Sazuna/UAT_keywords huggingface dataset:
Ultra-deep Keck/MOSFIRE Spectroscopic Observations of z   2 Galaxies: Direct Oxygen Abundances and Nebular Excitation Properties. Using deep near-infrared Keck/MOSFIRE observations, we analyze the rest-optical spectra of eight star-forming galaxies in the COSMOS and GOODS-N fields. We reach integration times of ~10 hr in the deepest bands, pushing the limits on current ground-based observational capabilities. The targets fall into two redshift bins, of five galaxies at z ~ 1.7 and three galaxies at z ~ 2.5, and were selected as likely to yield significant auroral-line detections. Even with long integration times, detection of the auroral lines remains challenging. We stack the spectra together into subsets based on redshift, improving the signal-to-noise ratio on the [O III]λ4364 auroral emission line and, in turn, enabling a direct measurement of the oxygen abundance for each stack. We compare these measurements to commonly employed strong-line ratios alongside measurements from the literature. We find that the stacks fall within the distribution of z &gt; 1 literature measurements, but a larger sample size is needed to robustly constrain the relationships between strong-line ratios and oxygen abundance at high redshift. We additionally report detections of [O I]λ6302 for nine individual galaxies and composite spectra of 21 targets in the MOSFIRE pointings. We plot their line ratios on the [O III]λ5008/Hβ versus [O I]λ6302/Hα diagnostic diagram, comparing our targets to local galaxies and H II regions. We find that the [O I]/Hα ratios in our sample of galaxies are consistent with being produced in gas ionized by α-enhanced massive stars, as has been previously inferred for rapidly forming galaxies at early cosmic times.

Keywords: Emission line galaxies, Galaxy evolution, Interstellar medium, High-redshift galaxies, Galaxies
The Spatial and Emission Properties of the Large [O III] Emission Nebula Near M31. Drechsler et al. reported the unexpected discovery of a 1.°5 long [O III] emission nebula 1.°2 southeast of the M31 nucleus. Here we present additional images of this large emission arc, called the Strottner-Drechsler-Sainty Object (SDSO), along with radial velocity and flux measurements from low-dispersion spectra. Independent sets of [O III] images show SDSO to be composed of broad streaks of diffuse emission aligned northeast-southwest. Deep Hα images reveal no strong coincident emission suggesting a high [O III]/Hα ratio. We also find no other [O III] emission nebulosity as bright as SDSO within several degrees of M31 and no filamentary Hα emission connected to SDSO. Optical spectra taken along the nebula's northern limb reveal [O III] λ λ4959, 5007 emissions matching the location and extent seen in our [O III] images. The heliocentric velocity of this [O III] nebulosity is -9.8 ± 6.8 km s-1 with a peak surface brightness of (4 ± 2) × 10-18 erg s-1 cm-2 arcsec-2 (~0.55 Rayleigh). We discuss SDSO as a possible unrecognized supernova remnant, a large and unusually nearby planetary nebula, a stellar bow shock nebula, or an interaction of M31's outer halo with Local Group circumgalactic gas. We conclude that galactic origins for SDSO are unlikely and favor instead an extragalactic M31 halo-circumgalactic cloud interaction scenario, despite the nebula's low radial velocity. We then describe new observations that may help resolve the nature and origin of this large nebulosity so close to M31 in the sky.

Keywords: Circumgalactic medium
Shock Enhanced [C II] Emission from the Infalling Galaxy Arp 25. We present SOFIA observations with HAWC+ and FIFI-LS of the peculiar galaxy Arp 25, also known as NGC 2276 or UGC 3740, whose morphology is deformed by its impact with the intragroup medium of the NGC 2300 galaxy group. These observations show the first direct proof of the enhancement of [C II] emission due to shocks caused by ram pressure in a group of galaxies. By comparing the [C II] emission to UV attenuation, dust emission, PAH, and CO emission in different regions of the galaxy, we find a clear excess of [C II] emission along the impact front with the intragroup medium. We estimate that the shock due to the impact with the intragroup medium increases the [C II] emission along the shock front by 60% and the global [C II] emission by approximately 25% with respect to the predicted [C II] emission assuming only excitation caused by stellar radiation. This result shows the danger of interpreting [C II] emission as directly related to star formation since shocks and other mechanisms can significantly contribute to the total [C II] emission from galaxies in groups and clusters. ∗ Data obtained with FIFI-LS and HAWC+ on board SOFIA.

Keywords: Molecular gas, Infrared galaxies, Interstellar medium, Galaxy environments
A Phase-resolved View of the Low-frequency Quasiperiodic Oscillations from the Black Hole Binary MAXI J1820+070. Although low-frequency quasiperiodic oscillations (LFQPOs) are commonly detected in the X-ray light curves of accreting black hole X-ray binaries, their origin still remains elusive. In this study, we conduct phase-resolved spectroscopy in a broad energy band for LFQPOs in MAXI J1820+070 during its 2018 outburst, utilizing Insight-HXMT observations. By employing the Hilbert-Huang transform method, we extract the intrinsic quasiperiodic oscillation (QPO) variability, and obtain the corresponding instantaneous amplitude, phase, and frequency functions for each data point. With well-defined phases, we construct QPO waveforms and phase-resolved spectra. By comparing the phase-folded waveform with that obtained from the Fourier method, we find that phase folding on the phase of the QPO fundamental frequency leads to a slight reduction in the contribution of the harmonic component. This suggests that the phase difference between QPO harmonics exhibits time variability. Phase-resolved spectral analysis reveals strong concurrent modulations of the spectral index and flux across the bright hard state. The modulation of the spectral index could potentially be explained by both the corona and jet precession models, with the latter requiring efficient acceleration within the jet. Furthermore, significant modulations in the reflection fraction are detected exclusively during the later stages of the bright hard state. These findings provide support for the geometric origin of LFQPOs and offer valuable insights into the evolution of the accretion geometry during the outburst in MAXI J1820+070.

Keywords: Accretion, X-ray binary stars, Stellar mass black holes
Radial and Local Density Dependence of Star Formation Properties in Galaxy Clusters from the Hyper Suprime-Cam Survey. This study examines the impact of cluster environments on galaxy properties using data from the Hyper Suprime-Cam Subaru Strategic Program and an optically selected CAMIRA cluster sample. Specifically, the study analyzes the fractions of quiescent and green valley galaxies with stellar masses above 108.6 M ⊙ at z ~ 0.2 and 109.8 M ⊙ at z ~ 1.1, investigating their trends in radius and density. The results indicate that a slow quenching mechanism is at work, as evidenced by a radially independent specific star formation rate reduction of 0.1 dex for star-forming galaxies in a cluster environment. The study also finds that slow quenching dominates fast quenching only for low-mass galaxies (&lt;109.2 M ⊙) near the cluster edge, based on their contributions to the quiescent fraction. After controlling for M *, z, and local overdensity, the study still finds a significant radial gradient in the quiescent fraction, indicating active ram pressure stripping in dense environments. That said, analyzing the density trend of the quiescent fraction with other fixed parameters suggests that radial and density-related quenching processes are equally crucial for low-mass cluster galaxies. The study concludes that ram pressure stripping is the primary environmental quenching mechanism for high stellar mass galaxies in clusters. By contrast, ram pressure stripping and density-related quenching processes act comparably for low-mass cluster galaxies around the center. Near the cluster boundary, starvation and harassment become the leading quenching processes for low stellar mass galaxies.

Keywords: Galaxy clusters, Galaxy environments, Large-scale structure of the universe, Galactic and extragalactic astronomy, Galaxy evolution, Extragalactic astronomy
Integral Field Spectroscopy of 13 Tidal Disruption Event Hosts from the Zwicky Transient Facility Survey. The host galaxies of tidal disruption events (TDEs) have been shown to possess peculiar properties, including high central light concentrations, unusual star formation histories, and "green" colors. The ubiquity of these large-scale galaxy characteristics among TDE host populations suggests that they may serve to boost the TDE rate in such galaxies by influencing the nuclear stellar dynamics. We present the first population study of integral field spectroscopy for 13 TDE host galaxies across all spectral classes and X-ray brightnesses with the purpose of investigating their large-scale properties. We derive the black hole masses via stellar kinematics (i.e., the M-σ relation) and find masses in the range $5.0\lesssim \mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })\lesssim 8.0$ , with a distribution dominated by black holes with M BH ~ 106 M ⊙. We find one object with M BH ≳ 108 M ⊙, above the "Hills mass", which if the disrupted star was of solar type, allows a lower limit of a ≳ 0.16 to be placed on its spin, lending further support to the proposed connection between featureless TDEs and jetted TDEs. We also explore the level of rotational support in the TDE hosts, quantified by (V/σ) e , a parameter that has been shown to correlate with the stellar age and may explain the peculiar host-galaxy preferences of TDEs. We find that the TDE hosts exhibit a broad range in (V/σ) e  following a similar distribution as E + A galaxies, which have been shown to be overrepresented among TDE host populations.

Keywords: Supermassive black holes, Black holes, Stellar kinematics, Tidal disruption, Galaxy stellar content, Scaling relations
LIMpy: A Semianalytic Approach to Simulating Multiline Intensity Maps at Millimeter Wavelengths. Mapping of multiple lines such as the fine-structure emission from [C II] (157.7 μm), [O III] (52 and 88.4 μm), and rotational emission lines from CO are of particular interest for upcoming line intensity mapping (LIM) experiments at millimeter wavelengths, due to their brightness features. Several upcoming experiments aim to cover a broad range of scientific goals, from detecting signatures of the epoch of reionization to the physics of star formation and its role in galaxy evolution. In this paper, we develop a semianalytic approach to modeling line strengths as functions of the star formation rate (SFR) or infrared luminosity based on observations of local and high-z galaxies. This package, LIMpy (Line Intensity Mapping in Python), estimates the intensity and power spectra of [C II], [O III], and CO rotational transition lines up to the J levels (1-0) to (13-12) based both on analytic formalism and on simulations. We develop a relation among halo mass, SFR, and multiline intensities that permits us to construct a generic formula for the evolution of several line strengths up to z ~ 10. We implement a variety of star formation models and multiline luminosity relations to estimate the astrophysical uncertainties on the intensity power spectrum of these lines. As a demonstration, we predict the signal-to-noise ratio of [C II] detection for an EoR-Spec-like instrument on the Fred Young Submillimeter Telescope. Furthermore, the ability to use any halo catalog allows the LIMpy code to be easily integrated into existing simulation pipelines, providing a flexible tool to study intensity mapping in the context of complex galaxy formation physics.

Keywords: CII region, Cosmology, Galaxy formation, Large-scale structure of the universe, Galaxy evolution, CO line emission, Reionization, Line intensities
Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1. Recent detections of aromatic species in dark molecular clouds suggest that formation pathways may be efficient at very low temperatures and pressures, yet current astrochemical models are unable to account for their derived abundances, which can often deviate from model predictions by several orders of magnitude. The propargyl radical, a highly abundant species in the dark molecular cloud TMC-1, is an important aromatic precursor in combustion flames and possibly interstellar environments. We performed astrochemical modeling of TMC-1 using the three-phase gas-grain code NAUTILUS and an updated chemical network, focused on refining the chemistry of the propargyl radical and related species. The abundance of the propargyl radical has been increased by half an order of magnitude compared to the previous GOTHAM network. This brings it closer in line with observations, but it remains underestimated by 2 orders of magnitude compared to its observed value. Predicted abundances for the chemically related C4H3N isomers within an order of magnitude of observed values corroborate the high efficiency of CN addition to closed-shell hydrocarbons under dark molecular cloud conditions. The results of our modeling provide insight into the chemical processes of the propargyl radical in dark molecular clouds and highlight the importance of resonance-stabilized radicals in polycyclic aromatic hydrocarbon formation.

Keywords: Radical-radical recombination, Polycyclic aromatic hydrocarbons, Molecular clouds, Chemical kinetics, Astrochemistry
Identification of 1RXS J165424.6-433758 as a Polar Cataclysmic Variable. We present the results of our X-ray, ultraviolet, and optical follow-up campaigns of 1RXS J165424.6-433758, an X-ray source detected with the Swift Deep Galactic Plane Survey. The source X-ray spectrum (Swift and NuSTAR) is described by thermal bremsstrahlung radiation with a temperature of kT = 10.1 ± 1.2 keV, yielding an X-ray (0.3-10 keV8) luminosity L  X  = (6.5 ± 0.8) × 1031 erg s-1 at a Gaia distance of 460 pc. Spectroscopy with the Southern African Large Telescope revealed a flat continuum dominated by emission features, demonstrating an inverse Balmer decrement, the λ4640 Bowen blend, almost a dozen He I lines, and He II λ4541, λ4686, and λ5411. Our high-speed photometry demonstrates a preponderance of flickering and flaring episodes, and revealed the orbital period of the system, P orb = 2.87 hr, which fell well within the cataclysmic variable (CV) period gap between 2 and 3 hr. These features classify 1RXS J165424.6-433758 as a nearby polar magnetic CV.

Keywords: X-ray astronomy, Cataclysmic variable stars, AM Herculis stars
New and Improved Lyα Reconstructions for M and K Dwarfs. The Lyα emission line is the brightest UV emission line in M and K dwarf spectra and serves as an important tool for studies of stellar chromospheres, the interstellar medium, and exoplanet atmospheres. However, Lyα observations have proven difficult due to the strong absorption by the interstellar medium, necessitating a reconstruction of the intrinsic stellar line from the observed spectrum. We have performed new Lyα reconstructions on the MUSCLES Treasury Survey stars, incorporating improved parameterizations for the intrinsic line wings and line core. We present an analysis of how the updated Lyα fluxes could impact photochemical and atmospheric escape studies and flux-flux scaling relations with other chromospheric emission lines such as Ca II H and K. We find the overall intrinsic Lyα flux of our star sample decreases by as little as 10% to as much as ~5× fainter compared to previous findings. The exception to this flux decrease is the M dwarf GJ 581, whose Lyα flux increased by 4%. These results will likely have a limited impact on the aforementioned studies that rely on Lyα fluxes.

Keywords: Exoplanets, Stellar activity, Ultraviolet astronomy, Low mass stars, Interstellar medium
Circumgalactic Medium at High Halo Masses-Signatures of Cold Gas Depletion in Luminous Red Galaxies. We study ultraviolet H I and metal-line transitions in the circumgalactic medium (CGM) of 15 massive, quenched luminous red galaxies (LRGs) at redshift z ~ 0.5 and with impact parameters up to 400 kpc. We selected eight LRG-CGM systems to study general properties of the CGM around LRGs, while the other seven are already known to contain cool CGM gas from Mg II optical studies (Mg II-LRGs). In the general LRG population, we detect H I in four of eight LRGs, in all cases with N H I &lt; 1016.7cm-2. In contrast, all Mg II-LRGs show H I; for four LRGs, the H I column density is N H I ≳ 1018cm-2. The CGM of LRGs also shows low and intermediate ionized lines (such as C III, C II, Si III, and Si II) and highly ionized lines of O VI (we detect O VI around five of seven Mg II-LRGs and one of eight in the random sample). Next, we combine our sample with literature LRGs and ≲L * galaxies, and we find that while for ≲L * galaxies CGM H I Lyα absorption is stronger as galaxies are more massive, the cool CGM traced by H I Lyα is suppressed above stellar masses of M* ~ 1011.5 M ⊙. While most LRG-CGM systems show weak or nondetectable O VI (equivalent width &lt; 0.2 Å), a few LRG-CGM systems show strong O VI 1031, which in most cases likely originates from groups containing both an LRG and a blue star-forming neighboring galaxy.

Keywords: Quenched galaxies, Quasar absorption line spectroscopy, Galaxy environments, Circumgalactic medium, Galaxy quenching
Influence of Crustal Magnetic Fields on Horizontal Plasma Transport and Ion Escape on Mars. Owing to its unevenly distributed crustal fields, Mars acts as a unique obstacle to the solar wind. In the presence of the crustal fields, the transport of the planetary ions on the dayside ionosphere exhibits north-south asymmetry. Additionally, the heavy-ion loss in the magnetotail is affected by the crustal fields. In this paper, a three-dimensional multispecies magnetohydrodynamic model is employed to simulate Mars-solar wind interactions. Numerical results indicate that the meridional transport is dominant in most areas on the dayside ionosphere. In the presence of the crustal fields, the meridional transport on the southern hemisphere (southward transport) is reduced by more than 70% above the strong crustal sources, and the zonal velocity shows local changes inside strong and weak crustal field regions. These effects result in an increase or decrease in the number density of the heavy ions reaching the terminator, thereby influencing the thickness of the ionosphere. Decreased southward velocity leads to a reduction in the heavy-ion loss on the southern magnetotail. The radial outward flux is reduced by more than 30% for O2 + and CO2 + and by 10% for O+. This study shows that in addition to the zonal transport, the meridional transport is important for the day-to-night transport on the dayside of Mars. Collectively, the horizontal plasma transport, controlled by crustal fields, is associated with the altered ionosphere structure and reduced heavy-ion loss in the magnetotail.

Keywords: Magnetic anomalies, Mars, Magnetohydrodynamical simulations
Refraction of Line and Continuum Light in Exoplanet Atmospheres. Exoplanet transit spectra are calculated including the effect of atmospheric opacity and refractive lightbending. While previous studies considered the case of continuum light, here the effect of an atomic resonance line is included. The model assumes a clear atmosphere and includes H and He, which contribute static polarizability and Rayleigh scattering, as well as the Na D doublet, which contributes dynamic polarizability and a resonant cross section. The image locations and magnifications are found using the lens equation. The model including lightbending is compared to the standard model in which the light travels on straight lines. It is found that near the line center, where the polarizability is large, bending angles are nevertheless small since the optical depth τ = 1 trajectory is at such a high altitude where the particle density is low. Moving away from the line center, the Na D resonance dominates the opacity over ~400 Å, and over most of this wavelength range the polarizability is dominated by hydrogen and helium and is nearly wavelength-independent. However, the density of the τ = 1 trajectory is wavelength-dependent, and hence the bending angle increases strongly away from the line center. The wavelength-dependent flux deviation between the straight-line and lightbending models occurs at the level of ΔF  λ /F 0 ~ 10-5 for a planet at orbital separation a = 10 R ⊙.

Keywords: Atmospheric refraction, Exoplanet atmospheres
TRAO Survey of Nearby Filamentary Molecular Clouds, the Universal Nursery of Stars (TRAO-FUNS). III. Filaments and Dense Cores in the NGC 2068 and NGC 2071 Regions of Orion B. We present the results of molecular line observations performed toward the NGC 2068 and NGC 2071 regions of the Orion B cloud as the TRAO-FUNS project to study the roles of the filamentary structure in the formation of dense cores and stars in the clouds. Gaussian decomposition for the C18O spectra with multiple velocity components and the application of a friends-of-friends algorithm for the decomposed components allowed us to identify a few tens of velocity-coherent filaments. We also identified 48 dense cores from the observations of N2H+ using a core finding tool, FellWalker. We performed a virial analysis for these filaments and dense cores, finding that the filaments with N2H+ dense core are thermally supercritical, and the filaments with a larger ratio between the line mass and the thermal critical line mass tend to have more dense cores. We investigated the contribution of the nonthermal motions in dense cores and filaments, showing the dense cores are mostly in transonic/subsonic motions while their natal filaments are mostly in supersonic motions. This may indicate that gas turbulent motions in the filaments have been dissipated at the core scale to form the dense cores there. The filaments with (dynamically evolved) dense cores in infalling motions or with NH2D bright (or chemically evolved) dense cores are all found to be gravitationally critical. Therefore, the criticality of the filament is thought to provide a key condition for its fragmentation, the formation of dense cores, and their kinematical and chemical evolution.

Keywords: Interstellar filaments, Molecular clouds, Star formation, Interstellar medium, Radio astronomy
Theory of Magnetic Switchbacks Fully Supported by Parker Solar Probe Observations. Magnetic switchbacks are rapid high-amplitude reversals of the radial magnetic field in the solar wind that do not involve a heliospheric current sheet crossing. First seen sporadically in the 1970s in Mariner and Helios data, switchbacks were later observed by the Ulysses spacecraft beyond 1 au and have been recently discovered to be a typical component of solar wind fluctuations in the inner heliosphere by the Parker Solar Probe spacecraft. While switchbacks are now well understood to be spherically polarized Alfvén waves thanks to Parker Solar Probe observations, their formation has been an intriguing and unsolved puzzle. Here we provide a simple yet predictive theory for the formation of these magnetic reversals: the switchbacks are produced by the distortion and twisting of circularly polarized Alfvén waves by a transversely varying radial wave propagation velocity. We provide an analytic expression for the magnetic field variation, establish the necessary and sufficient conditions for the formation of switchbacks, and show that the proposed mechanism works in a realistic solar wind scenario. We also show that the theoretical predictions are in excellent agreement with observations, and the high-amplitude radial oscillations are strongly correlated with the shear of the wave propagation speed. The correlation coefficient is around 0.3-0.5 for both encounter 1 and encounter 12. The probability of this being a lucky coincidence is essentially zero with p-values below 0.1%.

Keywords: Interplanetary turbulence, Magnetohydrodynamics, Solar wind