Sazuna/UAT_keywords huggingface dataset:
Probing the Origin of the Star Formation Excess Discovered by JWST through Gamma-Ray Bursts. The recent observations by the James Webb Space Telescope (JWST) have revealed a larger number of bright galaxies at z ≳ 10 than was expected. The origin of this excess is still under debate, although several possibilities have been presented. We propose that gamma-ray bursts (GRBs) are a powerful probe to explore the origin of the excess and, hence, the star and galaxy formation histories in the early universe. Focusing on the recently launched mission, Einstein Probe (EP), we find that EP can detect several GRBs annually at z ≳ 10, assuming the GRB formation rate calibrated by events at z ≲ 6 can be extrapolated. Interestingly, depending on the excess scenarios, the GRB event rate may also show an excess at z ≃ 10, and its detection will help to discriminate between the scenarios that are otherwise difficult to distinguish. Additionally, we discuss that the puzzling, red-color, compact galaxies discovered by JWST, the so-called "little red dots," could host dark GRBs if they are dust-obscured star-forming galaxies. We are eager for unbiased follow-up of GRBs and encourage future missions such as HiZ-GUNDAM to explore the early universe.

Keywords: Gamma-ray bursts
The Flattest Infrared Extinction Curve in Four Isolated Dense Molecular Cloud Cores. The extinction curve of interstellar dust in the dense molecular cloud cores is crucial for understanding dust properties, particularly size distribution and composition. We investigate the infrared extinction law in four nearby isolated molecular cloud cores—L429, L483, L673, and L1165—across the 1.2–8.0 μm wavelength range, using deep near-infrared and mid-infrared photometric data from UKIRT Infrared Deep Sky Survey and Spitzer Space Telescope. These observations probe an unprecedented extinction depth, reaching A  V  ∼ 40–60 mag in these dense cloud cores. We derive color-excess ratios E(K ‑ λ)/E(H ‑ K) by fitting color–color diagrams of (K ‑ λ) versus (H ‑ K), which are subsequently used to calculate the extinction law A  λ /A  K . Our analysis reveals remarkably similar and exceptionally flat infrared extinction curves for all four cloud cores, exhibiting the most pronounced flattening reported in the literature to date. This flatness is consistent with the presence of large dust grains, suggesting significant grain growth in dense environments. Intriguingly, our findings align closely with the Astrodust model for a diffuse interstellar environment proposed by Hensley and Draine. This agreement between dense core observations and a diffuse medium model highlights the complexity of dust evolution and the need for further investigation into the processes governing dust properties in different interstellar environments.

Keywords: Interstellar extinction, Interstellar dust, Dense interstellar clouds, Reddening law
Discovery of a Rare Group of Dwarf Galaxies in the Local Universe. We report the discovery of a rare isolated group of five dwarf galaxies located at z = 0.0086 (D = 36 Mpc). All member galaxies are star forming, blue, and gas rich, with g ‑ r indices ranging from 0.2 to 0.6 mag, and two of them show signs of ongoing mutual interaction. The most massive member of the group has a stellar mass that is half of the Small Magellanic Cloud stellar mass, and the median stellar mass of the group members is 7.87 × 107 M ☉. The derived total dynamical mass of the group is M dyn = 6.02 × 1010 M ☉, whereas its total baryonic mass (stellar + H I) is 2.6 × 109 M ☉, which gives us the dynamical to baryonic mass ratio of 23. Interestingly, all galaxies found in the group are aligned along a straight line in the plane of the sky. The observed spatial extent of the member galaxies is 154 kpc, and their relative line-of-sight velocity span is within 75 km s‑1. Using the spatially resolved optical spectra provided by the Dark Energy Spectroscopic Instrument early data release, we find that three group members share a common rotational direction. With these unique properties of the group and its member galaxies, we discuss the possible importance of such a system in the formation and evolution of dwarf galaxy groups and in testing the theory of large-scale structure formation.

Keywords: Dwarf galaxies, Interacting galaxies, Galaxy groups
Limits on Planetary-mass Primordial Black Holes from the OGLE High-cadence Survey of the Magellanic Clouds. Observations of the Galactic bulge revealed an excess of short-timescale gravitational microlensing events that are generally attributed to a large population of free-floating or wide-orbit exoplanets. However, in recent years, some authors suggested that planetary-mass primordial black holes (PBHs) comprising a substantial fraction (1%–10%) of the dark matter in the milky Way may be responsible for these events. If that was the case, a large number of short-timescale microlensing events should also be seen toward the Magellanic Clouds. Here, we report the results of a high-cadence survey of the Magellanic Clouds carried out from 2022 October through 2024 May as part of the Optical Gravitational Lensing Experiment. We observed almost 35 million source stars located in the central regions of the Large and Small Magellanic Clouds and found only one long-timescale microlensing event candidate. No short-timescale events were detected despite high sensitivity to such events. That allows us to infer the strongest available limits on the frequency of planetary-mass PBHs in dark matter. We find that PBHs and other compact objects with masses from 1.4 × 10‑8 M ⊙ (half of the Moon mass) to 0.013 M ⊙ (planet/brown dwarf boundary) may comprise at most 1% of dark matter. That rules out the PBH origin hypothesis for the short-timescale events detected toward the Galactic bulge and indicates they are caused by the population of free-floating or wide-orbit planets.

Keywords: Milky Way dark matter halo, Small Magellanic Cloud, Large Magellanic Cloud, Free floating planets, Gravitational microlensing, Dark matter, Primordial black holes
GRB 240529A: A Tale of Two Shocks. Thanks to the rapidly increasing time-domain facilities, we are entering a golden era of research on gamma-ray bursts (GRBs). In this Letter, we report our observations of GRB 240529A with the Burst Optical Observer and Transient Exploring System, the 1.5 m telescope at Observatorio de Sierra Nevada, the 2.5 m Wide Field Survey Telescope of China, the Large Binocular Telescope, and the Telescopio Nazionale Galileo. The prompt emission of GRB 240529A shows two comparable energetic episodes separated by a quiescence time of roughly 400 s. Combining all available data on the GRB Coordinates Network, we reveal the simultaneous apparent X-ray plateau and optical rebrightening around 103–104 s after the burst. Rather than the energy injection from the magnetar as widely invoked for similar GRBs, the multiwavelength emissions could be better explained as two shocks launched from the central engine separately. The optical peak time and our numerical modeling suggest that the initial bulk Lorentz factor of the later shock is roughly 50, which indicates that the later jet should be accretion driven and have a higher mass loading than a typical one. The quiescence time between the two prompt emission episodes may be caused by the transition between different accretion states of a central magnetar or black hole, or the fallback accretion process. A sample of similar bursts with multiple emission episodes in the prompt phase and sufficient follow-up could help to probe the underlying physics of GRB central engines.

Keywords: Optical observation, Gamma-ray bursts, High energy astrophysics, Relativistic jets, Non-thermal radiation sources
A 2.9 hr Periodic Radio Transient with an Optical Counterpart. We present a long-period radio transient (GLEAM-X J0704−37) discovered to have an optical counterpart, consistent with a cool main-sequence star of spectral type M3. The radio periodicity occurs at the longest period yet found, 2.9 hr, and was discovered in archival low-frequency data from the Murchison Widefield Array. High time resolution observations from MeerKAT show that pulsations from the source display complex microstructure and high linear polarisation, suggesting a pulsar-like emission mechanism occurring due to strong, ordered magnetic fields. The timing residuals, measured over more than a decade, show tentative evidence of a ∼6 yr modulation. The high Galactic latitude of the system and the M-dwarf star excludes a magnetar interpretation, suggesting a more likely M-dwarf/white dwarf binary scenario for this system.

Keywords: M dwarf stars, Binary stars, White dwarf stars, Radio transient sources, Radio pulsars
An Extreme Radio Fluctuation of Pulsar B1929+10. We report the detection of an extreme flux decrease accompanied by clear dispersion measure (DM) and rotation measure (RM) variations for pulsar B1929+10 during the 110 minute radio observation with the Five-hundred-meter Aperture Spherical radio Telescope. The radio flux decreases by 2–3 orders of magnitude within a rapid timescale of about 20 minutes. Meanwhile, the variations of DM and RM are approximately 0.05 pc cm‑3 and 0.7 rad m‑2, respectively. Frequency-dependent analysis of DM indicates an extremely weak chromatic DM feature, which does not notably affect the radiative behavior detected. Moreover, the pulsar timing analysis shows an additional time delay from 100 μs to 400 μs in the event. These results are speculated to be due to the eclipse and bend for the radio emission of pulsar B1929+10 by a highly dense outflow from the pulsar. This not only impacts the intrinsic radio emission feature but also affects the pulsar timing behavior. Nevertheless, a plasma lens effect lasting around 20 minutes could also be responsible for the event.

Keywords: Plasma astrophysics, Interstellar medium, Radio pulsars
Observational Signatures of Dust Traffic Jams in Polar-aligning Circumbinary Disks. Misaligned circumbinary disks will produce dust traffic jams during alignment or antialignment to the binary orbital plane. We conduct a hydrodynamical simulation of an initially misaligned circumbinary disk undergoing polar alignment with multiple dust species. Due to differential precession between the gas and dust components, multiple dust traffic jams are produced within the disk during polar alignment. The radial locations of the dust traffic jams depend on the Stokes number of the grains, which depends on grain size. We compute the dust temperature structure using postprocessing radiative transfer to produce continuum images at centimeter wavelengths. Multiple distinct rings emerge in the continuum images, corresponding to the dust traffic jams. The angular resolution of upcoming observations from the Square Kilometre Array and the next-generation Very Large Array will be sufficient to detect centimeter-sized grains in protoplanetary disks and resolve the widths of dust traffic jams. Therefore, dust traffic jams resulting from the differential precession of gas and dust in misaligned circumbinary disks will be a prime target for more extended wavelength observations.

Keywords: Astronomical techniques, Binary stars, Protoplanetary disks
X-Ray Weak Active Galactic Nuclei from Super-Eddington Accretion onto Infant Black Holes. A simple model for the X-ray weakness of James Webb Space Telescope–selected broad-line active galactic nuclei (AGNs) is proposed under the assumption that the majority of these sources are fed at super-Eddington accretion rates. In these conditions, the hot inner corona above the geometrically thin disk that is responsible for the emission of X-rays in "normal" AGNs will be embedded instead in a funnel-like reflection geometry. The coronal plasma will Compton upscatter optical/UV photons from the underlying thick disk as well as the surrounding funnel walls, and the high soft-photon energy density will cool down the plasma to temperatures in the range 30–40 keV. The resulting X-ray spectra are predicted to be extremely soft, with power-law photon indices Γ ≃ 2.8–4.0, making high-z super-Eddington AGNs largely undetectable by Chandra.

Keywords: Accretion, James Webb Space Telescope, Active galactic nuclei, Black holes
JWST/MIRI Detection of [Ne V], [Ne VI], and [O IV] Wind Emission in the O9 V Star 10 Lacertae. We report the detection of broad, flat-topped emission in the fine-structure lines of [Ne V], [Ne VI], and [O IV] in mid-infrared spectra of the O9 V star 10 Lacertae obtained with James Webb Space Telescope/Mid-Infrared Instrument. Optically thin emission in these high ions traces a hot, low-density component of the wind. The observed line fluxes imply a mass-loss rate of &gt;3 × 10‑8 M⊙ yr‑1, which is 1 order of magnitude larger than previous estimates based on UV and optical diagnostics. The presence of this hot component reconciles measured values of the mass-loss rate with theoretical predictions and appears to solve the "weak wind" problem for the particular case of 10 Lac.

Keywords: Massive stars, Stellar winds, Infrared spectroscopy, Stellar mass loss
Detection of Hidden Emissions in Two Rotating Radio Transients with High Surface Magnetic Fields. Rotating radio transients (RRATs) are neutron stars emitting sporadic radio pulses. The unique emission of RRATs has been proposed to resemble those of known pulsar types, such as extreme nulling pulsars or pulsars with giant pulses. However, the presence of additional radiation beyond these sporadic pulses remains unclear. Through high-sensitivity observations and extended tracking, we detected the sequential weak emissions in two RRATs with relatively high surface magnetic fields (Bs ∼ 1013 G): J1846-0257 and J1854+0306. These emissions show peak flux densities of 0.15 and 0.41 mJy, up to 687 and 512 times weaker than our detected RRAT single pulses, respectively. The weak emissions contribute small fractions (~16% and 5%) to the total radio pulse energy releases, contrasting significantly with giant-pulse pulsars where normal pulses dominate. Polarization analysis of J1854+0306 suggests that its sporadic RRAT pulses may originate from intermittent enhanced sparking processes due to magnetospheric evolution. Our findings indicate that some RRATs may represent a novel class of pulsars, distinct from any previously known subclass. Further observations of sources with similar rotational properties using high-sensitivity instruments could validate the generality of these hidden emissions.

Keywords: Radio pulsars
Ionized Gas Kinematics with FRESCO: An Extended, Massive, Rapidly Rotating Galaxy at z = 5.4. With the remarkable sensitivity and resolution of JWST in the infrared, measuring rest-optical kinematics of galaxies at z &gt; 5 has become possible for the first time. This study pilots a new method for measuring galaxy dynamics for highly multiplexed, unbiased samples by combining FRESCO NIRCam grism spectroscopy and JADES medium-band imaging. Here we present one of the first JWST kinematic measurements for a galaxy at z &gt; 5. We find a significant velocity gradient, which, if interpreted as rotation, yields V rot = 305 ± 70 km s‑1, and we hence refer to this galaxy as Twister-z5. With a rest-frame optical effective radius of r  e  = 2.25 kpc, the high rotation velocity in this galaxy is not due to a compact size, as may be expected in the early Universe, but rather to a high total mass,  . This is a factor of roughly 10× higher than the stellar mass within r  e . We also observe that the radial Hα equivalent width profile and the specific star formation rate map from resolved stellar population modeling are centrally depressed by a factor of ∼1.5 from the center to r  e . Combined with the morphology of the line-emitting gas in comparison to the continuum, this centrally suppressed star formation is consistent with a star-forming disk surrounding a bulge growing inside out. While large, rapidly rotating disks are common to z ∼ 2, the existence of one after only 1 Gyr of cosmic time, shown for the first time in ionized gas, adds to the growing evidence that some galaxies matured earlier than expected in the history of the Universe.

Keywords: Galaxy formation, Galaxy bulges, Galaxy dynamics, Galaxy stellar content, Galaxy disks, Galaxy kinematics, Galaxy evolution, Galaxy masses, Galaxy rotation curves, Galaxy spectroscopy, High-redshift galaxies, Galaxy radii
The Truncated Circumgalactic Medium of the Large Magellanic Cloud. The Large Magellanic Cloud (LMC) is the nearest massive galaxy to the Milky Way (MW). Its circumgalactic medium (CGM) is complex and multiphase, containing both stripped H I structures like the Magellanic Stream and Bridge and a diffuse warm corona seen in high-ion absorption. We analyze 28 active galactic nucleus sight lines passing within 35 kpc of the LMC with archival Hubble Space Telescope/Cosmic Origins Spectrograph spectra to characterize the cool (T ≈ 104 K) gas in the LMC CGM, via new measurements of UV absorption in six low ions (O I, Fe II, Si II, Al II, S II, and Ni II) and one intermediate ion (Si III). We show that a declining column-density profile is present in all seven ions, with the low-ion profiles having a steeper slope than the high-ion profiles in C IV and Si IV reported by D. Krishnarao et al. Crucially, absorption at the LMC systemic velocity is only detected (in all ions) out to 17 kpc. Beyond this distance, the gas has a lower velocity and is associated with the Magellanic Stream. These results demonstrate that the LMC's CGM is composed of two distinct components: a compact inner halo extending to 17 kpc and a more extended stripped region associated with the Stream. The compactness and truncation of the LMC's inner CGM agree with recent simulations of ram-pressure stripping of the LMC by the MW's extended corona. ∗ Based on archival observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Archival funding was associated with program 17053.

Keywords: Galaxy physics, Galaxy dynamics, Large Magellanic Cloud, Galactic and extragalactic astronomy, Magellanic Stream, Magellanic Clouds, Milky Way Galaxy
Solar System Migration Points to a Renewed Concept: Galactic Habitable Orbits. Astrophysical evidence suggests that the Sun was born near 5 kpc from the Galactic center, within the corotation radius of the Galactic bar, around 6–7 kpc. This presents challenges for outward migration due to the Jacobi energy constraint, preventing stars from easily overcoming the corotation barrier. In this study, we use test particle simulations to explore two possible migration pathways for the Sun: a "trapped" scenario, where the Sun's orbit was influenced by a slowing Galactic bar, and an "untrapped" scenario driven by dynamic spiral arms. Our results demonstrate that both mechanisms can explain how the Sun migrated from its birth radius (≈5 kpc) to its current orbital radius around 8.5–9 kpc. Furthermore, we investigate the environmental changes experienced by the Sun along these migration pathways, focusing on variations in radiation hazards and comet fluxes, which may have impacted planetary habitability. These findings highlight the dynamic nature of galactic habitability, emphasizing that the path a star takes within the Milky Way can significantly affect its surrounding environment and the potential for life. We propose a new concept of "Galactic habitable orbits," which accounts for evolving galactic structures and their effects on stellar and planetary systems. This work contributes to a deeper understanding of the solar system's migration and its implications for habitability within the Milky Way.

Keywords: Galaxy chemical evolution, Stellar abundances, Galaxy dynamics, Solar system, Stellar dynamics, Solar abundances, Spiral arms, Milky Way Galaxy, Galactic bar
Composition and Provenance of the Chang'e-6 Lunar Samples: Insights from the Simulation of the Impact Gardening Process. In 2024 June, China's Chang'e-6 (CE-6) mission successfully returned 1935.3 grams of samples from the lunar farside for the first time. The origin and composition of the unique samples could offer valuable insights into fundamental questions on the Moon's evolutional history. Besides the local materials of mare basalts, a certain quantity of foreign ejecta materials are expected in the samples, while their percentage was mostly overestimated since the influence of impact gardening was not fully considered. In this study, we model the impact gardening process surrounding the CE-6 landing site by numerical simulations. Our simulations show that impact gardening played a key role in overturning the local materials and diluting the foreign ones in the top-meters-deep layer at the landing site. About 90% of the CE-6 drilled samples, which were sampled within the top ∼1 m deep layer, are predicted to be the local intermediate-Ti mare basalts originating in the deeper area of 1–60 m, and the underlying low-Ti basalts may make up &lt;1%. The foreign materials in the CE-6 drilled samples likely constitute a minor portion, with an abundance of ∼3.0%. As the primary contributor (∼2.1%) of foreign materials, Chaffee S ejecta may contain lunar mantle materials excavated by the South Pole–Aitken basin.

Keywords: The Moon, Lunar composition
Cross-field Diffusion Effects on Particle Transport in a Solar Coronal Flux Rope. Solar energetic particles associated with solar flares and coronal mass ejections (CMEs) are key agents of space weather phenomena, posing severe threats to spacecraft and astronauts. Recent observations by Parker Solar Probe indicate that the magnetic flux ropes of a CME can trap energetic particles and act as barriers, preventing other particles from crossing. In this Letter, we introduce the novel COCONUT+PARADISE model to investigate the confinement of energetic particles within a flux rope and the effects of cross-field diffusion (CFD) on particle transport in the solar corona, particularly in the presence of a CME. Using the global magnetohydrodynamic coronal model COolfluid COroNal UnsTructured (COCONUT), we generate background configurations containing a CME modeled as a Titov–Démoulin flux rope (TDFR). We then utilize the particle transport code PArticle Radiation Asset Directed at Interplanetary Space Exploration (PARADISE) to inject monoenergetic 100 keV protons inside one of the TDFR legs near its footpoint and evolve the particles through the COCONUT backgrounds. To study CFD, we employ two different approaches regarding the perpendicular proton mean free path (MFP): a constant MFP and a Larmor radius-dependent MFP. We contrast these results with those obtained without CFD. While particles remain fully trapped within the TDFR without CFD, we find that even relatively small perpendicular MFP values allow particles on the outer layers to escape. In contrast, the initially interior trapped particles stay largely confined. Finally, we highlight how our model and this Letter's results are relevant for future research on particle acceleration and transport in an extended domain encompassing both the corona and inner heliosphere.

Keywords: Solar energetic particles, Solar wind, Solar corona, Solar coronal mass ejections, Solar particle emission