ray strikes the top of Earth's atmosphere, a shower of secondary particles moves toward the surface. Some of these secondary particles are charged muons that subsequently enter water Cerenkov detectors (WCDs) on the ground. Many of these muons, traveling near the speed of light in vacuum, are moving faster than the speed of light in water and so trigger isotropic Cerenkov radiation in the WCDs. Inside many WCDs are photomultiplier tubes (PMTs) that detect this Cerenkov radiation. When the radial component of the speed of a muon toward a PMT drops from superluminal to subluminal, the PMT will record Cerenkov light from a little-known optical phenomenon called Relativistic Image Doubling (RID). Were the RID-detecting PMTs replaced by high resolution video recorders, they would see two Cerenkov images of the muon suddenly appear inside the tank, with one image moving with a velocity component toward the recorders, the other away. Even without a video, the RID phenomenon will cause different PMTs to record markedly different light curves for the same muon. In this paper, we present a study hoping to inspire the explicit detection and reporting of RID effects in WCDs. We consider three example cases of muon RIDs in High-Altitude Water Cerenkov (HAWC)-like systems: vertical, horizontal, and oblique. Monte Carlo simulations show that RID effects in HAWC-like systems are not rare—they occur for over 85% of all muon tracks.

Keywords: cosmic ray showers; special relativity; astronomical optics
Accretion Belt Characteristics in a Hydrodynamic Evolution of a Contact Binary

We compare features from the circulation model developed in Stȩpień for contact binaries to a long-term hydrodynamical evolution of a symmetric contact binary. The numerical evolution is fully three-dimensional and begins from an equilibrium structure in contact at one grid cell. As the evolution is conducted with Flow-ER, an explicit hydrodynamics code for self-gravitating fluids, we are not able to address energy transport or evolution on a thermal timescale. However, we are able to investigate the width and height of the equatorial accretion belt and the flow of material in and out of the inner Lagrange point. The flow of material between the two components arises quickly in the evolution and does not change significantly through tens of orbital periods. As the stellar components are modeled as polytropes of index 3/2 a slight numerical mass imbalance causes one component to only gain mass over the course of the simulation leading eventually to a dynamical merger of the contact binary.

Keywords: contact binary stars; hydrodynamical simulations