Sazuna/UAT_keywords huggingface dataset:
A SPectroscopic Survey of Biased Halos In the Reionization Era (ASPIRE): JWST Supports Earlier Reionization around [O III] Emitters. Understanding when and how reionization happened is crucial for studying the early structure formation and the properties of the first galaxies in the Universe. At z &gt; 5.5, the observed intergalactic medium (IGM) optical depth shows a significant scatter, indicating an inhomogeneous reionization process. However, the nature of the inhomogeneous reionization remains debated. A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE) is a JWST Cycle 1 program that has spectroscopically identified &gt;400 [O III] emitters in 25 quasar fields at z &gt; 6.5. Combined with deep ground-based optical spectroscopy of ASPIRE quasars, the ASPIRE program provides the current largest sample for IGM-galaxy connection studies during cosmic reionization. We present the first results of IGM effective optical depth measurements around [O III] emitters using 14 ASPIRE quasar fields. We find the IGM transmission is tightly related to reionization era galaxies to the extent that a significant excess of Lyα transmission exists around [O III] emitters. We measure the stacked IGM effective optical depth of IGM patches associated with [O III] emitters and find they reach the same IGM effective optical depth at least d z ∼ 0.1 ahead of those IGM patches where no [O III] emitters are detected, supporting earlier reionization around [O III] emitters. Our results indicate an enhancement in IGM Lyα transmission around [O III] emitters at scales beyond 25 h −1 cMpc, consistent with the predicted topology of reionization from fluctuating UV background models.

Keywords: Reionization, High-redshift galaxies, Quasar absorption line spectroscopy, Intergalactic medium
Study on the Temporal Evolution of the Radial Differential Rotation of Solar Corona Using Radio Emissions. The daily measurements of the disk-integrated solar radio flux, observed by the Radio Solar Telescope Network, at 245, 410, 610, 1415, 2695, 4995, and 8800 MHz during the time interval of 1989 January 1 to 2019 December 17, are used to investigate the temporal evolution of radial differential rotation of the solar corona using the methods of ensemble empirical mode decomposition (EEMD) and wavelet analysis. Overall, the results reveal that over the 30 yr period, the rotation rates for the observed solar radio flux within the frequency range of 245–8800 MHz show an increase with frequency. This verifies the existence of the radial differential rotation of the solar corona over long timescales of nearly three solar cycles. Based on the radio emission mechanism, to some extent, the results can also serve as an indicator of how the rotation of the solar upper atmosphere varies with altitude within a specific range. From the temporal variation of rotation cycle lengths of radio flux, the coronal rotation at different altitudes from the low corona to approximately 1.3 R ⊙ exhibits complex temporal variations with the progression of the solar cycle. However, in this altitude range, over the past 30 yr from 1989 to 2019, the coronal rotation consistently becomes gradually slower as the altitude increases. Finally, the EEMD method can extract rotation cycle signals from these highly randomized radio emissions, and so it can be used to investigate the rotation periods for the radio emissions at higher or lower frequencies.

Keywords: Solar rotation, Solar corona
Synthesis and Spectroscopic Characterization of Interstellar Candidate Ethynyl Thiocyanate: HCCSCN. This work aims to spectroscopically characterize and provide for the first time direct experimental frequencies of the ground vibrational state and two excited states of the simplest alkynyl thiocyanate (HCCSCN) for astrophysical use. Both microwave (8–16 GHz) and millimeter-wave regions (50–120 GHz) of the spectrum have been measured and analyzed in terms of Watson's semirigid rotor Hamiltonian. A total of 314 transitions were assigned to the ground state of HCCSCN, and a first set of spectroscopic constants have been accurately determined. Spectral features of the molecule were then searched for in Sgr B2(N), NGC 6334I, G+0.693‑0.027, and TMC-1 molecular clouds. Upper limits to the column density are provided.

Keywords: Rotational spectroscopy, Molecular spectroscopy, Millimeter-wave spectroscopy, Microwave spectroscopy, Interstellar medium, Radio astronomy
Mildly Super-Eddington Accretion onto Slowly Spinning Black Holes Explains the X-Ray Weakness of the Little Red Dots. JWST has revealed a population of low-luminosity active galactic nuclei at z &gt; 4 in compact, red hosts (the "Little Red Dots," or LRDs), which are largely undetected in X-rays. We investigate this phenomenon using General Relativistic Radiation Magnetohydrodynamics simulations of super-Eddington accretion onto a supermassive black hole (SMBH) with M • = 107 M ⊙ at z ∼ 6, representing the median population; the spectral energy distributions (SEDs) that we obtain are intrinsically X-ray weak. The highest levels of X-ray weakness occur in SMBHs accreting at mildly super-Eddington rates (1.4 &lt; f Edd &lt; 4) with zero spin, viewed at angles &gt;30° from the pole. X-ray bolometric corrections in the observed 2–10 keV band reach ∼104 at z = 6, ∼5 times higher than the highest constraint from X-ray stacking. Most SEDs are extraordinarily steep and soft in the X-rays (median photon index Γ = 3.1, mode of Γ = 4.4). SEDs strong in the X-rays have harder spectra with a high-energy bump when viewed near the hot (&gt;108 K) and highly relativistic jet, whereas X-ray weak SEDs lack this feature. Viewing an SMBH within 10° of its pole, where beaming enhances the X-ray emission, has a ∼1.5% probability, matching the LRD X-ray detection rate. Next-generation observatories like AXIS will detect X-ray-weak LRDs at z ∼ 6 from any viewing angle. Although many SMBHs in the LRDs are already estimated to accrete at super-Eddington rates, our model explains 50% of their population by requiring that their masses are overestimated by a mere factor of ∼3. In summary, we suggest that LRDs host slowly spinning SMBHs accreting at mildly super-Eddington rates, with large covering factors and broad emission lines enhanced by strong winds, providing a self-consistent explanation for their X-ray weakness and complementing other models.

Keywords: Accretion, Supermassive black holes, Black holes, Active galaxies, Spectral energy distribution
Nonlinear Perturbations and Weak Shock Waves in Isentropic Atmospheres. Acoustic perturbations to stellar envelopes can lead to the formation of weak shock waves via nonlinear wave steepening. Close to the stellar surface, the weak shock wave increases in strength and can potentially lead to the expulsion of part of the stellar envelope. While accurate analytic solutions to the fluid equations exist in the limits of low-amplitude waves or strong shocks, connecting these phases generally requires simulations. We address this problem using the fact that the plane-parallel Euler equations, in the presence of a constant gravitational field, admit exact Riemann invariants when the flow is isentropic. We obtain exact solutions for acoustic perturbations and show that after they steepen into shock waves, Whitham's approximation can be used to solve for the shock's dynamics in the weak to moderately strong regimes, using a simple ordinary differential equation. Numerical simulations show that our analytic shock approximation is accurate up to moderate (∼few–15) Mach numbers, where the accuracy increases with the adiabatic index.

Keywords: Shocks, Hydrodynamics
Constraining the Diffusion Coefficient and Cosmic-Ray Acceleration Efficiency Using Gamma-Ray Emission from the Star-forming Region RCW 38. Stellar winds from massive stars may be significant sources of cosmic rays (CRs). To investigate this connection, we report a detailed study of gamma-ray emission near the young Milky Way star cluster (≈0.5 Myr old) in the star-forming region RCW 38 and compare this emission to its stellar wind properties and diffuse X-ray emission. Using 15 yr of Fermi-LAT data in the 0.2–300 GeV band, we find a significant (σ &gt; 22) detection coincident with the star cluster, producing a total gamma-ray luminosity (extrapolated over 0.1–500 GeV) of L  γ  =(2.66 ± 0.92) × 1034 erg s‑1 adopting a power-law spectral model (Γ = 2.34 ± 0.04). Using an empirical relationship and STARBURST99, we estimate the total wind power to be 8 × 1036 erg s‑1, corresponding to a CR acceleration efficiency of η CR ≃ 0.4 for an assumed diffusion coefficient consistent with D = 1028 cm2 s‑1. Alternatively, a lower acceleration efficiency of 0.1 can produce this L  γ  if the diffusion coefficient is smaller, D ≃ 2.5 × 1027 cm2 s‑1. Additionally, we analyze Chandra X-ray data from the region and compare the hot-gas pressure to the CR pressure. We find the former is 4 orders of magnitude greater, suggesting that the CR pressure is not dynamically important relative to stellar winds. As RCW 38 is too young for supernovae to have occurred, the high CR acceleration efficiency in RCW 38 demonstrates that stellar winds may be an important source of Galactic CRs.

Keywords: Stellar feedback, Young star clusters, Galactic cosmic rays, Stellar winds, X-ray sources, Gamma-ray astronomy
GTC Optical/Near-infrared Upper Limits and NICER X-Ray Analysis of SGR J1935+2154 for the Outburst in 2022. The Galactic magnetar SGR J1935+2154 has undergone another outburst since 2022 October 10. We present the results of searching for an optical/near-infrared (NIR) counterpart of SGR J1935+2154 before and during this outburst. No counterpart was detected at the magnetar's position in  r'  and  z'  bands, providing stringent upper limits of  r'≳28.65  and  z'≳26.27 . Using archival X-ray data from NICER, we investigated the properties of the bursts and the spectral evolution of persistent emission. The burst flux F showed a power-law distribution of N ∝ F ‑0.76±0.10 for flux ≳2.6 × 10‑9erg cm‑2 s‑1, while the temperature and radius followed a log-normal distribution with  kT=1.63‑0.50+0.73keV  and  Rbb=4.35‑1.35+1.95km , respectively. The persistent flux evolution experienced a quick decay and an enhancement ∼27 days after the Burst Alert Telescope trigger. Using the NIR and X-ray emission, together with the Gran Telescopio Canarias optical/NIR upper limits, we discussed the origin of the NIR emission from the magnetar based on the fallback disk model and magnetosphere model. We found that either model cannot be ruled out with currently available data. Further mid-infrared observations are needed to find out the mechanism for producing the NIR emission from SGR J1935+2154.

Keywords: Neutron stars, Soft gamma-ray repeaters, X-ray transient sources, Magnetars, X-ray bursts
"Halfway to Rayleigh" and Other Insights into the Rossby Wave Instability. The Rossby wave instability (RWI) is the fundamental nonaxisymmetric radial shear instability in disks. The RWI can facilitate disk accretion, set the shape of planetary gaps, and produce large vortices. It arises from density and/or temperature features, such as radial gaps, bumps, or steps. A general, sufficient condition to trigger the RWI is lacking, which we address by studying the linear RWI in a suite of simplified models, including incompressible and compressible shearing sheets and global, cylindrical disks. We focus on enthalpy amplitude and width as the fundamental properties of disk features with various shapes. We find analytic results for the RWI boundary and growth rates across a wide parameter space, in some cases with exact derivations and in others as a description of numerical results. Features wider than a scale height generally become unstable about halfway to Rayleigh instability, i.e., when the squared epicyclic frequency is about half the Keplerian value, reinforcing our previous finding. RWI growth rates approximately scale as enthalpy amplitude to the 1/3 power, with a weak dependence on width, across much of the parameter space. Global disk curvature affects wide planetary gaps, making the outer gap edge more susceptible to the RWI. Our simplified models are barotropic and height integrated, but the main results should carry over to more complex and realistic scenarios.

Keywords: Planet formation, Astrophysical fluid dynamics, Protoplanetary disks, Hydrodynamics
Medium Bands, Mega Science: A JWST/NIRCam Medium-band Imaging Survey of A2744. In this paper, we describe the "Medium Bands, Mega Science" JWST Cycle 2 survey (JWST-GO-4111) and demonstrate the power of these data to reveal both the spatially integrated and spatially resolved properties of galaxies from the local Universe to the era of cosmic dawn. Executed in 2023 November, MegaScience obtained ∼30 arcmin2 of deep multiband NIRCam imaging centered on the z ∼ 0.3 A2744 cluster, including 11 medium-band filters and the two shortest-wavelength broadband filters, F070W and F090W. Together, MegaScience and the UNCOVER Cycle 1 treasury program provide a complete set of deep (∼28–30 magAB) images in all NIRCam medium- and broadband filters. This unique data set allows us to precisely constrain photometric redshifts, map stellar populations and dust attenuation for large samples of distant galaxies, and examine the connection between galaxy structures and formation histories. MegaScience also includes ∼17 arcmin2 of NIRISS parallel imaging in two broadband and four medium-band filters from 0.9 to 4.8 μm, expanding the footprint where robust spectral energy distribution (SED) fitting is possible. We provide example SEDs and multiband cutouts at a variety of redshifts, and use a catalog of JWST spectroscopic redshifts to show that MegaScience improves both the scatter and catastrophic outlier rate of photometric redshifts by factors of 2–3. Additionally, we demonstrate the spatially resolved science enabled by MegaScience by presenting maps of the [O III] line emission and continuum emission in three spectroscopically confirmed z &gt; 6 galaxies. We show that line emission in reionization-era galaxies can be clumpy, extended, and spatially offset from continuum emission, implying that galaxy assembly histories are complex even at these early epochs. We publicly release fully reduced mosaics and photometric catalogs for both the NIRCam primary and NIRISS parallel fields (jwst-uncover.github.io/megascience).

Keywords: Galaxy formation, Galaxy structure, High-redshift galaxies, Galaxy evolution
The First Catalog of Candidate White Dwarf─Main-sequence Binaries in Open Star Clusters: A New Window into Common Envelope Evolution. Close binary systems are the progenitors to both Type Ia supernovae and the compact object mergers that can be detected via gravitational waves. To achieve a binary with a small radial separation, it is believed that the system likely undergoes common envelope (CE) evolution. Despite its importance, CE evolution may be one of the largest uncertainties in binary evolution due to a combination of computational challenges and a lack of observed benchmarks where both the post-CE and pre-CE conditions are known. Identifying post-CE systems in star clusters can partially circumvent this second issue by providing an independent age constraint on the system. For the first time, we conduct a systematic search for white dwarf and main-sequence binary systems in 299 Milky Way open star clusters. Coupling Gaia DR3 photometry and kinematics with multiband photometry from Pan-STARRS1 and the Two Micron All Sky Survey, we apply a machine learning-based approach and find 52 high-probability candidates in 38 open clusters. For a subset of our systems, we present follow-up spectroscopy from the Gemini and Lick Observatories and archival light curves from the Transiting Exoplanet Survey Satellite, Kepler/K2, and the Zwicky Transient Facility. Examples of M dwarfs with hot companions are spectroscopically observed, along with regular system variability. While the kinematics of our candidates are consistent with their host clusters, some systems have spatial positions offset relative to their hosts, potentially indicative of natal kicks. Ultimately, this catalog is a first step to obtaining a set of observational benchmarks to better link post-CE systems to their pre-CE progenitors.

Keywords: Binary stars, Multiple star evolution, Close binary stars, White dwarf stars, Open star clusters, Catalogs
Light Echoes of Protoplanetary Disks. Light echoes offer a means of studying protoplanetary disks, including their geometry and composition, even when they are not spatially resolved. We present a test of this approach applied specifically to optically thick, geometrically flared disks around active stars. Here we adopt stellar parameters of an active M dwarf to calculate light echoes for disks and rings with radii that would produce time delays consistent with TESS short cadence (about 2 minutes) time bins. Our results show successful fits to disk parameters, highlighting the potential effectiveness of this method in the search for protoplanetary disks.

Keywords: Protoplanetary disks, Flare stars
On the Formation of Super-Alfvénic Flows Downstream of Collisionless Shocks. Super-Alfvénic jets, with kinetic energy densities significantly exceeding that of the solar wind, are commonly generated downstream of Earth's bow shock under both high- and low-beta plasma conditions. In this study, we present theoretical evidence that these enhanced kinetic energy flows can be driven by firehose-unstable fluctuations and compressive heating within collisionless plasma environments. Using a fluid formalism that incorporates pressure anisotropy, we estimate that the downstream flow of a collisionless plasma shock can be accelerated by a factor of 2–4 following the compression and saturation of firehose instability. By analyzing quasi-parallel magnetosheath jets observed in situ by the Magnetospheric Multiscale (MMS) mission, we find that approximately 11% of plasma measurements within these jets exhibit firehose-unstable fluctuations. Our findings offer an explanation for the distinctive generation of fast downstream flows in both low (β &lt; 1) and high (β &gt; 1) beta plasmas, and provide new evidence that kinetic processes are crucial for accurately describing the formation and evolution of magnetosheath jets.

Keywords: Interplanetary turbulence, Interplanetary shocks, Planetary bow shocks
High Spectral Resolution Observations of Propynal (HCCCHO) toward TMC-1 from the GOTHAM Large Program on the GBT. We used new high spectral resolution observations of propynal (HCCCHO) toward TMC-1 and in the laboratory to update the spectral line catalog available for transitions of HCCCHO—specifically at frequencies lower than 30 GHz, which were previously discrepant in a publicly available catalog. The observed astronomical frequencies provided a high enough spectral resolution that, when combined with high-resolution (∼2 kHz) measurements taken in the laboratory, a new, consistent fit to both the laboratory and astronomical data was achieved. Now with a nearly exact (&lt;1 kHz) frequency match to the J = 2–1 and 3–2 transitions in the astronomical data, using a Markov Chain Monte Carlo analysis, a best fit to the total HCCCHO column density of  7.28‑1.94+4.08×1012  cm‑2 was found with a surprisingly low excitation temperature of just over 3 K. This column density is around a factor of 5 times larger than reported in previous studies. Finally, this work highlights that care is needed when using publicly available spectral catalogs to characterize astronomical spectra. The availability of these catalogs is essential to the success of modern astronomical facilities and will only become more important as the next generation of facilities comes online.

Keywords: Astrochemistry
Systematic Study of the Inner Structure of Molecular Tori in Nearby U/LIRGs Using Velocity Decomposition of CO Rovibrational Absorption Lines. Determining the inner structure of the molecular torus around an active galactic nucleus is essential for understanding its formation mechanism. However, spatially resolving the torus is difficult because of its small size. To probe the clump conditions in the torus, we therefore perform the systematic velocity-decomposition analyses of the gaseous 12CO rovibrational absorption lines (v = 0 → 1, ΔJ = ±1) at λ ∼ 4.67 μm observed toward four (ultra)luminous infrared galaxies using the high-resolution (R ∼ 5000–10,000) spectroscopy from the Subaru Telescope. We find that each transition has two to five distinct velocity components with different line-of-sight (LOS) velocities (V LOS ∼ ‑240 to +100 km s‑1) and dispersions (σ  V  ∼ 15–190 km s‑1), i.e., the components (a), (b), ⋯, beginning with the broadest one in each target, indicating that the tori have clumpy structures. By assuming a hydrostatic disk ( σV∝Rrot‑0.5 ), we find that the tori has dynamic inner structures, with the innermost component (a) outflowing with velocity ∣V LOS∣ ∼ 160–240 km s‑1, and the outer components (b) and (c) outflowing more slowly or infalling with ∣V LOS∣ ≲ 100 km s‑1. In addition, we find that the innermost component (a) can be attributed to collisionally excited hot (≳530 K) and dense ( log(nH2/cm‑3)≳6 ) clumps, based on the level populations. Conversely, the outer component (b) can be attributed to cold (∼30–140 K) clumps radiatively excited by a far-infrared-to-submillimeter background with a brightness temperature higher than ∼20–400 K. These observational results demonstrate the clumpy and dynamic structure of tori in the presence of background radiation. *This research is based on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. We are honored by and grateful for the opportunity to observe the universe from Maunakea, which has cultural, historical, and natural significance in Hawaii.

Keywords: High resolution spectroscopy, Molecular gas, Infrared astronomy, Active galactic nuclei, Ultraluminous infrared galaxies
A New IW And-type Star: Karachurin 12 with Tilted Disks and Diverse Cycles. The IW And-type phenomenon in cataclysmic variables presents a significant challenge to the accretion disk instability model. Using photometric data from the All-Sky Automated Survey for Supernovae, the Zwicky Transient Facility, and the Transiting Exoplanet Survey Satellite, we identify Karachurin 12 as a new noneclipsing IW And-type object with a cycle period of 35.69(3) days. We also report for the first time that Karachurin 12 is a negative superhump (NSH) system featuring precessing tilted disks, with precession, orbital, and NSH periods of 4.9588(2) days, 0.3168895(13) days, and 0.2979861(8) days, respectively. Our analysis, using dips as the index and NSHs as the probe, reveals diverse cycle patterns in Karachurin 12, with NSH amplitude varying throughout the cycle. These findings offer new insights for studying tilted disks and the IW And-type phenomenon. The mass-transfer burst model has difficulty explaining the observed variations in NSH amplitude, especially given the uncertainty surrounding the origin of the mass-transfer burst. Meanwhile, the tilted thermally unstable disk model indicates a possible connection to the IW And-type phenomenon, but it also struggles to account for the detailed variations in Karachurin 12. Therefore, a wider range of factors must be considered to fully understand the complex changes in Karachurin 12.

Keywords: Dwarf novae, Cataclysmic variable stars, Semi-detached binary stars