Sazuna/UAT_keywords huggingface dataset:
The Role of Filamentary Structures in the Formation of Two Dense Cores, L1544 and L694-2. We present mapping results of two prestellar cores, L1544 and L694-2, embedded in filamentary clouds in C18O (3-2), 13CO (3-2), 12CO (3-2), HCO+ (4-3), and H13CO+ (4-3) lines with the James Clerk Maxwell Telescope to examine the role of the filamentary structures in the formation of dense cores in the clouds, with new distance estimates for L1544 ( ${175}_{-3}^{+4}$ pc) and L694-2 ( ${203}_{-7}^{+6}$ pc). From these observations, we found that the nonthermal velocity dispersion of two prestellar cores and their surrounding clouds is smaller than or comparable to the sound speed. This may indicate that the turbulence has already been dissipated for both filaments and cores during their formation time. We also found a λ/4 shift between the periodic oscillations in the velocity and the column density distributions, implying the possible presence of gravitational core-forming flow motion along the axis of the filament. The mass accretion rates due to these flow motions are estimated to be 2-3 M ⊙ Myr-1, being comparable to that for Serpens cloud but much smaller than those for the Hub filaments, cluster, or high-mass forming filaments by 1 or 2 orders of magnitude. From this study, we suggest that the filaments in our targets might be formed from the shock compression of colliding clouds, and then the cores are formed by gravitational fragmentation of the filaments to evolve to the prestellar stage. We conclude that the filamentary structures in the clouds play an important role in the entire process of formation of dense cores and their evolution.

Keywords: Interstellar line emission, Interstellar filaments, Star forming regions, Molecular clouds, Star formation, Dust continuum emission
Formation of c-C<SUB>6</SUB>H<SUB>5</SUB>CN Ice Using the SPACE TIGER Experimental Setup. Benzonitrile (c-C6H5CN) has been recently detected in cold and dense regions of the interstellar medium, where it has been used as a signpost of a rich aromatic organic chemistry that might lead to the production of polycyclic aromatic hydrocarbons. One possible origin of this benzonitrile is interstellar ice chemistry involving benzene (c-C6H6) and nitrile molecules (organic molecules containing the -C≡N group). We have addressed the plausibility of this c-C6H5CN formation pathway through laboratory experiments using our new setup SPACE TIGER. The SPACE TIGER experimental setup is designed to explore the physics and chemistry of interstellar ice mantles using laser-based ice processing and product detection methods. We have found that c-C6H5CN is formed upon irradiation of c-C6H6:CH3CN binary ice mixtures with 2 keV electrons and Lyα photons at low temperatures (4-10 K). Formation of c-C6H5CN was also observed when c-C6H6 and CH3CN were embedded in a CO ice matrix, but it was efficiently quenched in a H2O ice matrix. The results presented in this work imply that interstellar ice chemistry involving benzene and nitrile molecules could contribute to the formation of the observed benzonitrile only if these species are present on top of the ice mantles or embedded in the CO-rich ice layer, instead of being mixed into the H2O-rich ice layer.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Laboratory astrophysics, Astrochemistry, Dense interstellar clouds, Interstellar medium
X-Ray Sources in the SSA22 Chandra Field. The Hawaii Survey Field SSA22 is the fourth deepest Chandra X-ray field. To allow for the fullest exploration of this field, we present new optical spectroscopy from Keck/DEIMOS and Keck/LRIS, which, in combination with the literature, brings the spectroscopic completeness of the 2-8 keV sample to 62%. We also make optical spectral classifications and estimate photometric redshifts for the sources without spectroscopic redshifts. We then determine hard X-ray luminosity functions (XLFs) for the full sample of active galactic nuclei (AGNs), as well as for the broad-line AGNs (BLAGNs) and the non-BLAGNs separately. Our XLF for the full sample is in good agreement with the literature, showing relatively strong evolution over the redshift range 0.25 ≤ z &lt; 4. The XLFs for the BLAGNs and the non-BLAGNs imply distinct evolution with redshift, with BLAGNs becoming increasingly dominant at higher redshifts and X-ray luminosities.

Keywords: Quasars, X-ray quasars, X-ray active galactic nuclei, Active galactic nuclei, Galaxy evolution
Near-infrared Extragalactic Background Light Fluctuations on Nonlinear Scales. Several fluctuation studies on the near-infrared extragalactic background light (EBL) find an excess power at tens of arcminute scales (ℓ ~ 103). Emission from the intra-halo light (IHL) has been proposed as a possible explanation for the excess signal. In this work, we investigate the emission from the integrated galaxy light (IGL) and IHL in the power spectrum of EBL fluctuations using the simulated galaxy catalog MICECAT. We find that at ℓ ~ 103, the one-halo clustering from satellite galaxies has comparable power to the two-halo term in the IGL power spectrum. In some previous EBL analyses, the IGL model assumed a small one-halo clustering signal, which may result in overestimating the IHL contribution to the EBL. We also investigate the dependence of the IGL+IHL power spectrum on the IHL distribution as a function of redshift and halo mass, and the spatial profile within the halo. Our forecast suggests that the upcoming SPHEREx deep field survey can distinguish different IHL models considered in this work with high significance. Finally, we quantify the bias in the power spectrum from the correlation of the mask and the signal, which has not been accounted for in previous analyses.

Keywords: Large-scale structure of the universe, Diffuse radiation, Galaxy evolution, Cosmic background radiation, Near infrared astronomy
Evidence for Large-scale Excesses Associated with Low H I Column Densities in the Sky. I. Dust Excess. Where dust and gas are uniformly mixed, atomic hydrogen can be traced through the detection of far-infrared (FIR) or UV emission of dust. We considered, for the origin of discrepancies observed between various direct and indirect tracers of gas outside the Galactic plane, possible corrections to the zero levels of the Planck High Frequency Instrument (HFI) detectors. We set the zero levels of the Planck-HFI skymaps as well as the 100 μm map from COBE/DIRBE and IRAS from the correlation between FIR emission and atomic hydrogen column density excluding regions of lowest gas column density. A modified blackbody model fit to those new zero-subtracted maps led to significantly different maps of the opacity spectral index β and temperature T and an overall increase in the optical depth at 353 GHz τ 353 of 7.1 × 10-7 compared to the data release 2 Planck map. When comparing τ 353 and the H I column density, we observed a uniform spatial distribution of the opacity outside regions with dark neutral gas and CO except in various large-scale regions of low N H I  that represent 25% of the sky. In those regions, we observed an average dust column density 45% higher than predictions based on N H I  with a maximum of 250% toward the Lockman Hole region. From the average opacity σ  e353 = (8.9 ± 0.1) × 10-27 cm2, we deduced a dust-to-gas mass ratio of 0.53 × 10-2. We did not see evidence of dust associated with a Reynolds layer of ionized hydrogen. We measured a far-ultraviolet isotropic intensity of 137 ± 15 photons s-1 cm-2 sr-1 Å-1 in agreement with extragalactic flux predictions and a near-ultraviolet isotropic intensity of 378 ± 45 photons s-1 cm-2 sr-1 Å-1 corresponding to twice the predicted flux.

Keywords: Interstellar thermal emission, Ultraviolet surveys, Far infrared astronomy, Dust continuum emission, Interstellar medium
Turbulent Transport of Dust Particles in Protostellar Disks: The Effect of Upstream Diffusion. We study the long-term radial transport of micron to millimeter-size grains in protostellar disks (PSDs) based on diffusion and viscosity coefficients measured from 3D global stratified-disk simulations with a Lagrangian hydrodynamic method. While gas drag tends to transport dust species radially inwards, stochastic diffusion can spread a considerable fraction of dust radially outwards (upstream) depending on the nature of turbulence. In gravitationally unstable disks, we measure a high radial diffusion coefficient D r ~ H 2Ω with little dependence on altitude. This leads to strong and vertically homogeneous upstream diffusion in early PSDs. In the solar nebula, the robust upstream diffusion of micron to millimeter-size grains not only efficiently transports highly refractory micron-size grains (such as those identified in the samples of comet 81P/Wild 2) from their regions of formation inside the snow line out to the Kuiper Belt, but can also spread millimeter-size calcium-aluminum-rich inclusions formed close to the Sun to distances where they can be assimilated into chondritic meteorites. In disks dominated by magnetorotational instability, the upstream diffusion effect is generally milder, with a separating feature due to diffusion being stronger in the surface layer than in the midplane. This variation becomes much more pronounced if we additionally consider a quiescent midplane with lower turbulence and larger characteristic dust size due to nonideal MHD effects. This segregation scenario helps to account for the dichotomy of the spatial distribution of two dust populations as observed in scattered light and Atacama Large Millimeter/submillimeter Array images.

Keywords: Accretion, Comet origins, Protoplanetary disks
The Volumetric Star Formation Law in the Almost Edge-on Galaxy NGC 4302 Revealed by the Atacama Large Millimeter/submillimeter Array. We observe the almost edge-on (i ~ 90°) galaxy NGC 4302 using the Atacama Large Millimeter/submillimeter Array (CO) and Very Large Array (H I) to measure the gas disk thickness for investigating the volumetric star formation law (SFL). The recent star formation rate (SFR) is estimated based on a linear combination of IR 24 μm and Hα emissions. The measured scale heights of CO and H I increase significantly with radius. Using the scale heights along with the vertically integrated surface densities, we derive the midplane volume densities of the gas (ρ H I, ${\rho }_{{{\rm{H}}}_{2}}$ , and ρ gas = ρ H I+ ${\rho }_{{{\rm{H}}}_{2}}$ ) and the SFR (ρ SFR) and compare the volumetric SFL (ρ SFR ∝ ρ gas n) with the vertically integrated SFL (ΣSFR ∝ Σgas N). We find tight power-law correlations between the SFR and the gas (H I, H2, and the total gas) in both volume and surface densities. The power-law indices of the total gas and H I for the volumetric SFL are noticeably smaller than the indices for the vertically integrated SFL while the H2 indices for both cases are similar to each other. In terms of the star formation efficiency (SFE), we find that the molecular and total gas SFEs are roughly constant, while the atomic SFE is clearly decreasing with radius in both cases.

Keywords: Galaxy structure, Galaxy dynamics, Bipolar sunspot groups, Galaxy kinematics, Interstellar medium, Barred spiral galaxies, Radio astronomy
A Data-constrained Magnetohydrodynamic Simulation of the X1.0 Solar Flare of 2021 October 28. The solar active region NOAA 12887 produced a strong X1.0 flare on 2021 October 28, which exhibits X-shaped flare ribbons and a circle-shaped erupting filament. To understand the eruption process with these characteristics, we conducted a data-constrained magnetohydrodynamics simulation using a nonlinear force-free field of the active region about an hour before the flare as the initial condition. Our simulation reproduces the filament eruption observed in the Hα images of GONG and the 304 Å images of SDO/AIA, and suggests that two mechanisms can possibly contribute to the magnetic eruption. One is the torus instability of the preexisting magnetic flux rope (MFR) and the other is upward pushing by magnetic loops newly formed below the MFR via continuous magnetic reconnection between two sheared magnetic arcades. The presence of this reconnection is evidenced by the SDO/AIA observations of the 1600 Å brightening in the footpoints of the sheared arcades at the flare onset. To clarify which process is more essential for the eruption, we performed an experimental simulation in which the reconnection between the sheared field lines is suppressed. In this case too, the MFR could erupt, but at a much reduced rising speed. We interpret this result as indicating that the eruption is not only driven by the torus instability, but additionally accelerated by newly formed and rising magnetic loops under continuous reconnection.

Keywords: Solar physics, Solar flares, Solar magnetic fields, Magnetohydrodynamics
Spatial Distribution and Low-frequency Disturbance Modulation of Magnetosheath Ion Polytropic Index. We, using the Cluster data from 2001 to 2010, studied spatial distribution of the ion polytropic index in the magnetosheath, and the modulation of polytropic process by the low-frequency disturbances (4-18 mHz). The total of 30,3283 samples is divided into two sorts: quasi-perpendicular and quasi-parallel propagating ones. The median polytropic index increases with spreads narrowing from the bow shock to the magnetopause. The median polytropic indices are basically between isothermal and adiabatic in the inner magnetosheath, and between isothermal and isobaric in the outer magnetosheath. The spatial distributions of the correlation coefficient (CC) between the perturbed ion number density and the parallel magnetic field CC (δn, δB ∥) have a good correlation with those of polytropic index. The quasi-perpendicular disturbances are mostly mirror-like modes (D  r  ≪ 1) except for some slow-mode disturbances (D  r  ≥ 1) in the regions near the Sun-Earth line and the inner magnetosheath. The polytropic indices in the inner and middle magnetosheath modulated by mirror-like-mode disturbances are between 0.9 and 1.3. The quasi-parallel propagating low-frequency disturbances are predominantly slow modes in the inner and middle magnetosheath, and Alfvén modes in the outer magnetosheath. For the samples with quasi-parallel propagating disturbances, the polytropic processes are basically between isothermal and isobaric except near the magnetopause. The good correlation between the spatial distributions of polytropic index and low-frequency disturbances indicates that the distribution of the polytropic index in the magnetosheath is modulated by low-frequency disturbances.

Keywords: Solar physics, Solar wind, Plasma physics
Multiple Transitions in Vacuum Dark Energy and H <SUB>0</SUB> Tension. We study the effects of multiple transitions in the vacuum dark energy density on the H 0 tension problem. We consider a phenomenological model in which the vacuum energy density undergoes multiple transitions in the early as well as the late universe and compare the model's predictions using the three sets of data from the cosmic microwave background, baryonic acoustic oscillations, and supernovae. The transient dark energy can be either positive (dS-like) or negative (AdS-like). We conclude that a transient late-time AdS-type vacuum energy typically yields the higher value of H 0, which can alleviate the H 0 tension. In addition, to obtain a value of H 0 comparable to the value obtained from the local cosmological measurements the spectral index n  s  moves toward its Harrison-Zel'dovich scale-invariant value.

Keywords: Hubble constant, Observational cosmology, Dark energy
TPHO: A Time-dependent Photoionization Model for AGN Outflows. Outflows in active galactic nuclei (AGN) are considered a promising candidate for driving AGN feedback at large scales. However, without information on the density of these outflows we cannot determine how much kinetic power they are imparting to the surrounding medium. Monitoring the response of the ionization state of the absorbing outflows to changes in the ionizing continuum provides the recombination timescale of the outflow, which is a function of the electron density. We have developed a new self-consistent time-dependent photoionization model, tpho, enabling the measurement of the plasma density through time-resolved X-ray spectroscopy. The algorithm solves the full time-dependent energy and ionization balance equations in a self-consistent fashion for all the ionic species. The model can therefore reproduce the time-dependent absorption spectrum of ionized outflows responding to changes in the ionizing radiation of the AGN. We find that when the ionized gas is in a nonequilibrium state its transmitted spectra are not accurately reproduced by standard photoionization models. Our simulations with the current X-ray grating observations show that the spectral features identified as multicomponent warm absorbers, might in fact be features of a time-changing warm absorber and not distinctive components. The tpho model facilitates accurate photoionization modeling in the presence of a variable ionizing source, thus providing constraints on the density and in turn the location of the AGN outflows. Ascertaining these two parameters will provide important insight into the role and impact of ionized outflows in AGN feedback. *Released on ...

Keywords: Photoionization, X-ray active galactic nuclei, Plasma astrophysics
Variability from Thermoresistive Instability in the Atmospheres of Hot Jupiters. The atmosphere of a hot Jupiter may be subject to a thermoresistive instability, in which the increasing electrical conductivity with temperature leads to runaway ohmic heating. We introduce a simplified model of the local dynamics in the equatorial region of a hot Jupiter that incorporates the back reaction on the atmospheric flow as the increasing electrical conductivity leads to flux freezing, which in turn quenches the flow and therefore the ohmic heating. We demonstrate a new time-dependent solution that emerges for a temperature-dependent electrical conductivity (whereas a temperature-independent conductivity always evolves to a steady state). The periodic cycle consists of bursts of Alfvén oscillations separated by quiescent intervals, with the magnetic Reynolds number alternating between values smaller than and larger than unity, maintaining the oscillation. We investigate the regions of pressure and temperature in which the instability operates. For the typical equatorial accelerations seen in atmospheric models, we find instability at pressures ~0.1-1 bar and temperatures ≈1300-1800 K for magnetic fields ~10 G. Unlike previous studies based on a constant wind velocity, we find that the instability is stronger for weaker magnetic fields. Our results add support to the idea that variability should be a feature of magnetized hot Jupiter atmospheres, particularly at intermediate temperatures. The temperature dependence of the electrical conductivity is an important ingredient that should be included in MHD models of hot Jupiter atmospheric dynamics.

Keywords: Exoplanet atmospheric dynamics, Magnetohydrodynamics, Exoplanet atmospheric variability, Astrophysical fluid dynamics
The Disk Population in a Distant Massive Protocluster. The unprecedented angular resolution and sensitivity of the Atacama Large Millimeter/submillimeter Array make it possible to unveil disk populations in distant (&gt;2 kpc), embedded young cluster environments. We have conducted an observation toward the central region of the massive protocluster G286.21+0.16 at 1.3 mm. With a spatial resolution of 23 mas and a sensitivity of 15 μJy beam-1, we detect a total of 38 protostellar disks. These disks have dust masses ranging from about 53 to 1825 M ⊕, assuming a dust temperature of 20 K. This sample is not closely associated with previously identified dense cores, as would be expected for disks around Class 0 protostars. Thus, we expect our sample, being flux-limited, to be mainly composed of Class I/flat-spectrum source disks, since these are typically more massive than Class II disks. Furthermore, we find that the distributions of disk masses and radii are statistically indistinguishable from those of the Class I/flat-spectrum objects in the Orion molecular cloud, indicating that similar processes are operating in G286.21+0.16 to regulate disk formation and evolution. The cluster center appears to host a massive protostellar system composed of three sources within 1200 au, including a potential binary with 600 au projected separation. Relative to this center, there is no evidence for widespread mass segregation in the disk population. We do find a tentative trend of increasing disk radius versus distance from the cluster center, which may point to the influence of dynamical interactions being stronger in the central regions.

Keywords: Protostars, Young stellar objects, Protoclusters, Circumstellar disks
Dynamic Evolution of Magnetic Flux Ropes in Active Region 11429. I. EUV Observations. Studying the formation and dynamic evolution of the magnetic flux rope (MFR) is key to understanding the physics of most solar eruptions. In the present study, we investigate the dynamic evolution of four MFRs, which involve in a major eruption. The MFR1, which represents as filament (F1), first appears about 31 hr before the major eruption. The MFR2 appears as a hot-channel with a small filament (F2) in its east part. The hot-channel becomes intermittently visible about 2 hr before the major eruption. The MFR3 is formed by the reconnection between MFR1 and MFR2. The annular components of MFR3 along the MFR2 part appear as a hollow helical structure from the background with the temperature of several MK after the reconnection. Coronal material then flows along the hollow structure from MFR1 part to MFR2 part to form a new filament (F3), which is hosted by MFR3 and acts as the axial component of MFR3 in the following evolution. The MFR4 appears during MFR3's eruption phase as conjugated extreme ultraviolet (EUV) brightenings. Both brightenings extend outward into irregular ribbons with conjugate EUV dimmings inside. Meanwhile, an erupted hot-channel, which roots in the conjugated brightening, is identified. The morphology of the MFRs are also profiled by four associated flare ribbon pairs. The on-disk observations shed light on our understanding of the topology of the MFRs and their formation and eruption. Further work should lay emphasis on the magnetic environment for the MFR formation and evolution.

Keywords: Solar filaments
Searching for Compact Objects in Binaries with Gaia DR3. We search for compact objects in binaries based on Gaia DR3. A sample of 10 targets is derived under the following conditions: the radial velocity variable, low temperature (T eff &lt; 6000 K), high mass function (f(M 2) &gt; 1M ⊙), and ellipsoidal-like light curves. Two targets have LAMOST spectroscopic observations, one of which is a double-lined spectroscopic binary. The observational data of seven targets are not self-consistent, since their photometric periods are even shorter than the theoretical minimum orbital periods calculated by the stellar parameters from Gaia DR3. After excluding these seven inconsistent targets and another target contaminated by a near-bright star, the remaining two targets may contain compact objects worth follow-up observations. This work may serve as an example to demonstrate the feasibility of searching for compact objects in the massive Gaia data.

Keywords: Close binary stars, Light curves, Compact binary stars, Spectroscopic binary stars, Radial velocity