Sazuna/UAT_keywords huggingface dataset:
Rotational Characteristics of the Solar Transition Region Using SDO/AIA 304 Å Images. To date, the rotational characteristics of the solar transition region remain unclear. In this work, by applying the flux modulation method to the images derived from the Solar Dynamics Observatory/Atmospheric Imaging Assembly between 2011 and 2022 at 304 Å wavelength, we have studied the rotation of the solar transition region, and the results obtained are as follows. The solar transition region rotates differentially, while, from the perspective of the entire time interval, the rotation coefficients A and B are 14.39 (±0.08) and -1.61 (±0.15), respectively, and we find no prominent asymmetry in the average rotation rate of the northern and southern hemispheres. The solar transition region rotates fastest during the solar cycle maximum, and the average rotation rate follows the overall trend of solar activity. Both the equatorial rotation rate (represented by coefficient A) and the latitudinal gradient (represented by coefficient B) of the solar transition region are smaller than that of the solar chromosphere and the corona, indicating the solar transition region rotates more slowly and more rigidly than the other two layers, and we speculate that the solar chromosphere and corona seem to restrain the rotation of the solar transition region at the same time.

Keywords: Solar cycle, Solar rotation, Solar differential rotation, Solar transition region, Solar activity
Wave Generation and Energetic Electron Scattering in Solar Flares. We conduct two-dimensional particle-in-cell simulations to investigate the scattering of electron heat flux by self-generated oblique electromagnetic waves. The heat flux is modeled as a bi-kappa distribution with a T ∥ &gt; T ⊥ temperature anisotropy maintained by continuous injection at the boundaries. The anisotropic distribution excites oblique whistler waves and filamentary-like Weibel instabilities. Electron velocity distributions taken after the system has reached a steady state show that these instabilities inhibit the heat flux and drive the total distributions toward isotropy. Electron trajectories in velocity space show a circular-like diffusion along constant energy surfaces in the wave frame. The key parameter controlling the scattering rate is the average speed, or drift speed v  d , of the heat flux compared with the electron Alfvén speed v Ae, with higher drift speeds producing stronger fluctuations and a more significant reduction of the heat flux. Reducing the density of the electrons carrying the heat flux by 50% does not significantly affect the scattering rate. A scaling law for the electron scattering rate versus v  d /v Ae is deduced from the simulations. The implications of these results for understanding energetic electron transport during energy release in solar flares are discussed.

Keywords: Active solar corona, Solar flares, Solar coronal waves, Plasma physics
Intercomparison of Brown Dwarf Model Grids and Atmospheric Retrieval Using Machine Learning. Understanding differences between substellar spectral data and models has proven to be a major challenge, especially for self-consistent model grids that are necessary for a thorough investigation of brown dwarf atmospheres. Using the random forest supervised machine-learning method, we study the information content of 14 previously published model grids of brown dwarfs (from 1997 to 2021). The random forest method allows us to analyze the predictive power of these model grids, as well as interpret data within the framework of Approximate Bayesian Computation. Our curated data set includes three benchmark brown dwarfs (Gl 570D, ϵ Indi Ba, and Bb) as well as a sample of 19 L and T dwarfs; this sample was previously analyzed by Lueber et al. using traditional Bayesian methods (nested sampling). We find that the effective temperature of a brown dwarf can be robustly predicted independent of the model grid chosen for the interpretation. However, inference of the surface gravity is model-dependent. Specifically, the BT-Settl, Sonora Bobcat, and Sonora Cholla model grids tend to predict $\mathrm{log}g\sim 3$ -4 (cgs units) even after data blueward of 1.2 μm have been disregarded to mitigate for our incomplete knowledge of the shapes of alkali lines. Two major, longstanding challenges associated with understanding the influence of clouds in brown dwarf atmospheres remain: our inability to model them from first principles and also to robustly validate these models.

Keywords: Astrostatistics techniques, Brown dwarfs, Atmospheric clouds
On the Likely Dynamical Origin of GW191109 and Binary Black Hole Mergers with Negative Effective Spin. With the growing number of binary black hole (BBH) mergers detected by LIGO/Virgo/KAGRA, several systems have become difficult to explain via isolated binary evolution, having components in the pair-instability mass gap, high orbital eccentricities, and/or spin-orbit misalignment. Here we focus on GW191109_010717, a BBH merger with component masses of ${65}_{-11}^{+11}$ and ${47}_{-13}^{+15}$ M ⊙ and an effective spin of $-{0.29}_{-0.31}^{+0.42}$ , which could imply a spin-orbit misalignment of more than π/2 rad for at least one of its components. Besides its component masses being in the pair-instability mass gap, we show that isolated binary evolution is unlikely to reproduce the proposed spin-orbit misalignment of GW191109 with high confidence. On the other hand, we demonstrate that BBHs dynamically assembled in dense star clusters would naturally reproduce the spin-orbit misalignment and masses of GW191109 and the rates of GW191109-like events if at least one of the components were to be a second-generation BH. Finally, we generalize our results to all events with a measured negative effective spin, arguing that GW200225 also has a likely dynamical origin.

Keywords: Black holes, Gravitational wave sources
The Single-pulse Observation of PSR B2111+46 with the Five-hundred-meter Aperture Spherical Radio Telescope. We report the observations of periodic nulling in PSR B2111+46 at 1250 MHz with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The nulling fractions (NF) as well as nulling period of this pulsar were calculated. The NF and nulling period are 17% ± 1% and 62.49 ± 0.99 P 1, respectively, and the periodic nulling shows variations in periodicity with time. The durations of each consecutive burst and nulling were investigated, which show that the power-law distribution and the indices are -1.11 ± 0.04 and -2.08 ± 0.23. In the observed frequency band, the width of the profile is narrowed with the increase in frequency, and the degree of polarization has no obvious trend with the increase in frequency. We discovered a weak emission component in front of the leading component of this triple-type profile pulsar that was not observed in other bands and by other telescopes. With the fitting of rotation vector model, we obtained that the angles of the magnetic inclination α and the line of sight ζ are ~13.°0 and ~11.°6, respectively. The high-sensitivity observation of FAST improves our understanding of the emission of this pulsar.

Keywords: Radio pulsars
Electron Acceleration and Heating during Magnetic Reconnection in the Earth's Quasi-parallel Bow Shock. We perform a 2.5-dimensional particle-in-cell simulation of a quasi-parallel shock, using parameters for the Earth's bow shock, to examine electron acceleration and heating due to magnetic reconnection. The shock transition region evolves from the ion-coupled reconnection dominant stage to the electron-only reconnection dominant stage, as time elapses. The electron temperature enhances locally in each reconnection site, and ion-scale magnetic islands generated by ion-coupled reconnection show the most significant enhancement of the electron temperature. The electron energy spectrum shows a power law, with a power-law index around 6. We perform electron trajectory tracing to understand how they are energized. Some electrons interact with multiple electron-only reconnection sties, and Fermi acceleration occurs during multiple reflections. Electrons trapped in ion-scale magnetic islands can be accelerated in another mechanism. Islands move in the shock transition region, and electrons can obtain larger energy from the in-plane electric field than the electric potential in those islands. These newly found energization mechanisms in magnetic islands in the shock can accelerate electrons to energies larger than the achievable energies by the conventional energization due to the parallel electric field and shock drift acceleration. This study based on the selected particle analysis indicates that the maximum energy in the nonthermal electrons is achieved through acceleration in ion-scale islands, and electron-only reconnection accounts for no more than half of the maximum energy, as the lifetime of sub-ion-scale islands produced by electron-only reconnection is several times shorter than that of ion-scale islands.

Keywords: Interplanetary particle acceleration, Planetary bow shocks, Solar magnetic reconnection
Turbulent Origins of Particle Intensity Dropout in Gradual Solar Energetic Particle Events During Solar Cycle 23. Dropout is a low-energy particle phenomenon in which the particle intensity drops sharply and then rises rapidly during an impulsive or gradual solar energetic particle (SEP) event. We investigated dropouts in gradual SEP events during solar cycle 23, in which we identified 77 dropout periods with an average duration of approximately 1 hr. During most of the dropout periods, we observe large angles between the mean magnetic field and the solar wind velocity, implying that the slab turbulent component dominates. We therefore explore the origin of particle intensity dropout in slab turbulent environments. At a wave frequency of 1 Hz in the spacecraft frame, we observed a significant positive correlation between the turbulent power spectral density (PSD) and its spectral index, both in the ion dissipation range. As the input PSD decreases, the correlation can amplify the reduction factor for pitch-angle scatterings, quickly suppressing particle scattering through the 90° pitch angle. Hence, particle dropout may occur due to lack of spatial diffusion of particles.

Keywords: Interplanetary turbulence, Solar energetic particles, Solar wind, Solar magnetic fields, Solar particle emission
Investigating the Correlation of Outflow Kinematics with Radio Activity. VII. Gas Outflows in AGNs. We explore the relationship between the ionized gas outflows and radio activity using a sample of ~6000 active galactic nuclei (AGNs) at z &lt; 0.4 with the kinematical measurement based on the $\left[{\rm{O}}\,{\rm\small{III}}\right]$ line profile and the radio detection in the VLA FIRST Survey. To quantify radio activity, we divide our sample into a series of binary subclasses based on the radio properties, i.e., radio luminous/radio weak, AGN-dominated/star-formation contaminated, compact/extended, and radio loud/radio quiet. None of the binary subclasses exhibits a significant difference in the normalized $\left[{\rm{O}}\,{\rm\small{III}}\right]$ velocity dispersion at a given $\left[{\rm{O}}\,{\rm\small{III}}\right]$ luminosity once we correct for the influence of the host galaxy's gravitational potential. We only detect a significant difference in $\left[{\rm{O}}\,{\rm\small{III}}\right]$ kinematics between the high and low radio-Eddington ratio (L 1.4 GHz/L Edd) AGNs. In contrast, we find a remarkable difference in ionized gas kinematics between high and low bolometric-Eddington ratio AGNs. These results suggest that accretion rate is the primary mechanism in driving ionized gas outflows, while radio activity may play a secondary role providing additional influence on gas kinematics.

Keywords: AGN host galaxies, Active galactic nuclei, Radio jets
Domain Adaptation for Simulation-based Dark Matter Searches with Strong Gravitational Lensing. The identity of dark matter has remained surprisingly elusive. While terrestrial experiments may be able to nail down a model, an alternative method is to identify dark matter based on astrophysical or cosmological signatures. A particularly sensitive approach is based on the unique signature of dark matter substructure in galaxy-galaxy strong lensing images. Machine-learning applications have been explored for extracting this signal. Because of the limited availability of high-quality strong lensing images, these approaches have exclusively relied on simulations. Due to the differences with the real instrumental data, machine-learning models trained on simulations are expected to lose accuracy when applied to real data. Here domain adaptation can serve as a crucial bridge between simulations and real data applications. In this work, we demonstrate the power of domain adaptation techniques applied to strong gravitational lensing data with dark matter substructure. We show with simulated data sets representative of Euclid and Hubble Space Telescope observations that domain adaptation can significantly mitigate the losses in the model performance when applied to new domains. Lastly, we find similar results utilizing domain adaptation for the problem of lens finding by adapting models trained on a simulated data set to one composed of real lensed and unlensed galaxies from the Hyper Suprime-Cam. This technique can help domain experts build and apply better machine-learning models for extracting useful information from the strong gravitational lensing data expected from the upcoming surveys.

Keywords: Strong gravitational lensing, Dark matter
Rocky Planet or Water World? Observability of Low-density Lava World Atmospheres. Super-Earths span a wide range of bulk densities, indicating a diversity in interior conditions beyond that seen in the solar system. In particular, an emerging population of low-density super-Earths may be explained by volatile-rich interiors. Among these, low-density lava worlds have dayside temperatures that are high enough to evaporate their surfaces, providing a unique opportunity to probe their interior compositions and test for the presence of volatiles. In this work, we investigate the atmospheric observability of low-density lava worlds. We use a radiative-convective model to explore the atmospheric structures and emission spectra of these planets, focusing on three case studies with high observability metrics and substellar temperatures spanning ~1900-2800 K: HD 86226 c, HD 3167 b, and 55 Cnc e. Given the possibility of mixed volatile and silicate interior compositions for these planets, we consider a range of mixed volatile and rock-vapor atmospheric compositions. This includes a range of volatile fractions and three volatile compositions: water-rich (100% H2O), water with CO2 (80% H2O+20% CO2), and a desiccated O-rich scenario (67% O2+33% CO2). We find that spectral features due to H2O, CO2, SiO, and SiO2 are present in the infrared emission spectra as either emission or absorption features, depending on dayside temperature, volatile fraction, and volatile composition. We further simulate JWST secondary-eclipse observations for each of the three case studies, finding that H2O and/or CO2 could be detected with as few as ~five eclipses. Detecting volatiles in these atmospheres would provide crucial independent evidence that volatile-rich interiors exist among the super-Earth population.

Keywords: Exoplanet atmospheric composition , Exoplanets, Super Earths, Exoplanet structure, Exoplanet atmospheres, Exoplanet atmospheric structure
The Temporal and Spatial Evolution of Magnetohydrodynamic Wave Modes in Sunspots. Through their lifetime, sunspots undergo a change in their area and shape and, as they decay, they fragment into smaller structures. Here, for the first time we analyze the spatial structure of the magnetohydrodynamic (MHD) slow-body and fast-surface modes in the observed umbrae as their cross-sectional shape changes. The proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) techniques were used to analyze 3 and 6 hr Solar Dynamics Observatory/Helioseismic and Magnetic Imager time series of Doppler velocities at the photospheric level of approximately circular and elliptically shaped sunspots. Each time series was divided into equal time intervals to evidence the change in the shape of the sunspots. To identify the physical wave modes, the POD/DMD modes were cross-correlated with a slow-body mode model using the exact shape of the umbra, whereas the shape obtained by applying a threshold level of the mean intensity for every time interval. Our results show that the spatial structure of MHD modes are affected, even by apparently small changes in the umbral shape, especially in the case of the higher-order modes. For the data sets used in our study, the optimal time intervals to consider the influence of the change in the shape on the observed MHD modes is 37-60 minutes. The choice of these intervals is crucial to properly quantify the energy contribution of each wave mode to the power spectrum.

Keywords: Radiative magnetohydrodynamics, Penumbra, Emerging flux tubes, Sunspots, Umbra, Solar coronal waves, Wavelet analysis, Active solar chromosphere
COSMOS-Web: An Overview of the JWST Cosmic Origins Survey. We present the survey design, implementation, and outlook for COSMOS-Web, a 255 hr treasury program conducted by the James Webb Space Telescope in its first cycle of observations. COSMOS-Web is a contiguous 0.54 deg2 NIRCam imaging survey in four filters (F115W, F150W, F277W, and F444W) that will reach 5σ point-source depths ranging ~27.5-28.2 mag. In parallel, we will obtain 0.19 deg2 of MIRI imaging in one filter (F770W) reaching 5σ point-source depths of ~25.3-26.0 mag. COSMOS-Web will build on the rich heritage of multiwavelength observations and data products available in the COSMOS field. The design of COSMOS-Web is motivated by three primary science goals: (1) to discover thousands of galaxies in the Epoch of Reionization (6 ≲ z ≲ 11) and map reionization's spatial distribution, environments, and drivers on scales sufficiently large to mitigate cosmic variance, (2) to identify hundreds of rare quiescent galaxies at z &gt; 4 and place constraints on the formation of the universe's most-massive galaxies (M ⋆ &gt; 1010 M ⊙), and (3) directly measure the evolution of the stellar-mass-to-halo-mass relation using weak gravitational lensing out to z ~ 2.5 and measure its variance with galaxies' star formation histories and morphologies. In addition, we anticipate COSMOS-Web's legacy value to reach far beyond these scientific goals, touching many other areas of astrophysics, such as the identification of the first direct collapse black hole candidates, ultracool subdwarf stars in the Galactic halo, and possibly the identification of z &gt; 10 pair-instability supernovae. In this paper we provide an overview of the survey's key measurements, specifications, goals, and prospects for new discovery.

Keywords: Weak gravitational lensing, Sky surveys, Large-scale structure of the universe, Galaxy evolution, Reionization
The Solar Origin of an In Situ Type III Radio Burst Event. Solar type III radio bursts are generated by beams of energetic electrons that travel along open magnetic field lines through the corona and into interplanetary space. However, understanding the source of these electrons and how they escape into interplanetary space remains an outstanding topic. Here we report multi-instrument, multiperspective observations of an interplanetary type III radio burst event shortly after the second perihelion of the Parker Solar Probe (PSP). This event was associated with a solar jet that produced an impulsive microwave burst event recorded by the Expanded Owens Valley Solar Array. The type III burst event also coincided with the detection of enhanced in situ energetic electrons recorded by both PSP at 0.37 au and WIND at 1 au, which were located very closely on the Parker spiral longitudinally. The close timing association and magnetic connectivity suggest that the in situ energetic electrons originated from the jet's magnetic reconnection region. Intriguingly, microwave imaging spectroscopy results suggest that the escaping energetic electrons were injected into a large opening angle of about 90°, which is at least nine times broader than the apparent width of the jet spire. Our findings provide an interpretation for the previously reported, longitudinally broad spatial distribution of flare locations associated with prompt energetic electron events and have important implications for understanding the origin and distribution of energetic electrons in interplanetary space.

Keywords: Solar energetic particles, Solar coronal transients, Solar radio emission, Solar flares
X-Ray/UVOIR Frequency-resolved Time Lag Analysis of Mrk 335 Reveals Accretion Disk Reprocessing. UV and optical continuum reverberation mapping is a powerful tool for probing the accretion disk and inner broad-line region. However, recent reverberation mapping campaigns in the X-ray, UV, and optical have found lags consistently longer than those expected from the standard disk reprocessing picture. The largest discrepancy to date was recently reported in Mrk 335, where UV/optical lags are up to 12 times longer than expected. Here, we perform a frequency-resolved time lag analysis of Mrk 335, using Gaussian processes to account for irregular sampling. For the first time, we compare the Fourier frequency-resolved lags directly to those computed using the popular interpolated cross-correlation function method applied to both the original and detrended light curves. We show that the anticipated disk reverberation lags are recovered by the Fourier lags when zeroing in on the short-timescale variability. This suggests that a separate variability component is present on long timescales. If this separate component is modeled as reverberation from another region beyond the accretion disk, we constrain a size scale of roughly 15 lt-days from the central black hole. This is consistent with the size of the broad-line region inferred from Hβ reverberation lags. We also find tentative evidence for a soft X-ray lag, which we propose may be due to light travel time delays between the hard X-ray corona and distant photoionized gas that dominates the soft X-ray spectrum below 2 keV.

Keywords: Accretion, Supermassive black holes, Reverberation mapping, Seyfert galaxies, Active galactic nuclei, Gaussian Processes regression
The Cygnus Loop: Shock Precursors and Electron-Ion Equilibration. The outermost edges of some supernova remnants are marked by filaments of pure Balmer line emission produced by nonradiative shock fronts. The Hα profiles of these filaments provide the shock speed and electron-proton temperature ratio in the shock. We have used the Hectochelle multiobject spectrograph on the MMT telescope to observe nine positions along the eastern nonradiative filaments of the Cygnus Loop, thereby extending the studies of Medina et al. to lower shock speeds. We complement the spectra with images from 1993 to 2020 to measure proper motions to further constrain the parameters. We also present observations of the photoionization precursor to show that the gas is strongly heated, and that the Hα emission from the precursor is dominated by collisional excitation rather than recombination.

Keywords: Supernova remnants, Interstellar plasma