adsabs/SciX_UAT_keywords huggingface dataset:
Comparative Mid-infrared Spectroscopy of Dark, Primitive Asteroids: Does Shared Taxonomic Class Indicate Shared Silicate Composition?

Primitive asteroids with low albedos and red slopes in the visible and near-infrared (VNIR) are found in both the main belt and the Jupiter Trojan clouds. In order to determine whether the VNIR spectral similarities of primitive main-belt asteroids and Jupiter Trojans are reflective of a true compositional similarity, we compare the mid-infrared silicate emission features of main-belt and Jupiter Trojan asteroids. Using archival data from the Spitzer Space Telescope's Infrared Spectrograph and observations from the Stratospheric Observatory for Infrared Astronomy's FORCAST instrument, we analyze the 5–40 μm spectra of 13 primitive main-belt asteroids and compare them to those of Jupiter Trojans in the literature. We find that while many primitive asteroids in the main belt resemble their Trojan counterparts with strong spectral signatures of olivine-rich high-porosity silicate regoliths, we identify (368) Haidea as a spectrally distinctive asteroid that lacks strong evidence of olivine in its mid-IR spectrum. Differences in silicate compositions among D-type asteroids imply a diversity of origins for primitive asteroids.

Keywords: asteroids; infrared astronomy; silicate grains; small solar system bodies
Dark Matter-Dark Energy Interaction and the Shape of Cosmic Voids

Interaction between dark matter (DM) and dark energy (DE) is one of the not completely solved problems in cosmology that has been studied extensively. This interaction affects cosmic structures. In this regard, the shape of cosmic voids can be influenced by the DM and DE interaction. Here, employing the dynamical DE model constrained by observational data, we study the effects of this interaction on the ellipticity of cosmic voids. With this aim, we apply the linear growth of density perturbation in the presence of interaction. The probability-density distribution for the ellipticity of cosmic voids is investigated. The results confirm that the ellipticity of cosmic voids increases when the DM and DE interaction is considered.

Keywords: dark matter; dark energy; large-scale structure of the universe
Wave Excitation by Power-law-Distributed Energetic Electrons with Pitch-angle Anisotropy in the Solar Corona

Radio waves from the Sun are emitted, as a rule, due to energized electrons. Observations infer that the related energized electrons follow (negative) power-law velocity distributions above a break velocity Ub. They might also distribute anisotropically in the pitch-angle space. To understand radio wave generation better, we study the consequences of anisotropic power-law-distributed energetic electrons in current-free collisionless coronal plasmas utilizing 2.5-dimensional particle-in-cell simulations. We assume that the velocity distribution fu of the energized electrons follows a plateau (∂fu/∂u = 0) and a power-law distribution with spectral index α for velocities below and above Ub, respectively. In the pitch-angle space, these energized electrons are spread around a center μc = 0.5. We found that the energetic plateau-power-law electrons can more efficiently generate coherent waves if the anisotropy of their pitch-angle distribution is sufficiently strong, i.e., a small pitch-angle spread μs. The break velocity Ub affects the excitation dominance between the electrostatic and electromagnetic waves: for larger Ub electrostatic waves are mainly excited, while intermediate values of Ub are required for an excitation dominated by electromagnetic waves. The spectral index α controls the growth rate, efficiency, saturation, and anisotropy of the excited electromagnetic waves as well as the energy partition in different wave modes. These excited electromagnetic waves are predominantly right-handed polarized, in X- and Z-modes, as observed, e.g., in solar radio spikes. Additionally about 90% of the kinetic energy loss of the energetic electrons is dissipated, heating the ambient thermal electrons. This may contribute to the coronal heating.

Keywords: solar corona; solar coronal heating; solar radio emission
Statistical Validation of Multiple Related Data Sets—Case Study Using Interstellar Boundary Explorer Satellite Data

Space scientists often face the question of whether data collected by different instruments are measurements of the same source population. This paper proposes a statistical validation method for evaluating the agreement between such related data sets. It offers a detailed case study focused on validating a new data set from the Interstellar Boundary Explorer (IBEX) mission, which serves as a practical how-to guide for similar analyses. Since 2008, the IBEX satellite has been gathering data on heliospheric energetic neutral atoms (ENAs) while being exposed to various sources of background noise, such as cosmic rays and solar energetic particles. The IBEX mission initially released only a qualified triple-coincidence (qABC) data product, which was designed to provide observations of ENAs free of background contamination. Further measurements revealed that the qABC data were in fact susceptible to contamination, having relatively low ENA counts and high background rates. To mitigate this issue, the mission team recently considered releasing a certain qualified double-coincidence (qBC) data product, which has roughly twice the detection rate of the qABC data product. This paper presents a simulation-based validation of the new qBC data product against the already-released qABC data product. The results show that the qBCs can plausibly be said to be measuring the same source population as the qABCs up to an average absolute deviation of 3.6%. Visual diagnostics provide additional confirmation of source rate coherence across data products. The framework introduced here is general and can be applied to other validation problems both within and outside the field of space physics.

Keywords: heliosphere; algorithms; astrostatistics
Planck Galactic Cold Clumps in Two Regions: The First Quadrant and the Anticenter Direction Region

Sixty-five Planck Galactic cold clumps (PGCCs) from the first quadrant (IQuad) and 39 from the anticenter direction region (ACent) were observed in 12CO, 13CO, and C18O J = 1-0 lines using the 13.7 m telescope of the Purple Mountain Observatory. All the targets were detected in all three lines, except for 12 IQuad and 8 ACent PGCCs without C18O detection. Seventy-six and 49 velocity components were obtained in IQuad and ACent respectively; 146 cores were extracted from 76 IQuad clumps and 100 cores from 49 ACent clumps. The average Tex of IQuad cores and ACent cores is 12.4 K and 12.1 K, respectively. The average line widths of 13CO of IQuad cores and ACent cores are 1.55 km s-1 and 1.77 km s-1, respectively. Among the detected cores, 24 in IQuad and 13 in ACent have asymmetric line profiles. The small blue excesses, ∼0.03 in IQuad and 0.01 in ACent, indicate that star formation is not active in these PGCC cores. Power-law fittings of the core mass function to the high-mass end give indices of -0.57 in IQuad and -1.02 in ACent, which are flatter than the slope of the initial mass function given by Salpeter. The large turnover masses of 28 M_{⊙} for IQuad cores and 77 M_{⊙} for ACent cores suggest low star formation efficiencies in PGCCs. The correlation between virial mass and gas mass indicates that most PGCC cores in both regions are not likely pressure-confined.

Keywords: dark interstellar clouds; interstellar molecules; star formation
SED Machine Spectra for HO Puppis and V722 Tauri

We present low-resolution spectra collected with the Spectral Energy Distribution Machine (SEDM) for an IW And-type dwarf nova, HO Puppis, and a Be star, V722 Tauri. The SEDM is an integrated field unit spectrograph mounted on the 60 inch telescope at the Palomar Observatory, with a spectral resolution of R ∼ 100 in the optical wavelength range. The Hα emission line was clearly detected for the bright Be star V722 Tauri at ∼12.5 mag, but barely detected in the spectra for the ∼13.7 mag HO Puppis. Our SEDM observations could be used as guidance for observing similar objects with the SEDM, as well as other R ∼ 100 spectrographs, in the future.

Keywords: emission line stars; spectroscopy; dwarf novae
Galaxy Alignments with Surrounding Structure in the Sloan Digital Sky Survey

Using data from the Sloan Digital Sky Survey Legacy Survey, we study the alignment of luminous galaxies with spectroscopic data with the surrounding larger-scale structure as defined by galaxies with only photometric data. We find that galaxies from the red sequence have a statistically significant tendency for their apparent long axes to align parallel to the projected surrounding structure. Red galaxies more luminous than the median of our sample (M r < -21.78) have a mean alignment angle <Φ> < 45°, indicating preferred parallel alignment, at a significance level >4.5σ on projected scales 0.1 Mpc < r p ≤ 7.5 Mpc. Fainter red galaxies have <Φ> < 45° at a significance level >4.3σ at scales 1 Mpc < r p < 3 Mpc. At a projected scale r p = 3.0 Mpc, the mean alignment angle decreases steadily with increasing luminosity for red galaxies with M r ≲ -22.5, reaching <Φ> = 40.°49 ± 0.°56 for the most luminous 1% (M r ~ -23.57). Galaxies from the blue sequence show no statistically significant tendency for their axes to align with larger-scale structure, regardless of galaxy luminosity. Galaxies in higher-density regions do not show a statistically significant difference in the mean alignment angle from galaxies in lower-density regions; this holds true for the faint blue, luminous blue, faint red, and luminous red subsets.

Keywords: clustering; cosmic web; galaxy properties; large-scale structure of the universe
Primordial Radius Gap and Potentially Broad Core Mass Distributions of Super-Earths and Sub-Neptunes

The observed radii distribution of Kepler exoplanets reveals two distinct populations: those that are more likely to be terrestrials (≲1.7R⊕) and those that are more likely to be gas-enveloped (≳2R⊕). There exists a clear gap in the distribution of radii that separates these two kinds of planets. Mass-loss processes like photoevaporation by high-energy photons from the host star have been proposed as natural mechanisms to carve out this radius valley. These models favor underlying core mass function of sub-Neptunes that is sharply peaked at ∼4-8M⊕, but the radial-velocity follow-up of these small planets hints at a more bottom-heavy mass function. By taking into account the initial gas accretion in gas-poor (but not gas-empty) nebula, we demonstrate that (1) the observed radius valley is a robust feature that is initially carved out at formation during late-time gas accretion; and (2) that it can be reconciled with core mass functions that are broad extending well into the sub-Earth regime. The maximally cooled isothermal limit prohibits cores lighter than ∼1-2M⊕ from accreting enough mass to appear gas-enveloped. The rocky-to-enveloped transition established at formation produces a gap in the radius distribution that shifts to smaller radii farther from the star, similar to that observed. For the best agreement with the data, our late-time gas accretion model favors dust-free accretion in hotter disks with cores slightly less dense than the Earth (∼0.8ρ⊕) drawn from a mass function that is as broad as ${dN}/{{dM}}_{\mathrm{core}}\propto {M}_{\mathrm{core}}^{-0.7}$ .

Keywords: exoplanet formation; exoplanet astronomy; exoplanet evolution; exoplanet structure
Bursting Bubbles: Feedback from Clustered Supernovae and the Trade-off Between Turbulence and Outflows

We present an analytic model for clustered supernovae (SNe) feedback in galaxy disks, incorporating the dynamical evolution of superbubbles formed from spatially overlapping SNe remnants. We propose two realistic outcomes for the evolution of superbubbles in galactic disks: (1) the expansion velocity of the shock front falls below the turbulent velocity dispersion of the interstellar medium in the galaxy disk, whereupon the superbubble stalls and fragments, depositing its momentum entirely within the galaxy disk; or (2) the superbubble grows in size to reach the gas scale height, breaking out of the galaxy disk and driving galactic outflows/fountains. In either case, we find that superbubble breakup/breakout almost always occurs before the last Type II SN (≲40 Myr) in the recently formed star cluster, assuming a standard high-end initial mass function slope, and scalings between stellar lifetimes and masses. The threshold between these two cases implies a break in the effective strength of feedback in driving turbulence within galaxies, and a resulting change in the scalings of, for example, star formation rates with gas surface density (the Kennicutt-Schmidt relation) and the star formation efficiency in galaxy disks.

Keywords: supernova remnants; superbubbles; star formation; interstellar medium; galaxy evolution; stellar feedback
Identifying and Tracking Solar Magnetic Flux Elements with Deep Learning

Deep learning has drawn significant interest in recent years due to its effectiveness in processing big and complex observational data gathered from diverse instruments. Here we propose a new deep learning method, called SolarUnet, to identify and track solar magnetic flux elements or features in observed vector magnetograms based on the Southwest Automatic Magnetic Identification Suite (SWAMIS). Our method consists of a data preprocessing component that prepares training data from the SWAMIS tool, a deep learning model implemented as a U-shaped convolutional neural network for fast and accurate image segmentation, and a postprocessing component that prepares tracking results. SolarUnet is applied to data from the 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory. When compared to the widely used SWAMIS tool, SolarUnet is faster while agreeing mostly with SWAMIS on feature size and flux distributions and complementing SWAMIS in tracking long-lifetime features. Thus, the proposed physics-guided deep learning-based tool can be considered as an alternative method for solar magnetic tracking.

Keywords: solar magnetic fields; solar photosphere; convolutional neural networks
Quantifying the Key Factors Affecting the Escape of Planetary Atmospheres

The habitability of Earth-like planets is an increasingly important subject in astrophysics and in planetary sciences. Atmospheric escape plays a vital role in the evolution of the habitability of Earth-like planets. By systematically analyzing the numerical simulation results of the interactions between the planetary atmospheres and the stellar winds, in this work, we evaluate various factors related to the atmospheric nonthermal ion escape rates, including planetary parameters (e.g., mass, density, radius, semimajor axis, etc.) and stellar wind parameters (e.g., density, velocity, and interplanetary magnetic field (IMF) strength). Furthermore, we determine and quantify the key factors affecting the planetary atmospheric nonthermal ion escape rates. Our results show that the correlation coefficients between planetary atmospheric nonthermal ion escape rates and stellar wind density, IMF strength, and the ratio of the planetary radius to the planetary semimajor axis are 0.98 (0.88), 0.95 (0.81), and 0.87 (0.59), respectively, in the scenario of maximum (minimum) dynamic wind pressure. This means that the planetary atmospheric nonthermal ion escape rates increase with the increasing stellar wind density, the increasing IMF strength, and the increasing ratio of the planetary radius to the planetary semimajor axis. Generally, the nonthermal ion escape rates of planetary atmospheres are more sensitive to stellar wind parameters than to others. In addition, we determine the functional relations of the above three significant parameters for evaluating and quantifying the effects of such key physical factors on the nonthermal ion escape rates of the planetary atmospheres. Our findings will be very useful for better understanding the key factors that influence the escapes of planetary atmospheres.

Keywords: stellar winds; star-planet interactions; solar system planets; habitable planets; exoplanet atmospheres; astrobiology
The z 2 [O III] Luminosity Function of Grism-selected Emission-line Galaxies

Upcoming missions such as Euclid and the Nancy Grace Roman Space Telescope (Roman) will use emission-line-selected galaxies to address a variety of questions in cosmology and galaxy evolution in the z > 1 universe. The optimal observing strategy for these programs relies on knowing the number of galaxies that will be found and the bias of the galaxy population. Here we measure the [O III] λ5007 luminosity function for a vetted sample of 1951 mJ+JH+H < 26 galaxies with unambiguous redshifts between 1.90 < z < 2.35, which were selected using Hubble Space Telescope (HST)/WFC3 G141 grism frames made available by the 3D-HST program. These systems are directly analogous to the galaxies that will be identified by the Euclid and Roman missions, which will utilize grism spectroscopy to find [O III] λ5007-emitting galaxies at 0.8 ≲ z ≲ 2.7 and 1.7 ≲ z ≲ 2.8, respectively. We interpret our results in the context of the expected number counts for these upcoming missions. Finally, we combine our dust-corrected [O III] luminosities with rest-frame ultraviolet star formation rates to present a new calibration of the star formation rate density associated with 1.90 < z < 2.35 [O III]-emitting galaxies. We find that these grism-selected galaxies contain roughly half of the total star formation activity at z ~ 2.

Keywords: galaxy evolution; high-redshift galaxies; observational cosmology
Probing the Magnetic Field in the GW170817 Outflow Using H.E.S.S. Observations

The detection of the first electromagnetic counterpart to the binary neutron star (BNS) merger remnant GW170817 established the connection between short γ-ray bursts and BNS mergers. It also confirmed the forging of heavy elements in the ejecta (a so-called kilonova) via the r-process nucleosynthesis. The appearance of nonthermal radio and X-ray emission, as well as the brightening, which lasted more than 100 days, were somewhat unexpected. Current theoretical models attempt to explain this temporal behavior as either originating from a relativistic off-axis jet or a kilonova-like outflow. In either scenario, there is some ambiguity regarding how much energy is transported in the nonthermal electrons versus the magnetic field of the emission region. Combining the Very Large Array (radio) and Chandra (X-ray) measurements with observations in the GeV-TeV domain can help break this ambiguity, almost independently of the assumed origin of the emission. Here we report for the first time on deep H.E.S.S. observations of GW170817/GRB 170817A between 124 and 272 days after the BNS merger with the full H.E.S.S. array of telescopes, as well as on an updated analysis of the prompt (<5 days) observations with the upgraded H.E.S.S. phase-I telescopes. We discuss implications of the H.E.S.S. measurement for the magnetic field in the context of different source scenarios.

Keywords: gamma-ray transient sources; stellar mergers; gamma-ray bursts; gamma-ray astronomy; ejecta
Electron Temperature Anisotropy and Electron Beam Constraints from Electron Kinetic Instabilities in the Solar Wind

Electron temperature anisotropies and electron beams are nonthermal features of the observed nonequilibrium electron velocity distributions in the solar wind. In collision-poor plasmas these nonequilibrium distributions are expected to be regulated by kinetic instabilities through wave-particle interactions. This study considers electron instabilities driven by the interplay of core electron temperature anisotropies and the electron beam, and first gives a comprehensive analysis of instabilities in arbitrary directions to the background magnetic field. It clarifies the dominant parameter regime (e.g., parallel core electron plasma beta ${\beta }_{\mathrm{ec}\parallel }$ , core electron temperature anisotropy ${A}_{\mathrm{ec}}\equiv {T}_{\mathrm{ec}\perp }/{T}_{\mathrm{ec}\parallel }$ , and electron beam velocity Veb) for each kind of electron instability (e.g., the electron beam-driven electron acoustic/magnetoacoustic instability, the electron beam-driven whistler instability, the electromagnetic electron cyclotron instability, the electron mirror instability, the electron firehose instability, and the ordinary-mode instability). It finds that the electron beam can destabilize electron acoustic/magnetoacoustic waves in the low- ${\beta }_{\mathrm{ec}\parallel }$ regime, and whistler waves in the medium- and large- ${\beta }_{\mathrm{ec}\parallel }$ regime. It also finds that a new oblique fast-magnetosonic/whistler instability is driven by the electron beam with ${V}_{\mathrm{eb}}\gtrsim 7{V}_{A}$ in a regime where ${\beta }_{\mathrm{ec}\parallel }\sim 0.1\mbox{--}2$ and Aec < 1. Moreover, this study presents electromagnetic responses of each kind of electron instability. These results provide a comprehensive overview for electron instability constraints on core electron temperature anisotropies and electron beams in the solar wind.

Keywords: plasma astrophysics; plasma physics; solar wind
A Disk and No Signatures of Tidal Distortion in the Galaxy "Lacking" Dark Matter NGC 1052-DF2

Using ultra-deep imaging (μg = 30.4 mag arcsec-2; 3σ, 10″ × 10″), we probed the surroundings of the first galaxy "lacking" dark matter (DM) KKS2000[04] (NGC 1052-DF2). Signs of tidal stripping in this galaxy would explain its claimed low content of DM. However, we find no evidence of tidal tails. In fact, the galaxy remains undisturbed down to a radial distance of 80″. This radial distance triples previous spatial explorations of the stellar distribution of this galaxy. In addition, the distribution of its globular clusters (GCs) is not extended in relation to the bulk of the galaxy (the radius containing half of the GCs is 21″). We also found that the surface brightness radial profiles of this galaxy in the g and r bands decline exponentially from 35″ to 80″. Together with a constant ellipticity and position angle in the outer parts of the galaxy, this strongly suggests the presence of a low-inclination disk. This is consistent with the evidence of rotation found for this object. This finding implies that the dynamical mass of this galaxy is a factor of 2 higher than previously reported, which brings the DM content of this galaxy in line with galaxies of similar stellar mass.

Keywords: low surface brightness galaxies; galaxy formation; dark matter