Sazuna/UAT_keywords huggingface dataset:
Parallel and Momentum Superdiffusion of Energetic Particles Interacting with Small-scale Magnetic Flux Ropes in the Large-scale Solar Wind. A recently developed time-dependent fractional Parker transport equation is solved to investigate the parallel and momentum superdiffusion of energetic charged particles in an inner heliospheric region containing dynamic small-scale flux ropes (SMFRs). Both types of superdiffusive transport are investigated with fractional transport terms containing a fractional time integral combined with normal spatial or momentum derivatives. Just as for normal diffusion, accelerated particles form spatial peaks with a maximum amplification factor that increases with particle energy. Instead of growth of the spatial peaks until a steady state is reached as for normal diffusion, parallel superdiffusion causes the peaks to dissipate into plateaus followed by a rollover at late times. The peaks dissipate at a faster rate when parallel transport is more superdiffusive. Furthermore, the accelerated particle spectral distribution function inevitably becomes an f 0 ∝ p -3 spectrum at late times in the test particle limit near the particle source despite the potential for spectral steepening from other transport terms. All this is a product of the growing domination of parallel spatial and especially momentum superdiffusion over other transport terms with time. Such extreme late time effects can be avoided by a transition to a normal diffusive state. Finally, fitting spatial peaks observed during SMFR acceleration events with the solution of the fractional Parker transport equation can potentially be used as a diagnostic for estimating the level of spatial and momentum superdiffusion in these events and how the levels of superdiffusion vary with distance from the Sun.

Keywords: Solar magnetic reconnection, Solar energetic particles, Interplanetary turbulence, Solar wind, Interplanetary particle acceleration, Interplanetary magnetic fields
A Superflare on YZ Canis Minoris Observed by the Seimei Telescope and TESS: Red Asymmetry of Hα Emission Associated with White-light Emission. Active M-type stars are known to often produce superflares on the surface. Radiation from stellar (super)flares is important for exoplanet habitability, but the mechanisms are not well understood. In this paper, we report simultaneous optical spectroscopic and photometric observations of a stellar superflare on an active M dwarf, YZ Canis Minoris, with the 3.8 m Seimei telescope and the Transiting Exoplanet Survey Satellite. The flare bolometric energy is ${1.3}_{-0.6}^{+1.6}\times {10}^{34}\,\mathrm{erg}$ and the Hα energy is ${3.0}_{-0.1}^{+0.1}\times {10}^{32}\,\mathrm{erg}$ . The Hα emission line profile shows red asymmetry throughout the flare, with a duration of 4.6-5.1 hr. The velocity of the red asymmetry is ~200-500 km s-1 and the line width of Hα broadens up to 34 ± 14 Å. The redshifted velocity and line width of Hα line decay more rapidly than the equivalent width, and their time evolutions are correlated with that of the white-light emission. This indicates the possibility of the white light, the Hα red asymmetry, and the Hα line broadening originating from nearly the same site, i.e., the dense chromospheric condensation region, heated by nonthermal electrons. On the other hand, the flux ratio of the redshifted excess components to the central components is enhanced one hr after the flare's onset. This may be due to the main source of the red asymmetry changing to post-flare loops in the later phase of the flare.

Keywords: M dwarf stars, Solar flares, Solar magnetic reconnection, Stellar phenomena, Stellar flares, Optical flares, Magnetic variable stars, Solar magnetic fields, Magnetic fields
A Complex Dust Morphology in the High-luminosity AGN Mrk 876. Recent models for the inner structures of active galactic nuclei (AGNs) advocate the presence of a radiatively accelerated dusty outflow launched from the outer regions of the accretion disk. Here, we present the first near-IR variable (rms) spectrum for the high-luminosity nearby AGN Mrk 876. We find that it tracks the accretion disk spectrum out to longer wavelengths than the mean spectrum, due to a reduced dust emission. The implied outer accretion disk radius is consistent with the IR results predicted by a contemporaneous optical accretion disk reverberation mapping campaign, and much larger than the self-gravity radius. The reduced flux variability of the hot dust could either be due to the presence of a secondary constant dust component in the mean spectrum or be introduced by the destructive superposition of the dust and accretion disk variability signals, or be some combination of the two. Assuming thermal equilibrium for optically thin dust, we derive the luminosity-based dust radii for different grain properties, using our measurement of the temperature. We find that in all the cases considered, the values are significantly larger than the dust response time measured by IR photometric monitoring campaigns, with the least discrepancy present relative to the result for a wavelength-independent dust emissivity law, i.e., a blackbody, which is appropriate for large grain sizes. This result can be well explained by assuming a flared disk-like structure for the hot dust.

Keywords: Dust physics, Quasars, Dust continuum emission, Active galactic nuclei, Near infrared astronomy
Crescent-shaped Molecular Outflow from the Intermediate-mass Protostar DK Cha Revealed by ALMA. We report on an Atacama Large Millimeter/submillimeter Array study of the Class I or II intermediate-mass protostar DK Cha in the Chamaeleon II region. The 12CO(J = 2-1) images have an angular resolution of ~1″ (~250 au) and show high-velocity blueshifted (≳70 km s-1) and redshifted (≳50 km s-1) emissions, which have 3000 au scale crescent-shaped structures around the protostellar disk traced in the 1.3 mm continuum. Because the high-velocity components of the CO emission are associated with the protostar, we concluded that the emission traces the pole-on outflow. The blueshifted outflow lobe has a clear layered velocity gradient with a higher-velocity component located on the inner side of the crescent shape, which can be explained by a model of an outflow with a higher velocity in the inner radii. Based on the directly driven outflow scenario, we estimated the driving radii from the observed outflow velocities and found that the driving region extends over 2 orders of magnitude. The 13CO emission traces a complex envelope structure with arc-like substructures with lengths of ~1000 au. We identified the arc-like structures as streamers because they appear to be connected to a rotating infalling envelope. DK Cha is useful for understanding characteristics that are visible by looking at nearly face-on configurations of young protostellar systems, providing an alternative perspective for studying the star formation process.

Keywords: Circumstellar envelopes, Molecular clouds, Star formation, Circumstellar disks, Protostars
First Analysis of In Situ Observation of Surface Alfvén Waves in an ICME Flux Rope. Alfvén waves (AWs) are ubiquitous in space and astrophysical plasma. Their crucial role in various physical processes has triggered intense research in solar-terrestrial physics. Simulation studies have proposed the generation of AWs along the surface of a cylindrical flux rope, referred to as surface AWs (SAWs); however, the observational verification of this distinct wave has been elusive to date. We report the first in situ observation of SAWs in a flux rope of an interplanetary coronal mass ejection. We apply the Walén test to identify them. We have used Elsässer variables to estimate the characteristics of SAWs. They may be excited by the movement of the flux rope's footpoints or by instabilities along the boundaries of the plasma magnetic cloud. Here, the change in plasma density or field strength in the surface-aligned magnetic field may trigger SAWs.

Keywords: Space plasmas, Alfven waves, Solar coronal mass ejections
X-Ray Spectral Correlations in a Sample of Low-mass Black Hole X-Ray Binaries in the Hard State. The power-law emission and reflection component provide valuable insights into the accretion process around a black hole. In this work, thanks to the broadband spectra coverage of the Nuclear Spectroscopic Telescope Array, we study the spectral properties for a sample of low-mass black hole X-ray binaries (BHXRBs). We find that there is a positive correlation between the photon index Γ and the reflection fraction R (the ratio of the coronal intensity that illuminates the disk to the coronal intensity that reaches the observer), consistent with previous studies, but except for MAXI J1820+070. It is quite interesting that this source also deviates from the well-known "V"-shaped correlation between the photon index Γ and the X-ray luminosity $\mathrm{log}{L}_{{\rm{X}}}$ , when it is in the bright hard state. More specifically, the Λ-shaped correlation between Γ and logL X is observed, as the luminosity decreases by a factor of 3 in a narrow range from ~1038 to 1037.5 erg s-1. Furthermore, we discover a strong positive correlation between R and the X-ray luminosity for BHXRBs in the hard state, which puts a constraint on the disk-corona coupling and the evolution.

Keywords: Accretion, Black hole physics, X-ray transient sources, Stellar accretion disks
A Broadband X-Ray Study of the Rabbit Pulsar Wind Nebula Powered by PSR J1418-6058. We report on broadband X-ray properties of the Rabbit pulsar wind nebula (PWN) associated with the pulsar PSR J1418-6058 using archival Chandra and XMM-Newton data, as well as a new NuSTAR observation. NuSTAR data above 10 keV allowed us to detect the 110 ms spin period of the pulsar, characterize its hard X-ray pulse profile, and resolve hard X-ray emission from the PWN after removing contamination from the pulsar and other overlapping point sources. The extended PWN was detected up to ~20 keV and is described well by a power-law model with a photon index Γ ≈ 2. The PWN shape does not vary significantly with energy, and its X-ray spectrum shows no clear evidence of softening away from the pulsar. We modeled the spatial profile of X-ray spectra and broadband spectral energy distribution in the radio to TeV band to infer the physical properties of the PWN. We found that a model with low magnetic field strength (B ~ 10 μG) and efficient diffusion (D ~ 1027 cm2 s-1) fits the PWN data well. The extended hard X-ray and TeV emission, associated respectively with synchrotron radiation and inverse Compton scattering by relativistic electrons, suggest that particles are accelerated to very high energies (≳500 TeV), indicating that the Rabbit PWN is a Galactic PeVatron candidate.

Keywords: Rotation powered pulsars, High energy astrophysics, Gamma-ray sources, Astronomy data analysis, Spectral energy distribution, Pulsar wind nebulae
Classification of BATSE, Swift, and Fermi Gamma-Ray Bursts from Prompt Emission Alone. Although it is generally assumed that there are two dominant classes of gamma-ray bursts (GRBs) with different typical durations, it has been difficult to classify GRBs unambiguously as short or long from summary properties such as duration, spectral hardness, and spectral lag. Recent work used t-distributed stochastic neighborhood embedding (t-SNE), a machine-learning algorithm for dimensionality reduction, to classify all Swift GRBs as short or long. Here, the method is expanded, using two algorithms, t-SNE and UMAP, to produce embeddings that are used to provide a classification for 1911 BATSE bursts, 1321 Swift bursts, and 2294 Fermi bursts for which both spectra and metadata are available. Although the embeddings appear to produce a clear separation of each catalog into short and long bursts, a resampling-based approach is used to show that a small fraction of bursts cannot be robustly classified. Further, three of the 304 bursts observed by both Swift and Fermi have robust but conflicting classifications. A likely interpretation is that in addition to the two predominant classes of GRBs, there are additional, uncommon types of bursts which may require multiwavelength observations in order to separate them from more typical short and long GRBs.

Keywords: Classification systems, Gamma-ray bursts, Gamma-ray bursters, Dimensionality reduction
Compression of Dust Aggregates via Sequential Collisions with High Mass Ratios. The structure of dust aggregates affects many aspects of planet formation, such as the dust collision outcome, opacity, and radiation field. The millimeter-wave scattering polarization in protoplanerary disks indicates that dust aggregates have relatively compact structures with a volume-filling factor ≳0.1. In this study, to explain such compact dust aggregates, we examined the compression of dust aggregates in sticking collisions with high mass ratios by performing a large number of N-body simulations of sequential dust collisions for a wide parameter range. Previous N-body simulations reported inefficient compression in equal-mass collisions between large dust aggregates. In contrast, we found that collisions with high mass ratios can compress the dust aggregate much more effectively. We also developed a new compression model that explains our results for sequential collisions with high mass ratios. Finally, we applied the new compression model to dust aggregates in protoplanetary disks and found a possible pathway to create relatively compact dust aggregates that explain the observed millimeter-wave scattering polarization.

Keywords: Circumstellar dust, Protoplanetary disks, Planet formation, Planetesimals
Updated Measurements of [O III] 88 μm, [C II] 158 μm, and Dust Continuum Emission from a z = 7.2 Galaxy. We present updated measurements of the [O III] 88 μm, [C II] 158 μm, and dust continuum emission from a star-forming galaxy at z = 7.212, SXDF-NB1006-2, by utilizing Atacama Large Millimeter/submillimeter Array (ALMA) archival data sets analysed in previous studies and data sets that have not been analysed before. The follow-up ALMA observations with higher angular resolution and sensitivity reveal a clumpy structure of the [O III] emission on a scale of 0.32-0.85 kpc. We also combined all the ALMA [O III] ([C II]) data sets and updated the [O III] ([C II]) detection to 5.9σ (3.6σ-4.5σ). The non-detection of [C II] with data from the REBELS large program implies the incompleteness of spectral-scan surveys using [C II] to detect galaxies with high star formation rates (SFRs) but marginal [C II] emission at high-z. The dust continuum at 90 and 160 μm remains undetected, indicating little dust content of &lt;3.9 × 106 M ☉ (3σ), and we obtained a more stringent constraint on the total infrared luminosity. We updated the [O III]/[C II] luminosity ratios to 10.2 ± 4.7 (6.1 ± 3.5) and 20 ± 12 (9.6 ± 6.1) for the 4.5σ and 3.6σ [C II] detections, respectively, where the ratios in the parentheses are corrected for the surface brightness dimming effect on the extended [C II] emission. We also found a strong [C II] deficit (0.6-1.3 dex) between SXDF-NB1006-2 and the mean L [C II]-SFR relation of galaxies at 0 &lt; z &lt; 9.

Keywords: Galaxy formation, High-redshift galaxies, Galaxy evolution, Interstellar medium
Likely Detection of γ-Ray Pulsations of PSR J1717+4308A in NGC 6341 and Implication of the γ-Ray Millisecond Pulsars in Globular Clusters. We report our analysis results for the globular cluster (GC) NGC 6341 (M92), as a millisecond pulsar (MSP) J1717+4308A has recently been reported found in this GC. The data used are from the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope (Fermi). We detect γ-ray pulsations of the MSP at a 4.4σ confidence level (the corresponding weighted H-test value is ~28.4). This MSP, the fourth γ-ray pulsar found in a GC, does not have significant off-pulse emission and has γ-ray luminosity and efficiency 1.3 × 1034 erg s-1 and 1.7%, respectively. In order to have a clear view on the properties of the known GC γ-ray MSPs, we reanalyze the Fermi-LAT data for the other three ones. These four MSPs share the properties of either having high $\dot{E}$ (~1036 erg s-1) or being in the GCs that contain only limited numbers of known MSPs. In addition, we find that PSRs J1823-3021A and B1821-24, in NGC 6624 and NGC 6626, respectively, have detectable off-pulse γ-ray emission and PSR J1835-3259B in NGC 6652 does not. Using the obtained off-pulse spectra or spectral upper limits, we constrain the numbers of other MSPs in the four GCs. The results are consistent with the numbers of the radio pulsars reported in them. While at least in NGC 6624 and NGC 6626, the contribution of other MSPs to their observed γ-ray emission can not be ignored, our study indicates that the presence of a bright MSP could be the dominant factor for whether a GC is detectable at γ-rays or not.

Keywords: Globular star clusters, Gamma-rays, Pulsars
Weak-lensing Mass Bias in Merging Galaxy Clusters. Although weak lensing (WL) is a powerful method to estimate a galaxy cluster mass without any dynamical assumptions, a model bias can arise when the cluster density profile departs from the assumed model profile. In a merging system, the bias is expected to become most severe because the constituent halos undergo significant structural changes. In this study, we investigate WL mass bias in binary cluster mergers using a suite of idealized hydrodynamical simulations. Realistic WL shear catalogs are generated by matching the source galaxy properties, such as intrinsic shape dispersion, measurement noise, source densities, etc., to those from Subaru and Hubble Space Telescope observations. We find that, with the typical mass-concentration (M-c) relation and the Navarro-Frenk-White profile, the halo mass bias depends on the time since the first pericenter passage and increases with the mass of the companion cluster. The time evolution of the mass bias is similar to that of the concentration, indicating that, to first order, the mass bias is modulated by the concentration change. For a collision between two ~1015 M ⊙ clusters, the maximum bias amounts to ~60%. This suggests that previous WL studies may have significantly overestimated the mass of the clusters in some of the most massive mergers. Finally, we apply our results to three merger cases: A2034, MACS J1752.0 + 4440, and ZwCl 1856.8 + 6616, and report their mass biases at the observed epoch, as well as their pre-merger masses, utilizing their merger shock locations as tracers of the merger phases.

Keywords: Galaxy clusters, Weak gravitational lensing
BICEP/Keck. XVI. Characterizing Dust Polarization through Correlations with Neutral Hydrogen. We characterize Galactic dust filaments by correlating BICEP/Keck and Planck data with polarization templates based on neutral hydrogen (H I) observations. Dust polarization is important for both our understanding of astrophysical processes in the interstellar medium (ISM) and the search for primordial gravitational waves in the cosmic microwave background (CMB). In the diffuse ISM, H I is strongly correlated with the dust and partly organized into filaments that are aligned with the local magnetic field. We analyze the deep BICEP/Keck data at 95, 150, and 220 GHz, over the low-column-density region of sky where BICEP/Keck has set the best limits on primordial gravitational waves. We separate the H I emission into distinct velocity components and detect dust polarization correlated with the local Galactic H I but not with the H I associated with Magellanic Stream I. We present a robust, multifrequency detection of polarized dust emission correlated with the filamentary H I morphology template down to 95 GHz. For assessing its utility for foreground cleaning, we report that the HI morphology template correlates in B modes at a ~10%-65% level over the multipole range 20 &lt; ℓ &lt; 200 with the BICEP/Keck maps, which contain contributions from dust, CMB, and noise components. We measure the spectral index of the filamentary dust component spectral energy distribution to be β = 1.54 ± 0.13. We find no evidence for decorrelation in this region between the filaments and the rest of the dust field or from the inclusion of dust associated with the intermediate velocity H I. Finally, we explore the morphological parameter space in the H I-based filamentary model.

Keywords: Interstellar dust, Galaxy magnetic fields, Interstellar phases, Interstellar filaments, Interstellar atomic gas, Milky Way magnetic fields, Cosmic microwave background radiation, Neutral hydrogen clouds, Interstellar magnetic fields, Interstellar medium, Magnetic fields
Testing the Radio-selection Method of Dual Active Galactic Nuclei in the Stripe 82 Field. We test the merger-induced dual active galactic nuclei (dAGNs) paradigm using a sample of 35 radio galaxy pairs from the Sloan Digital Sky Survey Stripe 82 field. Using Keck optical spectroscopy, we confirm 21 pairs have consistent redshifts, constituting kinematic pairs; the remaining 14 pairs are line-of-sight projections. We classify the optical spectral signatures via emission line ratios, equivalent widths, and excess of radio power above star formation predicted outputs. We find six galaxies are classified as LINERs and seven are AGN/starburst composites. Most of the LINERs are retired galaxies, while the composites likely have AGN contribution. All of the kinematic pairs exhibit radio power more than 10× above the level expected from just star formation, suggestive of a radio AGN contribution. We also analyze high-resolution (0.″3) imaging at 6 GHz from the NSF's Karl G. Jansky Very Large Array for 17 of the kinematic pairs. We find six pairs (two new, four previously known) host two separate radio cores, confirming their status as dAGNs. The remaining 11 pairs contain single AGNs, with most exhibiting prominent jets/lobes overlapping their companion. Our final census indicates a dAGN duty cycle slightly higher than predictions of purely stochastic fueling, although a larger sample (potentially culled from VLASS) is needed to fully address the dAGN fraction. We conclude that while dAGNs in the Stripe 82 field are rare, the merger process plays some role in their triggering and it facilitates low to moderate levels of accretion.

Keywords: Active galactic nuclei, Active galaxies, Interacting galaxies
Insights on the Origin of Odd Radio Circles from Cosmological Simulations. We investigate shock structures driven by merger events in high-resolution simulations that result in a galaxy with a virial mass M ≈ 1012 M ⊙. We find that the sizes and morphologies of the internal shocks resemble remarkably well those of the newly detected class of odd radio circles (ORCs). This would highlight a so-far overlooked mechanism to form radio rings, shells, and even more complex structures around elliptical galaxies. Mach numbers of ${ \mathcal M }$ = 2-3 for such internal shocks are in agreement with the spectral indices of the observed ORCs. We estimate that ~5% of galaxies could undergo merger events, which occasionally lead to such prominent structures within the galactic halo during their lifetime, explaining the low number of observed ORCs. At the time when the shock structures are matching the physical sizes of the observed ORCs, the central galaxies are typically classified as early-type galaxies, with no ongoing star formation, in agreement with observational findings. Although the energy released by such mergers could potentially power the observed radio luminosity already in Milky Way-like halos, our predicted luminosity from a simple, direct shock acceleration model is much smaller than the observed one. Considering the estimated number of candidates from our cosmological simulations and the higher observed energies, we suggest that the proposed scenario is more likely for halo masses around 1013 M ⊙ in agreement with the observed stellar masses of the galaxies at the center of ORCs. Such shocks might be detectable with next-generation X-ray instruments like the Line Emission Mapper (LEM).

Keywords: Radio continuum emission, Hydrodynamical simulations, Galaxy mergers, Galaxies