adsabs/SciX_UAT_keywords huggingface dataset:
The Cosmic Thermal History Probed by Sunyaev-Zeldovich Effect Tomography

The cosmic thermal history, quantified by the evolution of the mean thermal energy density in the universe, is driven by the growth of structures as baryons get shock heated in collapsing dark matter halos. This process can be probed by redshift-dependent amplitudes of the thermal Sunyaev-Zeldovich (SZ) effect background. To do so, we cross-correlate eight sky intensity maps in the Planck and Infrared Astronomical Satellite missions with two million spectroscopic redshift references in the Sloan Digital Sky Surveys. This delivers snapshot spectra for the far-infrared to microwave background light as a function of redshift up to z ∼ 3. We decompose them into the SZ and thermal dust components. Our SZ measurements directly constrain $\langle {{bP}}_{{\rm{e}}}\rangle $ , the halo bias-weighted mean electron pressure, up to z ∼ 1. This is the highest redshift achieved to date, with uncorrelated redshift bins thanks to the spectroscopic references. We detect a threefold increase in the density-weighted mean electron temperature ${\overline{T}}_{{\rm{e}}}$ from 7 × 105 K at z = 1 to 2 × 106 K today. Over z = 1-0, we witness the build-up of nearly 70% of the present-day mean thermal energy density ρth, with the corresponding density parameter Ωth reaching 1.5 × 10-8. We find the mass bias parameter of Planck's universal pressure profile of B = 1.27 (or 1 - b = 1/B = 0.79), consistent with the magnitude of nonthermal pressure in gas motion and turbulence from mass assembly. We estimate the redshift-integrated mean Compton parameter y ∼ 1.2 × 10-6, which will be tested by future spectral distortion experiments. More than half originates from the large-scale structure at z < 1, which we detect directly.

Keywords: diffuse radiation; large-scale structure of the universe; cosmology
Rapid Accretion State Transitions following the Tidal Disruption Event AT2018fyk

Following a tidal disruption event (TDE), the accretion rate can evolve from quiescent to near-Eddington levels and back over timescales of months to years. This provides a unique opportunity to study the formation and evolution of the accretion flow around supermassive black holes (SMBHs). We present 2 yr of multiwavelength monitoring observations of the TDE AT2018fyk at X-ray, UV, optical, and radio wavelengths. We identify three distinct accretion states and two state transitions between them. These appear remarkably similar to the behavior of stellar-mass black holes in outburst. The X-ray spectral properties show a transition from a soft (thermal-dominated) to a hard (power-law-dominated) spectral state around Lbol ∼ few × 10-2 LEdd and the strengthening of the corona over time ∼100-200 days after the UV/optical peak. Contemporaneously, the spectral energy distribution (in particular, the UV to X-ray spectral slope αox) shows a pronounced softening as the outburst progresses. The X-ray timing properties also show a marked change, initially dominated by variability at long (>day) timescales, while a high-frequency (∼10-3 Hz) component emerges after the transition into the hard state. At late times (∼500 days after peak), a second accretion state transition occurs, from the hard into the quiescent state, as identified by the sudden collapse of the bolometric (X-ray+UV) emission to levels below 10-3.4 LEdd. Our findings illustrate that TDEs can be used to study the scale (in)variance of accretion processes in individual SMBHs. Consequently, they provide a new avenue to study accretion states over seven orders of magnitude in black hole mass, removing limitations inherent to commonly used ensemble studies.

Keywords: transient sources; time domain astronomy; high energy astrophysics; accretion; active galactic nuclei; low-mass x-ray binary stars
Calculations of Dielectronic Recombination and Electron-impact Excitation Rate Coefficients of Highly Charged Sulfur Ions

Connected to the experiment performed at the Stockholm electron beam ion trap, a systematic relativistic configuration-interaction calculation is carried out to compare with the experimental spectra. In particular, separate rate coefficients are calculated for dominant recombination and excitation processes in the range of the impact electron energy determined by the experiment. By means of the relevant experimental parameters, the presently calculated dielectronic recombination rate coefficients for S15+ and S14+ ions and electron-impact excitation ones for S15+, S14+, and S13+ ions are employed further to synthesize overall theoretical spectra for comparison with the experimentally measured spectra. Overall, very good agreements with the experimental results are found except for one missing excitation peak around the impact electron energy 2.52 keV, which cannot be explained by the present calculations and thus remains open.

Keywords: dielectronic recombination; theoretical models; excitation rates
Instabilities Driven by Proton Temperature Anisotropy in the Presence of Alpha Particles: Implications for Proton-temperature-anisotropy Constraint in the Solar Wind

In situ measurements reveal that proton temperature anisotropy is ubiquitous in the solar wind. Various plasma instabilities have been proposed to regulate the distribution of the proton temperature anisotropy in the solar wind; detailed constraint processes are still unclear. In this paper, we study the effects of alpha beams on both the forward and backward proton temperature anisotropy instabilities at parallel and oblique propagation with the Vlasov theory, and compare the theoretical results with the Wind observation. As the alpha-beam drift velocity v α /v A increases, the growth rates of forward Alfvén/ion-cyclotron (FA/IC) and backward magnetosonic/whistler (BM/W) instabilities increase, those of backward Alfvén/ion-cyclotron (BA/IC) and forward magnetosonic/whistler (FM/W) instabilities decrease, and those of the mirror and forward Alfvén wave (FAW) instabilities are nearly constant. In particular, there are different constraining mechanisms on the distribution of proton temperature anisotropy for different values of the alpha-beam drift velocity. The proton temperature anisotropy instability together with the alpha beam can provide a potential explanation for the distribution of the proton temperature anisotropy in the solar wind.

Keywords: solar wind; space plasmas; interplanetary physics; interplanetary magnetic fields
Surveying the Giant H II Regions of the Milky Way with SOFIA: V. DR7 and K3-50

We present our fifth set of results from our mid-infrared imaging survey of Milky Way Giant H II (GH II) regions with our detailed analysis of DR7 and K3-50. We obtained 20/25 and 37 μm imaging maps of both regions using the FORCAST instrument on the Stratospheric Observatory For Infrared Astronomy. We investigate the multiscale properties of DR7 and K3-50 using our data in conjunction with previous multiwavelength observations. Near- to far-infrared spectral energy distributions of individual compact infrared sources were constructed and fitted with massive young stellar object (MYSO) models. We find eight out of the ten (80%) compact sources in K3-50 and three out of the four (75%) sources in DR7 are likely to be MYSOs. We derived luminosity-to-mass ratios of the extended radio subregions of DR7 and K3-50 to estimate their relative ages. The large spread in evolutionary state for the subregions in K3-50 likely indicates that the star-forming complex has undergone multiple star-forming events separated more widely in time, whereas the smaller spread in DR7 likely indicates the star formation subregions are more co-eval. DR7 and K3-50 have Lyman continuum photon rates just above the formal threshold criterion for being categorized as a GH II region (1050 photons s-1) but with large enough errors that this classification is uncertain. By measuring other observational characteristics in the infrared, we find that K3-50 has properties more akin to previous bona fide GH II regions we have studied, whereas DR7 has values more like those of the non-GH II regions we have previously studied.

Keywords: h ii regions; compact h ii region; star formation; star forming regions; massive stars; interstellar medium; protostars; infrared astronomy; infrared sources
Protostellar and Protoplanetary Disk Masses in the Serpens Region

We present the results from an Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum and 12CO (J = 2 - 1) line survey spread over 10 deg2 in the Serpens star-forming region of 320 young stellar objects, 302 of which are likely members of Serpens (16 Class I, 35 flat-spectrum, 235 Class II, and 16 Class III). From the continuum data, we derive disk dust masses and show that they systematically decline from Class I to flat-spectrum to Class II sources. Grouped by stellar evolutionary state, the disk mass distributions are similar to other young (<3 Myr) regions, indicating that the large-scale environment of a star-forming region does not strongly affect its overall disk dust mass properties. These comparisons between populations reinforce previous conclusions that disks in the Ophiuchus star-forming region have anomalously low masses at all evolutionary stages. Additionally, we find a single deeply embedded protostar that has not been documented elsewhere in the literature and, from the CO line data, 15 protostellar outflows, which we catalog here.

Keywords: protoplanetary disks; pre-main sequence stars; submillimeter astronomy
Solar Flare Prediction Using Magnetic Field Diagnostics above the Photosphere

In this article, we present the application of the weighted horizontal gradient of magnetic field (WGM) flare prediction method to three-dimensional (3D) extrapolated magnetic configurations of 13 flaring solar active regions (ARs). The main aim is to identify an optimal height range, if any, in the interface region between the photosphere and lower corona, where the flare onset time prediction capability of WGM is best exploited. The optimal height is where flare prediction, by means of the WGM method, is achieved earlier than at the photospheric level. 3D magnetic structures, based on potential and nonlinear force-free field extrapolations, are constructed to study a vertical range from the photosphere up to the low corona with a 45 km step size. The WGM method is applied as a function of height to all 13 flaring AR cases that are subject to certain selection criteria. We found that applying the WGM method between 1000 and 1800 km above the solar surface would improve the prediction of the flare onset time by around 2-8 hr. Certain caveats and an outlook for future work along these lines are also discussed.

Keywords: the sun; space weather; solar corona; solar flares; solar activity; solar photosphere; solar chromosphere; solar magnetic bright points; solar active regions; sunspots; delta sunspots; solar active region magnetic fields
Hot Jupiters from Disruption of Resonant Chains in Postdisk Evolution

The formation of hot Jupiters has been a subject of interest in the field of exoplanet science. According to conventional scenarios, these gas giants are believed to form beyond the snow line and subsequently migrate inward. Although the early formation history of hot Jupiters is not well understood, they may emerge in resonant chains as a result of disk migration. Here we study the formation of hot Jupiters via the disruption of resonant chains after the gas disk disappears. We perform N-body simulations on planetary systems consisting of one gas giant and several super-Earths. The initial configuration involves all neighboring planet pairs being in a 3:2 mean motion resonance. We track the evolution of these resonant chains after the gas disk has vanished. Our results reveal that the resonant chains are prone to instability following the dispersal of the gas disk, with more than 80% of instabilities occurring within 3 million years. Only approximately 4% of resonant chains can survive the dynamical evolution. Notably, we find that resonant chains hosting hot Jupiters are more likely to be unstable compared to those hosting warm Jupiters. Our simulations indicate that 33% ± 4% hot Jupiters and 70% ± 4% warm Jupiters could possess nearby companions. Furthermore, incorporating the effects of general relativity and tidal dissipation increases the isolation of hot Jupiters, resulting in nearby companion occurrence rates of 20% ± 4% for hot Jupiters and 69% ± 6% for warm Jupiters.

Keywords: exoplanets; exoplanet systems; hot jupiters
Evidence for Transient Atmospheres during Eruptive Outgassing on the Moon

Events following the giant impact formation of the Moon are thought to have led to volatile depletion and concurrent mass-dependent fractionation of the isotopes of moderately volatile elements (MVE). The detailed processes and conditions surrounding this episode remain obscured and are not unified by a single model for all volatile elements and compounds. Using available data, including new Zn isotope data for eight lunar samples, we demonstrate that the isotopic fractionation of MVE in the Moon is best expressed by nonideal Rayleigh distillation, approaching the fractionation factor α using the reduced masses of the evaporated isotopologs. With these calculations, a best fit for the data is obtained when the lunar MVE isotope data are normalized to ordinary or enstatite chondrites ( ${{\rm{\Delta }}}_{\mathrm{Moon}-\mathrm{OC},\mathrm{EC}}$ ), rather than a bulk silicate Earth composition. This analysis further indicates that the parent body from which the Moon formed cannot have partitioned S into its core based on S isotope compositions of lunar rocks. The best fit between ${{\rm{\Delta }}}_{\mathrm{Moon}-\mathrm{OC},\mathrm{EC}}$ and modeled nonideal Rayleigh fractionation is defined by a slope that corresponds to a saturation index of 90% ± 4%. In contrast, the older Highland suite is defined by a saturation index of 75% ± 2%, suggesting that the vapor phase pressure was higher during mare basalt eruptions. This provides the first tangible evidence that the Moon was veiled by a thin atmosphere during mare basalt eruption events spanning at least from 3.8 to 3 billion years ago and implies that MVE isotope fractionation dominantly occurred after the Moon had accreted.

Keywords: earth-moon system; the moon; lunar atmosphere; lunar evolution
Trapping of Cosmic Rays in MHD Turbulence

Astrophysical plasmas are turbulent and magnetized. The interaction between cosmic rays (CRs) and magnetohydrodynamic (MHD) turbulence is a fundamental astrophysical process. Based on the current understanding of MHD turbulence, we revisit the trapping of CRs by magnetic mirrors in the context of MHD turbulence. In compressible MHD turbulence, isotropic fast modes dominate both trapping and gyroresonant scattering of CRs. The presence of trapping significantly suppresses the pitch-angle scattering and the spatial diffusion of CRs along the magnetic field. The resulting parallel diffusion coefficient has a weaker dependence on CR energy at higher energies. In incompressible MHD turbulence, the trapping by pseudo-Alfvén modes dominates over the gyroresonant scattering by anisotropic Alfvén and pseudo-Alfvén modes at all pitch angles and prevents CRs from diffusion.

Keywords: magnetohydrodynamics; galactic cosmic rays; magnetic fields
Physics-driven Machine Learning for the Prediction of Coronal Mass Ejections' Travel Times

Coronal Mass Ejections (CMEs) correspond to dramatic expulsions of plasma and magnetic field from the solar corona into the heliosphere. CMEs are scientifically relevant because they are involved in the physical mechanisms characterizing the active Sun. However, more recently, CMEs have attracted attention for their impact on space weather, as they are correlated to geomagnetic storms and may induce the generation of solar energetic particle streams. In this space weather framework, the present paper introduces a physics-driven artificial intelligence (AI) approach to the prediction of CMEs' travel time, in which the deterministic drag-based model is exploited to improve the training phase of a cascade of two neural networks fed with both remote sensing and in situ data. This study shows that the use of physical information in the AI architecture significantly improves both the accuracy and the robustness of the travel time prediction.

Keywords: solar coronal mass ejections; neural networks
The Mass-Metallicity Relation at z ≃ 8: Direct-method Metallicity Constraints and Near-future Prospects

Physical properties of galaxies at z > 7 are of interest for understanding both the early phases of star formation and the process of cosmic reionization. Chemical abundance measurements offer valuable information on the integrated star formation history, and hence ionizing photon production, as well as the rapid gas accretion expected at such high redshifts. We use reported measurements of [O III] 88 μm emission and star formation rate to estimate gas-phase oxygen abundances in five galaxies at z = 7.1-9.1 using the direct ${T}_{{\rm{e}}}$ method. We find typical abundances $12+\mathrm{log}({\rm{O}}/{\rm{H}})$ = 7.9 (∼0.2 times the solar value) and an evolution of 0.9 ± 0.5 dex in oxygen abundance at fixed stellar mass from z ≃ 8 to 0. These results are compatible with theoretical predictions, albeit with large (conservative) uncertainties in both mass and metallicity. We assess both statistical and systematic uncertainties to identify promising means of improvement with the Atacama Large Millimeter/submillimeter Array (ALMA) and the James Webb Space Telescope (JWST). In particular we highlight [O III] 52 μm as a valuable feature for robust metallicity measurements. Precision of 0.1-0.2 dex in ${T}_{{\rm{e}}}$ -based O/H abundance can be reasonably achieved for galaxies at z ≈ 5-8 by combining [O III] 52 μm with rest-frame optical strong lines. It will also be possible to probe gas mixing and mergers via resolved ${T}_{{\rm{e}}}$ -based abundances on kiloparsec scales. With ALMA and JWST, direct metallicity measurements will thus be remarkably accessible in the reionization epoch.

Keywords: galaxy chemical evolution; high-redshift galaxies; galaxy evolution; reionization
Cryogenic-specific Reddish Coloration by Cryoplasma: New Explanation for Color Diversity of Outer Solar System Objects

Reddish coloration and color diversity among icy bodies in the outer solar system are significant clues for understanding the status and history of the solar system. However, the origin of color distribution remains debatable. Here, we demonstrate reddish coloration that is stable only at cryogenic temperatures in a laboratory experiment. The reddish coloration was produced on methanol- and water-containing ice irradiated with nitrogen-containing cryoplasma at 85 K. The reddish color visually faded and disappeared at 120-150 K as the ice was heated, unlike well-known refractory organic tholins that are stable even when heated to room temperature. This temperature dependence of reddish coloration under cryogenic conditions could provide a new possible explanation for the absence of ultra-red coloration closer to the Sun in the outer solar system. Our result implies that a reddish material specific to cryogenic environments is useful for the investigation of color diversity and the formation mechanism of the outer solar system.

Keywords: solar system gas giant planets; trans-neptunian objects; surface ices
Statistical Study of the Star Formation Efficiency in Bars: Is Star Formation Suppressed in Gas-rich Bars?

The dependence of the star formation efficiency (SFE) on galactic structures-especially whether the SFE in the bar region is lower than those in other regions-has recently been debated. We report the SFEs of 18 nearby gas-rich massive star-forming barred galaxies with large apparent bar major axes (≧75″). We statistically measure the SFE by distinguishing the center, the bar end, and the bar regions for the first time. The molecular gas surface density is derived from archival CO(1-0) and/or CO(2-1) data by assuming a constant CO-to-H2 conversion factor (α CO), and the star formation rate surface density is derived from a linear combination of far-UV and mid-IR intensities. The angular resolution is 15″, which corresponds to 0.3-1.8 kpc. We find that the ratio of the SFE in the bar to that in the disk was systematically lower than unity (typically 0.6-0.8), which means that the star formation in the bar is systematically suppressed. Our results are inconsistent with similar recent statistical studies, which have reported that the SFE tends to be independent of galactic structures. This inconsistency can be attributed to the differences in the definitions of the bar region, the spatial resolutions, the α CO, and the sample galaxies. Furthermore, we find a negative correlation between the SFE and the velocity width of the CO spectrum, which is consistent with the idea that the large dynamical effects-such as strong shocks, large shears, and fast cloud-cloud collisions caused by the noncircular motion of the bar-result in a low SFE.

Keywords: molecular gas; interstellar medium; star formation; barred spiral galaxies; co line emission; galaxies
Void Galaxies Follow a Distinct Evolutionary Path in the Environmental COntext Catalog

We measure the environmental dependence, where environment is defined by the distance to the third nearest neighbor, of multiple galaxy properties inside the Environmental COntext (ECO) catalog. We focus primarily on void galaxies, which we define as the 10% of galaxies having the lowest local density. We compare the properties of void and non-void galaxies: baryonic mass, color, fractional stellar mass growth rate (FSMGR), morphology, and gas-to-stellar-mass ratio (estimated from a combination of H I data and photometric gas fractions calibrated with the REsolved Spectroscopy Of a Local VolumE survey). Our void galaxies typically have lower baryonic masses than galaxies in denser environments, and they display the properties expected of a lower mass population: they have more late types, are bluer, have a higher FSMGR, and are more gas-rich. We control for baryonic mass and investigate the extent to which void galaxies are different at fixed mass. Void galaxies are bluer, more gas-rich, and more star-forming at fixed mass than non-void galaxies, which is a possible signature of galaxy assembly bias. Furthermore, we show that these trends persist even at fixed mass and morphology, and we find that voids host a distinct population of early types that are bluer and more star-forming than the typical red and quenched early types. In addition to these empirical observational results, we also present theoretical results from mock catalogs with built-in galaxy assembly bias. We show that a simple matching of galaxy properties to (sub)halo properties, such as mass and age, can recover the observed environmental trends in ECO galaxies.

Keywords: galaxy evolution; galaxy environments; voids; extragalactic astronomy
Disks as Inhomogeneous, Anisotropic Gaussian Random Fields

We model astrophysical disk surface brightness fluctuations as an inhomogeneous, anisotropic, time-dependent Gaussian random field. The field locally obeys the stochastic partial differential equation of a Matérn field, which has a power spectrum that is flat at large scales and falls off as a power law at small scales. We provide a series of pedagogical examples and along the way provide a convenient parameterization for the local covariance. We then consider two applications to disks. In the first we generate an animation of a disk. In the second, by integrating over an animation of a disk, we generate synthetic light curves and show that the high frequency slope of the resulting power spectrum depends on the local covariance model. We finish with a summary and a brief discussion of other possible astrophysical applications.

Keywords: black holes; accretion; computational methods; astrostatistics techniques