Sazuna/UAT_keywords huggingface dataset:
Absolute Properties of Two Double-lined Algol-type Binaries with Cyclic Period Changes. The formation, evolution, and stability of multiple star systems are still open questions in the field of astrophysics. Algol-type binaries are important for obtaining precise physical parameters, investigating the reversal of the mass ratio, and studying the multiplicity of stars. We present a detailed analysis of RW Leo and RT Per with the high-precision time-series radial velocities from the LAMOST-medium-resolution spectroscopic survey and TESS light curves, and we first obtained their absolute parameters. We found that RT Per and RW Leo are post-mass transfer SD2-type semidetached binaries with mass ratios of 0.29 and 0.176, respectively, and the evolved secondary components almost fill their Roche lobe (both ∼99.4%). Moreover, their O − C diagrams show double-cycle oscillations, and the oscillation periods are ∼78 yr and ∼41 yr for RW Leo and ∼247 yr and ∼41 yr for RT Per, respectively. The long-period of them may be caused by the presence of a third body with a mass not less than 0.4M⊙, but we did not detect the third light. For RT Per, our fitting data do not fully cover a complete long-period oscillation (∼247 yr), and longer duration observations are needed to check our results in the future. For the 41 yr oscillations of RW Leo and RT Per, the cyclic magnetic activity from their active secondary components is a probable reason. Besides, after 2451218.604 (HJD), we also discovered that the magnetic activity cycle of RT Per suddenly halved to 20.88 yr because of a possible change in the geometry of the secondary's magnetic field.

Keywords: Multiple stars, Fundamental parameters of stars, Algol variable stars, Stellar activity, Eclipsing binary stars, Radial velocity
Tides in Massive Binaries: Numerical Solutions and Semianalytical Comparisons. We present a systematic comparison between the tidal secular evolution timescales predicted by the direct numerical method and those given by the commonly used semianalytic prescriptions implemented in 1D hydrostatic binary evolution codes. Our study focuses on binary systems with intermediate- to high-mass primaries (M1 = 5─50 M⊙), companion masses between 1.4 M⊙and 10 M⊙, and orbital periods ranging from 0.5─50 days. Before mass transfer, both approaches predict synchronization and orbital decay timescales that agree within ∼2 orders of magnitude and typically exceed the stellar main-sequence lifetime, implying negligible tidal impact on secular orbital evolution. However, the implied dissipation channels differ, and the differences become more pronounced once mass transfer begins. To test the theoretical predictions against observations, we apply both approaches to the well-characterized PSR J0045─7319 system, which has an orbital decay timescale of 0.5 Myr. The numerical solution reveals strong resonances with internal gravity waves, bringing the predicted orbital period change rate close to the observed value. In contrast, the semianalytic prescriptions predict orbital decay timescales longer than the Hubble time. These results suggest that for population studies, modestly calibrated parameterized equations may suffice, but for individual systems, reliable interpretation requires direct numerical approaches.

Keywords: Binary stars, Astronomy software, Close binary stars, Stellar populations, Tidal interaction, Stellar evolutionary models, Interacting binary stars, Stellar astronomy, Stellar oscillations, Stellar evolution
First Results from HERA Phase II. We report the first upper limits on the power spectrum of 21 cm fluctuations during the Epoch of Reionization and Cosmic Dawn from Phase II of the Hydrogen Epoch of Reionization Array (HERA) experiment. HERA Phase II constitutes several significant improvements in the signal chain compared to Phase I, most notably resulting in expanded frequency bandwidth, from 50─250 MHz. In these first upper limits, we investigate a small two-week subset of the available Phase II observations, with a focus on identifying new systematic characteristics of the instrument, and establishing an analysis pipeline to account for them. We report 2σ upper limits in eight spectral bands, spanning 5.6 ≤ z ≤ 24.4 that are consistent with thermal noise at the 2σ level for k ≳ 0.6─0.9 h Mpc−1 (band dependent). Our tightest limit during Cosmic Dawn (z &gt; 12) is 1.13 × 106 mK2 at (k = 0.55 h Mpc−1, z = 16.78), and during the EoR (5.5 &lt; z &lt; 12), it is 1.78 × 103 mK2 at (k = 0.70 h Mpc−1, z = 7.05). We find that mutual coupling has become our dominant systematic, leaking foreground power that strongly contaminates the low-k modes, resulting in the loss of modes from k = 0.35 to 0.55 compared to Phase I data.

Keywords: Galaxy formation, Astronomy data analysis, Radio interferometers, Reionization, Radio astronomy
A Correlation between the Final Separation and Mass Ratio from Common-envelope Simulations. Analytical models for common-envelope evolution (CEE), particularly the energy formalism, are used in binary population synthesis to predict post-CEE configurations. This formalism is based on an efficiency parameter α, which relates the orbital energy released during CEE to that required to unbind the envelope of the giant. However, one of the main challenges is that CEE is a multiscale, multiphysics process. As a result, there may not be a universal value for α, or even a general expression. Using 13 3D simulations of CEE with red giant branch (RGB) stars (1 and 2 M⊙ primary; four mass ratios; with and without corotation), we present an empirical linear correlation between the post-plunge-in separation and the mass ratio, normalized by the giant radius. This trend for the plunge-in phase of CEE persists across simulations of RGB stars, asymptotic giant branch stars, and supergiants in the literature, even for partially bound envelopes. Therefore, α from simulations should not be used to predict the final separation, but rather as a diagnostic of whether sufficient orbital energy has been liberated to completely eject the envelope immediately after the radial plunge. If this condition is not met, further orbital decay is expected in later stages of CEE, which may explain why the final separation of post-CEE observations is generally smaller than those predicted by the linear fit. Our results reinforce the idea that a better description could emerge if CEE is treated as a sequence of distinct phases, rather than as a single event governed by α.

Keywords: Hydrodynamical simulations, Close binary stars, Asymptotic giant branch stars, Red giant stars, Supergiant stars, Common envelope evolution
A Closer Look at the Dynamical State of the High-redshift Galaxy Cluster SPT-CL J2215-3537. We present a comprehensive reanalysis of the dynamical state of the high-redshift galaxy cluster SPT-CL J2215-3537 (z = 1.16), using the full set of available Chandra observations to characterize the thermodynamic and morphological properties of the intracluster medium. Although previously identified as one of the most distant dynamically relaxed systems based on X-ray morphological statistics, we find compelling evidence that SPT-CL J2215-3537 displays some level of dynamical activity. This includes temperature anisotropies consistent with the first detection of a pair of core-sloshing cold fronts at z &gt; 1. We identify a ghost cavity candidate and estimate its mechanical power as  log10(Pcav/1042erg s−1)=2.66±0.23 , confirming that radiative cooling strongly exceeds active galactic nucleus feedback heating. We show that SPT-CL J2215-3537 is likely in a short transient phase preceding the onset of a self-regulated cooling-feedback cycle. We recalculate traditional X-ray morphological parameters and discuss how non-self-similar evolution of parameters sensitive to the surface brightness cuspiness can bias dynamical classifications at high redshift.

Keywords: High-redshift galaxy clusters
Accretion Geometry of the New Galactic Black Hole Candidate AT2019wey in the Hard State. We perform broadband spectral and timing studies of the Galactic low-mass black hole candidate AT2019wey using quasi-simultaneous NICER, Swift, and NuSTAR observations obtained in 2022. The long-term MAXI light curve, along with the hardness─intensity diagram, indicates that the source remained in the hard state and did not switch to the soft state. Spectral modeling using two different model combinations reveals that the broadband spectrum is best described by two distinct Comptonizing regions, associated reflection components, and thermal emission from the disk. The harder Comptonizing region dominates (≳80%) the total flux and is primarily responsible for the observed reflection features from the distant part of the disk. We find that the accretion disk is truncated at a radius of ∼16─56 rg, while the luminosity is ∼1.9% of the Eddington limit, assuming a black hole mass of 10 M⊙ and distance of 8 kpc. Our spectral results also show consistency in the estimated inner disk radius obtained through two independent methods: modeling the disk continuum and the reflection spectrum. The variability studies imply the presence of intrinsic disk variability, likely originating from an instability in the disk. We also detect hard time lags at low frequencies, possibly arising from the inward propagation of mass accretion rate fluctuations from the outer to the inner regions of the accretion disk. Moreover, an observed deviation of the lag-energy spectrum from the log-linear trend at ≲0.7 keV is most likely attributed to thermal reverberation, arising from the reprocessing of hard coronal photons in the accretion disk.

Keywords: Low-mass x-ray binary stars, Stellar accretion disks, Stellar mass black holes, High energy astrophysics
Time-integrated Southern-sky Neutrino Source Searches with 10 yr of IceCube Starting-track Events at Energies Down to 1 TeV. In the IceCube Neutrino Observatory, a signal of astrophysical neutrinos is obscured by backgrounds from atmospheric neutrinos and muons produced in cosmic-ray interactions. IceCube event selections used to isolate the astrophysical neutrino signal often focus on the morphology of the light patterns recorded by the detector. The analyses presented here use the new IceCube Enhanced Starting Track Event Selection (ESTES), which identifies events likely generated by muon─neutrino interactions within the detector geometry, focusing on neutrino energies of 1─500 TeV with a median angular resolution of 1.4 ° . Selecting for starting-track events filters out not only the atmospheric-muon background but also the atmospheric-neutrino background in the southern sky. This improves IceCube's muon─neutrino sensitivity to southern-sky neutrino sources, especially for Galactic sources that are not expected to produce a substantial flux of neutrinos above 100 TeV. In this work, the ESTES sample was applied for the first time to search for astrophysical sources of neutrinos, including a search for diffuse neutrino emission from the Galactic plane. No significant excesses were identified from any of the analyses; however, constraining limits are set on the hadronic emission from TeV gamma-ray Galactic plane objects and models of the diffuse Galactic plane neutrino flux.

Keywords: Neutrino astronomy, High energy astrophysics
No Evidence for Second-scale Periodicity in FRB 20201124A from 2021 April to June FAST Observations. Fast radio bursts (FRBs) are bright and short radio flashes of cosmological origin. Although a great number of FRBs have been detected in the last two decades, their progenitors and the physical processes that create them are unknown. In recent years, magnetars have been proposed as one of the leading progenitor candidates. A striking feature that can hint at such a magnetar origin is second-scale periodicity. In this paper, we define a robust procedure to search for such periodicity and estimate the significance of its results. We search for such periodicity in the bursts of FRB 20201124A, observed by the Five-hundred-meter Aperture Spherical Telescope between 2021 April and June. Our analysis does not find any significant periodicity. We discuss the differences between our nondetection and the ∼1.7 s periodicity claim by C. Du et al.

Keywords: Magnetars, Astrostatistics, Radio transient sources
The Astrophysical Birth Environment of the Solar System Inferred from Cometary Noble Gases. The stellar sources that contributed to the chemical and isotopic composition of the solar system, their mixing in the Galactic environment, and the evolution and longevity of the molecular cloud from which our solar system formed can be probed with isotopic measurements of presolar grains, meteorites, and comets. The isotopic compositions of cometary xenon (Xe) and krypton (Kr) measured in the coma of 67P/Churyumov─Gerasimenko (67P/C-G) are distinct from those of the Sun. As noble gases in cometary ices are thought to be derived from the same molecular cloud from which the Sun formed, such nonsolar isotopic compositions suggest that a compositionally distinct reservoir of noble gases was present in the presolar molecular cloud that is currently absent from 67P/C-G. This likely requires that a noble gas component was cotrapped in volatile ice which was later destroyed by processing within the protoplanetary disk. Here, we show that this hypothetical component was enriched in r-process and potentially p-process isotopes compared to the solar composition, and that these isotopes formed over a hundred million years before coalescence and cosmochemical isolation of the solar system. We discuss a scenario where this component was accreted by the presolar molecular cloud sometime after the formation of water ice containing cotrapped Xe and Kr with the composition of 67P/C-G. Such a component could have been derived from a diffuse, heterogeneous molecular portion of the interstellar medium accreted by the presolar molecular cloud, or incorporated from another molecular cloud via a cloud─cloud collision. These observations support two distinct r-processes contributing to the overall solar r-process abundance pattern.

Keywords: Pre-solar nebulae, Ice composition, Nucleosynthesis, Protoplanetary nebulae, R-process, Molecular clouds, P-process, Comets, Comet origins, Comet volatiles
JWST/NIRSpec Detects Warm CO Emission in the Terrestrial-planet Zone of HD 131488. We have obtained a high-resolution, JWST NIRSpec 2.87─5.14 μm spectrum of the debris disk around HD 131488. We discover CO fundamental emission indicating the presence of warm fluorescent gas within ∼10 au of the star. The large discrepancy in CO's vibrational and rotational temperature indicates that CO is out of thermal equilibrium and is excited with UV fluorescence. Our UV fluorescence model gives a best fit of 1150 K with an effective temperature of 450, 332, and 125 K for the warm CO gas kinetic temperature within 0.5, 1, and 10 au to the star and a gas vibrational temperature of 8800 K. The newly discovered warm CO gas population likely resides between sub─astronomical unit scales and ∼10 au, interior to the cold CO reservoir detected beyond 35 au with the Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph and Atacama Large Millimeter/submillimeter Array (ALMA). The discovery of warm, fluorescent gas in a debris disk is the first such detection ever made. The detection of warm CO raises the possibility of unseen molecules (H2O, H2, etc.) as collisional partners to excite the warm gas. We estimated a lower mass limit for CO of 1.25 × 10−7M⊕, which is 10−5 of the cold CO mass detected with ALMA and HST. We demonstrate that UV fluorescence emerges as a promising avenue for detecting tenuous gas at 10−7 Earth-mass level in debris disks with JWST.

Keywords: Infrared spectroscopy, Exozodiacal dust, Planetary system formation, Circumstellar disks, Debris disks
Globular Cluster Systems in Dwarf Galaxies: Catalogs and Comparisons. The connection between a galaxy's total globular cluster system (GCS) mass and its halo mass has been studied for decades and it has been found that galaxies at nearly all observed masses adhere to a linear scaling relation between these properties. However, while we have ample, homogeneous data for galaxies with halo masses Mh ≳ 1010 M⊙ the data available for low-mass galaxies are more sparse, and both GCS mass and halo mass estimates are determined using varying methodologies. This work compiles all available literature data for dwarf galaxies with confident stellar mass and globular cluster (GC) count estimates, and converts these estimates to GCS masses and peak halo masses using a standard conversion. This allows for a consistent comparison of these masses to be made and a complete study of the behaviour of the MGCS─Mh relation to be conducted. We compare the positions of classical dwarfs on the scaling relation to those of ultradiffuse galaxies and extremely low surface brightness galaxies and find that these nonclassical dwarfs have, on average, systematically higher GC specific frequencies. This also makes them, on average, systematically positively offset from the MGCS─Mh relation, driving much of the high-MGCS scatter observed.

Keywords: Globular star clusters, Dwarf galaxies, Scaling relations, Catalogs, Low surface brightness galaxies
ALMA Lensing Cluster Survey: Molecular Gas Properties of Line-emitting Galaxies from a Blind Survey. We present results of a blind search for line-emitting galaxies using Atacama Large Millimeter/submillimeter Array (ALMA) Lensing Cluster Survey data. We detected seven line emitters, one of which is [C II] at z = 6.071, four are CO at z = 0.8─1.1, and the remaining two are possibly CO or [C I] within photometric redshift ranges. Three of the four CO emitters are multiple images of the same galaxy. Compared to previous line-emitter searches in ALMA deep fields, our sample probes molecular gas masses ∼1 dex below the lower bound, thanks to gravitational lensing (typically μ ∼ 4, up to ∼30 in extreme cases). Most emitters are located in a region similar to normal star-forming galaxies in the star formation rate (SFR) versus molecular gas mass plane. To reduce dependence on SFR and stellar mass, we analyzed the molecular gas fraction and depletion timescale as a function of distance from the star formation main sequence. We found that most emitters broadly follow the scaling relations from previous studies, consistent within the intrinsic scatter. In addition, we serendipitously detected the CH N = 1, J = 3/2 → 1/2 Λ-doublet transition from one CO emitter at z = 1.142, representing the first detection of CH from an individual galaxy at cosmological distances through a blind survey. The CH/CO column density ratio of ∼10−4 is comparable to that of local active galactic nucleus (AGN)-host galaxies, suggesting that CH traces molecular gas associated with AGN activity, possibly irradiated by X-rays.

Keywords: Cosmology, Galaxy formation, Millimeter astronomy, Galaxy evolution, High-redshift galaxies, Interferometry
Taming the Plunge: A Circularization Trap of Supermassive Black Hole Binaries. We investigate the orbital eccentricity evolution of supermassive black hole binaries (SMBHBs; 104─107 M⊙) within galactic environments. Merger timescales depend on eccentricity when gravitational-wave (GW) emission dominates. We analyze the dynamics in triaxial merger remnants and subsequent interactions with geometrically thick nuclear disks. Gravitational torques in triaxial potentials extract angular momentum (TJ ≪ TE), resulting in binary formation with high initial eccentricities (e &gt; 0.95). We analyze the binary─disk interaction using a 3D analytical framework incorporating the Airy formalism and present a self-consistent derivation demonstrating that the 3D suppression of high-order torques leads to distinct scalings with disk thickness (h), with migration rates  τa−1∝h−3  and eccentricity damping rates  τe−1∝h−5 , which establish a timescale hierarchy, τe/τa ∝ h2. For typical parameters, eccentricity damping is significantly faster than orbital decay (τe ≍ 0.04τa). We further develop a wavelet-based formalism to quantify the impact of disk inhomogeneities arising from accretion feedback and turbulence. We derive the stochastic torque variance in the wavelet domain and employ a Fokker─Planck analysis to determine the equilibrium eccentricity distribution. While stochastic fluctuations counteract deterministic damping, the strong damping imposed by the thick disk geometry ensures the equilibrium eccentricity remains small unless the fluctuations are highly nonlinear. Hence, highly eccentric born SMBHBs are rapidly circularized. This "circularization trap" forces binaries to approach the GW-dominated regime on nearly circular orbits, prolonging the total merger timescale. This introduces a cosmological delay (0.3─2.5 Gyr) governed by stellar relaxation.

Keywords: Gravitational wave sources, Cosmology, Galaxies
Unified g- and r-mode Analysis of Accreting White Dwarf Stars. Dwarf novae are a subset of cataclysmic variables that accrete material intermittently in short-duration outbursts with sometimes long quiescent intervals in between. During the quiescent state, the white dwarf (WD) photosphere may be observable. Some of these systems show periodic variability consistent with a nonradial oscillation. Asteroseismology has become a unique tool for the measurement of the internal structure of the WDs, such as their masses, radii, temperatures, and rotation profiles. A few stable periodicities have been observed for accreting WDs, but the lack of complete and accurate theoretical models has hindered the real diagnosis of the observed pulsations. Though the associated pulsations in accreting WDs are thought to be g-modes, some work in the literature suggests that these pulsations could be Rossby modes (r-modes). Here, to elucidate this, we present a first simultaneous analysis of g- and r-mode pulsations in accreting WDs, including a full computation of visibility accounting for the distribution of variation over the WD surface. We show that, up to the second lowest degree (ℓ = 2), neither g- nor r-modes have a clear advantage in visibility. Although a few retrograde r-mode orders exhibit a larger visibility, the low-order g-modes possess a higher frequency in the star's frame, making them more likely to be driven within the convective driving scenario commonly applied to isolated WDs. Therefore, we favor a g-mode origin for the observed periods in accreting WDs, though r-modes will be important for stars with more observed modes.

Keywords: White dwarf stars, Dwarf novae, Stellar oscillations, Cataclysmic variable stars, Asteroseismology, Stellar evolution
Particle Transport from First Principles in the Early Heliosphere: κ<SUP>1</SUP> Ceti as a Case Study for the Young Sun. Several studies of Galactic cosmic-ray (GCR) modulation within the astrospheres of stars deemed to be proxies for the young Sun have concluded that the intensities of these particles would, at early stages of the Sun's evolution, be negligible at 1 au. These studies, however, do not take into account the varying interstellar conditions the young Sun would have encountered as it traversed its Galactic orbit, nor do they realistically model the transport of GCRs. The present study, for the first time, examines the influence of various interstellar parameters in the Galactic spiral arms on the astrosphere of κ1 Ceti, a young Sun proxy, through magnetohydrodynamic modelling. We demonstrate that these conditions lead to an astrosphere with considerably smaller dimensions than previous estimates. We also model the transport of turbulence parameters within said astrosphere for the first time, demonstrating that turbulence levels could be significantly higher than observed in the heliosphere. Finally, these insights are implemented in a 3D, ab initio GCR transport model to compute GCR intensities at 1 au, demonstrating the importance of drift effects in astrospheric modulation: full drift effects lead to GCR intensities comparable to modern observations, while turbulence-reduced drift coefficients lead to significantly smaller intensities.

Keywords: Astrospheres, Interplanetary turbulence, Galactic cosmic rays, Solar evolution, Magnetohydrodynamical simulations