Sazuna/UAT_keywords huggingface dataset:
Insight-HXMT Observations of the Extremely Bright GRB 221009A. The Insight Hard X-ray Modulation Telescope (Insight-HXMT) detected GRB 221009A, the brightest gamma-ray burst (GRB) observed to date, with all its three telescopes, i.e., the High Energy (HE) telescope (20–250 keV), Medium Energy (ME) telescope (5–30 keV), and Low Energy (LE) telescope (1–10 keV). Here we present the detailed observation results of all three telescopes of Insight-HXMT on the prompt emission of GRB 221009A. After dead-time and data saturation correction, we recovered the light curves of the HE, ME, and LE telescopes and find that they generally track the low-gain light curves of the third member of the Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM-C) that are free of data saturation issues. Particularly, the ME light curve matches the GECAM-C light curve in low gain mode above 400 keV, while the LE light curve is more consistent with the GECAM-C above 1.5 MeV. Based on simulation, we find that the signals recorded by ME and LE are actually caused by the secondary particles produced by the interaction between GRB gamma-ray photons and the material of the satellite. Interestingly, the consistency between the ME and LE light curves and GECAM-C demonstrates that ME and LE data could be used to characterize the GRB properties. Especially, the high-time-resolution light curve of ME allowed us, for the first time, to calculate the minimum variability timescale (0.10 s) of the main burst episode of GRB 221009A.

Keywords: Gamma-ray bursts
Three-body Mean Motion Resonance Chains as a Delivery Mechanism for White Dwarf Pollution. In this work, we used numerical integration of the four-body problem to study three-body resonance chains (two planets and an asteroid in the innermost orbit) as a possible mechanism for white dwarf pollution. Two three-body resonance chains were selected for study: the 6:3:2 and the 4:2:1. Asteroids in both a dynamically colder initial orbit in the 6:3:2 resonance and hotter initial orbits in both resonances were studied. An asteroid had up to a 1.08% chance of being delivered to the stellar Roche limit of the white dwarf. This probability was strongly linearly correlated with the mass of the inner planet but was not correlated with the mass of the outer planet for both colder and hotter orbits. Average dynamical lifetimes ranged from 23 to 1137 kyr for the dynamically colder orbit and from 12.9 to 89.2 kyr and 10.8 to 793.4 kyr for the dynamically hotter orbits in the 6:3:2 and 4:2:1 resonances, respectively. Average dynamical lifetime was exponentially anticorrelated with the outer planet mass and usually with the inner planet mass except in one case. The hotter 4:2:1 resonance delivered 1.1 times more asteroids to the stellar Roche limit than the hotter 6:3:2 resonance. The hotter 6:3:2 resonance delivered 1.2 times more asteroids to the stellar Roche limit than the colder 6:3:2 resonance. A typical accretion rate for a white dwarf star of 108 g s‑1 could be explained by the accretion of an equivalent mass of one of our simulated asteroids every 13.8 Myr.

Keywords: Exoplanet dynamics, Asteroids, Exoplanets, Asteroid dynamics, Tidal disruption, White dwarf stars, Orbital resonances, Tidal radius, Extrasolar gaseous planets, Stellar photospheres, Stellar atmospheres
Evidence for YORP-induced Spin Deceleration in Asteroid (433) Eros. Theoretically, the Yarkovsky–O'Keefe–Radzievskii–Paddack (YORP) effect induced by thermal reemission from asteroid surfaces can either accelerate or decelerate their rotation. However, in the past decade or so, 12 asteroids confirmed to exhibit the YORP effect all show spinning-up behavior, raising questions about whether spinning-down asteroids exist and why they have not been definitively observed. Here, we present evidence that asteroid (433) Eros is undergoing spin deceleration, with an estimated YORP strength of υ = (‑5.0 ± 4.6) × 10‑10 rad day‑2 based on light curves spanning from 1953 to 2023. To account for possible systematic errors, we applied bootstrap resampling at the light-curve level. Besides, we also repeated the analysis on a subset of data with the most reliable light curves. While this reduced data set yields υ = (‑3.0 ± 4.4) × 10‑10 rad day‑2, the optimal υ remains negative, suggesting a consistent trend. The discrepancy of υ values highlights the significant role of systematic errors in YORP detection. We calculated the theoretical YORP strength υmod using both 1D and 3D heat conduction models and found it smaller than the observed value υ, perhaps due to surface heterogeneity. The well-studied Eros would be a perfect study object to make the YORP theory clearer.

Keywords: Near-Earth objects, Eros, Asteroid dynamics, Light curves, Asteroid rotation
Quantum Plasma Creation near a Magnetar. Magnetars in quiescent states continue to emit hard X-rays with a power far exceeding the loss of rotational energy. It has recently been noted that this hard X-ray continuum may bear a direct signature of quantum electrodynamic effects in magnetic fields stronger than the Schwinger field (BQ = 4.4 × 1013 G). Where the current flowing into the magnetosphere is driven by narrow structures in the solid crust, the e± pair plasma supporting the current relaxes to a collisional and transrelativistic state. The decay of a pair into two photons produces a broad, bremsstrahlung-like spectrum of hard X-rays, similar to that observed and extending up to 0.5‑1 MeV. The conversion of two gamma-rays to a pair is further enhanced by a factor ∼B/BQ. Monte Carlo calculations of pair creation in a dipole magnetic field are presented. Nonlocal particle injection is found to be strong enough to suppress the high voltage that otherwise would accompany a weaker, global twist; the hard X-rays are mostly emitted away from the magnetic poles. Some of the pairs annihilate in an optically thin surface layer. The prototypical anomalous X-ray pulsar 1E 2259+586, which shows a hard X-ray continuum but relatively weak torque noise, slow spindown, and no radio emission, is a Rosetta Stone for understanding the magnetar circuit, consistent with the picture advanced here. For a 15‑60 keV luminosity as low as 1034 erg s‑1, the polar flux of subrelativistic pairs produces an optical depth of 3‑30 to electron cyclotron scattering in the 1‑10 keV band, reducing the net X-ray polarization.

Keywords: Cosmic electrodynamics, Plasma astrophysics, Non-thermal radiation sources, Magnetars, Magnetic fields, Gamma-rays
A Candidate for True Type-2 AGN without Hidden Central Broad-line Regions Identified by Central Tidal Disruption Event. In this manuscript, through applications of tidal disruption event (TDE) expected variability properties, a potential candidate for True Type-2 active galactic nuclei (TT2AGN) without hidden central broad-line regions (=TT2AGN) is reported in SDSS J233454.07+145712.9 (=SDSS J2334). Through analyzing the 20 yr optical light curves of SDSS J2334 from different Sky Survey projects, a TDE is preferred with a 4.7 M⊙ main-sequence star tidally disrupted by the central black hole (BH) with mass 11.7 × 106 M⊙, indicating that central region within a distance of about 20 light days to the central BH in SDSS J2334 is directly in the line of sight. Moreover, active galactic nucleus (AGN) activities in SDSS J2334 can be confirmed through applications of (Baldwin, Phillips, &amp; Terlevich (BPT) diagrams. Meanwhile, comparing virial BH mass determined through assumed broad Balmer emission components and M-sigma expected BH mass by well-measured stellar velocity dispersion through stellar absorption features, optical broad emission lines in SDSS J2334 are disfavored with confidence level higher than 6σ. Therefore, combining the unique properties of the TDE and the spectroscopic results with only narrow emission lines, SDSS J2334 can be well identified as a potential candidate for a TT2AGN. The results indicate that to detect TDE expected flares in normal Type-2 AGN classified by spectroscopic results should be a new practicable method for identifying TT2AGN.

Keywords: Supermassive black holes, Tidal disruption, Emission line galaxies, Active galactic nuclei, Time domain astronomy
Mapping the Excitation Mechanisms in the LINER I Active Galactic Nucleus NGC 5005: Positive Feedback and a Thin LINER Cocoon. We present a spatially resolved Baldwin─Phillips─Terlevich analysis of the narrow-line region (NLR) in the low-ionization nuclear emission-line region (LINER) I galaxy NGC 5005 using Hubble Space Telescope narrowband imaging of [O III]λ5007, Hβ, Hα, and [S II]λλ6717,6731. With a resolution of ≲0 .″ 1 (≲10 pc at z = 0.003), we dissect the NLR into H II (star-forming), Seyfert, and LINERs across spatial scales extending up to r ∼ 8 kpc from the nucleus. Our results reveal a compact nuclear region exhibiting Seyfert-like emission, consistent with photoionization by a low-luminosity active galactic nucleus (AGN). Surrounding this Seyfert-like nucleus is a thin (∼20 pc thick) higher-excitation LINER-like cocoon, likely arising from shock-excited gas in the interstellar medium (ISM). Beyond this cocoon, a centrally localized extended (r ∼ 1 kpc) LINER-like region surrounds the Seyfert-like nucleus and cocoon, likely ionized by the AGN, while a more extended (r ≳ 2 kpc) LINER-like zone may be ionized by a combination of post-AGB stars and shocks from gas inflows. We also detect H II─like regions at both small and large scales. In the inner 500 pc, these regions may be triggered by jet─ISM interactions, potentially inducing localized star formation. At r ∼ 4 kpc, we identify an outer H II─like region tracing a large-scale star-forming ring, where ionization is dominated by young stars.

Keywords: LINER galaxies
Propagation and Transmission of Jupiter's Internal Waves. Observations from the Juno spacecraft show that Jupiter has a large dilute core rather than a compact core. To investigate the effects of different core structures on wave propagation and transmission in Jupiter's interior, we consider three models: (1) an isentropic sphere, (2) an isentropic envelope with a rigid core, and (3) an isentropic envelope with a dilute core. We study the propagation and transmission of p-modes (sound waves), g-modes (gravity waves), r-modes (inertial waves), and gravito-inertial waves (GIWs) by solving the linear equations of a compressible, self-gravitating, uniformly rotating polytropic model, fully taking into account the the effects of the Coriolis force but neglecting centrifugal flattening. Our results show that energy flux is primarily carried by fast waves with higher frequencies, whereas kinetic energy is carried by slow waves with lower frequencies. Rotation has a greater effect on nonaxisymmetric modes than on axisymmetric ones. In Model 2, rigid core facilitates propagation of r-modes. In Model 3, rotation enhances the transmission of GIWs across the interface between the dilute core and the isentropic envelope, particularly at high latitudes. This suggests that Jupiter's internal structure may be inferred by detecting the oscillation signals in its polar regions.

Keywords: Internal waves, Solar system gas giant planets
Here There Be (Dusty) Monsters: High-redshift Active Galactic Nuclei Are Dustier than Their Hosts. JWST spectroscopy has discovered a population of z ≳ 3.5 galaxies with broad Balmer emission lines and narrow forbidden lines that are consistent with hosting active galactic nuclei (AGN). Many of these systems, now known as "little red dots," are compact and have unique colors that are very red in the optical/near-infrared and blue in the ultraviolet. The relative contribution of galaxy starlight and AGN to these systems remains uncertain, especially for the galaxies with unusual blue+red spectral energy distributions. In this work, we use Balmer decrements to measure the independent dust attenuation of the broad and narrow emission-line components of a sample of 29 broad-line AGN identified from three public JWST spectroscopy surveys: CEERS, JADES, and RUBIES. Stacking the narrow components from the spectra of 25 sources with broad Hα and no broad Hβ results in a median narrow Hα/Hβ =  2.47‑0.05+0.05  (consistent with Av = 0) and broad Hα/Hβ &gt;8.85 (Av &gt; 3.63). The narrow and broad Balmer decrements imply little to no attenuation of the narrow emission lines, which are consistent with being powered by star formation and located on larger physical scales. Meanwhile, the lower limit in the broad Hα/Hβ decrement, with broad Hβ undetected in the stacked spectrum of 25 broad Hα AGN, implies significant dust attenuation of the broad-line emitting region that is presumably associated with the central AGN. Our results indicate that these systems, on average, are consistent with heavily dust-attenuated AGN powering the red parts of their SED, while their blue UV emission is powered by unattenuated star formation in the host galaxy.

Keywords: AGN host galaxies, Supermassive black holes, Active galactic nuclei, Spectroscopy, High-redshift galaxies
Revisiting the Li Abundances of Stars with and without Detected Planets from High-resolution Spectroscopy. Whether the presence of planets affects the lithium (Li) abundance of their host stars is still an open question. To investigate the difference in the Li abundance between planet-host stars (HSs) and isolated stars (ISs) with no detected planets, we analyze a large sample of stars with temperatures ranging from 4600 to 6600 K and metallicity ranging from ‑0.55 to +0.50. The sample consists of 279 HSs whose spectra were taken from the California-Kepler Survey, which followed up planets detected by Kepler, and 171 ISs whose spectra were taken from the Keck archive. The non–local thermodynamic equilibrium (non-LTE) effects were taken into consideration. It is found that the distributions of Li abundances in both the HS and IS groups are generally consistent with each other. This suggests that the presence of Kepler-like planets does not have a significant impact on Li depletion. We also found that the non-LTE corrections cannot be neglected for stars with A(Li) over ∼2.5 dex.

Keywords: Stellar abundances, Stellar spectral lines, Planet hosting stars
The Physical Origin of Positive Metallicity Radial Gradients in High-redshift Galaxies: Insights from the FIRE-2 Cosmological Hydrodynamic Simulations. Using the FIRE-2 cosmological zoom-in simulations, we investigate the temporal evolution of gas-phase metallicity radial gradients of Milky Way–mass progenitors in the redshift range of 0.4 &lt; z &lt; 3. We pay special attention to the occurrence of positive (i.e., inverted) metallicity gradients—where metallicity increases with galactocentric radius. This trend, contrary to the more commonly observed negative radial gradients, has been frequently seen in recent spatially resolved grism observations. The rate of occurrence of positive gradients in FIRE-2 is about ∼7% for 0.4 &lt; z &lt; 3 and ∼13% at higher redshifts (1.5 &lt; z &lt; 3), broadly consistent with observations. Moreover, we investigate the correlations among galaxy metallicity gradient, stellar mass, star formation rate (SFR), and degree of rotational support. Metallicity gradients show a strong correlation with both sSFR and the rotational-to-dispersion velocity ratio (vc/σ), implying that starbursts and kinematic morphology of galaxies play significant roles in shaping these gradients. The FIRE-2 simulations indicate that galaxies with high sSFR ( log(sSFR[yr‑1])≳‑9.2 ) and weak rotational support (vc/σ ≲ 1) are more likely—by ∼15%—to develop positive metallicity gradients. This trend is attributed to galaxy-scale gas flows driven by stellar feedback, which effectively redistribute metals within the interstellar medium. Our results support the important role of stellar feedback in governing the chemo-structural evolution and disk formation of Milky Way–mass galaxies at the cosmic noon epoch.

Keywords: Hydrodynamical simulations, Galaxy formation, Galaxy evolution, Interstellar medium, Metallicity, High-redshift galaxies
Study of Waveguides and Resonant Cavities over Sunspot Volumes Using Multichannel Solar Dynamics Observatory Observations. For the first time, we have determined the spatial distribution of magnetic waveguides and resonant cavities at different heights of sunspot atmosphere. We analyzed the time series of EUV/UV images observed by the Solar Dynamics Observatory in the different temperature channels. We have decomposed these images into narrowband oscillating components, interpreted as wave sources. The methods of pixelized wavelet filtering and oscillation mode decomposition were used. For all studied sunspots, the presence of selected bands in the spectra was shown. Each band corresponds to oscillations forming spatial waveguides in the volume of the sunspot atmosphere. The formation of waveguide bundles in the height from photospheric to coronal levels is shown. The regions of the waveguides with maximum oscillating power, where resonant cavities are formed, are identified. Their detection is an experimental proof of the theory of resonant layers, previously proposed to explain the presence of significant harmonics in the oscillation spectrum. The different shapes of the cavities reflect the structure of the magnetic tubes along which the waves propagate. The distribution of sources in the height layers indicates the influence of the wave cutoff frequency caused by the inclinations of the magnetic field lines. We discuss the possibility of upward wave transport due to periodic amplification of the oscillating power in the detected cavities.

Keywords: Solar atmosphere, Sunspot groups, Solar ultraviolet emission, Solar magnetic fields, Solar oscillations
Orbital Phase-resolved Analysis of X-Ray and Gamma-Ray Observations of the High-mass Gamma-Ray Binary 4FGL J1405.1‑6119. We present the results of multiwavelength observations of the high-mass gamma-ray binary (HMGB) 4FGL J1405.1‑6119. A pair of joint XMM-Newton and NuSTAR observations taken in 2019 (sampling the gamma-ray maximum and X-ray maximum) characterize the emissiong of soft and hard X-rays. We find variability of the hydrogen column density along our line of sight, NH, and photon index, Γ, and find no evidence of pulsations in X-rays. We also refine a new best-fit orbital period to P = 13.7157 ± 0.0014 days, the first orbital phase-resolved analysis based on nearly 16 yr of Fermi-LAT observations of 4FGL J1405.1‑6119 and the evolution of the spectral shape as a function of orbital phase. Finally, the X-ray and gamma-ray spectra for the phases sampled in the new X-ray observations can be interpreted in the framework of the intrabinary shock model, previously applied to HMGBs such as LS 5039.

Keywords: Neutron stars, X-ray binary stars, High mass x-ray binary stars
X-Ray Polarization of the High-synchrotron-peaked BL Lac H 1426+428. We report the X-ray polarization properties of the high-synchrotron-peaked BL Lac H 1426+428, based on two-epoch observational data from the Imaging X-ray Polarimetry Explorer (IXPE). For the first observation, only an upper limit of polarization degree (ΠX), ΠX &lt; 19.5%, at the 99% confidence level (CL) is determined. In contrast, for the second observation, we derive ΠX = 20.6% ± 2.9% with a polarization angle (ψX) of ψX = 116 .° 1 ± 4 .° 1 at a CL of 7.1σ. The time-resolved and energy-resolved polarization analysis reveals no significant variation in ψX and no detectable polarization within narrower energy bins for the first observation, while the polarization during the second observation is dominated by low-energy photons. Furthermore, the X-rays during the second observation are found to be in a higher flux state with a harder spectrum compared to that observed during the first observation, consistent with a harder-when-brighter behavior. We propose that the enhanced X-ray emission observed during the second observation is produced by shock-accelerated electrons within an ordered magnetic field region via synchrotron radiation. Nonetheless, no significant detection of polarization during the first IXPE observation may be due to the limited number of detected photons.

Keywords: Spectropolarimetry, Blazars, Relativistic jets, Non-thermal radiation sources, X-ray active galactic nuclei
The Spectra of Solar Magnetic Energy and Helicity. Previous studies have used magnetic energy and helicity spectra, the latter computed using the two-scale method, to search for signatures of mean-field dynamos. In this study, we compare cotemporal HMI and SOLIS synoptic vector magnetograms to illustrate the instrument-dependence of even qualitative features of the energy and helicity spectra. Around the minimum between solar cycles 24 and 25, we find that the magnetic energy spectrum computed from HMI observations exhibits two distinct peaks. One of these peaks is only present near the cycle minimum and corresponds to large-scale magnetic fields at high latitudes. Nevertheless, such magnetic fields are not present in contemporaneous synoptic vector magnetograms from SOLIS. Further, even when magnetograms from both instruments are apodized, the helicity spectra calculated using the two-scale method disagree (on both the sign and the value of the fractional helicity). This suggests that currently available synoptic magnetograms are not reliable enough for such studies.

Keywords: Solar cycle, Observational astronomy, Solar magnetic fields
Challenging the LyC─Lyα Relation: Strong Lyα Emitters without LyC Leakage at z ∼ 2.3. The escape fraction of Lyman continuum (LyC) ionizing radiation ( fescLyC ) is crucial for understanding reionization, yet difficult to measure at z ≳ 4. Recently, studies have focused on calibrating indirect indicators of  fescLyC  at z ∼ 0.3, finding that Lyα is closely linked to it. What is still unclear is whether the LyC─Lyα relation evolves with redshift, and if Lyα is truly applicable as an  fescLyC  indicator during the Epoch of Reionization. In this study, we investigate seven −21 ≲ MUV ≲ −19 gravitationally lensed galaxies from the BOSS Emission-Line Lens Survey for GALaxy-Lyα EmitteR sYstems (or BELLS GALLERY) at z ∼ 2.3. Our targets have rest-frame Lyα equivalent widths between 40 Å and 200 Å and low dust content (−2.4 ≲ β ≲ −2.0), both indicative of high LyC escape. Surprisingly, direct estimates of  fescLyC  using Hubble Space Telescope imaging with F275W and F225W reveal that our targets are not LyC emitters, with an absolute  fescLyC  &lt; 13% (assuming the median intergalactic medium transmission). The low  fescLyC , coupled with the high Lyα equivalent width and escape fraction, could potentially be attributed to the redshift evolution of the neutral hydrogen column density and dust content, as well as covering fractions of optically thick gas below 1 in high-redshift galaxies. Additionally, our analysis suggests that the emission for each lensed component is uniformly absorbed. Our results challenge the validity of the extrapolation of z ∼ 0 Lyα-based LyC indirect estimators into the Epoch of Reionization.

Keywords: Strong gravitational lensing, HST photometry, Lyman-alpha galaxies, Reionization, High-redshift galaxies