Sazuna/UAT_keywords huggingface dataset:
Blueshifted Fe II and Balmer Broad Emission lines in a Reddened Quasar. We present detailed analysis of the optical and near-infrared spectrum of the reddened radio-loud quasar F2M J154043.74+492323.9 with strong optical Fe II emission of ${R}_{4570}\equiv \tfrac{\mathrm{Fe}\,{\rm\small{II}}\lambda \lambda \,4434,4684}{{\rm{H}}\beta }=1.60\pm 0.14$ . It is found that the peaks of broad emission lines (BELs), including Hα, Hβ, and Hγ, and the peaks of individual Fe II BELs, are blueshifted as large as v ≈ 1500 km s-1 with respect to the systemic redshift determined by the low-ionization [O II] narrow emission line. BEL components at the systemic redshift are also significantly detected, though much weaker than the corresponding blueshifted components. Interestingly, the Mg II BEL also shows a similar double-peaked profile, yet with a weaker blueshifted component relative to the unshifted one. We interpret these exceptional BELs as originating from massive outflows, possibly with both densities and column densities much higher than those of the normal BEL region (BELR). Alternative scenarios, however, cannot be completely ruled out based on the data available, including a gravitationally bound binary of active supermassive black holes (SMBHs), each with an unattached BELR, or a recoiling SMBH caused by anisotropic gravitational radiation during the coalescence of the progenitor binary. Follow-up observations will be able to disentangle these scenarios, and to also provide valuable clues to understand the growth of SMBHs and the assembly of their host galaxies.

Keywords: Radio loud quasars, Double quasars, Active galaxies, Emission line galaxies
Dwarf Galaxies Show Little ISM Evolution from z   1 to z   0: A Spectroscopic Study of Metallicity, Star Formation, and Electron Density. We present gas-phase metallicity measurements for 583 emission line galaxies at 0.3 &lt; z &lt; 0.85, including 388 dwarf galaxies with $\mathrm{log}({M}_{\star }/{M}_{\odot })\lt 9.5$ , and explore the dependence of the metallicity on the stellar mass and star formation (SF) properties of the galaxies. Metallicities are determined through the measurement of emission lines in very deep (~7 hr exposure) Keck/DEIMOS spectra taken primarily from the HALO7D survey. We measure metallicity with three strong-line calibrations (O3Hβ, R23, and O3O2) for the overall sample, as well as with the faint [Ne III]λ3869 and [O III]λ4363 emission lines for 112 and 17 galaxies where robust detections were possible. We construct mass-metallicity relations (MZR) for each calibration method, finding MZRs consistent with other strong-line results at comparable redshift, as well as with z ~ 0 galaxies. We quantify the intrinsic scatter in the MZR as a function of mass, finding it increases with lower stellar mass. We also measure a weak but significant correlation between increased MZR scatter and higher specific star formation rate (SFR). We find a weak influence of SFR in the fundamental metallicity relation as well, with an SFR coefficient of α = 0.21. Finally, we use the flux ratios of the [O II]λ λ 3727,3729 doublet to calculate gas electron density in ~1000 galaxies with $\mathrm{log}({M}_{\star }/{M}_{\odot })\lt 10.5$ as a function of redshift. We measure low electron densities (n  e  ~ 25 cm-3) for z &lt; 1 galaxies, again consistent with z ≈ 0 conditions, but measure higher densities (n  e  ~ 100 cm-3) at z &gt; 1. These results all suggest that there is little evolution in star-forming interstellar medium conditions from z ~ 1 to z = 0, confirmed with a more complete sample of low-mass galaxies than has previously been available in this redshift range.

Keywords: Dwarf galaxies, Emission line galaxies, Star formation, Metallicity, Galaxies
Validating Posteriors Obtained by an Emulator When Jointly Fitting Mock Data of the Global 21 cm Signal and High-z Galaxy UV Luminosity Function. Although neural-network-based emulators enable efficient parameter estimation in 21 cm cosmology, the accuracy of such constraints is poorly understood. We employ nested sampling to fit mock data of the global 21 cm signal and high-z galaxy ultraviolet luminosity function (UVLF) and compare for the first time the emulated posteriors obtained using the global signal emulator globalemu to the "true" posteriors obtained using the full model on which the emulator is trained using ARES. Of the eight model parameters we employ, four control the star formation efficiency (SFE) and thus can be constrained by UVLF data, while the remaining four control UV and X-ray photon production and the minimum virial temperature of star-forming halos ( ${T}_{\min }$ ) and thus are uniquely probed by reionization and 21 cm measurements. For noise levels of 50 and 250 mK in the 21 cm data being jointly fit, the emulated and "true" posteriors are consistent to within 1σ. However, at lower noise levels of 10 and 25 mK, globalemu overpredicts ${T}_{\min }$ and underpredicts γ lo, an SFE parameter, by ≈3σ-4σ, while the "true" ARES posteriors capture their fiducial values within 1σ. We find that jointly fitting the mock UVLF and 21 cm data significantly improves constraints on the SFE parameters by breaking degeneracies in the ARES parameter space. Our results demonstrate the astrophysical constraints that can be expected for global 21 cm experiments for a range of noise levels from pessimistic to optimistic, as well as the potential for probing redshift evolution of SFE parameters by including UVLF data.

Keywords: Luminosity function, Bayesian statistics, Neural networks, Nested sampling, Posterior distribution, Reionization, Radio astronomy
Nature of Turbulence inside Small-scale Magnetic Flux Ropes near the Sun: Parker Solar Probe Observations. In this study, we probe the turbulence characteristic within the small-scale magnetic flux ropes (SSMFRs) close to the Sun using Parker Solar Probe (PSP) magnetic field data. The study includes 50 SSMFRs observed by PSP during Encounter 1, 2, and 3 between 35.74 R ☉ and 142.29 R ☉ distance from the Sun. We observed that the average spectral index for all the selected SSMFR events is -1.49 ± 0.21. In line with expectations, we also saw average ∣σ  m ∣ values close to zero throughout the inertial range. We also observed that the size of the eddy at the highest frequency is much smaller than the size of the SSMFRs, indicating anisotropy within it. Thus, our finding supports anisotropic models that feature the Iroshnikov-Kraichnan index. Our findings agree with the turbulence properties of the solar wind near the Sun. We also observe low ~0.1 compressibility, indicating SSMFRs are dominant by Alfvénic fluctuations. In light of this, we believe such an incompressible MHD spectrum results from nonlinear interactions between Alfvénic fluctuations. As a result, our research contributes to understanding the energy cascade process and its transport in solar plasma within the inner heliosphere.

Keywords: Interplanetary turbulence, Space plasmas, Solar wind, Alfven waves
Accretion Disk Wind of Hercules X-1 during the Short High State. Hercules X-1 is a nearly edge-on X-ray binary with a warped, precessing accretion disk, which manifests through a 35-day cycle of alternating High and Low flux states. This disk precession introduces a changing line of sight toward the X-ray source, through an ionized accretion disk wind. The sightline variation allows us to uniquely determine how the wind properties vary with height above the disk. All the previous wind measurements were made in the brighter Main High state of Her X-1. Here, we analyze the only Chandra observation during the fainter "Short" High state and significantly detect blueshifted ionized absorption. We find a column density of ${2.0}_{-0.6}^{+1.1}\times {10}^{22}$ cm-2, an ionization parameter $\mathrm{log}(\xi $ /erg cm s-1) = ${3.41}_{-0.12}^{+0.15}$ , and an outflow velocity of 380 ± 40 km s-1. The properties of the outflow measured during the Short High state are in good agreement with those measured at equivalent precession phases during the Main High state. We conclude that we are sampling the same wind structure, seen during both the Main and Short High states, which is precessing alongside the warped accretion disk every 35 days. Finally, the high spectral resolution of Chandra gratings above 1 keV in this observation enabled us to measure the abundances of certain elements in the outflow. We find Mg/O $\,=\,{1.5}_{-0.4}^{+0.5}$ , Si/O =1.5 ± 0.4, and S/O $\,=\,{3.0}_{-1.1}^{+1.2}$ , whereas in our previous study of Her X-1 with XMM-Newton, we found an overabundance of N, Ne, and Fe compared with O. These peculiar abundance ratios were likely introduced by the pollution of the donor by the supernova that created Her X-1.

Keywords: Accretion, Neutron stars, X-ray binary stars
The Metallicity and Distance of Leo A from Blue Supergiants. We have obtained high-quality spectra of blue supergiant candidates in the dwarf irregular galaxy Leo A with the Low Resolution Imaging Spectrometer at the Keck I telescope. From the quantitative analysis of seven B8-A0 stars, we derive a mean metallicity [Z] = -1.35 ± 0.08, in excellent agreement with the gas-phase chemical abundance. From the stellar parameters and the flux-weighted gravity-luminosity relation (FGLR), we derive a spectroscopic distance modulus m - M = 24.77 ± 0.11 mag, significantly larger (~0.4 mag) than the value indicated by RR Lyrae and other stellar indicators. We explain the bulk of this discrepancy with blue loop stellar evolution at very low metallicity and show that the combination of metallicity effects and blue loop evolution amounts, in the case of Leo A, to an ~0.35 mag offset of the FGLR to fainter bolometric luminosities. We identify one outlier of low bolometric magnitude as a post-AGB star. Its metallicity is consistent with that of the young population, confirming the slow chemical enrichment of Leo A.

Keywords: Stellar abundances, Galaxy abundances, Galaxy stellar content
The Triggering Process of an X-class Solar Flare on a Small Quadrupolar Active Region. The occurrence of X-class solar flares and their potential impact on space weather often receive greater attention than other flares. But predicting when and where an X-class flare will occur is still a challenge. With the multiwavelength observation from the Solar Dynamics Observatory and FengYun-3E satellite, we investigate the triggering of a GOES X1.0 flare occurring in the NOAA active region (AR) 12887. Our results show that this unique X-class flare is bred in a relatively small but complex quadrupolar AR. Before the X-class flare, two filaments (F1 and F2) exist below a null-point topology of the quadrupolar AR. Magnetic field extrapolation and observation reveal that F1 and F2 correspond to two magnetic flux ropes with the same chirality and that their adjacent feet are respectively rooted at nonconjugated opposite polarities. Interestingly, these two polarities collide rapidly, accompanied by photospheric magnetic flux emergence, cancellation, and shear motion in the AR center. Above this site, F1 and F2 subsequently intersect with each other and merge into a longer filament (F3) via a tether-cutting-like reconnection process. As a result, F3 rises and erupts upward, eventually leading to a coronal mass ejection and the X-class flare. This observation suggests that the rapid collision of nonconjugated opposite polarities provides a key condition for the triggering of this X-class flare and also provides a featured case for a flare trigger mechanism and space weather forecasting.

Keywords: Solar flares, Space weather, Solar active regions, Solar filaments, Solar magnetic fields
A Possible Mechanism for the "Late Phase" in Stellar White-light Flares. M dwarf flares observed by the Transiting Exoplanet Survey Satellite (TESS) sometimes exhibit a peak-bump light-curve morphology, characterized by a secondary, gradual peak well after the main, impulsive peak. A similar late phase is frequently detected in solar flares observed in the extreme ultraviolet from longer hot coronal loops distinct from the impulsive flare structures. White-light emission has also been observed in off-limb solar flare loops. Here, we perform a suite of one-dimensional hydrodynamic loop simulations for M dwarf flares inspired by these solar examples. Our results suggest that coronal plasma condensation following impulsive flare heating can yield high electron number density in the loop, allowing it to contribute significantly to the optical light curves via free-bound and free-free emission mechanisms. Our simulation results qualitatively agree with TESS observations: the longer evolutionary timescale of coronal loops produces a distinct, secondary emission peak; its intensity increases with the injected flare energy. We argue that coronal plasma condensation is a possible mechanism for the TESS late-phase flares.

Keywords: Solar coronal loops, Solar flares, Stellar flares, Hydrodynamical simulations
X-PSI Parameter Recovery for Temperature Map Configurations Inspired by PSR J0030+0451. In the last few years, the NICER collaboration has provided mass and radius inferences, via pulse profile modeling, for two pulsars: PSR J0030+0451 and PSR J0740+6620. Given the importance of these results for constraining the equation of state of dense nuclear matter, it is crucial to validate them and test their robustness. We therefore explore the reliability of these results and their sensitivity to analysis settings and random processes, including noise, focusing on the specific case of PSR J0030+0451. We use X-ray Pulse Simulation and Inference (X-PSI), one of the two main analysis pipelines currently employed by the NICER collaboration for mass and radius inferences. With synthetic data that mimic the PSR J0030+0451 NICER data set, we evaluate the recovery performances of X-PSI under conditions not previously tested, including complex modeling of the thermally emitting neutron star surface. For the test cases explored, our results suggest that X-PSI is capable of recovering the true mass and radius within reasonable credible intervals. This work also reveals the main vulnerabilities of the analysis: a significant dependence on noise and the presence of multimodal structure in the posterior surface. Noise particularly impacts our sensitivity to the analysis settings and widths of the posterior distributions. The multimodal structure in the posterior suggests that biases could be present if the analysis is unable to exhaustively explore the parameter space. Convergence testing, to ensure an adequate coverage of the parameter space and a suitable representation of the posterior distribution, is one possible solution to these challenges.

Keywords: Neutron stars, X-ray astronomy, High energy astrophysics, Astronomy data analysis, Nuclear astrophysics, Astronomical simulations
Wide-bandwidth Observations of PSR J0941-39 and PSR J1107-5907. We present a polarization analysis of PSR J0941-39 and PSR J1107-5907, which exhibit transitions between being pulsars and rotating radio transients (RRATs), using the ultrawide-bandwidth low-frequency receiver on Murriyang, the Parkes 64 m radio telescope. The spectral index of each pulsar was measured, revealing distinct variations among different states. By using the rotating vector model, we determined that the geometry of the magnetosphere remains consistent between the RRAT state and the pulsar state for PSR J0941-39, with emissions originating from the same height in the magnetosphere. The occurrence of the RRAT state could be attributed to variations in currents within the pulsar's magnetosphere. Our results suggest that the emission mechanism of an RRAT may share similarities with that of a typical pulsar.

Keywords: Radio pulsars, Pulsars
Surface Volatile Composition as Evidence for Hydrothermal Processes Lasting Longer in Triton's Interior than Pluto's. Ocean worlds, or icy bodies in the outer solar system that have or once had subsurface liquid water oceans, are among the most compelling topics of astrobiology. Typically, confirming the existence of a subsurface ocean requires close spacecraft observations. However, combining our understanding of the chemistry that takes place in a subsurface ocean with our knowledge of the building blocks that formed potential ocean worlds provides an opportunity to identify tracers of endogenic activity in the surface volatiles of Pluto and Triton. We show here that the current composition of the volatiles on the surfaces and in the atmospheres of Pluto and Triton are deficient in carbon, which can only be explained by the loss of CH4 through a combination of aqueous chemistry and atmospheric processes. Furthermore, we find that the relative nitrogen and water abundances are within the range observed in building block analogs, comets, and chondrites. A lower limit for N/Ar in Pluto's atmosphere also suggests source building blocks that have a cometary or chondritic composition, all pointing to an origin for their nitrogen as NH3 or organics. Triton's lower abundance of CH4 compared to Pluto, and the detection of CO2 at Triton but not at Pluto points to aqueous chemistry in a subsurface ocean that was more efficient at Triton than Pluto. These results have applications to other large Kuiper Belt objects as well as the assessment of formation locations and times for the four giant planets given future probe measurements of noble gas abundances and isotope ratios.

Keywords: Solar system formation, Triton, Planet formation, Pluto
Constraining a Companion of the Galactic Center Black Hole Sgr A*. We use 23 yr of astrometric and radial velocity data on the orbit of the star S0-2 to constrain a hypothetical intermediate-mass black hole orbiting the massive black hole Sgr A* at the Galactic center. The data place upper limits on variations of the orientation of the stellar orbit at levels between 0.°02 and 0.°07 per year. We use a combination of analytic estimates and full numerical integrations of the orbit of S0-2 in the presence of a black hole binary. For a companion intermediate-mass black hole outside the orbit of S0-2 (1020 au), we find that a companion black hole with mass m  c  between 103 and 105 M ☉ is excluded, with a boundary behaving as ${a}_{c}\sim {m}_{c}^{1/3}$ . For a companion with a  c  &lt; 1020 au, a black hole with mass between 103 and 105 M ☉ is excluded, with ${a}_{c}\sim {m}_{c}^{-1/2}$ . These bounds arise from quadrupolar perturbations of the orbit of S0-2. Significantly stronger bounds on an inner companion arise from the fact that the location of S0-2 is measured relative to the bright emission of Sgr A* and that separation is perturbed by the "wobble" of Sgr A* about the center of mass between it and the companion. The result is a set of bounds as small as 400 M ☉ at 200 au; the numerical simulations suggest a bound from these effects varying as ${a}_{c}\sim {m}_{c}^{-1}$ . We compare and contrast our results with those from a recent analysis by the GRAVITY collaboration.

Keywords: Supermassive black holes, Galactic center, Gravitation, Milky Way dynamics, Three-body problem, Astrophysical black holes
Multifrequency General Relativistic Radiation Magnetohydrodynamic Simulations of Thin Disks. We present a set of six general relativistic, multifrequency, radiation magnetohydrodynamic simulations of thin accretion disks with different target mass accretion rates around black holes with spins ranging from nonrotating to rapidly spinning. The simulations use the M 1 closure scheme with 12 independent frequency (or energy) bins ranging logarithmically from 5 × 10-3 keV to 5 × 103 keV. The multifrequency capability allows us to generate crude spectra and energy-dependent light curves directly from the simulations without a need for special postprocessing. While we generally find roughly thermal spectra with peaks around 1-4 keV, our high-spin cases showed harder-than-expected tails for the soft or thermally dominant state. This leads to radiative efficiencies that are up to five times higher than expected for a Novikov-Thorne disk at the same spin. We attribute these high efficiencies to the high-energy, coronal emission. These coronae mostly occupy the effectively optically thin regions near the inner edges of the disks and also cover or sandwich the inner ~15GM/c 2 of the disks.

Keywords: Accretion, Radiative magnetohydrodynamics, Rotating black holes, Low-mass x-ray binary stars, Relativistic disks
SPLUS J142445.34-254247.1: An r-process-enhanced, Actinide-boost, Extremely Metal-poor Star Observed with GHOST. We report on a chemo-dynamical analysis of SPLUS J142445.34-254247.1 (SPLUS J1424-2542), an extremely metal-poor halo star enhanced in elements formed by the rapid neutron-capture process (r-process). This star was first selected as a metal-poor candidate from its narrowband S-PLUS photometry and followed up spectroscopically in medium resolution with Gemini-South/GMOS, which confirmed its low-metallicity status. High-resolution spectroscopy was gathered with GHOST at Gemini-South, allowing for the determination of the chemical abundances for 36 elements, from carbon to thorium. At [Fe/H] = -3.39, SPLUS J1424-2542 is one of the lowest-metallicity stars with measured Th and has the highest $\mathrm{log}\epsilon (\mathrm{Th}/\mathrm{Eu})$ observed to date, making it part of the "actinide-boost" category of r-process-enhanced stars. The analysis presented here suggests that the gas cloud from which SPLUS J1424-2542 formed must have been enriched by at least two progenitor populations. The light-element (Z ≤ 30) abundance pattern is consistent with the yields from a supernova explosion of metal-free stars with 11.3-13.4 M ☉, and the heavy-element (Z ≥ 38) abundance pattern can be reproduced by the yields from a neutron star merger (1.66 M ☉ and 1.27 M ☉) event. A kinematical analysis also reveals that SPLUS J1424-2542 is a low-mass, old halo star with a likely in situ origin, not associated with any known early merger events in the Milky Way.

Keywords: High resolution spectroscopy, Chemical abundances, Narrow band photometry, Metallicity, Stellar atmospheres
X-Ray Polarization of the BL Lacertae Type Blazar 1ES 0229+200. We present polarization measurements in the 2-8 keV band from blazar 1ES 0229+200, the first extreme high synchrotron peaked source to be observed by the Imaging X-ray Polarimetry Explorer (IXPE). Combining two exposures separated by about two weeks, we find the degree of polarization to be ΠX = 17.9% ± 2.8% at an electric-vector position angle ψ X = 25.°0 ± 4.°6 using a spectro-polarimetric fit from joint IXPE and XMM-Newton observations. There is no evidence for the polarization degree or angle varying significantly with energy or time on both short timescales (hours) or longer timescales (days). The contemporaneous polarization degree at optical wavelengths was &gt;7× lower, making 1ES 0229+200 the most strongly chromatic blazar yet observed. This high X-ray polarization compared to the optical provides further support that X-ray emission in high-peaked blazars originates in shock-accelerated, energy-stratified electron populations, but is in tension with many recent modeling efforts attempting to reproduce the spectral energy distribution of 1ES 0229+200, which attribute the extremely high energy synchrotron and Compton peaks to Fermi acceleration in the vicinity of strongly turbulent magnetic fields.

Keywords: X-ray quasars, Radio galaxies, Polarimetry