Sazuna/UAT_keywords huggingface dataset:
A Core-sensitive Mixed f/g-mode of the Sun Predicted by Wave Topology and Hydrodynamical Simulation. Helioseismology has revolutionized our understanding of the Sun by analyzing its global oscillation modes. However, the solar core remains elusive, limiting a full understanding of its evolution. In this work, we study a previously unnoticed global oscillation mode of the Sun using a fully compressible hydrodynamical simulation of the solar interior and assess that it is a mixed f/g-mode with a period of about 1 hr. This is the first global stellar hydrodynamics simulation to successfully couple compressible and gravity modes. To understand this coupling, we invoke a recent theory on the nature of f-modes seen through the prism of wave topology, characterizing their ability to propagate deep into stellar interiors. We demonstrate that the mixed f/g-mode is highly sensitive to the core's rotation rate, providing a new promising pathway to explore the Sun's core.

Keywords: Stellar interiors, Hydrodynamical simulations, Hydrodynamics, Helioseismology, Stellar physics, Solar physics, Stellar oscillations, Asteroseismology
Correlations between Event Rates of Short Gamma-Ray Bursts and Star Formation Rates with/without Time Delay. In this Letter, we systematically investigate the redshift and luminosity distributions as well as the event rates of short gamma-ray bursts (SGRBs) detected by Swift, Fermi, and Konus–Wind satellites. It is found that the distributions of redshift and luminosity of Fermi and Konus–Wind SGRBs are identical, and they obviously differ from those of Swift/Burst Alert Telescope (BAT) SGRBs. The luminosity distributions of SGRBs detected by diverse detectors can be uniformly fitted by a smoothly broken power-law function. The median luminosity of Swift SGRBs is about 1 order of magnitude smaller than that of Fermi/Gamma-ray Burst Monitor (GBM) or Konus–Wind SGRBs. We also compare the local event rates of Swift/BAT, Fermi/GBM, and Konus–Wind SGRBs and find that the local rate of Swift SGRBs is around 2 orders of magnitude larger than that of either Fermi or Konus–Wind SGRBs, while the latter two rates are comparable. The observed SGRB rates can be successfully fitted by a power law plus Gauss function. The SGRB rates of three kinds of detectors match the delayed/undelayed star formation rates (SFRs) well, except the delayed lognormal and/or Gaussian SFRs at higher redshift, and exceed all types of SFRs at lower redshifts of z &lt; 1. After deducting the diverse SFR components from the SGRB rates, to our surprise, we notice that the remaining SGRB rates steeply decline with redshift in a power-law-like form, indicating that these SGRBs could emerge from the old star populations or compact binary star mergers.

Keywords: Gamma-ray bursts, Star formation
An Ejection Event Captured by Very Long Baseline Interferometry during the Outburst of Swift J1727.8–1613. We observed a newly discovered Galactic black hole X-ray binary Swift J1727.8–1613 with the European VLBI Network (EVN) at 5 GHz. The observation was conducted immediately following a radio quenching event detected by the Karl G. Jansky Very Large Array. The visibility amplitude evolution over time reveals a large-amplitude radio flare and is consistent with an ejection event. The data can be interpreted either as a stationary component (i.e., the radio core) and a moving blob, or as two blobs moving away from the core symmetrically in opposite directions. The initial angular separation speed of the two components was estimated to 30 mas day‑1. We respectively fitted a single circular Gaussian model component to each of 14 sliced visibility data sets. For the case of including only European baselines, during the final hour of the EVN observation, the fitted sizes exhibited linear expansion, indicating that the measured sizes were dominated by the angular separation of the two components. The 6 hr EVN observation took place in a rising phase of an even larger 4 day long radio flare, implying that the ejection events were quite frequent and therefore continuous radio monitoring is necessary to correctly estimate the power of the transient jet. Combined with X-ray monitoring data, the radio quenching and subsequent flares/ejections were likely driven by instabilities in the inner hot accretion disk.

Keywords: X-ray photometry, Jets, Very long baseline interferometry, Radio continuum emission, Low-mass x-ray binary stars
A High-Caliber View of the Bullet Cluster through JWST Strong and Weak Lensing Analyses. The Bullet Cluster (1E 0657-56) is a key astrophysical laboratory for studying dark matter, galaxy cluster mergers, and shock propagation in extreme environments. Using new JWST imaging, we present the highest-resolution mass reconstruction to date, combining 146 strong lensing constraints from 37 systems with high-density (398 sources arcmin‑2) weak lensing data, without assuming that light traces mass. The main cluster's mass distribution is highly elongated (northwest–southeast) and consists of at least three subclumps aligned with the brightest cluster galaxies. The subcluster is more compact but elongated along the east–west direction, with a single dominant peak. We also detect a possible mass and intracluster light (ICL) trail extending from the subcluster's eastern side toward the main cluster. Notably, these detailed features are closely traced by the ICL, with a modified Hausdorff distance of 19.80 ± 12.46 kpc. Together with multiwavelength data, the complex mass distribution suggests that the merger history of the Bullet Cluster may be more complex than previous binary cluster merger scenarios.

Keywords: Weak gravitational lensing, Galaxy clusters, Strong gravitational lensing, James Webb Space Telescope, Dark matter
A Nanosecond-duration Radio Pulse Originating from the Defunct Relay 2 Satellite. We report the detection of a burst of emission over a 695.5–1031.5 MHz bandwidth by the Australian Square Kilometre Array Pathfinder. The burst was localized through analysis of near-field time delays to the long-decommissioned Relay 2 satellite and exhibited a dispersion measure of 2.26 × 10‑5 pc cm‑3—69.7 total electron content units, consistent with expectations for a single pass through the ionosphere. After coherent dedispersion, the burst was determined to be less than 30 ns in width, with an average flux density of at least 300 kJy. We consider an electrostatic discharge (ESD) or plasma discharge following a micrometeoroid impact to be plausible explanations for the burst. ESDs have previously been observed with the Arecibo radio telescope, but on 1000 times longer timescales. Our observation opens new possibilities for the remote sensing of ESD, which poses a serious threat to spacecraft, and reveals a new source of false events for observations of astrophysical transients.

Keywords: Artificial satellites, Time domain astronomy, Radio transient sources
Decoding Long-duration Gravitational Waves from Binary Neutron Stars with Machine Learning: Parameter Estimation and Equations of State. Gravitational waves (GWs) from binary neutron stars (BNSs) offer a valuable understanding of the nature of compact objects and hadronic matter, and the science potential will be greatly enhanced by the third-generation (3G) GW detectors, which are expected to detect BNS signals with order-of-magnitude improvements in duration, detection rates, and signal strength. However, the resulting computational demands for analyzing such prolonged signals pose a critical challenge that existing Bayesian methods cannot feasibly address in the 3G era. To bridge this critical gap, we demonstrate a machine learning–based workflow capable of producing source parameter estimation and constraints on equations of state (EOSs) for hours-long BNS signals in seconds with minimal hardware costs. We employ efficient compression of the GW data and EOS using neural networks, based on which we build normalizing flows for inference that can deliver results in seconds. The optimized computational cost of BNS signal analysis with our framework shows that machine learning has the potential to be an indispensable tool for future catalog-level BNS analyses, paving the way for large-scale investigations of BNS-related physics across the 3G observational landscape.

Keywords: Neutron stars, Astronomy data analysis, Gravitational wave astronomy, Nuclear astrophysics, Gravitational waves
Colors and Dynamics of a Near-Sun Orbital Asteroid Family: 2021 PH27 and 2025 GN1. We observed the dynamically similar near-Sun asteroids 2021 PH27 and 2025 GN1 for their optical colors. These objects have the lowest known semimajor axes of any asteroids. 2021 PH27 has the largest general relativistic effects of any known solar system object. The small semimajor axis and very close passage to the Sun suggest the extreme thermal and gravitational environment should highly modify these asteroids' surfaces. From g'-, r'-, i'-, and z'-band imaging, we find the colors of 2021 PH27 ( g'‑r'=0.58±0.02 ,  r'‑i'=0.12±0.02 , and  i'‑z'=‑0.08±0.05  mag) to be between the two major asteroid types: the S and C classes. With a spectral slope of 6.8 ± 0.03 percent per 100 nm, 2021 PH27 is an X-type asteroid and requires albedo or spectral features to further identify its composition. We find the dynamically similar 2025 GN1 also has very similar colors ( g'‑r'=0.55±0.06  and  r'‑i'=0.14±0.04 ) as 2021 PH27, suggesting these objects are fragments from a once larger parent asteroid or 2021 PH27 is shedding material. The colors are not blue like some other near-Sun asteroids such as 3200 Phaethon that have been interpreted to be from the loss of reddening substances from the extreme temperatures. There is no evidence of activity or a large amplitude period for 2021 PH27, whereas 2025 GN1 might have a more significant rotational light curve. 2025 GN1 may have a very close encounter or hit Venus in about 2300 yr and likely separated from 2021 PH27 in the last ∼10 kyr.

Keywords: Near-Earth objects, Atira group
Polarized Multiwavelength Emission from Pulsar Wind—Accretion Disk Interaction in a Transitional Millisecond Pulsar. Transitional millisecond pulsars (tMSPs) bridge the evolutionary gap between accreting neutron stars in low-mass X-ray binaries and millisecond radio pulsars. These systems exhibit a unique subluminous X-ray state characterized by the presence of an accretion disk and rapid switches between high and low X-ray emission modes. The high mode features coherent millisecond pulsations spanning from the X-ray to the optical band. We present multiwavelength polarimetric observations of the tMSP PSR J1023+0038 aimed at conclusively identifying the physical mechanism powering its emission in the subluminous X-ray state. During the high mode, we report a probable detection of polarized emission in the 2─6 keV energy range, with a polarization degree of (12 ± 3)% and a polarization angle of −2∘ ± 9∘measured counterclockwise from the north celestial pole toward the east (99.7% confidence level, c.l.; uncertainties are quoted at 1σ). At optical wavelengths, we find a polarization degree of (1.41 ± 0.04)% and a polarization angle aligned with that in the X-rays, suggesting a common physical mechanism operating across these bands. Remarkably, the polarized flux spectrum matches the pulsed emission spectrum from optical to X-rays. The polarization properties differ markedly from those observed in other accreting neutron stars and isolated rotation-powered pulsars and are also inconsistent with an origin in a compact jet. Our results provide direct evidence that the polarized and pulsed emissions both originate from synchrotron radiation at the boundary region formed where the pulsar wind interacts with the inner regions of the accretion disk.

Keywords: Neutron stars, Accretion, Millisecond pulsars, Relativistic jets, Compact binary stars
The Double Tidal Disruption Event AT 2022dbl Implies that at Least Some "Standard" Optical Tidal Disruption Events Are Partial Disruptions. Flares produced following the tidal disruption of stars by supermassive black holes can reveal the properties of the otherwise dormant majority of black holes and the physics of accretion. In the past decade, a class of optical-ultraviolet tidal disruption flares has been discovered whose emission properties do not match theoretical predictions. This has led to extensive efforts to model the dynamics and emission mechanisms of optical-ultraviolet tidal disruptions in order to establish them as probes of supermassive black holes. Here we present the optical-ultraviolet tidal disruption event AT 2022dbl, which showed a nearly identical repetition 700 days after the first flare. Ruling out gravitational lensing and two chance unrelated disruptions, we conclude that at least the first flare represents the partial disruption of a star, possibly captured through the Hills mechanism. Since both flares are typical of the optical-ultraviolet class of tidal disruptions in terms of their radiated energy, temperature, luminosity, and spectral features, it follows that either the entire class are partial rather than full stellar disruptions, contrary to the prevalent assumption, or some members of the class are partial disruptions, having nearly the same observational characteristics as full disruptions. Whichever option is true, these findings could require revised models for the emission mechanisms of optical-ultraviolet tidal disruption flares and a reassessment of their expected rates.

Keywords: Black hole physics, Tidal disruption, Black holes
How Reconnection-unfavored Magnetic Flux Emergence Suppresses Solar Filament Eruptions. Magnetic flux emergence is traditionally considered to be a key trigger of solar filament eruptions, yet its role in suppressing filament eruptions remains less understood. Using multiwavelength observations from the Solar Dynamics Observatory, this study investigates a unique case of flux emergence below a quiescent filament from 2016 January 3 to 5, where the newly emerging magnetic flux suppressed rather than promoted the eruption of the filament. It is found that the emerging magnetic bipole within the filament channel directly interacted and reconnected with the overlying filament magnetic field and produced a series of two-sided coronal jets along the filament axis. Instead of eruption, the filament kept stable but broke into two segments at the reconnection site. Further magnetic cancellation or recession of the emerged bipole allowed the filament to recover its original structure. Our analysis results revealed that the flux emergence suppressed the filament eruption by reducing the upward net force. The formation and evolution of the filament fine structures (such as filament threads) are closely linked to the reconnection processes between the emerging bipole and the filament's horizontal magnetic field. This study provides direct observational evidence for accounting for the stabilization of solar filaments driven by flux emergence, offering new insights into magnetic emergence's dual role in triggering and suppressing solar eruptions.

Keywords: Solar activity, Solar chromosphere, Solar filaments, Solar magnetic fields
Asymmetries in Fe IX 17.1 nm and Fe XII 19.5 nm Line Profiles as Possible Signatures of Obscuration Dimming in Sun-as-a-star Spectra. We report the possible detection of obscuration dimming, inferred from spectral line asymmetries in Sun-as-a-star extreme ultraviolet spectra. By analyzing asymmetries in the Fe IX 17.1 nm and Fe XII 19.5 nm line profiles obtained from the Solar Dynamics Observatory/Extreme Ultraviolet Variability Experiment during coronal dimming events from 2011 to 2014, we identify two candidate obscuration dimming events associated with M9.3- and X5.4-class flares, respectively. Both events demonstrated prominent irradiance reductions, characterized by greater decreases in blue-wing emission relative to the red wing. These line-profile asymmetries may be attributed to cooler filament material ejected during the flares, moving along the line of sight and partially obscuring hotter coronal emission. The possible obscuration dimming accounted for roughly 18% of the total irradiance loss and persisted for approximately 5–6 hr. Doppler velocity analysis of line profiles enabled us to infer possible motion trends of filament eruptions, which may represent the core regions of coronal mass ejections (CMEs). For event 1, the filament eruption possibly experienced deceleration with partial fallback toward the solar surface or deflection away from the Sun–Earth line, consistent with minimal geomagnetic activity. In contrast, event 2 showed potential acceleration toward Earth, correlating with a significant geomagnetic storm. Our results suggest that the obscuration dimming method presented in this study may serve as a useful diagnostic for constraining CME properties and informing space weather forecasts. In addition, this observational approach may provide a pathway toward identifying stellar CMEs and assessing whether they display the typical three-part structure seen in solar CMEs.

Keywords: Solar extreme ultraviolet emission, Stellar coronal mass ejections, Solar filament eruptions, Spectroscopy, Solar coronal mass ejections
Predictions for New Horizons' SWAP Measurements Downstream of the Heliospheric Termination Shock. Currently ∼62 au from the Sun, the New Horizons spacecraft is en route to the outer heliosphere boundaries. The first boundary it will encounter is the heliospheric termination shock (HTS), where the solar wind ion (SWI) and interstellar pickup ion (PUI) plasma mixture is slowed down to subsonic speeds, compressed, and heated. Some particles, mostly PUIs, undergo preferential acceleration at the HTS due to their higher energies and thus gain the capability to reflect from the shock and undergo, e.g., shock drift acceleration. This produces a tail in the downstream PUI energy distribution, with the potential for multiple power-law breaks. In anticipation of crossing the HTS, we have constructed a test particle model with synthetic turbulence to simulate New Horizons' Solar Wind Around Pluto (SWAP) observations downstream of the HTS. SWAP can measure the energy/charge of multiple particle populations (thermal solar wind (SW) protons, alphas, and PUIs). Here, we calculate what SWAP might observe after it crosses the HTS. Our model shows that the count rate distribution will be very different from what is observed in the supersonic SW, with a hotter SW+PUI distribution and no sharp PUI cutoff. This will require a different method to quantify the moments of the SWIs and PUIs in the heliosheath. SWAP may be able to observe part of the PUI tail downstream of the HTS, if the upstream SW speed is  ≲ 300 km s−1. Moreover, if the shock compression ratio is also  ≳ 2, SWAP may observe multiple populations of the accelerated PUI distribution.

Keywords: Heliosphere, Termination shock, Solar wind, Pickup ions, Interplanetary particle acceleration
Evolution of Cluster Alignments as Evidence of Large-scale Structure Formation in the Universe. The Universe's large-scale structure forms a vast, interconnected network of filaments, sheets, and voids known as the cosmic web. For decades, astronomers have observed that the orientations of neighboring galaxy clusters within these elongated structures are often aligned over separations of tens of Mpc. Using the largest available catalog of galaxy clusters, we show for the first time that cluster orientations are correlated over even larger scales—up to 200–300 comoving Mpc—and such alignments are seen to redshifts of at least z ≃ 1. Comparison with numerical simulations suggests that coherent structures on similar scales may be expected in ΛCDM models.

Keywords: Galaxy clusters, Cosmology, Cosmic web, Large-scale structure of the universe
Was Earth's Water Acquired Locally during the Earliest Phases of the Solar System Formation?. The origin of the terrestrial water remains debated, as standard solar system formation models suggest that Earth formed from dry grains, inside the snowline of the protosolar nebula (PSN). Here, we revisit this issue through the lens of computational chemistry. While the classically used snowline relies on a single condensation temperature, recent work in quantum chemistry shows that the binding energy (BE) of water on icy grains has a Gaussian distribution, which implies a gradual sublimation of water rather than a sharp transition. We use the computed distribution of BEs to estimate the radial distribution of adsorbed ice on the dust grains across the PSN protoplanetary disk. Our model reproduces the full range of estimated water abundances on Earth and matches the hydration trends observed in chondrite groups at their predicted formation distances. Thus, we suggest that a significant fraction of Earth's water may have been acquired locally at early stages of the solar system formation, without requiring delivery from beyond the classical snowline.

Keywords: Solar nebulae, Solar system formation, Astrochemistry
A Relativistic Jet in the Radio-quiet Active Galactic Nucleus Mrk 110. We report the discovery of a relativistic jet in Mrk 110, a narrow-line Seyfert 1 galaxy historically classified as a radio-quiet active galactic nucleus (AGN). Very long baseline interferometry observations reveal intermittent jet activity during 2015–2016 and 2022–2024, with proper-motion measurements yielding superluminal velocities of ∼3.6 ± 0.6c and ∼2.1 ± 0.2c, respectively. The recent jet component decelerates to ∼1.5 ± 0.2c at a projected distance of 1.1 pc from the core, coinciding with the transition zone between broad-line and narrow-line regions. This deceleration accompanies dramatic spectral evolution from steep (spectral index α ≈ ‑0.63 ± 0.04) to inverted (α ≈ +0.69 ± 0.10) as the 7.6 GHz flux density more than doubled. These episodic jet ejections and their evolutionary pattern match theoretical predictions from magnetically arrested disk (MAD) models for temporary jet formation in systems with Mrk 110's physical parameters on timescales of months to years. The observed jet deceleration distance matches expectations for relativistic outflows interacting with the circumnuclear environment. These findings demonstrate that the traditional radio-loud/quiet AGN dichotomy may reflect time-averaged states rather than intrinsic capabilities, suggesting that jets may form across the AGN population but become observable only during specific accretion phases when MAD conditions are temporarily established. Mrk 110 serves as a critical "missing link" between radio-loud and radio-quiet AGN, providing insight into jet formation mechanisms, environmental interactions, and physical processes that unify various AGN classifications.

Keywords: Relativistic jets, Active galactic nuclei, Very long baseline interferometers
On the Formation of S stars from a Recent Massive Black Hole Merger in the Galactic Center. The Galactic center hosts a rotating disk of young stars between 0.05 and 0.5 pc of Sgr A*. The "S stars" at a distance &lt;0.04 pc, however, are on eccentric orbits with nearly isotropically distributed inclinations. The dynamical origin of the S-star cluster has remained a theoretical challenge. Using a series of N-body simulations, we show that a recent massive black hole merger with Sgr A* can self-consistently produce many of the orbital properties of the Galactic nuclear star cluster within 0.5 pc. A black hole merger results in a gravitational-wave recoil kick, which causes the surrounding cluster to form an apse-aligned eccentric disk. We show that stars near the inner edge of an eccentric disk migrate inward and are driven to high eccentricities and inclinations due to secular torques similar to the eccentric Kozai–Lidov mechanism. In our fiducial model, starting with a thin eccentric disk with e = 0.3, the initially unoccupied region within 0.04 pc is populated with high-eccentricity, high-inclination S stars within a few Myr. This formation channel requires a black hole of mass  2‑1.2+3×105M⊙  to have merged with Sgr A* within the last 10 Myr.

Keywords: Supermassive black holes, Galactic center, Stellar dynamics