Sazuna/UAT_keywords huggingface dataset:
JWST/NIRCam Paβ Narrowband Imaging Reveals Ordinary Dust Extinction for Hα Emitters within the Spiderweb Protocluster at z = 2.16. We combine JWST/NIRCam and Subaru/MOIRCS dual Paβ+Hα narrowband imaging to trace the dust attenuation and the star formation activities of a sample of 43 Hα emitters at the core of one of the most massive and best-studied clusters in formation at the cosmic noon: the Spiderweb protocluster at z = 2.16. We find that most Hα emitters display Paβ/Hα ratios compatible with Case B recombination conditions, which translates into nebular extinction values ranging at AV ≈ 0–3 mag, and dust corrected Paβ star formation rates consistent with coeval main sequence field galaxies at fixed stellar mass ( ) during this cosmic epoch. Furthermore, we investigate possible environmental impacts on dust extinction across the protocluster large-scale structure and find no correlation between the dustiness of its members and environmental proxies such as phase-space position, clustercentric radius, or local density. These results support the scenario for which dust production within the main galaxy population of this protocluster is driven by secular star formation activities fueled by smooth gas accretion across its large-scale structure. This downplays the role of gravitational interactions in boosting star formation and dust production within the Spiderweb protocluster, in contrast with observations in higher redshift and less evolved protocluster cores.

Keywords: Protoclusters, Interstellar dust extinction, Emission line galaxies, Star formation, Galaxy evolution, Near infrared astronomy
Modeling Competing Line-broadening Mechanisms in Neutron Star Atmospheres: Interference between Motional Stark and Ion Broadening. Neutron star surfaces have extremely high magnetic fields. In the atmosphere, the broadening of spectral lines will be substantial from the dense plasma as well as from the magnetic field. One broadening mechanism of note is due to the motional Stark effect (MSE)—an additional electric field that arises from the motion of the atom in the magnetic field. However, approximate formulae are often used to construct atmosphere models, and the MSE is assumed to be the dominant line-broadening mechanism even in ions. Detailed pressure-broadening models in these extreme magnetic fields are now currently being developed. In these more detailed models, it was suggested that the MSE may not be as large as previously predicted. If correct, this hypothesis implies that neutron star line widths might be dominated by pressure broadening rather than by motional Stark broadening. We find that, in the absence of plasma perturbations, for typical magnetic fields (B = 1012 G), mid-Z elements, such as oxygen, have motional Stark widths of order 1 eV for transitions between dipole-allowed transitions from the ground state, though higher temperatures and transitions to higher-energy states are expected to have more broadening. The MSE also breaks down selection rules, giving rise to forbidden transitions, which have much larger widths. When plasma perturbations are included, we find that the plasma perturbation and motional Stark processes are not independent and, as a result, the spectral lines become narrow in a nontrivial way and display harmonics of the ion cyclotron frequency.

Keywords: Neutron stars, Atomic spectroscopy, Stellar atmospheres, Atomic physics
On the Acceleration Site of Anomalous Cosmic Rays: Voyager 2 Observations of Their Anisotropy in the Heliosheath. We present the diffusive flow anisotropy vector components for ∼0.5–35 MeV anomalous cosmic-ray (ACR) protons observed during Voyager 2 roll maneuvers for the magnetometer instrument in the inner heliosheath. The diffusive flow results are derived from the differences between the observed anisotropy components presented in A. C. Cummings et al. (2021) and the Compton–Getting anisotropies based on measurements of the solar wind speeds from the Plasma Science instrument. We find that the tangential component of the derived diffusive anisotropy vector is in reasonable agreement, both in direction and magnitude, with a numerical model of the acceleration and transport of ACRs by diffusive shock acceleration along a nonspherical solar wind termination shock (TS). The results suggest that there exists a diffusive flow of these particles from the flank or tail of the heliosphere toward the nose, and support models in which higher-energy ACRs are accelerated in the flank or tail of the TS.

Keywords: Cosmic rays
Connecting the X-Ray/UV Variability of Fairall 9 with NICER: A Possible Warm Corona. The Seyfert 1 active galactic nucleus Fairall 9 was targeted by NICER, Swift, and ground-based observatories for a ∼1000 day long reverberation mapping campaign. The following analysis of NICER spectra taken at a 2 day cadence provides new insights into the structure and heating mechanisms of the central black hole environment. Observations of Fairall 9 with NICER and Swift revealed a strong relationship between the flux of the UV continuum and the X-ray soft excess, indicating the presence of a "warm" Comptonized corona that likely lies in the upper layers of the innermost accretion flow, serving as a second reprocessor between the "hot" X-ray corona and the accretion disk. The X-ray emission from the hot corona lacks sufficient energy and variability to power slow changes in the UV light curve on timescales of 30 days or longer, suggesting an intrinsic disk-driven variability process in the UV and soft X-rays. Fast variability in the UV on timescales shorter than 30 days can be explained through X-ray reprocessing, and the observed weak X-ray/UV correlation suggests that the corona changes dynamically throughout the campaign.

Keywords: High energy astrophysics, Reverberation mapping, X-ray telescopes, X-ray active galactic nuclei, Active galactic nuclei
Visual Orbits of Wolf–Rayet Stars. I. The Orbit of the Dust-producing Wolf–Rayet Binary WR 137 Measured with the CHARA Array. Classical Wolf–Rayet (W-R) stars are the descendants of massive OB stars that have lost their hydrogen envelopes and are burning helium in their cores prior to exploding as Type Ib/c supernovae. The mechanisms for losing their hydrogen envelopes are either through binary interactions or through strong stellar winds potentially coupled with episodic mass loss. Among the bright classical W-R stars, the binary system WR 137 (HD 192641; WC7d + O9e) is the subject of this paper. This binary is known to have a 13 yr period and produces dust near periastron. Here we report on interferometry with the Center for High Angular Resolution Astronomy Array collected over a decade of time and providing the first visual orbit for the system. We combine these astrometric measurements with archival radial velocities to measure masses of the stars of M WR = 9.5 ± 3.4 M ⊙ and M O = 17.3 ± 1.9 M ⊙ when we use the most recent Gaia distance. These results are then compared to predicted dust distribution using these orbital elements, which match the observed imaging from JWST as discussed recently by Lau et al. Furthermore, we compare the system to the Binary Population And Spectral Synthesis models, finding that the W-R star likely formed through stellar winds and not through binary interactions. However, the companion O star did likely accrete some material from the W-R star's mass loss to provide the rotation seen today that drives its status as an Oe star.

Keywords: WC stars, Dust formation, Long baseline interferometry, Wolf-Rayet stars, Interferometric binary stars
The Environments of Green Pea Galaxies. II. The Hα Dot Sample. We use spectroscopic redshifts obtained with the WIYN 3.5 m telescope to study the local galactic environment around 18 Green Pea (GP) galaxies. Our sample of GPs were discovered in the Hα Dot Survey via their [O III]λ5007 emission and span the redshift range 0.32 &lt; z &lt; 0.34. We present the environmental analyses near the location of the Hα Dot GPs. We utilize three different density estimators, chosen based on the geometry of the redshift survey data within the Hα Dot GP fields. We classify each Hα Dot GP into an environment category, from extremely isolated to highly clustered. We find that our entire sample of Hα Dot GPs reside in extremely isolated or low-density environments, with none located in the intermediate- to high-density regimes. We interpret this to indicate that major mergers and interactions do not drive the activity seen in these galaxies.

Keywords: Starburst galaxies, Large-scale structure of the universe, Galaxy environments, Emission line galaxies, Voids, Galaxy mergers, Redshift surveys, Galaxy processes
Fate of the Remnant in Tidal Stripping Event: Repeating and Nonrepeating. Tidal disruption events (TDE) occur when a star ventures too close to a massive black hole. In a partial TDE (pTDE), the star only grazes the tidal radius, causing the outer envelope of the star to be stripped away while the stellar core survives. Previous research has shown that a star, once tidally stripped in a parabolic orbit, can acquire enough orbital energy for its remnant to become a high-velocity star potentially capable of escaping the galaxy. Conversely, some studies have reported that the remnant may lose orbital energy and undergo re-disruption, leading to a recurring pTDE. This study aims to uncover the physical mechanisms and determine the conditions that lead to these divergent outcomes. We find that the orbital energy change only depends on the impact factor and the stellar structure, and barely depends on the mass of the black hole or the exact mass or orbital eccentricity of the star. For a γ = 5/3 (or γ = 4/3) polytropic star, after a pTDE its remnant gains orbital energy when the impact factor β ≳ 0.62 (or ≳1.1) or loses energy and vice versa. Additionally, we verify an analytical equation for orbital energy change that is applicable across various systems. Through hydrodynamic simulations, we also explore the structure of the stellar remnant post-tidal stripping. Our findings provide critical insights for interpreting observed pTDEs and advancing knowledge on the orbital evolution and event rate of these events.

Keywords: Black hole physics, Hydrodynamical simulations, Intermediate-mass black holes, Tidal disruption, Roche lobe overflow, Galaxies
Mining for Protoclusters at z ∼ 4 from Photometric Data Sets with Deep Learning. Protoclusters are high-z overdense regions that will evolve into clusters of galaxies by z = 0, making them ideal for studying galaxy evolution expected to be accelerated by environmental effects. However, it has been challenging to identify protoclusters beyond z = 3 only by photometry due to large redshift uncertainties hindering statistical study. To tackle the issue, we develop a new deep-learning-based protocluster detection model, PCFNet, which considers a protocluster as a point cloud. To detect protoclusters at z ∼ 4 using only optical broadband photometry, we train and evaluate PCFNet with mock g-dropout galaxies based on the N-body simulation with the semianalytic model. We use the sky distribution, i-band magnitude, (g ‑ i) color, and the redshift probability density function surrounding a target galaxy on the sky. PCFNet detects 5 times more protocluster member candidates while maintaining high purity (recall = 7.5% ± 0.2%, precision = 44% ± 1%) than conventional methods. Moreover, PCFNet is able to detect more progenitors ( ) that are less massive than supermassive clusters like the Coma cluster. We apply PCFNet to the observational photometric data set of the Hyper Suprime-Cam Strategic Survey Program Deep/UltraDeep layer (∼17 deg2) and detect 121 protocluster candidates at z ∼ 4. We find that the rest-UV luminosities of our protocluster member candidates are brighter than those of field galaxies, which is consistent with previous studies. Additionally, the quenching of satellite galaxies depends on both the core galaxy's halo mass at z ∼ 4 and accumulated mass until z = 0 in the simulation. PCFNet is very flexible and can find protoclusters at other redshifts or in future extensive surveys by Euclid, Legacy Survey of Space and Time, and Roman.

Keywords: High-redshift galaxy clusters, Protoclusters, Lyman-break galaxies, Galaxy environments
The Nature of a Recently Discovered Wolf─Rayet Binary: Archetype of Stripping?. LMCe055-1 was recently discovered in a survey for Wolf─Rayets (WRs) in the Large Magellanic Cloud, and classified as a WN4/O4, a lower-excitation version of the WN3/O3 class discovered as part of the same survey. Its absolute magnitude precluded it from being a WN4+O4 binary. Optical Gravitational Lensing Experiment photometry shows shallow primary and secondary eclipses with a 2.2 days period. The spectral characteristics and short period pointed to a possible origin due to binary stripping. Such stripped WR binaries should be common but have proven elusive to identify conclusively. In order to establish its nature, we obtained Hubble Space Telescope ultraviolet and Magellan optical spectra, along with imaging. Our work shows that the WR emission and He II absorption arise in one star, and the He I absorption in another. The He I contributor is the primary of the 2.2 days system and exhibits ∼300 km s−1 radial velocity variations on that timescale. However, the WR star shows 30─40 km s−1 radial velocity variations, with a likely 35 days period and a highly eccentric orbit. Possibly LMCe055-1 is a physical triple, but that would require the 2.2 days pair to have been captured by the WR star. A more likely explanation is that the WR star has an unseen companion in a 35 days orbit and that the 2.2 days pair is in a longer-period orbit about the two. Such examples of multiple systems are well known among massive stars, such as HD 5980. Regardless, we argue that it is highly unlikely that the WR component of the LMCe055-1 system resulted from stripping. * This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. It also uses observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations were associated with programs GO-16299 (PI: Massey) and GO-16093 (ULLYSES, PI: Roman-Duval).

Keywords: Wolf-Rayet stars, Massive stars, Binary stars
uGMRT Sub-GHz View of the Sausage Cluster Diffuse Radio Sources. CIZA J2242.8+5301, or the Sausage cluster, is well-studied over a range of frequencies. Since its first discovery, a lot of interesting features and unique characteristics have been uncovered. In this work, we report some more new morphological features using the uGMRT band-3 and band-4 data. In the north relic, we observe variation in the spectral index profiles across the relic width from the east to west, which may indicate a decrease in the downstream cooling rate in that direction. We reconfirm the presence of an additional ∼930 kpc relic in the north. We classify the filamentary source in the downstream region to be a narrow-angle tail (NAT) radio galaxy. The bright arc in the east relic shows a substructure in the spectral index profile, which may indicate the presence of finer filaments. We further report the presence of a double-strand structure in the east relic similar to the "Toothbrush" relic. We categorize the bright "L"-shaped structure in the southern relic to be a NAT radio galaxy, as well as trace the actual ∼1.1 Mpc relic component. We reconfirm the existence of the faint southern extent, measuring the relic length to be ∼1.8 Mpc. Furthermore, we suggest the southern relic to be a union of individual component relics rather than a single giant filamentary relic. Lastly, based on the morphological symmetry between northern and southern relics, we suggest a schematic shock structure associated with the merger event in an attempt to explain their formation scenario.

Keywords: Galaxy clusters, High energy astrophysics, Non-thermal radiation sources, Extragalactic astronomy, Intracluster medium
First Observation of the Complete Rotation Period of the Ultraslowly Rotating Magnetic O Star HD 54879. HD 54879 is the most recently discovered magnetic O-type star. Previous studies ruled out a rotation period shorter than 7 yr, implying that HD 54879 is the second most slowly rotating known magnetic O-type star. We report new high-resolution spectropolarimetric measurements of HD 54879, which confirm that a full stellar rotation cycle has been observed. We derive a stellar rotation period from the longitudinal magnetic field measurements of   days (about 7.02 yr). The radial velocity of HD 54879 has been stable over the last decade of observations. We explore equivalent widths and longitudinal magnetic fields calculated from lines of different elements, and conclude the atmosphere of HD 54879 is likely chemically homogeneous, with no strong evidence for chemical stratification or lateral abundance nonuniformities. We present the first detailed magnetic map of the star, with an average surface-magnetic-field strength of 2954 G, and a strength for the dipole component of 3939 G. There is a significant amount of magnetic energy in the quadrupole components of the field (23%). Thus, we find HD 54879 has a strong magnetic field with a significantly complex topology.

Keywords: Early-type stars, Spectropolarimetry, O stars, Massive stars, Stellar magnetic fields
Far-side Active Regions Based on Helioseismic and EUV Measurements: A New Data Set for Heliospheric Machine Learning Advancements. Active Regions (ARs) are regions of strong magnetic flux in the solar atmosphere. Understanding the global evolution of ARs is critical for solar magnetism as well as for accurate space-weather forecasting. We present the first far-side AR data set based on EUV observation and helioseismic measurements. For the EUV observations, we use synchronic maps at 304 Å comprised of observations from the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Solar TErrestrial RElations Observatory/Extreme UltraViolet Imager, in heliocentric orbit with direct vantages into the Sun's far hemisphere. We used the brightening of the solar transition region in EUV/304 Å maps as a proxy for the magnetic regions. For the far-side helioseismic measurements, we used seismic phase-shift maps of the Sun's far hemisphere, computed from helioseismic Dopplergrams observed by NSO/Global Oscillations Network Group (GONG). In this study, we present the first global EUV AR data set of the whole Sun, providing several basic parameters, such as location, area, tilt angle, EUV brightness, and latitudinal/longitudinal extents of the identified ARs. We also present a similar data set for the far-side GONG ARs where the helioseismic phase shift parameters are included. Helioseismic far-side GONG ARs are examined, and their success at predicting strong ARs is assessed. We discuss the temporal and spatial evolution for the EUV AR signatures and far-side GONG AR signatures during the ascending and maximum phases of Solar Cycle 24 (2010 May─2016 May). We examine the correlation between the helioseismic signatures and the respective EUV source distributions in the Sun's far hemisphere. We present the first far-side AR butterfly diagram based on helioseismic measurements.

Keywords: Solar extreme ultraviolet emission, Helioseismology, Space weather, Solar physics, Solar active regions, Solar oscillations, Solar activity
Fe/O Variations Relative to Source Longitude and Heliospheric Current Sheet in Large Solar Energetic Particle Events. The Fe/O enhancements exhibit significant variations in gradual solar energetic particle (SEP) events. Several causes have been suggested including transport effects in the interplanetary space and flare contribution. In this study, we investigate the relationship between the integrated Fe/O ratios of 27 gradual SEP events, locations of associated solar flares, and positions along the heliospheric current sheet (HCS) between 2010 and 2014. We employ synchronic potential field source surface (PFSS) extrapolations at 2.5R ⊙, derived in near real-time using Artificial Intelligence (AI)-generated far side and Helioseismic and Magnetic Imager (HMI) magnetograms, referred to as AIHMI-PFSS extrapolations. We examine low-energy (∼0.5 MeV/nucleon) Fe and O ion measurements obtained from Suprathermal Ion Telescope on Solar Terrestrial Relations Observatories and Ultra Low Energy Isotope Spectrometer on Advanced Composition Explorer. We found a moderate anticorrelation between the Fe/O ratios and the absolute longitudinal separation angles from the source regions to the spacecraft magnetic footpoints. Furthermore, we investigate the variations in Fe/O ratios with respect to the separation angle, grouped by the same and opposite polarity sectors of the SEP source regions. We found that the mean and median Fe/O values are higher in the same polarity group compared to the opposite polarity group, with the largest contrast at separation angles between 25° and 50°, where the values are approximately 3 times larger. The results imply that the enhanced Fe/O ratios in the examined gradual SEP events are likely associated with direct source regions, while the HCS affects particle transport.

Keywords: Solar energetic particles
Weak Lensing Analysis of A2390 Using Short Exposures. We present a weak lensing analysis of the galaxy cluster A2390 at z = 0.23 using second moment shape measurements made in 411 short 60 s exposures. The exposures are obtained in three broadband photometric filters (g, r, and i) using WIYN-ODI. Shape measurement in individual exposures is done using a moment-matching algorithm. Forced measurement is used when the moment-matching algorithm fails to converge at low signal-to-noise ratio. The measurements made in individual images are combined using inverse error weighting to obtain accurate shapes for the sources and hence recover shear. We use PhoSim simulations to validate the shear measurements recovered by our pipeline. We find the mass of A2390 is in agreement with previously published results. We also find the E-mode maps show filamentary structures consistent with baryonic structures and recover most clusters/groups of galaxies found using optical and X-ray data. Thus, we demonstrate the feasibility of using weak lensing to map large-scale structure of the Universe. We also find the central portion of the cluster has a bimodal mass distribution and the relative orientation of the peaks is similar to X-ray. We discuss earlier research on this galaxy cluster, and show that a late-stage merger accounts for all the observed data.

Keywords: Weak gravitational lensing, Galaxy clusters