Sazuna/UAT_keywords huggingface dataset:
Irradiated Atmospheres. II. Interplay between Scattering and Vertical-mixing-induced Energy Transport. Scattering is crucial for the atmospheric thermal profiles. The energy transport by vertical mixing plays an essential role in the greenhouse or anti-greenhouse effect. This work explores the interaction between scattering and vertical mixing, specifically whether these processes enhance or mitigate each other's effects on atmospheric temperature. The interaction between mixing flux and scattering is nonlinear. Our calculations indicate that thermal scattering intensifies the greenhouse effects caused by vertical mixing in the middle atmosphere but reduces them in the lower layers. In the middle atmosphere, increased vertical mixing enhances the warming effect of thermal scattering while diminishing the cooling effect of visible scattering. In the lower atmosphere, it enhances the anti-greenhouse effect linked to visible scattering and diminishes the greenhouse effect produced by thermal scattering. The combined influence of thermal scattering and vertical mixing on the lower atmosphere's greenhouse effect is weaker than their separate impacts, akin to 1 + 1 &lt; 2. It is also interesting to note that the joint effect may also influence chemistry and cloud formation, altering the thermal structure.

Keywords: Radiative transfer simulations, Radiative transfer equation, Exoplanet atmospheres, Atmospheric structure
Measurement of Methane Line Broadening in Hot Hydrogen/Helium Atmospheres at λ = 1.60–1.63 μm for Substellar Object Spectroscopy. Recent high-dispersion spectroscopy from ground-based telescopes and high-precision spectroscopy from space observatories have enabled atmospheric observations of substellar objects, such as brown dwarfs and hot gaseous exoplanets, with sufficient precision to make ambient gas differences in molecular line broadening a significant factor. In this paper, we experimentally measured the pressure broadening of methane in a high-temperature hydrogen–helium background atmosphere in the H band, which had not been previously measured. The experiment used glass cells, inserted in a tube furnace, filled with methane in a hydrogen–helium background atmosphere or pure methane gas. Spectra were obtained at four temperatures ranging from room temperature to 1000 K, in the wavelength range 1.60–1.63 μm, using a tunable laser, yielding eight high-resolution spectra in total. A full Bayesian analysis was performed on the obtained spectra, using the differentiable spectral model ExoJAX and the Hamiltonian Monte Carlo for inferring a large number of parameters, allowing us to infer the H2/He pressure broadening for 22 transitions mainly in the R branch of the 2ν3 band. As a result, we found a temperature exponent of approximately 0.27 and a reference width at 296 K of around 0.040 for Jlower = 13–20. This temperature dependency is much milder than that provided by the molecular database ExoMol, yielding a line width approximately 5%–45% smaller than ExoMol at 296 K, but similar at 1000 K. Our results suggest the need for further accumulation of experimental data for spectral analysis of substellar objects with hydrogen–helium atmospheres.

Keywords: High resolution spectroscopy, Brown dwarfs, Methane, Molecular spectroscopy, Exoplanet atmospheres
UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters. JWST has revealed diverse new populations of high-redshift (z ∼ 4–11) active galactic nuclei (AGNs) and extreme star-forming galaxies that challenge current photoionization models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGNs. From a parent sample of 205 zspec &gt; 3 UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 galaxies with C IV, He II, and/or C III] emission. Three of these galaxies also exhibit clear N III] and/or N IV] lines. Leveraging the combined rest-optical and UV coverage of PRISM, we limit the emission-line model space using the sample's [O III]/Hβ distribution, significantly decreasing the overlap between AGN and star formation models in the UV diagnostics. We then find that the five He II emitters are the strongest AGN candidates, with further support from two [Ne V] detections and one X-ray detection from Chandra. Our Balmer line fits also reveal one new broad-line AGN at z = 6.87. We cannot robustly quantify the AGN fraction in this sample, but we note that close to 20% of M* &gt; 2 × 109 M⊙ parent sample galaxies are AGN candidates. The lower-mass line emitters, which are consistent with both AGN and star-forming photoionization models, have more compact sizes and higher specific star formation rates than the parent sample. Higher-resolution and deeper data on these UV line emitters should provide much stronger constraints on the obscured AGN fraction at z &gt; 3.

Keywords: Early universe, Active galactic nuclei, High-redshift galaxies, Emission line galaxies
Shining a Light on the Connections between Galactic Outflows Seen in Absorption and Emission Lines. Galactic outflows provide important feedback effects to regulate the evolution of host galaxies. Two primary diagnostics of outflows are broad and/or blueshifted emission and absorption lines. Even though well-established methods exist to analyze these outflow signatures, connections between them are rarely studied and largely unknown. In this paper, we conduct such a study in a sample of 33 low-redshift starburst galaxies. Their UV absorption lines are detected by the Hubble Space Telescope, and optical emission lines are observed by Keck or the Very Large Telescope. We find that the outflow properties derived from emission and absorption lines are tightly correlated. These include outflow maximum velocity, line width, and radial extent. On average, in the same galaxy, the maximum velocity and line width of outflows measured from emission lines reach only 60%─70% of those from the absorption lines. We also find outflow rates derived from emission lines are consistently lower than those from absorption lines by 0.2─0.5 dex. These findings can be explained by a radial decline in density and a corresponding increase in outflow velocity, combined with the fact that emission line luminosity scales with the square of the density while absorption line depth scales linearly. We test both spherical and biconical outflow models and find that the same radial outflow velocity and density distributions can explain the observed correlations. These results provide novel calibration between galactic outflow properties measured from the two diagnostics and underscore the need for high-fidelity UV and optical spectra to accurately assess galactic feedback effects in high-z galaxies.

Keywords: Galactic winds, Starburst galaxies, Ultraviolet spectroscopy, Galaxy kinematics, Galaxy evolution, Galaxy spectroscopy
The JWST/PASSAGE Survey: Testing Reionization Histories with JWST's First Unbiased Survey for Lyα Emitters at Redshifts 7.5─9.5. Lyα emission is one of a few observable features of galaxies that can trace the neutral hydrogen content in the Universe during the Epoch of Reionization (EoR). To accomplish this, we need an efficient way to survey for Lyα emitters (LAEs) at redshifts beyond 7, requiring unbiased emission-line observations that are both sufficiently deep and wide to cover enough volume to detect them. Here we present results from PASSAGE—a pure-parallel JWST/NIRISS slitless spectroscopic survey to detect LAEs deep into the EoR, without the bias of photometric preselection. We identify four LAEs at 7.5 ≤ z ≤ 9.5 in four surveyed pointings and estimate the luminosity function (LF). We find that the LF does show a marked decrease compared to post-reionization measurements, but the change is a factor of ≲10, which is less than expected from theoretical calculations and simulations, as well as observational expectations from the pre-JWST literature. Modeling of the intergalactic medium and expected Lyα profiles implies that these galaxies reside in ionized bubbles of ⪆2 physical Mpc. We also report that in the four fields we detect {3, 1, 0, 0} LAEs, which could indicate strong field-to-field variation in the LAE distribution, consistent with a patchy H I distribution at z ∼ 8. We compare the recovered LAE number counts with expectations from simulations and discuss the potential implications for reionization and its morphology.

Keywords: Lyman-alpha galaxies, Reionization, High-redshift galaxies
On the Signature of Black Holes on the Quenched Stellar Mass Function. As star-forming galaxies approach or exceed a stellar mass of around 1011M⊙, they are increasingly likely to be quenched in a process generically called mass quenching. Central galaxies, which are quenched via mass rather than environmental quenching, therefore accumulate in a peak around this characteristic mass. While a number of processes may influence the shape of the quenched central stellar mass function, we find that its low-mass slope is strongly affected by the scatter in the mass of black holes at a given stellar mass, with higher scatters in the black hole population yielding shallower slopes. Higher scatters in the black hole mass spread out the stellar mass range over which quenching occurs, leading to shallower slopes. This trend holds across a variety of semianalytic models and cosmological hydrodynamic simulations. A comparison with observations provides indirect evidence for a large scatter in black hole mass   dex, and a joint constraint on active galactic nuclei feedback physics and the coevolution of galaxies and black holes.

Keywords: Galaxy quenching, Galaxy formation, Galaxy evolution
Investigating an Erupting Metric-decimetric Radio Depression and Its Physical Origin. We present direct metric-decimetric radio imaging observations of a fascinating quiescent filament eruption on 2024 March 17 using data from the DAocheng Radio Telescope, with a combination of the Solar Dynamics Observatory and the Chinese Hα Solar Explorer. At the radio band, even though the filament is difficult to identify in its early phase, it rapidly became distinct and formed a continuous loop-like dark structure during the eruption, i.e., so-called radio depression. Compared with the fragmentation of the erupting filament observed at the Hα and EUV bands, the radio depression appeared more coherently. Based on synthetic radio images from a three-dimensional magnetohydrodynamics simulation of a flux-rope-filament eruption, it is suggested that the radio depression originates from the absorption of cold and dense materials within the erupting flux rope to the background emission. The absorption seems to be stronger than that at the Hα and EUV bands, thus leading to their apparent discrepancies. Moreover, the radio depression is also found to occupy the lower part but not the whole body of the flux rope.

Keywords: Solar radio emission, Solar filaments, Solar filament eruptions
A Discussion on the Origin of the Sub-PeV Galactic Gamma-Ray Emission. Galactic diffuse gamma-ray flux measured by the Tibet ASγ experiment and the total Galactic gamma-ray flux measured by the Large High Altitude Air Shower Observatory (LHAASO) are found to be consistent, within the statistical and systematic uncertainties, for the inner Galactic plane region in the sub-PeV energy range (E &gt; 1014 eV). The result suggests that the sub-PeV Galactic gamma-ray flux is dominated by the diffuse emission. On the other hand, the LHAASO observations suggest that the sub-PeV gamma-ray sources presented in the first LHAASO catalog possibly give a significant contribution to the total sub-PeV Galactic gamma-ray emission (≈60%). However, the estimate must be regarded as a conservative upper limit in the sub-PeV energy range. In fact, current gamma-ray observations imply that many of the sub-PeV gamma-ray sources detected by LHAASO have a cutoff or significant softening in their energy spectra in the several tens of TeV energy range, and the resolved-source contribution to the total sub-PeV Galactic gamma-ray emission should be much lower than the above estimate. More sophisticated discussion about the origin of the sub-PeV Galactic gamma-ray emission requires detailed spectral studies of the individual gamma-ray sources and an accurate estimate of the contamination of the source fluxes from the diffuse emission.

Keywords: Galactic cosmic rays, Gamma-ray astronomy, High-energy cosmic radiation
Reconstructing He I 10830 Å Images Using Hα Images through Deep Learning. He I 10830 Å, as an important spectrum line to diagnose the solar chromosphere and corona, has had consistent observations within the past two decades. This study aims to reconstruct synthetic He I 10830 Å images, addressing the limited availability of historical data compared to the extensive record of Hα images spanning over a century. To achieve this, we generate He I 10830 Å images from Hα using a deep learning method, pix2pixHD. For model development, we use He I 10830 Å images from the National Solar Observatory (NSO)/Synoptic Optical Long-term Investigations of the Sun and Hα images from NSO/Global Oscillation Network Group. Our model achieves a high correlation coefficient (CC) of 0.867 to reconstruct full-disk He I 10830 Å images. For solar structures like active regions, nonpolar, and polar crown filaments, we can achieve CCs of 0.903, 0.844, and 0.871, respectively. The model also shows reasonable performance on coronal holes with a CC of 0.536. Moreover, the model effectively generalized to data from multiple observatories, producing reliable results. In the early 2000s, when He I 10830 Å data was scarce, our model successfully reconstructed a scenario of an X-class flare eruption in the He I 10830 Å line covering the full observing period. This reconstruction included the formation of dark flare ribbons during the flare and postflare phases, showing a strong match with the postflare scenario observed by the Mauna Loa Solar Observatory/Chromospheric Helium Imaging Photometer.

Keywords: Solar physics, Neural networks
The Formation of Direct Collapse Black Holes at Cosmic Dawn and 21 cm Global Spectrum. JWST reveals numerous high-z galaxies and supermassive black holes (SMBHs), suggesting that stars and SMBH seeds formation at z ≳ 10 may be more efficient than previously derived. One popular SMBH seed scenario is the direct collapse black holes (DCBHs) formed in pristine atomic-cooling halos irradiated by nearby galaxies. Therefore, the efficient star formation likely facilitates the formation of DCBH. We calculate the first critical   curves for DCBH formation under the influence of X-ray radiation using the one-zone model. We then build the UV luminosity function consistent with JWST observations and incorporate it into the model that calculates the DCBH-triggering probability. We confirm that enhanced star formation promotes the DCBH formation. However, the DCBH abundance nDCBH is significantly influenced by the X-ray radiation that is also related to star formation. Since the 21 cm global spectrum is also X-ray dependent, the 21 cm absorption depth   at Cosmic Dawn encodes the DCBH abundance information. We provide a tentative trend in the nDCBH–   relation, which could be a useful guide. In our fiducial model, if   mK, then the DCBH is rather rare; if   mK,   cMpc‑3 (comoving Mpc‑3), consistent with the HST/JWST observed SMBHs abundance at z ≳ 6; if   mK, nDCBH can largely exceed   cMpc‑3. The 21 cm global spectrum observations will help to constrain the DCBH abundance.

Keywords: Intermediate-mass black holes, Population III stars, H I line emission, Reionization, High-redshift galaxies, Cosmic background radiation
Measuring Mass of Gas in Central Galaxies Using Weak Lensing and Satellite Kinematics in MOND. In Milgrom's MOdified Newtonian Dynamics (MOND) framework, the dynamical mass of a galaxy is fully determined by its baryonic matter distribution. Using this framework, we fit the distribution of cold and hot gas halos—focusing on the hot gas—around Sloan Digital Sky Survey central galaxies, utilizing weak lensing signals from the DECaLS survey. The central galaxies are classified into the total sample and the star-forming sample. Hot gas halo densities nearly follow Plummer's profile for both samples across all mass bins out to extended radii. We then demonstrate the rotation curves of the galaxy samples. Furthermore, the stellar fraction, M*/(M* + Mg), is between 0.3 and 0.8 in all mass bins of the star-forming sample, which is higher than in the total sample. Additionally, we use the satellite kinematics method in MOND to verify our findings from the weak lensing method. We find good agreement between the two methods, indicating that weak lensing signals reliably measure the dynamical mass of central galaxies and can constrain the distribution of missing baryons in galaxy clusters. Combining both methods, we discover a baryonic mass to line-of-sight velocity dispersion of satellites (Mb–σs) relation. More sophisticated models, such as Osipkov–Merritt anisotropy profiles, were found unnecessary, as simple isotropic or mildly radially anisotropic MOND models align well with the observed Mb–σs relation. Moreover, the isotropic model remains consistent with this relation even when considering external fields from large-scale structures.

Keywords: Weak gravitational lensing, Missing mass, Galaxy dynamics, Galaxy rotation curves, Modified Newtonian dynamics
Investigating the Spectral Nature of Gigahertz-peaked Spectra Pulsar Candidates. We report the measurements of low radio frequency spectra of 14 gigahertz-peaked spectra (GPS) pulsar candidates, between 300 and 700 MHz, using the upgraded Giant Metrewave Radio Telescope. Combining newly collected measurements with archival results, the spectral nature of each pulsar was examined using four different physical models: simple power law, broken power law, low-frequency turnover power law, and free–free thermal absorption. Based on this analysis, we confirm the GPS nature of five pulsars, three of them being new detections. In addition, one pulsar can be classified as having a broken power law spectrum, and we found the typical power-law spectra in four other cases. In the remaining four pulsars, the spectra showed tendencies of low-frequency turnover that require further investigations at lower frequency ranges. These results demonstrate the effectiveness of wideband measurements at low frequencies, below 1 GHz, in characterizing the spectral nature in pulsars. Our results also underline the need for more systematic theoretical studies to refine existing models and better interpret pulsar emission properties.

Keywords: Spectral index, Radio interferometry, Interstellar medium, Radio pulsars
High-energy Gamma-Ray and Neutrino Emissions from Interacting Supernovae Based on Radiation Hydrodynamic Simulations: A Case of SN 2023ixf. Recent observations of core-collapse supernovae revealed that the existence of dense circumstellar matter (CSM) around their progenitors is ubiquitous. Interaction of supernova ejecta with such a dense CSM is a potential production site of high-energy cosmic rays (CRs), gamma rays, and neutrinos. We estimate the gamma-ray and neutrino signals from SN 2023ixf, a core-collapse supernova occurred in a nearby galaxy M101, which exhibits signatures of the interaction with the confined, dense CSM. Using a radiation-hydrodynamic simulation model calibrated by the optical and ultraviolet observations of SN 2023ixf, we find that the CRs cannot be accelerated in the early phase because the sharp velocity jump at the shock disappears due to strong radiation pressure. Roughly 4 days after the explosion, the collisionless subshock is formed in the CSM, which enables the CR production and leads to gamma-ray and neutrino emissions. The shock sweeps up the entire dense CSM roughly 9 days after the explosion, which ceases the high-energy radiation. Based on this scenario, we calculate the gamma-ray and neutrino signals, which have a peak around 9 days after the explosion. We can constrain the CR production efficiency to be less than 10% by comparing our prediction to the Fermi Large Area Telescope upper limits. Future multimessenger observations with an enlarged sample of nearby supernovae will provide a better constraint on the CR production efficiency in the early phases of supernovae.

Keywords: Gamma-ray sources, Type II supernovae, Neutrino astronomy, Cosmic ray sources, Shocks, Particle astrophysics
The Distance to the Magellanic Stream: Constraints from Optical Absorption along Stellar Sight Lines. The Magellanic Stream is a large tail of neutral and ionized gas originating from tidal and hydrodynamical interactions between the Magellanic Clouds as they orbit the Milky Way (MW). It carries a significant gas reservoir that could impact the future evolution of the MW. Despite its importance, no direct observational constraints on the Stream's distance have been previously published. In this study, we analyze Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph spectra of five blue horizontal branch stars in the MW halo located at distances ranging from 13 to 56 kpc near two regions of the Stream (near Stream longitudes of ─79∘ and ─98∘), with the aim of detecting Ca II and Na I absorption. No Ca II or Na I absorption is detected at Stream velocities in any of the individual spectra or in higher signal-to-noise stacks of the spectra. The resulting limits on the Ca II absorption are significantly lower than the Ca II columns measured in the Stream along extragalactic sight lines. These nondetections establish a firm lower distance limit of 42 kpc for one region of the Stream. For the other region, we set a firm lower limit of 20 kpc and a tentative lower limit of 55 kpc from the most distant star, but deeper spectra are needed to confirm this. Our results provide the first observational constraints on the gaseous Stream's distance.

Keywords: Stellar streams, Quasar absorption line spectroscopy, Interstellar line absorption, Magellanic Stream, Magellanic Clouds
The Evolving Power Spectrum for the Light Cone Epoch of Reionization 21 cm Signal. The rapid evolution of the cosmological neutral hydrogen (H I) distribution during the Epoch of Reionization (EoR) is imprinted along the line of sight (LoS) in the redshifted 21 cm signal due to the light cone (LC) effect. The LC EoR 21 cm signal ceases to be ergodic along the LoS, and the Fourier-transform-based three-dimensional power spectrum fails to capture the full two-point statistics. Several earlier studies have used the multifrequency angular power spectrum (MAPS)   to overcome this limitation. However, we do not have a simple interpretation of   in terms of comoving length scale, and the data volume is large. Here we introduce the evolving power spectrum (ePS) to quantify the two-point statistics of the LC EoR 21 cm signal. This has a simple interpretation in terms of redshift evolution and comoving length scales, and the binned ePS reduces the data volume by several orders of magnitude compared to MAPS. Considering simulations, we study the first three even angular multipoles of ePS to quantify the LoS anisotropy of the signal. We find that as reionization progresses, at large k (≥0.6 Mpc‑1), Pe 0(k, z), the monopole moment decreases as  , the mean neutral H I fraction, which, in principle, can be used to observationally determine the reionization history. Furthermore, Pe 2(k, z), the quadrupole moment, is negative at small k and positive at large k. We propose the binned ePS, which captures all of the information contained in MAPS, to quantify the full two-point statistics of the LC EoR 21 cm signal.

Keywords: Large-scale structure of the universe, Diffuse radiation, Astrostatistics, Reionization, Interferometry