Sazuna/UAT_keywords huggingface dataset:
Searching for Low-redshift Hot Dust-obscured Galaxies. Hot dust-obscured galaxies (Hot DOGs), discovered by the "W1W2 dropout" selection at high redshifts (z ∼ 2–4), are a rare population of hyperluminous obscured quasars. Their number density is comparable to similarly luminous type 1 quasars in the same redshift range, potentially representing a short, yet critical stage in galaxy evolution. The evolution in their number density toward low redshift, however, remains unclear as their selection function is heavily biased against objects at z ≲ 2. We combine data from the Wide-field Infrared Survey Explorer and Herschel archives to search for Hot DOGs at z &lt; 0.5 based on their unique spectral energy distributions. We find 68 candidates, and spectroscopic observations confirm that 3 of them are at z &lt; 0.5. For those three, we find their black hole accretion is close to the Eddington limit, with lower bolometric luminosities and black hole masses than those of higher-z Hot DOGs. Compared to high-z systems, these low-z systems are closer to the local relation between host galaxy stellar mass and black hole mass but still lie above it, and we discuss several possible scenarios for it. Finally, we also find the surface number density of z &lt; 0.5 Hot DOGs is 2.4 × 10‑3 deg‑2, about an order of magnitude lower than high-z Hot DOGs but comparable to hyperluminous unobscured quasars in the same redshift range. These results further support the idea that Hot DOGs may be a transitional phase of galaxy evolution.

Keywords: Active galaxies, Infrared galaxies, Galaxy evolution
Spatially Resolved Galactic Winds at Cosmic Noon: Outflow Kinematics and Mass Loading in a Lensed Star-forming Galaxy at z = 1.87. We study the spatially resolved outflow properties of CSWA13, an intermediate-mass (M* = 109 M⊙), gravitationally lensed star-forming galaxy at z = 1.87. We use Keck/KCWI to map outflows in multiple rest-frame UV interstellar medium (ISM) absorption lines, along with fluorescent Si II* emission, and nebular emission from C III] tracing the local systemic velocity. The spatial structure of the outflow velocity mirrors that of the nebular kinematics, which we interpret to be a signature of a young galactic wind that is pressurizing the ISM of the galaxy but is yet to burst out. From the radial extent of Si II* emission, we estimate that the outflow is largely encapsulated within 3.5 kpc. We explore the geometry (e.g., patchiness) of the outflow by measuring the covering fraction at different velocities, finding that the maximum covering fraction is at velocities v ≃ ‑150 km s‑1. Using the outflow velocity (vout), radius (R), column density (N), and solid angle (Ω) based on the covering fraction, we measure the mass-loss rate   and mass loading factor   for the low-ionization outflowing gas in this galaxy. These values are relatively large and the bulk of the outflowing gas is moving with speeds less than the escape velocity of the galaxy halo, suggesting that the majority of the outflowing mass will remain in the circumgalactic medium and/or recycle back into the galaxy. The results support a picture of high outflow rates transporting mass and metals into the inner circumgalactic medium, providing the gas reservoir for future star formation.

Keywords: Interstellar absorption, Galaxy winds, Galaxy evolution, Circumgalactic medium
A Planet Candidate Orbiting near the Hot Jupiter TOI-2818 b Inferred through Transit Timing. TOI-2818 b is a hot Jupiter orbiting a slightly evolved G-type star on a 4.04 day orbit that shows transit timing variations (TTVs) suggestive of a decreasing orbital period. In the most recent year of TESS observations, transits were observed ∼8 minutes earlier than expected for a constant period. The implied orbital decay rate is 1.35 ± 0.25 s yr−1, too fast to be explained by tidal dissipation, even considering the evolved nature of the host star. Radial velocity (RV) monitoring and astrometric data make the possibility of perturbations from a long-period companion unlikely; further Doppler spectroscopy observations can efficiently confirm or rule out such a companion. Apsidal precession due to the tidal distortion of the planet is also physically implausible. The most plausible explanation for the TTVs appears to be gravitational perturbations from a hitherto undetected planet with mass ≲10 M⊕ that is in (or near) a mean-motion resonance with the hot Jupiter. Such a planet could be responsible for the observed TTVs while avoiding detection with the available RV and transit data.

Keywords: Hot Jupiters, Exoplanets, Exoplanet tides, Transit timing variation method, Radial velocity, Transit photometry
Source Materials and Heating of Alfvénic Slow and Hot Solar Wind Revealed by Heavy Ions. This work quantitatively studies the differences of heavy ions among non-Alfvénic slow wind (N-ASSW), classical fast wind (FSW), and Alfvénic slow and hot wind (ASSW and AHSW) by effect size and Kolmogorov–Smirnov statistic. Statistics of ACE measurements in solar cycle 23 show that He/O and Fe/O in ASSW and AHSW are significantly similar to those in N-ASSW, but are distinct from FSW. The mean Fe16+/Fe13+ in ASSW (AHSW) is in the middle of the two mean values of FSW and N-ASSW. However, Fe16+/Fe13+ in the three categories of solar wind are similarly low during solar minimum. Charges of C and O ions in ASSW and AHSW are significantly different from those in FSW during solar minimum, but have obvious overlaps to those in FSW during solar maximum. Besides, the speed ratio of He2+, C5+, O6+, and Fe10+ against protons is studied, and that of O6+ in ASSW and AHSW is most like that in FSW. AHSW has two peaks of proton specific entropy showing negative and positive relations to electron temperature. The results support that ASSW, AHSW, and N-ASSW experience the same fractionation in the chromosphere. The heating in ASSW (AHSW) differs from N-ASSW between the freeze-in heights of O and Fe during solar maximum, possibly caused by interchange reconnection. The preferential acceleration of heavy ions may be proportional to the gyroradius scale. Dissipation of Alfvén waves to electrons may happen in AHSW.

Keywords: Solar coronal holes, Solar coronal heating, Solar wind, Alfven waves
Why Artificial Disruption Is Not a Concern for Current Cosmological Simulations. Recent studies suggest that cold dark matter subhalos are hard to disrupt and almost all cases of subhalo disruption observed in numerical simulations are due to numerical effects. However, these findings primarily relied on idealized numerical experiments, which do not fully capture the realistic conditions of subhalo evolution within a hierarchical cosmological context. Based on the Aquarius simulations, we identify clear segregation in the population of surviving and disrupted subhalos, which corresponds to two distinct acquisition channels of subhalos. We find that all of the first-order subhalos accreted after redshift 2 survive to the present time without suffering from artificial disruption. On the other hand, most of the disrupted subhalos are sub-subhalos accreted at high redshift. Unlike the first-order subhalos, sub-subhalos experience preprocessing and many of them are accreted through major mergers at high redshift, resulting in very high mass loss rates. We confirm these high mass loss rates are physical through both numerical experiments and semianalytical modeling, thus supporting a physical origin for their rapid disappearance in the simulation. Even though we cannot verify whether these subhalos have fully disrupted or not, their extreme mass loss rates dictate that they can at most contribute a negligible fraction to the very low mass end of the subhalo mass function. We thus conclude that current state-of-the-art cosmological simulations have reliably resolved the subhalo population.

Keywords: Galaxy dark matter halos, Dark matter
Expansion-induced Three-part Morphology of the 2021 December 4 Coronal Mass Ejection. The typical structure of a coronal mass ejection (CME) was identified as a three-part morphology, which includes a bright front, a dark cavity, and a bright core, with the cavity and the core generally regarded as flux rope and eruptive prominence. However, there are three-part CMEs that are not associated with prominences. In this work, we conduct a high-resolution simulation of the 2021 December 4 CME mimicked with a spheromak flux rope to investigate the formation of the three-part morphology in the solar corona. The CME, with no signatures of prominence at the beginning, evolves into a high–low–high-density structure, which appears in a coronagraph image as a bright front immediately followed by a dark cavity with a bright core behind. The moving and expanding spheromak flux rope sweeps up the solar wind plasma and meanwhile, the plasma at its utmost edge is compressed, which produces the high-density front overlying the flux rope. It is also found that the expansion of the flux rope is uneven, with strong expansion at its outlying area and weak expansion at its central and rear parts. The differential expansion rates lead to the distinct rarefaction rates of the plasma, which results in the formation of the low-density cavity and the high-density core within the flux rope. Our three-dimensional study for the first time demonstrates that the evolution of the flux rope can self-consistently generate the three-part density structure, which improves the understanding of CME's morphologies in coronagraph images.

Keywords: Magnetohydrodynamics, Solar wind, Solar coronal mass ejections
Building on the Archives: Connecting the CN/CO Intensity Ratio with Global Galaxy Properties in Nearby U/LIRGs. We use the CN/CO intensity ratio to obtain the dense gas fraction, fdense, for a sample of 16 ultraluminous and luminous infrared (IR) galaxies and compare fdense with a suite of global galaxy properties. We find a significant correlation between fdense and star formation rate calculated using both IR luminosities and radio continuum, although there is significant scatter in each relation. We find no trend between global or peak fdense and merger stage. We find no correlation between global fdense and X-ray luminosity; however, the correlation becomes significant when we measure fdense at the location of peak X-ray emission. Our interpretation is that the dense gas is co-localized with strong X-ray emission from active galactic nuclei or strong central star formation.

Keywords: AGN host galaxies, Starburst galaxies, Molecular gas, Active galaxies, Interacting galaxies, Galaxy nuclei, Seyfert galaxies, Star formation, Active galactic nuclei, Interstellar medium, Ultraluminous infrared galaxies, Luminous infrared galaxies
X-Ray Emission Properties of a Compact Symmetric Object Sample. We present a comprehensive analysis of the X-ray observations obtained from XMM-Newton and Chandra for a sample of bona-fide Compact Symmetric Objects (CSOs) to investigate their X-ray emission properties. Ultimately, we obtain 32 effective X-ray observational spectra from 17 CSOs. Most spectra can be well described by an absorbed single power-law model, with the exception of six spectra requiring an additional component in the soft X-ray band and two spectra exhibiting an iron emission line component. The data analysis results unveil the diverse characteristics of X-ray emission from CSOs. The sample covers X-ray luminosity ranging within 1040‑1045 erg s‑1, intrinsic absorbing column density ( ) ranging within 1020‑1023 cm‑2, and photon spectral index (ΓX) ranging within 0.75–3.0. None of the CSOs in our sample have   &gt; 1023 cm‑2, indicating that the X-ray emission in these CSOs is not highly obscured. The distribution of ΓX for these CSOs closely resembles that observed in a sample of radio-loud quasars and low-excitation radio galaxies (RGs). In the radio–X-ray luminosity panel, these CSOs exhibit a distribution more akin to FR I RGs than FR II RGs, characterized by higher luminosities. The positive correlation between ΓX and the Eddington ratio, which has been noted in radio-quiet active galactic nuclei, is not observed in these CSOs. These findings suggest that although the contribution of the disk-corona system cannot be completely ruled out, jet/lobe radiation likely plays a dominant role in the X-ray emission of these CSOs.

Keywords: Non-thermal radiation sources, X-ray active galactic nuclei, Active galactic nuclei, Relativistic jets
Unimolecular Chemical Kinetics in the Interstellar Environment: Competition of Infrared Radiation and Collision Activation Mechanisms. Unimolecular gas phase chemical reactions could be activated by both infrared (IR) radiation and intermolecular collision in the interstellar environment. Understanding the interplay and competition between the radiation and collision activation mechanisms is crucial for assessing accurate reaction rate constants with an appropriate model. In this work, guided by an extended version of the Lindemann theory, we show that the relative importance of the two mechanisms can be measured by a dimensionless number PR that is the ratio of the collision frequency to the radiation absorption rate of the molecule. The reaction kinetics is dominated by collision activation or radiation activation depending on whether PR is larger or smaller than a reference value PR*, which is determined to be PR* ≈ 10 based on magnitudes of molecular properties, and is verified by detailed calculations of a number of typical interstellar unimolecular reactions. The determination of the PR number requires only information on the environment and molecular properties rather than detailed simulations of chemical reactions; thus, the PR number can serve as an indicator for a priori evaluations before detailed calculations. This method of evaluating the relative importance of the two mechanisms is checked against master equation calculations of two interstellar reactions, the dissociation reaction of silicic acid around an asymptotic giant branch star and the methyl radical association in Titan's atmosphere, and the validity is verified. The method can be used in the future to help determine the appropriate and effective modeling approach for chemical reactions in astrophysical environments.

Keywords: Cosmochemistry, Astrochemistry
A Quasar-anchored Protocluster at z = 6.6 in the ASPIRE Survey. I. Properties of [O III] Emitters in a 10 Mpc Overdensity Structure. A SPectroscopic survey of bIased halos in the Reionization Era is a quasar legacy survey primarily using JWST to target a sample of 25 z &gt; 6 quasars with NIRCam slitless spectroscopy and imaging. The first study in this series found evidence of a strong overdensity of galaxies around J0305‑3150, a luminous quasar at z = 6.61, within a single NIRCam pointing obtained in JWST Cycle 1. Here we present the first results of a JWST Cycle 2 mosaic that covers 35 arcmin2 with NIRCam imaging/wide-field slitless spectroscopy of the same field to investigate the spatial extent of the putative protocluster. The F356W grism data target [O III]+Hβ at 5.3 &lt; z &lt; 7 and reveal a population of 124 line emitters down to a flux limit of 1.2 × 10‑18 erg s‑1 cm‑2. Fifty-three of these galaxies lie at 6.5 &lt; z &lt; 6.8 spanning 10 cMpc on the sky, corresponding to an overdensity within a 2500 cMpc3 volume of 12.5 ± 2.6, anchored by the quasar. Comparing to the [O III] luminosity function from the Emission line galaxies and Intergalactic Gas in the Epoch of Reionization project, we find a dearth of faint [O III] emitters at log(L/erg s‑1) &lt; 42.3, which we suggest is consistent with either bursty star formation causing galaxies to scatter around the grism detection limit or modest suppression from quasar feedback. While we find a strong filamentary overdensity of [O III] emitters consistent with a protocluster, we suggest that we could be insensitive to a population of older, more massive Lyman break galaxies with weak nebular emission on scales &gt;10 cMpc.

Keywords: Quasars, Protoclusters, James Webb Space Telescope, Galaxy spectroscopy, High-redshift galaxies
A Quasar-anchored Protocluster at z = 6.6 in the ASPIRE Survey. II. An Environmental Analysis of Galaxy Properties in an Overdense Structure. We present in this paper (Paper II of the series) a 35 arcmin2 JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar at z = 6.61. The F356W grism data reveal 124 [O III]+Hβ emitters at 5.3 &lt; z &lt; 7, 53 of which constitute a protocluster spanning (10 cMpc)2 across 6.5 &lt; z &lt; 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median Hβ FWHM of 585 ± 152 km s‑1; however, the mass–excitation diagram and "little red dot" color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [O III] emitters with Prospector and Bagpipes and find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3σ level, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure.

Keywords: AGN host galaxies, AB photometry, High-redshift galaxy clusters, Protoclusters, James Webb Space Telescope, Galaxy evolution, Galaxy spectroscopy
Spiral Density Waves in the Multiple-armed Galaxy NGC 628. Radial profiles of pattern speeds are measured at subkiloparsec resolution for NGC 628. The radial profiles are directly measured using a general form of the Tremaine–Weinberg method that allows for the pattern speed to vary with radius. The method is applied to both stars and CO, H I, and Hα spectral lines. The trends in the results are consistent for all of the data, showing that sources and sinks in the interstellar medium have a negligible effect when applying the integrated continuity equation. The spiral pattern rotates at a greater angular frequency in the inner region of the disks than in their outer region. Most of the measured values of the pattern speed are less than the material speed. The results for the inner disk show an approximately constant trend, consistent with rigidly rotating density waves. The offsets in stellar photometric and spectral line intensity data corroborate this result. There are radially decreasing trends in the results for the outer region of the disks that are similar to the material speed, consistent with shearing patterns or what is expected for overlapping wave modes of decreasing pattern speed. There is no single theory for the origin of the spiral patterns that can explain all of the results, but the results fail to provide evidence for a single global wave mode.

Keywords: Interstellar medium, Galaxy dynamics, Galaxy evolution, Spiral galaxies
Using Polar Faculae to Determine the Sun's High-latitude Rotation Rate. II. Simulations and New Measurements. In a previous paper, I described a new way of determining the high-latitude solar rotation rate statistically from spacetime maps of polar faculae observed in the 6767 Å continuum by the Michelson Doppler Interferometer on the Solar and Heliospheric Observatory. Now, I have tested the technique by applying it to simulated images whose faculae have known speeds, and I have been able to recover those speeds with an accuracy better than 0.01 km s‑1. Repeated measurements of the Sun's polar faculae gave the same high-latitude profile as before, but with a slightly faster synodic rotation rate of   and a rotation period of 39.6 days. Applying this spacetime tracking procedure to magnetic flux elements observed with the Helioseismic Magnetic Imager on the Solar Dynamics Observatory, I obtained a similar rotation profile with a speed of 9.55° day‑1 and a synodic rotation period of 37.7 days. These rates are comparable to polar rotation rates, obtained by other techniques, but the new latitude profiles are noticeably flatter than the quartic fits to those prior measurements.

Keywords: Solar faculae, Solar rotation, Solar magnetic fields, Solar cycle
Using Neural Networks to Automate the Identification of Brightest Cluster Galaxies in Large Surveys. Brightest cluster galaxies (BCGs) lie deep within the largest gravitationally bound structures in existence. Though some cluster finding techniques identify the position of the BCG and use it as the cluster center, other techniques may not automatically include these coordinates. This can make studying BCGs in such surveys difficult, forcing researchers to either adopt oversimplified algorithms or perform cumbersome visual identification. For large surveys, there is a need for a fast and reliable way of obtaining BCG coordinates. We propose machine learning to accomplish this task and train a neural network to identify positions of candidate BCGs given no more information than multiband photometric images. We use both mock observations from THE THREE HUNDRED project and real ones from the Sloan Digital Sky Survey, and we quantify the performance. Training on simulations yields a squared correlation coefficient, R2, between predictions and ground truth of R2 ≈ 0.94 when testing on simulations, which decreases to R2 ≈ 0.60 when testing on real data owing to discrepancies between data sets. Limiting the application of this method to real clusters more representative of the training data, such as those with a BCG r-band magnitude rBCG ≤ 16.5, yields R2 ≈ 0.99. The method performs well up to a redshift of at least z ≈ 0.6. We find this technique to be a promising method to automate and accelerate the identification of BCGs in large data sets.

Keywords: Galaxy clusters, Brightest cluster galaxies, Hydrodynamical simulations, Neural networks