Sazuna/UAT_keywords huggingface dataset:
Testing Tidal Theory Using Gaia Binaries: The Red Giant Branch. Tidal interaction is a major ingredient in the theory of binary evolution. Here, we study tidal circularization in binaries with red giant primaries. We compute the tidal evolution for binaries as their primary stars evolve along the red giant branch, under dissipation of dynamical tides in the convective envelope. We then compare this evolution with a sample of ∼30,000 red giant binaries reported by Gaia DR3. These binaries clearly show the expected gradual advance of tidal circularization, as the primary expands. But some tension with theory remains. While our calculations always predict a critical separation for tidal circularization at about 3‑4 times the stellar radii, binaries with less evolved giants are observed to be circularized out to about twice as far. They also exhibit an overly extended "cool island," a collection of circular orbits that reach a couple of times beyond the circularization limit. These discrepancies are reminiscent of, but less severe than, the situation for main-sequence binaries. We also find that tides can spin giant stars up to rotation rates that should affect their mass-loss. Additionally, many binaries may begin mass transfer while still eccentric.

Keywords: Tides, Binary stars, Hydrodynamics, Stellar evolution
Formation of All Three C<SUB>2</SUB>H<SUB>4</SUB>O Isomers—Ethylene Oxide (c-C<SUB>2</SUB>H<SUB>4</SUB>O), Acetaldehyde (CH<SUB>3</SUB>CHO), and Vinyl Alcohol (CH<SUB>2</SUB>CHOH)—in Ethanol-containing Interstellar Analog Ices. Oxygen-containing complex organic molecules are key precursors to biorelevant compounds fundamental for the origins of life. However, the untangling of their interstellar formation mechanisms has just scratched the surface, especially for oxygen-containing cyclic molecules. Here, we present the first laboratory simulation experiments featuring the formation of all three C2H4O isomers—ethylene oxide (c–C2H4O), acetaldehyde (CH3CHO), and vinyl alcohol (CH2CHOH)—in low-temperature model interstellar ices composed of carbon monoxide (CO) and ethanol (C2H5OH). Ice mixtures were exposed to galactic cosmic-ray proxies with an irradiation dose equivalent to a cold molecular cloud aged (7 ± 2) × 105 yr. These biorelevant species were detected in the gas phase through isomer-selective photoionization reflectron time-of-flight mass spectrometry during temperature-programmed desorption. Isotopic labeling experiments reveal that ethylene oxide is produced from ethanol alone, providing the first experimental evidence to support the hypothesis that ethanol serves as a precursor to the prototype epoxide in interstellar ices. These findings reveal feasible pathways for the formation of all three C2H4O isomers in ethanol-rich interstellar ices, offering valuable constraints on astrochemical models for their formation. Our results suggest that ethanol is a critical precursor to C2H4O isomers in interstellar environments, representing a critical step toward unraveling the formation mechanisms of oxygen-containing cyclic molecules, aldehydes, and their enol tautomers from alcohols in interstellar ices.

Keywords: Interstellar molecules, Mass spectrometry, Laboratory astrophysics, Astrochemistry, Complex organic molecules
Pulse Profile Variability of PSR J1022+1001 in NANOGrav Data. Pulse profile stability is a central assumption of standard pulsar timing methods. Thus, it is important for pulsar timing array experiments such as the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) to account for any pulse profile variability present in their data sets. We show that in the NANOGrav 15 yr data set, the integrated pulse profile of PSR J1022+1001 as seen by the Arecibo radio telescope at 430, 1380, and 2030 MHz varies considerably in its shape from observation to observation. We investigate the possibility that this is due to the "ideal feed assumption" (IFA), on which NANOGrav's routine polarization calibration procedure relies. PSR J1022+1001 is ∼90% polarized in one pulse profile component, and also has significant levels of circular polarization. Time-dependent deviations in the feed's polarimetric response (PR) could cause mixing between the intensity I and the other Stokes parameters, leading to the observed variability. We calibrate the PR using a mixture of measurement equation modeling and measurement equation template matching techniques. The resulting profiles are no less variable than those calibrated using the IFA method, nor do they provide an improvement in the timing quality of this pulsar. We observe the pulse shape in 25 MHz bandwidths to vary consistently across the band, which cannot be explained by interstellar scintillation in combination with profile evolution with frequency. Instead, we favor phenomena intrinsic to the pulsar as the cause.

Keywords: Millisecond pulsars, Polarimetry, Radio pulsars
The Morphology and Kinematics of a Giant, Symmetric Nebula around a Radio-loud Quasar 3C 57: Extended Rotating Gas or Biconical Outflows?. Gas flows between galaxies and the circumgalactic medium play a crucial role in galaxy evolution. When ionized by a quasar, these gas flows can be directly traced as giant nebulae. We present a study of a giant nebula around a radio-loud quasar, 3C 57 at z ≍ 0.672. Observations from MUSE reveal that the nebula is elongated with a major axis of 70 kpc and a minor axis of 40 kpc. The nebula displays an approximately symmetric blueshifted─redshifted pattern along the major axis and multicomponent emission features in its [O II] and [O III] profiles. The morphology and kinematics can be explained as rotating gas or biconical outflow, both of which qualitatively reproduce the observed position─velocity diagram. The 3C 57 nebula is significantly more kinematically disturbed, with W80 (the line width encompassing 80% of the flux) of approximately 300─400 km s−1, compared to H I gas in local early-type galaxies, which typically shows W80 ≍ 50 km s−1. This velocity dispersion is comparable to the gas in cool-core clusters despite originating in a group 100 times less massive. For biconical outflow models, the inferred 10°─20° inclination angle is in tension with the unobscured nature of the quasar, as the dusty torus is expected to be perpendicular to the outflow. Neither a quiescent rotating gas origin nor an biconical outflow fully reproduces the observed kinematics and morphology of the 3C 57 nebula, suggesting a more intricate origin likely involving both rotation and active galactic nuclei feedback.

Keywords: Quasars, Cool intergalactic medium, Circumgalactic medium
The Detectability of Coronal Mass Ejections in the Low Corona Using Multislit Extreme-ultraviolet Spectroscopy. The spectra of coronal mass ejections (CMEs) in the low corona play a crucial role in understanding their origins and physical mechanisms and enhancing space weather forecasting. However, capturing these spectra faces significant challenges. This paper introduces a scheme of a multislit spectrometer design with five slits, acquiring the global spectra of the solar corona simultaneously with a focus on the spectra of CMEs in the low corona. The chosen wavelength range of the spectrometer (170–180 Å) includes four extreme ultraviolet emission lines (Fe X 174.53 Å, Fe IX 171.07 Å, Fe X 175.26 Å, Fe X 177.24 Å), which provides information on the plasma velocity, density, and temperature. Utilizing a numerical simulation of the global corona for both the on-disk and the off-limb scenarios, we focus on resolving the ambiguity associated with various Doppler velocity components of CMEs, particularly for a fast CME in the low corona. A new application of our decomposition technique is adopted, enabling the successful identification of multiple discrete CME velocity components. Our findings demonstrate a strong correlation between the synthetic model spectra and the inverted results, indicating the robustness of our decomposition method and its significant potential for global monitoring of the solar corona, including CMEs.

Keywords: Solar coronal mass ejections, Solar corona, Spectroscopy
The GHOSDT Simulations: I. Magnetic Support in Gas-rich Disks. Galaxies at redshift z ∼ 1–2 display high star formation rates with elevated cold gas fractions and column densities. Simulating a self-regulated interstellar medium (ISM) in a hydrodynamical, self-consistent context has proven challenging due to strong outflows triggered by supernova (SN) feedback. At sufficiently high gas column densities, if magnetic fields or other mitigating measures are not implemented, these outflows can prevent a quasi-steady disk from forming for several 100 Myr. To this end, we present GHOSDT (galaxy hydrodynamical simulations with SN-driven turbulence), a suite of magneto-hydrodynamical simulations that implement ISM physics at high resolution. We demonstrate that magnetic pressure is important in the dense ISM of gas-rich star-forming disks. We show that a relation between the magnetic field and gas surface density emerges naturally from our simulations. We argue that the magnetic field in the dense, star-forming gas may be set by the SN-driven turbulent gas motions. When compared to pure-hydrodynamical runs, we find that the inclusion of magnetic fields increases the cold gas fraction by up to 40%, reduces the disk scale height by up to a factor of ∼2, and reduces the star formation burstiness. In dense (n &gt; 100 cm‑3) gas, we find steady-state magnetic field strengths of 10–40 μG, comparable to those observed in Galactic molecular clouds. Finally, we demonstrate that our simulation framework is consistent with the E. C. Ostriker and C.-G. Kim pressure-regulated feedback-modulated theory of star formation and stellar feedback.

Keywords: Hydrodynamical simulations, Interstellar medium
"Ashfall" Induced by Molecular Outflow in Protostar Evolution. II. Analytical Study on the Maximum Size of Dust Grains Lifted by Outflows. In this paper, we study the dust dynamics in the molecular outflow using an analytical magnetohydrodynamical outflow model. Specifically, we investigate the maximum size of dust grains   that can be lifted by the outflow and whether they can escape into interstellar space. We also investigate the dependence of the maximum size of the dust grains on various outflow parameters, such as the mass ejection rate of the outflow  , the disk size rdisk, the mass of the central protostar M*, and the internal dust density ρmat. We find the empirical formula for the maximum dust size as a function of the outflow parameters. Parameter   depends on the parameters as   ∝        . We also find that the dust grains with sizes of 100 μm to 1 mm can be lifted by the outflow and can distribute well outside of the disk when the mass ejection rate of the outflow has a value of 10‑7 to 10‑6 M⊙ yr‑1. This result is consistent with recent observations that show a correlation between the mass ejection rate of the outflow and the spectral index β of the dust opacity at the envelope scale.

Keywords: Young stellar objects, Protoplanetary disks, Interstellar medium, Protostars, Planet formation
Suppressed Accretion onto Massive Black Hole Binaries Surrounded by Thin Disks. We demonstrate that gas disks around binary systems might deliver gas to the binary components only when the circumbinary disk is relatively warm. We present new grid-based hydrodynamics simulations, performed with the binary on the grid and a locally isothermal equation of state, in which the binary is seen to functionally "stop accreting" if the orbital Mach number in the disk exceeds a threshold value of about 40. Above this threshold, the disk continues to extract angular momentum from the binary orbit, but it delivers very little mass to the black holes and instead piles up mass in a ring surrounding the binary. This ring will eventually become viscously relaxed and deliver mass to the binary at the large-scale inflow rate. However, we show that the timescale for such relaxation can far exceed the implied binary lifetime. We demonstrate that the ability of a binary–disk system to equilibrate is dependent on the efficiency at which accretion streams deposit mass onto the binary, which, in turn is highly sensitive to the thermodynamic conditions of the inner disk. If disks around massive black hole binaries do operate in such nonaccreting regimes, it suggests these systems may be dimmer than their single black hole counterparts but could exhibit dramatic rebrightening after the black holes inspiral and merge. This dimming begins in the UV/optical and could completely choke high-energy emission, such that these systems would likely be intrinsically X-ray weak with reddened continua, potentially resembling the spectra of "little red dots" recently identified in JWST observations.

Keywords: Accretion, Hydrodynamical simulations, Supermassive black holes, Active galactic nuclei
Quasar Milli-lensing and Cold Dark Matter (TNG50) Subhaloes. I. Image Splitting. We use numerical mass density profiles from the TNG50 simulation to study the impact of gravitational milli-lensing by dark matter subhaloes on the images of lensed quasars. Specifically, we study the formation of subimages and the probability of their detection. For high-concentration density profiles, the mass determines the amplitude of the image splitting, but for less compact subhaloes, the separation between subimages also depends on the interplay between the inner slope of the density profile and the macro-magnification induced by the lens galaxy. For a log-slope m = −2, close to the mean value of TNG50 density profiles, the detection possibilities increase with respect to less steep, commonly used, analytical models. For typical values of the concentration, 104 ≤ Cv ≤ 106, and macro-magnification μ ≥ 10, subhaloes in the entire studied mass range (Msh ≥ 3.5 × 108M⊙) can produce separations between subimages detectable with the Hubble Space Telescope or JWST. Considering the absence of reported image splitting in optical observations of lensed quasars, we establish an upper limit on the subhaloes mass fraction  , consistent within uncertainties with the abundance of lensing-efficient subhaloes directly inferred from the TNG50 simulation,  . We show that subhalo density profiles that were initially proposed to explain anomalies in the gravitational arcs of three lensed quasar systems, have also the potential to cause observable point image splitting. This presents an intriguing statistical puzzle when comparing the absence of image splitting in 400 quasar images to the three claimed detections of subhaloes in a small sample of modeled gravitational arcs.

Keywords: Quasar microlensing, Strong gravitational lensing, Gravitational lensing
High-energy Emission from the Intrabinary Shocks in Redback Pulsars. The intrabinary shocks (IBS) of spider pulsars emit nonthermal synchrotron X-rays from accelerated electrons and positrons in the shocked pulsar wind, likely energized by magnetic reconnection. In redback spider pulsars, the IBS typically wraps around the pulsar, leading to a near-normal IBS shock with relatively bright X-ray emission. The characteristic energies of radiating particles and the magnetic fields in the IBS suggest spectral features in the hard X-ray band. Here, we perform joint soft–hard X-ray analyses of three redback pulsars, J1723-2837, J2215+5135, and J2339-0533, including new J2215 NuSTAR data. We identify a significant cooling break in J1723-2837 and a marginal break in J2215+5135, while placing constraints on the break energy in J2339-0533. Interpreting these as synchrotron cooling features allows us to estimate the IBS magnetic field BIBS ∼ 40–100 G and place lower bounds on the maximum radiating electron energy. Our results constrain the magnetization of the pulsar wind as well as pair production in millisecond pulsar magnetospheres.

Keywords: Millisecond pulsars, Pulsars, Non-thermal radiation sources, Shocks, Binary pulsars
Discovery of Two Ultra-diffuse Galaxies with Unusually Bright Globular Cluster Luminosity Functions via a Mark-dependently Thinned Point Process (MATHPOP). We present MArk-dependently THinned POint Process (MATHPOP), a novel method to infer the globular cluster (GC) counts in ultra-diffuse galaxies (UDGs) and low-surface brightness galaxies (LSBGs). Many known UDGs have a surprisingly high ratio of GC number to surface brightness. However, standard methods to infer GC counts in UDGs face various challenges, such as photometric measurement uncertainties, GC membership uncertainties, and assumptions about the GC luminosity functions (GCLFs). MATHPOP tackles these challenges using the mark-dependent thinned point process, enabling joint inference of the spatial and magnitude distributions of GCs. In doing so, MATHPOP allows us to infer and quantify the uncertainties in both GC counts and GCLFs with minimal assumptions. As a precursor to MATHPOP, we also address the data uncertainties coming from the selection process of GC candidates: we obtain probabilistic GC candidates instead of the traditional binary classification based on the color─magnitude diagram. We apply MATHPOP to 40 LSBGs in the Perseus cluster using GC catalogs from a Hubble Space Telescope imaging program. We then compare our results to those from an independent study using the standard method. We further calibrate and validate our approach through extensive simulations. Our approach reveals two LSBGs having GCLF turnover points much brighter than the canonical value with Bayes' factor being ∼4.5 and ∼2.5, respectively. An additional crude maximum-likelihood estimation and simulation study show that their GCLF TO points are approximately 0.9 mag and 1.1 mag brighter than the canonical value, with p-values of ∼10−8 and ∼10−5, respectively.

Keywords: Globular star clusters, Bayesian statistics, Spatial point processes, Astrostatistics, Low surface brightness galaxies
Deep Photometric Observations of Ultrafaint Milky Way Satellites Centaurus I and Eridanus IV. We present deep Magellan+Megacam imaging of Centaurus I (Cen I) and Eridanus IV (Eri IV), two recently discovered Milky Way ultrafaint satellites. Our data reach ∼2–3 mag deeper than the discovery data from the DECam Local Volume Exploration Survey. We use these data to constrain their distances, structural properties (e.g., half-light radii, ellipticity, and position angle), and luminosities. We investigate whether these systems show signs of tidal disturbance and identify new potential member stars using Gaia EDR3. Our deep color–magnitude diagrams show that Cen I and Eri IV are consistent with an old (τ ∼ 13.0 Gyr) and metal-poor ([Fe/H] ≤ ‑2.2) stellar population. We find Cen I to have a half-light radius of  (90.6 ± 11 pc), an ellipticity of ϵ = 0.36 ± 0.05, a distance of D = 119.8 ± 4.1 kpc (m ‑ M = 20.39 ± 0.08 mag), and an absolute magnitude of MV = ‑5.39 ± 0.19. Similarly, Eri IV has  (65.9 ± 10 pc), ϵ = 0.26 ± 0.09, D = 69.9 ± 3.6 kpc (m ‑ M = 19.22 ± 0.11 mag), and MV = ‑3.55 ± 0.24. These systems occupy a space on the size–luminosity plane consistent with other known Milky Way dwarf galaxies, which supports the findings from our previous spectroscopic follow-up. Cen I has a well-defined morphology that lacks any clear evidence of tidal disruption, whereas Eri IV hosts a significant extended feature with multiple possible interpretations. *This paper includes data gathered with the 6.5 m Magellan Telescopes at Las Campanas Observatory, Chile.

Keywords: Galaxy structure, Stellar populations, Dwarf galaxies, Direct imaging
Evolution of the Convective Core Mass during the Main Sequence. We construct a semianalytical model that describes the convective core mass evolution of massive stars experiencing mass loss during the main-sequence stage. We first conduct a suite of 1D stellar evolution calculations to build insight into how convective core masses behave under idealized mass loss. Based on these simulations, we find several universal relations between global properties of the star that hold regardless of the mass loss history. By combining these relations, we construct a semianalytic framework that can predict the convective core mass evolution for arbitrary mass-loss histories, and hence the helium core mass at the end of the main sequence. Our formulae improve upon existing methods for predicting the core mass in rapid population synthesis codes.

Keywords: Massive stars, Binary stars, Stellar evolution
Scaling of Particle Heating in Shocks and Magnetic Reconnection. Particles are heated efficiently through energy conversion processes, such as shocks and magnetic reconnection, in collisionless plasma environments. While empirical scaling laws for the temperature increase have been obtained, the precise mechanism of energy partition between ions and electrons remains unclear. Here we show, based on coupled theoretical and observational scaling analyses, that the temperature increase, ΔT, depends linearly on three factors: the available magnetic energy per particle, the Alfvén Mach number (or reconnection rate), and the characteristic spatial scale L. Based on statistical data sets obtained from Earth's plasma environment, we find that L is on the order of: (1) the ion gyroradius for ion heating at shocks; (2) the ion inertial length for ion heating in magnetic reconnection; and (3) the hybrid inertial length for electron heating in both shocks and magnetic reconnection. With these scales, we derive the ion-to-electron ratios of temperature increases as   for shocks and   for magnetic reconnection, where βi is the ion plasma beta and mi and me are the ion and electron particle masses, respectively. We anticipate that this study will serve as a starting point for a better understanding of particle heating in space plasmas, enabling more sophisticated modeling of its scaling and universality.

Keywords: Space plasmas, Solar magnetic reconnection, Plasma physics, Scaling relations, Shocks
An Upper Limit on the Interstellar Meteoroid Flux at Video Sizes from the Global Meteor Network. Material arriving at our solar system from the Galaxy may be detected on Earth in the form of meteors ablating in our atmosphere. Here, we report on a search for interstellar meteors within the highest-quality events in the Global Meteor Network (GMN) database. No events were detected that were conclusively hyperbolic with respect to the Sun; however, our search was not exhaustive and examined only the top 57% of events, with a deeper examination planned for future work. This study's effective meteoroid mass limit is 6.6 ± 0.8 × 10‑5 kg (5 mm diameter at a density of 1000 kg m‑3). Theoretical rates of interstellar meteors at these sizes range from 3 to 200 events globally per year. The highest rates can already be largely excluded by this study, while at the lowest rates, GMN would have to observe for 25 more years to be 50% confident of seeing at least one event. GMN is thus well-positioned to provide substantial constraints on the interstellar population at these sizes over the coming years. This study's results are statistically compatible with a rate of interstellar meteors at the Earth at less than 1 per million meteoroid impacts at Earth at millimeter sizes, or a flux rate of less than 8 ± 2 × 10‑11 km‑2 hr‑1 at the 95% confidence level.

Keywords: Meteors, Interstellar objects