Sazuna/UAT_keywords huggingface dataset:
A Generalized Method for Characterizing 21 cm Power Spectrum Signal Loss from Temporal Filtering of Drift-scanning Visibilities. A successful detection of the cosmological 21 cm signal from intensity mapping experiments (e.g., during the Epoch of Reionization or Cosmic Dawn) is contingent on the suppression of subtle systematic effects in the data. Some of these systematic effects, with mutual coupling a major concern in interferometric data, manifest with temporal variability distinct from that of the cosmological signal. Fringe-rate filtering—a time-based Fourier filtering technique—is a powerful tool for mitigating these effects; however, fringe-rate filters also attenuate the cosmological signal. Analyses that employ fringe-rate filters must therefore be supplemented by careful accounting of the signal loss incurred by the filters. In this paper, we present a generalized formalism for characterizing how the cosmological 21 cm signal is attenuated by linear time-based filters applied to interferometric visibilities from drift-scanning telescopes. Our formalism primarily relies on analytic calculations, and therefore has a greatly reduced computational cost relative to traditional Monte Carlo signal loss analyses. We apply our signal loss formalism to a filtering strategy used by the Hydrogen Epoch of Reionization Array (HERA) and compare our analytic predictions against signal loss estimates obtained through a Monte Carlo analysis. We find excellent agreement between the analytic predictions and Monte Carlo estimates and therefore conclude that HERA, as well as any other drift-scanning interferometric experiment, should use our signal loss formalism when applying linear, time-based filters to the visibilities.

Keywords: Cosmology, Radio interferometry, Time series analysis
The Low-redshift Lyman Continuum Survey: The Roles of Stellar Feedback and Interstellar Medium Geometry in LyC Escape. One of the fundamental questions of cosmology is the origin and mechanism(s) responsible for the reionization of the Universe beyond z ∼ 6. Many studies have focused on Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) observations of local (z ∼ 0.3) galaxies emitting ionizing radiation (Lyman continuum, or LyC) for insight. However, LyC measurements can depend on chance alignment of optically thin channels with the observer. In addition, low signal in the spectra of these faint LyC emitters inhibits constraints on gas geometry and stellar populations. To circumvent these limitations, we analyze stacks of a consolidated sample of HST/COS observations of the LyC in 89 galaxies at z ∼ 0.3. From fitting of the continuum, we obtain information about the underlying stellar populations, emergent LyC, and neutral interstellar medium geometry. We find that most LyC nondetections are not leaking appreciable LyC ( fescLyC  &lt; 1%), but also that exceptional cases point to spatial variations in the LyC escape fraction  fescLyC . Stellar populations younger than 3 Myr lead to an increase in ionizing feedback, which in turn increases the isotropy of LyC escape. Wolf–Rayet stars and 3–6 Myr populations appear to play little role in LyC escape. Mechanical feedback from supernovae in 8–10 Myr stellar populations is important for anisotropic gas distributions needed for LyC escape. While mechanical feedback is necessary for any LyC escape, high  fescLyC  (&gt;5%) also requires a confluence of young stars and ionizing feedback. A two-stage burst of star formation is critical to producing this optimal LyC escape scenario, and should be considered fundamental to identifying LyC emitters at the Epoch of Reionization.

Keywords: Stellar feedback, Hubble Space Telescope, Galaxy stellar content, Emission line galaxies, Galactic and extragalactic astronomy, Interstellar medium, Reionization
Trials and Tribulations of Chemodynamical Tagging: Investigating the Recovery of Open Clusters in the Gaia Data Release 3 and GALAH Data Release 4 Catalogs. Chemodynamical tagging has been suggested as a powerful tool to trace stars back to their birth clusters. However, the efficacy of chemodynamical tagging as a means to recover individual stellar clusters is still under debate. In this study, we present a detailed investigation of chemodynamical tagging of open clusters using both dynamical and chemical data from the Gaia Data Release 3 and GALAH Data Release 4 surveys, respectively. Using a sample of open clusters and mock field stars, we conduct a bootstrap analysis to evaluate every unique combination of orbital components (E, JR, Jϕ, JZ) and chemical abundances ([X/Fe] for O, Na, Mg, Al, Si, K, Ca, Sc, Ti, Cr, Mn, Ni, Cu, Y, and Ba) on how well they recover open clusters when used as parameters in the clustering algorithm HDBSCAN. We find that using primarily dynamical orbital parameters leads to the highest recovery rate of open cluster stars. Nevertheless, even employing the best performing parameter combinations leads to low open cluster recovery rates. We find that, in most cases, chemodynamical tagging of open clusters using blind clustering algorithms is not efficient, which is in line with previous theoretical and observational work. However, we show that the addition of cuts based on metallicity, age, and birth radius in order to reduce the size of the clustering catalog can marginally improve the recovery rate of open clusters.

Keywords: Open star clusters, Stellar ages, Milky Way formation, Chemical abundances
SOFIA/upGREAT Imaging Spectroscopy of the [C II] 158 μm Fine-structure Line toward the Sgr A Region in the Galactic Center. We present SOFIA/upGREAT velocity-resolved spectral imaging and analysis of the λ158 μm [C II] spectral line toward the central 80 by 43 pc region of the Central Molecular Zone of the Galaxy. The field we imaged with 14″ (0.6 pc) spatial and 1 km s‑1 spectral resolution contains the circumnuclear disk (CND) around the central black hole Sgr A*, the neighboring thermal Arched Filaments, the nonthermal filaments of the Radio Arc, and the three luminous central star clusters. [C II] traces emission from the CND's inner edge to material orbiting at a distance of approximately 6 pc. Its velocity field reveals no sign of inflowing material nor interaction with winds from the Sgr A East supernova remnant. Wide-field imaging of the Sgr A region shows multiple circular segments, including the thermal Arched Filaments, that are centered on a region that includes the Quintuplet cluster. We examine the possibility that the Arched Filaments and other large-scale arcs trace transient excitation events from supernova blast waves. Along the Arched Filaments, comparisons among far-infrared fine-structure lines show changes in the ionization state over small scales and that high-excitation lines are systematically shifted in position from the other lines. These also point to transient fast winds that produce shocks on the surface of the Arches cloud to produce additional local ultraviolet (UV) radiation to excite the Arched Filaments on a cloud surface illuminated by UV from hot stars.

Keywords: High resolution spectroscopy, Galactic center, Star forming regions, Photodissociation regions, Interstellar medium
Exploring Cosmological Constraints of the Weak Gravitational Lensing and Galaxy Clustering Joint Analysis in the CSST Photometric Survey. We explore the joint weak lensing and galaxy clustering analysis from the photometric survey operated by the China Space Station Telescope (CSST) and study the strength of the cosmological constraints. We employ a high-resolution JiuTian-1G simulation to construct a partial-sky light cone to z = 3 covering 100 deg2 and obtain the CSST galaxy mock samples based on an improved semianalytical model. We perform a multi-lens-plane algorithm to generate corresponding synthetic weak lensing maps and catalogs. Then we generate the mock data based on these catalogs considering the instrumental and observational effects of the CSST and use the Markov Chain Monte Carlo method to perform the constraints. The covariance matrix includes non-Gaussian contributions and supersample covariance terms, and the systematics from intrinsic alignments, galaxy bias, photometric redshift uncertainties, shear calibration, and nonlinear effects are considered in the analysis. We find that the constraint result is comparable to that from Stage III surveys, and it can be significantly improved further in the full CSST survey with 17,500 deg2. This indicates the CSST photometric survey is powerful for exploring the Universe.

Keywords: Large-scale structure of the universe, Dark matter, Cosmological parameters
Cosmology from Point Clouds with Dark Matter Halos from the Quijote Simulations. We train a novel deep learning architecture to perform likelihood-free inference on the value of the cosmological parameters from halo catalogs of the Quijote N-body simulations. Our model takes as input a halo catalog where each halo is characterized by its position, mass, and velocity modulus. By construction, our model is E(3) invariant and is designed to extract information hierarchically. Unlike graph neural networks, it does not require the transformation of the input halo (or galaxy) catalog into a graph. Given its simplicity, our model can process point clouds with large numbers of points. We discuss the advantages of this class of methods but also point out their limitations and potential ways to improve them for cosmological data.

Keywords: N-body simulations, Cosmological parameters from large-scale structure
A Comparison of Geminid Models with the PSP/WISPR-observed Phaethon Dust Trail. White-light observations from the Wide-Field Imager for Parker Solar Probe (WISPR) instrument on NASA's Parker Solar Probe recently revealed the presence of a narrow, dense dust trail close to the orbit of asteroid 3200 Phaethon. Although Geminid related, it aligns imperfectly with Phaethon's orbit and known Geminid meteoroid orbits. To address the nature of this dust trail, we performed a detailed comparison between the WISPR trail observations and several well-developed Geminid models. Simulating these models in the WISPR field of view visually demonstrates that the WISPR trail almost certainly represents the true "density core" of the Geminid stream. Trends in model trail width and offset from Phaethon's orbit, both as functions of true anomaly, agree with observations to varying extents. All the models, however, place their apparent core interior to the parent orbit due to Poynting–Robertson forces, contradictory to the WISPR trail, which is exterior to Phaethon's orbit. Therefore, Phaethon's current orbit likely does not represent the orbit of the system parent, which most probably had a larger semimajor axis. These findings provide new initial conditions for future Geminid models, with WISPR identifying the Geminid core's position.

Keywords: Meteoroid dust clouds, Asteroids, Small Solar System bodies
Collisionless Shocks Having Relativistic Velocities in Relativistically Hot Plasmas. Shocks in relativistically hot plasmas are thought to exist in various high-energy astrophysical phenomena, but it is not clear how relativistic collisionless shocks are formed, and whether particles are accelerated by the shock as in the case of cold upstream. In this work, collisionless shocks with a relativistic shock velocity in relativistically hot, unmagnetized electron–positron plasmas are investigated by two-dimensional particle-in-cell simulations. It is shown that the upstream flow is dissipated by the Weibel instability, so that the relativistic collisionless shock is formed as in the case of cold upstream. The density and magnetic field structures around the shock front are almost independent of the upstream temperature when the spatial scale is normalized by the inertial length scale, which takes into account the relativistic temperature. This can be understood by considering the pressure anisotropy, which asymptotically approaches a finite value due to the relativistic beaming effect, even as the temperature becomes relativistically hotter and hotter. In addition, as long as the shock velocity is relativistic, some particles are accelerated, forming a power-law energy spectrum similar to that in the cold upstream.

Keywords: Gamma-ray bursts, High energy astrophysics, Plasma physics, Plasma astrophysics, Shocks
The Impact of Plasma Angular Momentum on Magnetically Arrested Flows and Relativistic Jets in Hot Accretion Flows around Black Holes. In certain scenarios, the accreted angular momentum of plasma onto a black hole could be low; however, how the accretion dynamics depend on the angular momentum content of the plasma is still not fully understood. We present three-dimensional, general relativistic magnetohydrodynamic simulations of low angular momentum accretion flows around rapidly spinning black holes (with spin a = +0.9). The initial condition is a Fishbone–Moncrief (FM) torus threaded by a large amount of poloidal magnetic flux, where the angular velocity is a fraction f of the standard value. For f = 0, the accretion flow becomes magnetically arrested and launches relativistic jets but only for a very short duration. After that, free-falling plasma breaks through the magnetic barrier, loading the jet with mass and destroying the jet–disk structure. Meanwhile, magnetic flux is lost via giant, asymmetrical magnetic bubbles that float away from the black hole. The accretion then exits the magnetically arrested state. For f = 0.1, the dimensionless magnetic flux threading the black hole oscillates quasiperiodically. The jet–disk structure shows concurrent revival and destruction while the gas outflow efficiency at the event horizon changes accordingly. For f ≥ 0.3, we find that the dynamical behavior of the system starts to approach that of a standard accreting FM torus. Our results thus suggest that the accreted angular momentum is an important parameter that governs the maintenance of a magnetically arrested flow and launching of relativistic jets around black holes.

Keywords: Accretion, Black hole physics, Black holes, High energy astrophysics, Relativistic jets, Plasma astrophysics, General relativity, Magnetohydrodynamical simulations
High-time-cadence Spectroscopy and Photometry of Stellar Flares on M-dwarf YZ Canis Minoris with Seimei Telescope and TESS. II. Statistical Properties of Blue/Red Asymmetries in the Hα Line. M-dwarfs frequently produce flares, and their associated coronal mass ejections (CMEs) may threaten the habitability of close-in exoplanets. M-dwarf flares sometimes show prominence eruption signatures, observed as blue/red asymmetries in the Hα line. In Paper I, we reported four candidates of prominence eruptions, which show large diversity in their durations and velocities. In this study, we statistically investigate how blue/red asymmetries are related to their flare and starspot properties, using the data set from 27 Hα flares in Paper I and previously reported 8 Hα flares on an M-dwarf, YZ Canis Minoris. We found that these asymmetry events tend to show larger Hα flare energies compared to nonasymmetry events. In particular, five out of six blue asymmetry events are not associated with white-light flares, whereas all seven red asymmetry events are associated with white-light flares. Furthermore, their starspot distributions estimated from the Transiting Exoplanet Survey Satellite light curve show that all prominence eruption candidates occurred when starspots were located on the stellar disk center as well as on the stellar limb. These results suggest that flares with lower heating rates may have a higher association rate with prominence eruptions and/or the possibility that prominence eruptions are more detectable on the limb than on the disk center on M-dwarfs. These results provide significant insights into CMEs that can affect the habitable world around M-dwarfs.

Keywords: M dwarf stars, Flare stars, Stellar flares, Optical flares, Stellar coronal mass ejections
Polarization Properties of the Electromagnetic Response to High-frequency Gravitational Wave. Electromagnetic waves (EMWs) can be generated by gravitational waves (GWs) within a magnetic field via the Gertsenshtein effect. The conversion probability between GWs and EMWs can be enhanced by inhomogeneities in the electron density and magnetic field within the magnetized plasma of both the Milky Way (MW) and the intergalactic medium in the expanding Universe. Polarized GWs can induce polarized EMWs, and the polarization properties of these EMWs can be altered by Faraday rotation as they propagate through magnetized plasma. Additionally, the polarization intensity of the EMWs may be weakened due to depolarization effects. In this study, we calculate the enhanced GW–EMW conversion in inhomogeneous magnetized plasma during the propagation of GWs through the Universe and our galaxy. We analyze the polarization states of the EMWs generated by polarized GWs and discuss the depolarization effects induced by the medium's irregularities, as well as the differential Faraday rotation occurring in multilayer polarized radiation. Our work provides alternative methods for detecting GWs and exploring their polarization states, and potentially constraining the parameters of the possible GW sources, especially the primordial black hole, contributing to the advancement of very-high-frequency GW detection and research.

Keywords: Radio astronomy, Polarimetry, Gravitational waves
Data-constrained Magnetohydrodynamic Simulation of a Filament Eruption in the Decaying Active Region 13079 on a Global Scale. Filaments are special plasma phenomena embedded in the solar atmosphere, characterized by unique thermodynamic properties and magnetic structures. Magnetohydrodynamic (MHD) simulations are useful to investigate the eruption mechanisms of filaments. We conduct a data-constrained zero-β MHD simulation in spherical coordinates to investigate a C3.5 class flare triggered by an eruptive filament on 2022 August 15 in the decaying weak active region 13079. We reconstruct the three-dimensional coronal magnetic field using vector magnetograms and synoptic maps from the Solar Dynamics Observatory/Helioseismic and Magnetic Imager. We transform the vector magnetic field into Stonyhurst heliographic spherical coordinates combined with a synoptic map and construct a potential field source surface model with a magnetic flux rope embedded using the regularized Biot–Savart laws. Subsequently, we conduct a spherical zero-β MHD simulation using the message-passing interface adaptive mesh refinement versatile advection code (MPI-AMRVAC) and replicate the entire dynamic process of the filament eruption consistent with observations. With the calculation of the time–distance profile, quasi-separatrix layers, and synthetic radiation from simulated current density, we find a good agreement between our simulation and observations in terms of dynamics and magnetic topology. Technically, we provide a useful method of advanced data-constrained simulation of weak active regions in spherical coordinates. Scientifically, the model allows us to quantitatively describe and diagnose the entire process of filament eruption.

Keywords: Solar filaments, Solar corona, Solar coronal mass ejections, Solar magnetic fields, Solar activity
Multimessenger Emission by Magnetically Arrested Disks and Relativistic Jets of Black Hole X-Ray Binaries. Black hole X-ray binaries (BHXBs) are observed in various wavelengths from radio to GeV gamma rays. Several BHXBs, including MAXI J1820+070 and Cygnus X-1, are also found to emit ultrahigh-energy (UHE; photon energy &gt; 100 TeV) gamma rays. The origin and production mechanism of the multiwavelength emission of BHXBs are under debate. We propose a scenario where relativistic particles from magnetically arrested disks (MADs), which could form when BHXBs are in quiescent or hard states, produce UHE gamma rays, while electrons in the jets produce GeV gamma-ray emission. Specifically, magnetic turbulence in MADs heats up and accelerates electrons and protons, while magnetic reconnection in jets accelerates electrons. Sub-PeV gamma rays and neutrinos are produced when relativistic protons interact with thermal protons and the radiation emitted by thermal electrons in the disk. We discuss the perspectives of observing sub-PeV multimessenger signals from individual BHXBs. Finally, we evaluate the integrated fluxes of the quiescent and hard-state BHXB population and find that BHXBs may contribute to the Galactic diffuse emission above ∼100 TeV.

Keywords: Accretion, Stellar mass black holes, Non-thermal radiation sources, Cosmic ray sources, Low-mass x-ray binary stars
Relativistic Time Transformations between the Solar System Barycenter, Earth, and Moon. Relativistic corrections are essential for time transformations between geocentric, solar system barycentric, and lunicentric reference systems to account for differences in gravitational potential and relative motion. As the primary reference for Earth-based systems, Terrestrial Time (TT) provides the foundation for precise synchronization across spatial and temporal frameworks. To ensure consistency with TT, Barycentric Dynamical Time (TDB) must exhibit no average rate difference from TT. Although the International Astronomical Union has established resolutions for transformations between TT and TDB, extending these frameworks to define a lunar surface timescale (TL) is essential for advancing lunar exploration. This paper derives the (TL ‑ TT) transformation, quantifying a secular drift of 56.0256 μs day‑1 and periodic terms, with the largest amplitude of ∼0.470 μs at the mean anomalistic period. Additionally, the TT-compatible spatial scale and Lorentz contraction of Moon-centered positional coordinates are computed, achieving subnanosecond timing precision. These transformations, implemented in JPL ephemeris generation software, provide a robust framework for high-fidelity relativistic models of lunar timekeeping, enabling further refinements and supporting navigation, communication, and scientific operations in cis-lunar space.

Keywords: Relativity
Upper Bounds on the Mass of Fundamental Fields from the Primordial Universe. We study the fluctuations in the vacuum zero-point energy associated with quantum fields and their statistical distributions during inflation. It is shown that the perturbations in the vacuum zero-point energy have large amplitudes that are highly non-Gaussian. The effects of vacuum zero-point fluctuations can be interpreted as the loop corrections in the primordial power spectrum and bispectrum. Requiring that the primordial curvature perturbation remains nearly Gaussian and the loop corrections are under perturbative control imposes strong upper bounds on the mass of fundamental fields during inflation. These bounds depend on the hierarchy of the masses in the theory, such as whether or not the masses are at similar orders. While the mass of the heaviest field in the hierarchy may not be constrained, it is shown that a combination of the masses of the fields cannot be much heavier than the Hubble scale during inflation, otherwise their vacuum zero-point fluctuations induce large non-Gaussianities in primordial perturbations. Considering the observational upper bound on the tensor to scalar ratio, we conclude that this combined mass scale is lighter than 1014 GeV.

Keywords: Cosmological constant, Cosmic inflation, Cosmological perturbation theory