adsabs/SciX_UAT_keywords huggingface dataset:
Investigation of the Broadband Emission of the Gamma-Ray Binary HESS J0632+057 Using an Intrabinary Shock Model

We investigated a wealth of X-ray and gamma-ray spectral energy distribution (SED) and multiband light-curve (LC) data of the gamma-ray binary HESS J0632+057 using a phenomenological intrabinary shock (IBS) model. Our baseline model assumes that the IBS is formed by colliding winds from a putative pulsar and its Be companion and that particles accelerated in the IBS emit broadband radiation via synchrotron (SY) and inverse Compton upscattering (ICS) processes. Adopting the latest orbital solution and system geometry, we reproduced the global X-ray and TeV LC features, two broad bumps at ϕ ~ 0.3 and ~0.7, with the SY and ICS model components. We found that these TeV LC peaks originate from ICS emission caused by the enhanced seed photon density near periastron and superior conjunction or Doppler-beamed emission of bulk-accelerated particles in the IBS at inferior conjunction. While our IBS model successfully explained most of the observed SED and LC data, we found that phase-resolved SED data in the TeV band require an additional component associated with ICS emission from preshock particles (produced by the pulsar wind). This finding indicates a possibility of delineating the IBS emission components and determining the bulk Lorentz factors of the pulsar wind at certain orbital phases.

Keywords: high mass x-ray binary stars; high energy astrophysics; relativistic binary stars; gamma-ray sources; radiative processes
Light Curves of Type IIP Supernovae from Neutrino-driven Explosions of Red Supergiants Obtained by a Semianalytic Approach

Type IIP supernovae (SNe IIP) mark the explosive death of red supergiants (RSGs), evolved massive stars with an extended hydrogen envelope. They are the most common supernova type and allow for the benchmarking of supernova explosion models by statistical comparison to observed population properties rather than by comparing individual models and events. We construct a large synthetic set of SNe IIP light curves (LCs) using the radiation hydrodynamics code SNEC and explosion energies and nickel masses obtained from an efficient semianalytic model for two different sets of stellar progenitor models. By direct comparison, we demonstrate that the semianalytic model yields very similar predictions as alternative phenomenological explosion models based on 1D simulations. We find systematic differences of a factor of ~2 in plateau luminosities between the two progenitor sets due to different stellar radii, which highlights the importance of the RSG envelope structure as a major uncertainty in interpreting the LCs of SNe IIP. A comparison to a volume-limited sample of observed SNe IIP shows decent agreement in plateau luminosity, plateau duration, and nickel mass for at least one of the synthetic LC sets. The models, however, do not produce sufficient events with very small nickel mass M Ni < 0.01 M ⊙ and predict an anticorrelation between plateau luminosity and plateau duration that is not present in the observed sample, a result that warrants further study. Our results suggest that a better understanding of RSG stellar structure is no less important for reliably explaining the LCs of SNe IIP than the explosion physics.

Keywords: core-collapse supernovae; type ii supernovae; supernova dynamics; radiative transfer simulations; light curves
First Observational Evidence for an Interconnected Evolution between Time Lag and QPO Frequency among AGNs

Quasiperiodic oscillations (QPOs) have been widely observed in black hole X-ray binaries (BHBs), which often exhibit significant X-ray variations. Extensive research has explored the long-term evolution of the properties of QPOs in BHBs. In contrast, such evolution in active galactic nuclei (AGNs) has remained largely unexplored due to limited observational data. By using the 10 new XMM-Newton observations for the narrow-line Seyfert 1 galaxy RE J1034+396 from publicly available data, we analyze the characteristics of its X-ray QPOs and examine their long-term evolution. The hard-band (1–4 keV) QPOs are found in all 10 observations and the frequency of these QPOs evolves ranging at (2.47–2.83) × 10‑4 Hz. Furthermore, QPO signals in the soft (0.3–1 keV) and hard bands exhibit strong coherence, although, at times, the variations in the soft band lead those in the hard band (the hard-lag mode), while at other times, it is the reverse (the soft-lag mode). The observations presented here serendipitously captured two ongoing lag reversals between these two modes within about two weeks, which are first seen in RE J1034+396 and also among all AGNs. A transition in QPO frequency also takes place within a two-week timeframe, two weeks prior to its corresponding lag reversal, indicating a possible coherence between the transitions of QPO frequency and lag mode with delay. The diagram of time lag versus QPO frequency clearly evidences this interconnected evolution with hysteresis, which is, for the first time, observed among AGNs.

Keywords: active galactic nuclei; galaxy accretion disks; x-ray active galactic nuclei
Identifying H I Emission and UV Absorber Associations near the Magellanic Stream

We present a new technique to identify associations of H I emission in the Magellanic Stream (MS) and ultraviolet (UV) absorbers from 92 QSO sight lines near the MS. We quantify the level of associations of individual H I elements to the main H I body of the Stream using Wasserstein distance-based models, and derive characteristic spatial and kinematic distances of the H I emission in the MS. With the emission-based model, we further develop a comparison metric, which identifies the dominant associations of individual UV absorbers with respect to the MS and nearby galaxies. For ionized gas associated with the MS probed by C II, C IV, Si II, Si III, Si IV, we find that the ion column densities are generally ∼0.5 dex higher than those that are not associated, and that the gas is more ionized toward the tail of the MS as indicated by the spatial trend of the C II/C IV ratios. For nearby galaxies, we identify potential new absorbers associated with the circumgalactic medium of M33 and NGC 300, and affirm the associations of absorbers with IC 1613 and the Wolf–Lundmark–Mellote galaxy. For M31, we find the previously identified gradient in column densities as a function of the impact parameter, and that absorbers with higher column densities beyond M31's virial radius are more likely to be associated with the MS. Our analysis of absorbers associated with the Magellanic Clouds reveals the presence of continuous and blended diffuse ionized gas between the Stream and the Clouds. Our technique can be applied to future applications of identifying associations within physically complex gaseous structures.

Keywords: magellanic stream; magellanic clouds; milky way galaxy; circumgalactic medium
Astronomical Detection of the Interstellar Anion C10H- toward TMC-1 from the GOTHAM Large Program on the Green Bank Telescope

Using data from the Green Bank Telescope (GBT) Observations of TMC-1: Hunting for Aromatic Molecules (GOTHAM) survey, we report the first astronomical detection of the C10H- anion. The astronomical observations also provided the necessary data to refine the spectroscopic parameters of C10H-. From the velocity stacked data and the matched filter response, C10H- is detected at >9σ confidence level at a column density of ${4.04}_{-2.23}^{+10.67}\times {10}^{11}$ cm-2. A dedicated search for the C10H radical was also conducted toward TMC-1. In this case, the stacked molecular emission of C10H was detected at a ~3.2σ confidence interval at a column density of ${2.02}_{-0.82}^{+2.68}\times {10}^{11}$ cm-2. However, as the determined confidence level is currently <5σ, we consider the identification of C10H as tentative. The full GOTHAM data set was also used to better characterize the physical parameters including column density, excitation temperature, line width, and source size for the C4H, C6H, and C8H radicals and their respective anions, and the measured column densities were compared to the predictions from a gas/grain chemical formation model and from a machine learning analysis. Given the measured values, the C10H-/C10H column density ratio is ~ ${2.0}_{-1.6}^{+5.9}$ -the highest value measured between an anion and neutral species to date. Such a high ratio is at odds with current theories for interstellar anion chemistry. For the radical species, both models can reproduce the measured abundances found from the survey; however, the machine learning analysis matches the detected anion abundances much better than the gas/grain chemical model, suggesting that the current understanding of the formation chemistry of molecular anions is still highly uncertain.

Keywords: astrochemistry; dark interstellar clouds
Quasi-simultaneous Spectroscopic and Multiband Photometric Observations of Blazar S5 0716+714 During 2018-2019

In order to study short timescale optical variability of γ-ray blazar S5 0716+714, quasi-simultaneous spectroscopic and multiband photometric observations were performed from 2018 November to 2019 March with the 2.4 m optical telescope located at Lijiang Observatory of Yunnan Observatories. The observed spectra are well fitted with a power law F λ = Aλ -α (spectral index α > 0). Correlations found between \dot{α }, \dot{A}, \dot{A}/A, \dot{{F}λ }, and \dot{{F}λ }/{F}λ are consistent with the trend of bluer-when-brighter (BWB). It is the same case for colors, magnitudes, color variation rates, and magnitude variation rates of photometric observations. The variations of α lead those of F λ . Also, the color variations lead magnitude variations. The observational data are mostly distributed in the I(+,+) and III(-,-) quadrants of the coordinate system. Both spectroscopic and photometric observations show BWB behaviors in S5 0716+714. The observed BWB may be explained by the shock-jet model, and its appearance may depend on the relative position of the observational frequency ranges with respect to the synchrotron peak frequencies, e.g., at the left of the peak frequencies. Fractional variability amplitudes are F var ∼ 40% for both spectroscopic and photometric observations. Variations of α indicate variations of relativistic electron distribution producing the optical spectra.

Keywords: bl lacertae objects; active galaxies; blazars; galaxy photometry; spectroscopy
Deciphering the 3D Orion Nebula-I: Expanding Shells in the Huygens Region

Based on imaging and spectroscopic data, we develop a 3D model for the Huygens Region of the Orion Nebula. θ^{1} Ori C, the hottest star in the Trapezium, is surrounded by a wind-blown Central Bubble that opens SW into the Extended Orion Nebula. Outside of this feature lies a layer of ionized gas at about 0.4 pc from θ^{1} Ori C. Both of these features are moving rapidly away from θ^{1} Ori C with an expansion age for the Central Bubble of only 15,000 yr.

Keywords: h ii regions
Searching for Candidates of Coalescing Binary Black Holes Formed through Chemically Homogeneous Evolution in GWTC-3

The LIGO, Virgo, and KAGRA (LVK) Collaboration has announced 90 coalescing binary black holes (BBHs) with p astro > 50% to date; however, the origin of their formation channels is still an open scientific question. Given various properties of BBHs (BH component masses and individual spins) inferred using the default priors by the LVK, independent groups have been trying to explain the formation of the BBHs with different formation channels. Of all formation scenarios, the chemically homogeneous evolution (CHE) channel has stood out with distinguishing features, namely, nearly equal component masses and preferentially high individual spins aligned with the orbital angular momentum. We perform Bayesian inference on the BBH events officially reported in GWTC-3 with astrophysically predicted priors representing different formation channels of the isolated binary evolution (common-envelope evolution channel, CEE; CHE; stable mass transfer, SMT). Given assumed models, we report strong evidence for GW190517_055101 being most likely to have formed through the CHE channel. Assuming the BBH events in the subsample are all formed through one of the isolated binary evolution channels, we obtain the lower limits on the local merger rate density of these channels at 11.45 Gpc-3 yr-1 (CEE), 0.18 Gpc-3 yr-1 (CHE), and 0.63 Gpc-3 yr-1 (SMT) at 90% credible level.

Keywords: gravitational wave sources; stellar mass black holes; close binary stars
KIC 3440495: A Rapidly Rotating δ Scuti-γ Doradus Hybrid Pulsator in a Binary System

In this paper, we study the pulsation properties of KIC 3440495 using Kepler and TESS data. A Fourier analysis of the light curve reveals 24 pulsation modes as well as 29 frequencies associated with rotation. The rotation frequency is derived to be f rot = 2.322909(2) day-1, and the rotational modulation is determined to be caused by starspots. A large frequency separation of Δν = 54.5 μHz is found by using a Fourier transform, the autocorrelation function, a histogram of frequency differences, and an échelle diagram. We use the large separation to estimate the refined stellar parameters of the star to be v = [239, 279] km s-1, M = [1.5, 1.65] M ⊙, R equator = [2.03, 2.30] R ⊙, R polar = [1.72, 1.78] R ⊙, and ω = [0.61, 0.77]. The phase modulations of the pulsating frequencies show a long-term trend which may be attributed to an orbital effect of a binary system; hence, the star may be a fast rotating pulsator in a binary system. KIC 3440495 has an amplitude spectrum similar to Altair, and is identified as a potential sister of Altair. Based on studies of Altair, KIC 3330495 is presumably a young star at a similar evolutionary stage.

Keywords: stellar rotation; stellar pulsations; starspots
Hunting for Runaways from the Orion Nebula Cluster

We use Gaia DR2 to hunt for runaway stars from the Orion Nebula Cluster (ONC). We search a region extending 45° around the ONC and out to 1 kpc to find sources that have overlapped in angular position with the cluster in the last ∼10 Myr. We find ∼17,000 runaway/walkaway candidates that satisfy this 2D traceback condition. Most of these are expected to be contaminants, e.g., caused by Galactic streaming motions of stars at different distances. We thus examine six further tests to help identify real runaways, namely: (1) possessing young stellar object (YSO) colors and magnitudes based on Gaia optical photometry; (2) having IR excess consistent with YSOs based on 2MASS and Wide-field Infrared Survey Explorer photometry; (3) having a high degree of optical variability; (4) having closest approach distances well-constrained to within the cluster half-mass radius; (5) having ejection directions that avoid the main Galactic streaming contamination zone; and (6) having a required radial velocity (RV) for 3D overlap of reasonable magnitude (or, for the 7% of candidates with measured RVs, satisfying 3D traceback). Thirteen sources, not previously noted as Orion members, pass all these tests, while another twelve are similarly promising, except they are in the main Galactic streaming contamination zone. Among these 25 ejection candidates, ten with measured RVs pass the most restrictive 3D traceback condition. We present full lists of runaway/walkaway candidates, estimate the high-velocity population ejected from the ONC, and discuss its implications for cluster formation theories via comparison with numerical simulations.

Keywords: astrometry; stellar kinematics; young star clusters; stellar dynamics; star formation; runaway stars
A Gigantic Mid-infrared Outburst in an Embedded Class I Young Stellar Object J064722.95+031644.6

We report the serendipitous discovery of a giant mid-infrared outburst from a previously unknown source near a star-forming region in the constellation Monoceros. The source gradually brightened by a factor of 5 from 2014-2016 before an abrupt rise by a factor of more than 100 in 2017. A total amplitude increase of >500 at 4.5 μm has since faded by a factor of about 10. Prior to the outburst, it was only detected at wavelengths longer than 1.8 μm in UKIDSS, Spitzer, and Herschel with a spectral energy distribution of a Class I young stellar object (YSO). It has not been detected in recent optical surveys, suggesting that it is deeply embedded. With a minimum distance of 3.5 kpc, the source has a bolometric luminosity of at least 9 L ☉ in the quiescent state and 400 L ☉ at the peak of the eruption. The maximum accretion rate is estimated to be at least a few 10-5 M ☉ yr-1. It shares several common properties with another eruptive event, WISE J142238.82-611553.7: exceptionally large amplitude, featureless near-infrared spectrum with the exception of H2 lines, intermediate eruption duration, an embedded Class I YSO, and a low radiative temperature (<600-700 K) in outburst. We interpret that the radiation from the inner accretion disk and young star is obscured and reprocessed by either an inflated outer disk or thick dusty outflow on scales >6.5 au during the outburst.

Keywords: eruptive variable stars; fu orionis stars; young stellar objects
The Tarda Meteorite: A Window into the Formation of D-type Asteroids

Dynamic models of solar system evolution suggest that D-type asteroids formed beyond Saturn's orbit and represent invaluable witnesses of the prevailing conditions in the outer solar system. Here, we report a comprehensive petrographic and isotopic characterization of the carbonaceous chondrite Tarda, a recent fall recovered in the Moroccan Sahara. We show that Tarda shares strong similarities with the D-type-derived chondrite Tagish Lake, implying that Tarda represents a rare sample of D-type asteroids. Both Tarda and Tagish Lake are characterized by the presence of rare 16O-rich chondrules and chondrule fragments, high C/H ratios, and enrichments in deuterium, 15N, and 13C. By combining our results with literature data on carbonaceous chondrites related to C-type asteroids, we show that the outer solar system 4.56 Gy ago was characterized by large-scale oxygen isotopic homogeneities in (i) the water-ice grains accreted by asteroids and (ii) the gas controlling the formation of FeO-poor chondrules. Conversely, the zone in which D-type asteroids accreted was significantly enriched in deuterium relative to the formation regions of C-type asteroids, features likely inherited from unprocessed, D-rich, molecular-cloud materials.

Keywords: asteroids; isotopic abundances; trans-neptunian objects; carbonaceous chondrites
Impact of Radiation Feedback on the Formation of Globular Cluster Candidates during Cloud-Cloud Collisions

To understand the impact of radiation feedback during the formation of a globular cluster (GC), we simulate a head-on collision of two turbulent giant molecular clouds (GMCs). A series of idealized radiation-hydrodynamic simulations is performed, with and without stellar radiation or Type II supernovae. We find that a gravitationally bound, compact star cluster of mass M GC ~ 105 M ⊙ forms within ≈3 Myr when two GMCs with mass M GMC = 3.6 × 105 M ⊙ collide. The GC candidate does not form during a single collapsing event but emerges due to the mergers of local dense gas clumps and gas accretion. The momentum transfer due to the absorption of the ionizing radiation is the dominant feedback process that suppresses the gas collapse, and photoionization becomes efficient once a sufficient number of stars form. The cluster mass is larger by a factor of ~2 when the radiation feedback is neglected, and the difference is slightly more pronounced (16%) when extreme Lyα feedback is considered in the fiducial run. In the simulations with radiation feedback, supernovae explode after the star-forming clouds are dispersed, and their metal ejecta are not instantaneously recycled to form stars.

Keywords: globular star clusters; young massive clusters; high-redshift galaxies
Study of the Effect of Martian Dust Storms on Ionospheric Electron Density Based on Physical-grid Deep Neural Learning Technology

The behavior of the Martian ionosphere during global dust storms has always been a popular topic. Based on many Mars Atmosphere and Volatile Evolution observations, a Martian ionospheric electron density model is constructed herein using a physical-grid deep neural network algorithm. The precision of the model is proved to be high, and the R 2 value of the test set is 0.979. On this basis, the effects of global dust storms on the electron density and peak height of the Martian ionosphere are explored. The results show that the MY34 global dust storm significantly raised the peak height of the Martian electron layer, and its effects mainly ranged from 20°N to 55°N. The periodicity of the global daily average peak electron layer height following this dust storm was more regular than that before the dust storm.

Keywords: neural networks; planetary atmospheres; planetary ionospheres
The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI). II. Moist Cases-The Two Waterworlds

To identify promising exoplanets for atmospheric characterization and to make the best use of observational data, a thorough understanding of their atmospheres is needed. Three-dimensional general circulation models (GCMs) are one of the most comprehensive tools available for this task and will be used to interpret observations of temperate rocky exoplanets. Due to parameterization choices made in GCMs, they can produce different results, even for the same planet. Employing four widely used exoplanetary GCMs-ExoCAM, LMD-G, ROCKE-3D, and the UM-we continue the TRAPPIST-1 Habitable Atmosphere Intercomparison by modeling aquaplanet climates of TRAPPIST-1e with a moist atmosphere dominated by either nitrogen or carbon dioxide. Although the GCMs disagree on the details of the simulated regimes, they all predict a temperate climate with neither of the two cases pushed out of the habitable state. Nevertheless, the intermodel spread in the global mean surface temperature is nonnegligible: 14 K and 24 K in the nitrogen- and carbon dioxide-dominated case, respectively. We find substantial intermodel differences in moist variables, with the smallest amount of clouds in LMD-Generic and the largest in ROCKE-3D. ExoCAM predicts the warmest climate for both cases and thus has the highest water vapor content and the largest amount and variability of cloud condensate. The UM tends to produce colder conditions, especially in the nitrogen-dominated case due to a strong negative cloud radiative effect on the day side of TRAPPIST-1e. Our study highlights various biases of GCMs and emphasizes the importance of not relying solely on one model to understand exoplanet climates.

Keywords: exoplanet atmospheres; planetary atmospheres; habitable planets; habitable zone; water vapor; atmospheric circulation; atmospheric clouds; atmospheric composition; exoplanet atmospheric variability; planetary climates
Preliminary Target Selection for the DESI Bright Galaxy Survey (BGS)

The Dark Energy Spectroscopic Instrument (DESI) will execute a nearly magnitude-limited survey of low redshift galaxies (0.05 ≤ z ≤ 0.4, median z ≈ 0.2). Clustering analyses of this Bright Galaxy Survey (BGS) will yield the most precise measurements to date of baryon acoustic oscillations and redshift-space distortions at low redshift. DESI BGS will comprise two target classes: (i) BRIGHT (r < 19.5 mag), and (ii) FAINT (19.5 < r < 20 mag). Here we present a summary of the star-galaxy separation, and different photometric and geometrical masks, used in BGS to reduce the number of spurious targets. The selection results in a total density of ∼800 objects deg-2 for the BRIGHT and ∼600 objects deg-2 for the FAINT selections. A full characterization of the BGS selection can be found in Ruiz-Macias et al.

Keywords: galaxies; redshift surveys; observational cosmology; large-scale structure of the universe; catalogs