Sazuna/UAT_keywords huggingface dataset:
Oblique Compressible Waves in the Reconnection Exhaust Region Embedded in the Inner Heliospheric Current Sheet Observed by Parker Solar Probe. Magnetic reconnection is an important physical process of energy conversion in the heliosphere. Parker Solar Probe (PSP) passes through current sheets of the inner heliosphere and is likely to encounter magnetic reconnection events there. PSP traversed a magnetic reconnection exhaust region that occurred in the coronal streamer during its perihelion Encounter 8. We report an observation of the counterstream of strahl electrons and compressible waves in the exhaust region on the antisunward side of the reconnection site. We analyze the wave characteristics using electromagnetic singular value decomposition techniques and find that the propagation direction of the compressible waves is quasi-perpendicular to the local magnetic field. Combining with the topology of the magnetic field, we infer that the compressible waves converge from the edge to the center of the exhaust region, and then propagate away from it. Further, we select 12 magnetic reconnection events during Encounter 5–8 for statistics and find that the oblique compressible waves are commonly detected throughout the inner heliospheric current sheet. In addition, we discuss the possible nature of wave branches for these compressible waves. Our work shows that magnetic reconnection in the heliosphere not only changes the topology of the large-scale magnetic field in the heliosphere, but also affects the transport characteristics of solar wind plasma and suprathermal particles, and regulates the states of waves and turbulence in the heliosphere.

Keywords: Solar wind, Alfven waves, Solar magnetic reconnection, Heliosphere
Source Region and Launch Characteristics of Magnetic-arch-blowout Solar Coronal Mass Ejections Driven by Homologous Compact-flare Blowout Jets. We study the formation of four coronal mass ejections (CMEs) originating from homologous blowout jets. All of the blowout jets originated from NOAA Active Region (AR) 11515 on 2012 July 2, within a time interval of ≈14 hr. All of the CMEs were wide (angular widths ≈ 95°–150°), and propagated with speeds ranging between ≈300 and 500 km s‑1 in LASCO coronagraph images. Observations at various EUV wavelengths in Solar Dynamics Observatory/Atmospheric Imaging Assembly images reveal that in all the cases, the source region of the jets lies at the boundary of the leading part of AR 11515 that hosts a small filament before each event. Coronal magnetic field modeling based on nonlinear force-free extrapolations indicates that in each case, the filament is contained inside of a magnetic flux rope that remains constrained by overlying compact loops. The southern footpoint of each filament is rooted in the negative polarity region where the eruption onsets occur. This negative polarity region undergoes continuous flux changes, including emergence and cancellation with opposite polarity in the vicinity of the flux rope, and the EUV images reveal brightening episodes near the filament's southeastern footpoint before each eruption. Therefore, these flux changes are likely the cause of the subsequent eruptions. These four homologous eruptions originate near adjacent feet of two large-scale loop systems connecting from that positive polarity part of the AR to two remote negative polarity regions, and result in large-scale consequences in the solar corona.

Keywords: Solar coronal transients, Solar flares, Solar active region filaments, Solar active regions, Solar coronal mass ejections, Solar magnetic fields
Relativistic Brueckner–Hartree–Fock Calculations for Cold and Hot Neutron Stars. This study investigates the properties of symmetric and asymmetric nuclear matter using the relativistic Brueckner–Hartree–Fock formalism, examining both zero and finite temperatures up to 70 MeV. Employing the full Dirac space, we incorporate three Bonn potentials (A, B, and C), which account for meson masses, coupling strengths, cutoff parameters, and form factors. The calculated properties of asymmetric nuclear matter form the basis for constructing equation-of-state (EOS) models tailored for neutron stars. These models, in turn, enable the computation of bulk properties for nonrotating, uniformly rotating, and differentially rotating neutron stars. Notably, the EOS models studied in this paper are sufficiently versatile to accommodate the mass of the most massive neutron star ever detected, PSR J0952–0607, estimated to be 2.35 ± 0.17 M ⊙. Furthermore, they yield masses and radii for PSR J0030+451 that align with the confidence intervals established for this pulsar.

Keywords: Neutron stars, Nuclear astrophysics, Compact objects
Comparing the VANDELS Sample to a Zoom-in Radiative Hydrodynamical Simulation: Using the Si II and C II Line Spectra as Tracers of Galaxy Evolution and Lyman Continuum Leakage. We compare mock ultraviolet C II and Si II absorption and emission line features generated using a ∼109 M ⊙ virtual galaxy with observations of 131 z ∼ 3 galaxies from the VANDELS survey. We find that the mock spectra reproduce reasonably well a large majority (83%) of the VANDELS spectra (χ 2 &lt; 2), but do not resemble the most massive objects (⪆1010 M ⊙), which exhibit broad absorption features. Interestingly, the best-matching mock spectra originate from periods of intense star formation in the virtual galaxy, where its luminosity is 4 times higher than in periods of relative quiescence. Furthermore, for each galaxy, we predict the Lyman continuum (LyC) escape fractions ( fesc(pred)LyC ) using the environment of the virtual galaxy. We derive an average  fesc(pred)LyC  of 0.01 ± 0.02, consistent with other estimates from the literature. The  fesc(pred)LyC  are tightly correlated with the Lyα escape fractions and highly consistent with observed empirical trends. Additionally, galaxies with larger  fesc(pred)LyC  exhibit bluer β slopes, more Lyα flux, and weaker low-ionization absorption lines. Building upon the good agreement between  fesc(pred)LyC  and observationally established LyC diagnostics, we examine the LyC leakage mechanisms in the simulation. We find that LyC photon leakage is enhanced in directions where the observed flux dominantly emerges from compact regions depleted of neutral gas and dust, mirroring the scenario inferred from observational data. In general, this study further highlights the potential of high-resolution radiation hydrodynamics simulations in analyzing UV absorption and emission line features and providing valuable insights into the LyC leakage of star-forming galaxies.

Keywords: Ultraviolet astronomy, Starburst galaxies, Galaxy evolution, Interstellar medium
On Calculating Diffusion Coefficients Numerically in Synthetic Turbulence Using Particle Pushers. Numerical simulations of test particle transport in the presence of synthetic turbulence with known properties still provide the most reliable estimations of the diffusion coefficients of charged particles in turbulent space plasmas available. The development and implementation of such simulations, however, are far from straightforward. The present study provides a comprehensive treatment of the development and testing of such a simulation code, detailing the simulation of synthetic turbulence and diffusion coefficients, as well as various numerical tests to validate code output. Furthermore, a novel test for such codes is proposed, namely, the transport of charged particles in pure slab turbulence, which proves sensitive to numerical factors prior tests remain insensitive to.

Keywords: Computational methods, Magnetic fields, Cosmic rays
High-precision Transition Energy Measurements of Neon-like Fe XVII Ions. We improve by a factor of 4–20 the energy accuracy of the strongest soft X-ray transitions of Fe XVII ions by resonantly exciting them in an electron beam ion trap with a monochromatic beam at the P04 beamline of the PETRA III synchrotron facility. By simultaneously tracking instantaneous photon-energy fluctuations with a high-resolution photoelectron spectrometer, we minimize systematic uncertainties down to 10–15 meV, or velocity equivalent ±∼5 km s‑1 in their rest energies, substantially improving our knowledge of this key astrophysical ion. Our large-scale configuration-interaction computations include more than 4 million relativistic configurations and agree with the experiment at a level without precedent for a 10-electron system. Thereby, theoretical uncertainties for interelectronic correlations become far smaller than those of quantum electrodynamics (QED) corrections. The present QED benchmark strengthens our trust in future calculations of many other complex atomic ions of interest to astrophysics, plasma physics, and the development of optical clocks with highly charged ions.

Keywords: Space plasmas, Theoretical techniques, Line positions, Experimental data, Laboratory astrophysics, Atomic spectroscopy, Atomic data benchmarking
The "Magnificent Seven" X-Ray Isolated Neutron Stars Revisited. I. Improved Timing Solutions and Pulse Profile Analysis. We present the first systematic X-ray pulse timing analysis of the six members of the so-called "Magnificent Seven" nearby thermally emitting isolated neutron stars (XINS) with detected pulsations. Using the extensive collection of archival XMM-Newton, Chandra, and NICER observations spanning over two decades, we obtain the first firm measurement of the spin-down rate for RX J2143.0+0654, while for the rest we improve upon previously published spin ephemerides and extend them by up to an additional decade. Five of the XINS follow steady spin-down with no indication of major anomalies in their long-term timing behavior; the notable exception is RX J0720.4−3125, for which, in addition to confirming the previously identified glitch, we detect a second spin derivative. The high-quality folded X-ray pulse profiles produced with the updated timing solutions exhibit diverse and complex morphologies, as well as striking energy dependence. These peculiarities cannot be readily explained by blackbody-like isotropic emission and simple hot-spot configurations, hinting at the presence of complex multitemperature surface heat distributions and highly anisotropic radiation patterns, such as may arise from a strongly magnetized atmospheric layer.

Keywords: Neutron stars, X-ray astronomy, Pulsars, X-ray sources, Compact objects
Sp1149. I. Constraints on the Balmer L─σ Relation for H II Regions in a Spiral Galaxy at Redshift z = 1.49 Strongly Lensed by the MACS J1149 Cluster. The luminosities (L) and velocity dispersions (σ) of the extinction-corrected Balmer emission lines of giant H II regions in nearby galaxies exhibit a tight correlation (∼0.35 dex scatter). There are few constraints, however, on whether giant H II regions at significant look-back times follow an L─σ relation, given the angular resolution and sensitivity required to study them individually. We measure the luminosities and velocity dispersions of Hα and Hβ emission from 11 H II regions in Sp1149, a spiral galaxy at redshift (z) z = 1.49 multiply imaged by the MACS J1149 galaxy cluster. Sp1149 is also the host galaxy of the first-known strongly lensed supernova with resolved images, SN Refsdal. We employ archival Keck I OSIRIS observations, and newly acquired Keck I MOSFIRE and Large Binocular Telescope LUCI long-slit spectra of Sp1149. When we use the GLAFIC simply parameterized lens model, we find that the Hα luminosities of the H II regions at z = 1.49 are a factor of  6.4−2.0+2.9  brighter than predicted by the low-redshift L─σ relation we measure from Very Large Telescope MUSE spectroscopy. If the lens model is accurate, then the H II regions in Sp1149 differ from their low-redshift counterparts. We identify an H II region in Sp1149 that is dramatically brighter (by 2.03 ± 0.44 dex) than our low-redshift L─σ relation predicts given its low velocity dispersion. Finally, the H II regions in Sp1149 are consistent, perhaps surprisingly, with the z ≍ 0 star-forming locus on the Baldwin─Phillips─Terlevich diagram.

Keywords: Galaxy clusters, Galactic and extragalactic astronomy, Gravitational lensing, H II regions, High-redshift galaxies
Slant, Fan, and Narrow: The Response of Stellar Streams to a Tilting Galactic Disk. Stellar streams are sensitive tracers of the gravitational potential, which is typically assumed to be static in the inner Galaxy. However, massive mergers like Gaia-Sausage-Enceladus can impart torques on the stellar disk of the Milky Way that result in the disk tilting at rates of up to 10°–20° Gyr‑1. Here, we demonstrate the effects of disk tilting on the morphology and kinematics of stellar streams. Through a series of numerical experiments, we find that streams with nearby apocenters (r apo ≲ 20 kpc) are sensitive to disk tilting, with the primary effect being changes to the stream's on-sky track and width. Interestingly, disk tilting can produce both more diffuse streams and more narrow streams, depending on the orbital inclination of the progenitor and the direction in which the disk is tilting. Our model of Pal 5's tidal tails for a tilting rate of 15° Gyr‑1 is in excellent agreement with the observed stream's track and width, and reproduces the extreme narrowing of the trailing tail. We also find that failure to account for a tilting disk can bias constraints on shape parameters of the Milky Way's local dark matter distribution at the level of 5%–10%, with the direction of the bias changing for different streams. Disk tilting could therefore explain discrepancies in the Milky Way's dark matter halo shape inferred using different streams.

Keywords: Stellar streams, Galaxy dynamics, Tidal tails, Galaxy mergers, Milky Way evolution
Observational Constraints on Sunyaev–Zeldovich Effect Halos around High-z Quasars. We present continuum observations from the Atacama Large Millimeter/submillimeter Array of 10 high-redshift (2.2 ≤ z ≤ 2.7) ultraluminous quasars (QSOs) and constrain the presence of hot, ionized, circumgalactic gas in a stacking analysis. We measure a Compton-y parameter profile with a peak value of (1.7 ± 1.1) × 10‑6 at a radius of ∼50 kpc. We compare our stacked observations to active galactic nucleus feedback wind models and generalized Navarro–Frenk–White pressure profile models to constrain the wind luminosity and halo mass of the stacked QSOs. Our observations constrain the observed average halo mass to M 500 &lt; 1 × 1013 M ⊙ and the average feedback wind power &lt;1 × 1012 L ⊙, which is &lt;1% of the bolometric luminosity of the quasar.

Keywords: Active galactic nuclei, Sunyaev-Zeldovich effect, Galaxy evolution, Quasars
Physical Properties of Type II Supernovae Inferred from ZTF and ATLAS Photometric Data. We report an analysis of a sample of 186 spectroscopically confirmed Type II supernova (SN) light curves (LCs) obtained from a combination of Zwicky Transient Facility (ZTF) and Asteroid Terrestrial-impact Last Alert System observations. We implement a method to infer physical parameters from these LCs using hydrodynamic models that take into account the progenitor mass, the explosion energy, and the presence of circumstellar matter (CSM). The CSM is modeled via the mass-loss rate, wind acceleration at the surface of the progenitor star with a β velocity law, and the CSM radius. We also infer the time of explosion, attenuation (A  V ), and the redshift for each SN. Our results favor low-mass progenitor stars (M ZAMS &lt; 14 M ⊙) with a dense CSM ( Ṁ  &gt; 10‑3 M ⊙ yr‑1, CSM radius ∼ 1015 cm, and β &gt; 2). Additionally, we find that the redshifts inferred from the SN LCs are significantly more accurate than those inferred using the host galaxy photometric redshift, suggesting that this method could be used to infer more accurate host galaxy redshifts from large samples of Type II SNe in the LSST era. Lastly, we compare our results with similar works from the literature.

Keywords: Core-collapse supernovae, Surveys, Type II supernovae, Astronomy data analysis, Markov chain Monte Carlo, Supernovae
A Generative Model for Realistic Galaxy Cluster X-Ray Morphologies. The X-ray morphologies of clusters of galaxies display significant variations, reflecting their dynamical histories and the nonlinear dependence of X-ray emissivity on the density of the intracluster gas. Qualitative and quantitative assessments of X-ray morphology have long been considered a proxy for determining whether clusters are dynamically active or "relaxed." Conversely, the use of circularly or elliptically symmetric models for cluster emission can be complicated by the variety of complex features realized in nature, spanning scales from megaparsecs down to the resolution limit of current X-ray observatories. In this work, we use mock X-ray images from simulated clusters from THE THREE HUNDRED project to define a basis set of cluster image features. We take advantage of the clusters' approximate self-similarity to minimize the differences between images before encoding the remaining diversity through a distribution of high-order polynomial coefficients. Principal component analysis then provides an orthogonal basis for this distribution, corresponding to natural perturbations from an average model. This representation allows novel, realistically complex X-ray cluster images to be easily generated, and we provide code to do so. The approach provides a simple way to generate training data for cluster image analysis algorithms and could be straightforwardly adapted to generate clusters displaying specific types of features or selected by physical characteristics available in the original simulations.

Keywords: Galaxy clusters, Intracluster medium
Formation Pathways of the Compact Stellar Systems. The formation pathways of compact stellar systems (CSSs) are still under debate. We utilize the NewHorizon simulation to investigate the origins of such objects in the field environment. We identified 55 CSS candidates in the simulation whose properties are similar to those of the observed ultracompact dwarfs and compact ellipticals (cEs). All but two most massive objects (cE candidates) are a result of a short starburst. Sixteen are formed by tidal stripping, while the other 39 are intrinsically compact from their birth. The stripped objects originate from dwarf-like galaxies with a dark halo, but most of their dark matter is stripped through their orbital motion around a more massive neighbor galaxy. The 39 intrinsically compact systems are further divided into associated or isolated groups, depending on whether they were born near a massive dark halo or not. The isolated intrinsically compact objects (seven) are born in a dark halo and their stellar properties are older and metal-poor compared to the associated counterparts (32). The stripped compact objects occupy a distinct region in the age–metallicity plane from the intrinsically compact objects. The associated intrinsically compact objects in our sample have never had a dark halo; they are the surviving star clumps of a massive galaxy.

Keywords: Ultracompact dwarf galaxies, Hydrodynamical simulations, Compact dwarf galaxies, Compact galaxies
Frequency-dispersed Ion Acoustic Waves in the Near-Sun Solar Wind: Signatures of Impulsive Ion Beams. This work reports a novel plasma wave observation in the near-Sun solar wind: frequency-dispersed ion acoustic waves. Similar waves have previously been reported in association with interplanetary shocks or planetary bow shocks, but the waves reported here occur throughout the solar wind sunward of ∼60 solar radii, far from any identified shocks. The waves reported here vary their central frequency by factors of 3─10 over tens of milliseconds, with frequencies that move up or down in time. Using a semiautomated identification algorithm, thousands of wave instances are recorded during each near-Sun orbit of the Parker Solar Probe spacecraft. Wave statistical properties are determined and used to estimate their plasma frame frequency and the energies of protons most likely to be resonant with these waves. Proton velocity distribution functions are explored for one wave interval, and proton enhancements that may be consistent with proton beams are observed. A conclusion from this analysis is that properties of the observed frequency-dispersed ion acoustic waves are consistent with driving by cold, impulsively accelerated proton beams near the ambient proton thermal speed. Based on the large number of observed waves and their properties, it is likely that the impulsive proton beam acceleration mechanism generating these waves is active throughout the inner heliosphere. This may have implications for the acceleration of the solar wind.

Keywords: Space plasmas, Interplanetary particle acceleration, Solar wind, Heliosphere
The 2018 Outburst of MAXI J1820+070 as Seen by Insight-HXMT. We present an analysis of the whole 2018 outburst of the black hole X-ray binary MAXI J1820+070 with Insight-HXMT data. We focus our study on the temporal evolution of the parameters of the source. We employ two different models to fit the disk's thermal spectrum: the Newtonian model diskbb and the relativistic model nkbb. These two models provide different pictures of the source in the soft state. With diskbb, we find that the inner edge of the disk is close to the innermost stable circular orbit of a fast-rotating black hole and the corona changes geometry from the hard to the soft state. With nkbb, we find that the disk is truncated in the soft state and that the coronal geometry does not change significantly during the whole outburst. However, the model with nkbb can predict an untruncated disk around a fast-rotating black hole if we assume that the disk inclination angle is around 30° (instead of ∼60°, which is the inclination angle of the jet and is usually adopted as the disk inclination angle in the literature) and we employ a high-density reflection model. In such a case, we measure a high value of the black hole spin parameter with observations in the soft state, in agreement with the high spin value found from the analysis of the reflection features and in disagreement with the low spin value found by previous continuum-fitting method measurements with the disk inclination angle set to the value of the jet inclination angle.

Keywords: Accretion, X-ray astronomy, Stellar mass black holes, Low-mass x-ray binary stars, Astrophysical black holes
Studying the Radio Eclipse of Spider Pulsar J1816+4510 with the FAST. We report on the radio eclipse properties of spider pulsar J1816+4510 using the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The high-sensitivity FAST observations will allow us to probe much deeper into the eclipse region of this pulsar at higher frequencies &gt;1 GHz. The duration of the full eclipse, eclipse ingress, and egress at 1100, 1200, 1300, and 1400 MHz are measured, respectively. The variation of eclipse duration with frequency is studied by splitting the FAST observations into four subbands. It is found that the eclipse egress of PSR J1816+4510 takes longer than the ingress and becomes more symmetrical with increasing frequency. The variations of the durations with the frequency for the full eclipse, eclipse ingress, and egress follow a power-law decay pattern with different indices. The pulse profile variations near the eclipse are studied. It is found that the broadening of pulse profiles becomes more prominent with deepening into the eclipse region due to the scattering from the companion star. Moreover, the pulse smearing induced by the scattering and the rapid dispersion measure (DM) fluctuations within a subintegration during the eclipse egress at different frequencies and orbital phases is comparatively studied. It is found that the scattering plays a more important role than the DM fluctuations for the pulse smearing of the eclipse. The observations of this paper will provide important clues for the theoretical studies of the radio eclipse mechanism of the spider pulsar systems.

Keywords: Radio pulsars, Rotation powered pulsars, Pulsars