Sazuna/UAT_keywords huggingface dataset:
Shock-cooling Constraints via Early-time Observations of the Type IIb SN 2022hnt. We report the results of a rapid follow-up campaign on the Type IIb supernova (SN) 2022hnt. We present a daily, multiband, photometric follow-up using the Las Cumbres Observatory, the Zwicky Transient Facility, the orbiting Swift observatory, and the Asteroid Terrestrial-impact Last Alert System. A distinctive feature in the light curve of SN 2022hnt and other IIb SNe is an early narrow peak prior to the 56Ni peak caused by rapid shock cooling of the hydrogen envelope, which can serve as an important probe of the properties of the massive progenitor star in the moments before explosion. Using SN 2022hnt as a case study, we demonstrate a framework of considerations for the application of shock cooling models to type IIb SNe, outlining a consistent procedure for future surveys of Type IIb SNe progenitor and explosion properties. We fit several recent models of shock-cooling emission and obtain progenitor radii between ∼50 and ∼100 R⊙, as well as hydrogen-enriched envelope masses between ∼0.01 and ∼0.1 M⊙, both consistent with values for other IIb SNe. One of these models is the model of J. Morag et al., marking the first time this model has been applied to a Type IIb SN. Finally, we evaluate contrasting predictions between shock-cooling models to construct a fiducial parameter set that can be used for comparison to other SNe.

Keywords: Type II supernovae, Supernovae, Core-collapse supernovae
A Search for Low-mass Neutron Stars in the Third Observing Run of Advanced LIGO and Virgo. Most observed neutron stars have masses around 1.4 M⊙, consistent with current formation mechanisms. To date, no subsolar-mass neutron star has been observed. Observing one would provide crucial constraints on the nuclear equation of state, unveil a new neutron star population, and advance understanding of their formation mechanisms. We present the first targeted search for tidally deformed subsolar-mass binary neutron stars (BNSs), with primary masses ranging from 0.1 to 2 M⊙ and secondary masses from 0.1 to 1 M⊙, using data from the third observing run of the Advanced LIGO and Virgo gravitational-wave detectors. We account for the tidal deformabilities of up to O(104) of these systems, as low-mass neutron stars are more easily distorted by their companions. Previous searches that neglect tidal deformability lose sensitivity to low-mass sources, potentially missing more than ∼30% of detectable signals from a system with a chirp mass of 0.6 M⊙ binaries. No statistically significant detections were made. In the absence of a detection, we place a 90% confidence upper limit on the local merger rate for subsolar BNSs, constraining it to be &lt;6.4 × 104 Gpc‑3 yr‑1 for a chirp mass of 0.2 M⊙ and &lt;2.2 × 103 Gpc‑3 yr‑1 for 0.7 M⊙. With future upgrades to detector sensitivity, development of next-generation detectors, and ongoing improvements in search pipelines, constraints on the minimum mass of neutron stars will improve, providing the potential to constrain the nuclear equation of state, reveal new insights into neutron star formation channels, and potentially identify new classes of stars.

Keywords: Neutron stars, Gravitational waves, Gravitational wave sources, Gravitational wave astronomy
Reacceleration of a C IV Broad Absorption Line in Quasar SDSS J083817.00+295526.5. We present a rare signature of reacceleration in a C IV broad absorption line (BAL) of the quasar SDSS J083817.00+295526.5. This quasar showcases three distinct BAL systems, labeled as systems A, B, and C. Notably, system A, which boasts the highest velocity of ∼‑22,000 km s‑1, initially demonstrates a deceleration of ∼3160 km s‑1 in its C IV ion over a rest-frame period of ∼2.3 yr. Subsequently, it exhibits an acceleration of ∼‑3366 km s‑1 over a rest-frame period of ∼2.6 yr. To elucidate the nature of these signatures, we conducted a thorough analysis, focusing on the ionization state, location, and variation situation of the three BAL systems. Our findings reveal that system A exhibits higher velocities, higher ionization states, and is situated closer to the central source compared to systems B and C. Collectively, these characteristics suggest that the outflow generating system A is located in an exceptionally extreme environment and experiences more pronounced impacts from background radiation energy than systems B and C. Given the currently limited observational data, the physical origin of this peculiar reacceleration phenomenon remains an open question. We briefly discuss several possibilities and hypothesize that the outflow winds initially interact with ambient galactic material, causing their deceleration, and are subsequently reaccelerated by the radiation pressure from the central source.

Keywords: Broad-absorption line quasar, Quasar absorption line spectroscopy, Quasars
The Nature of Gravitational Wave Events with Host Environment Escape Velocities. We propose a novel method to probe the parameters and origin channels of gravitational wave events using the escape velocities of their host environments. This method could lead to more convergent posterior distributions offering additional insights into the physical properties, formation, and evolution of the sources. The method provides more accurate parameter estimation for events that represent previous mergers in the hierarchical triple merger scenario and is valuable for the search for such mergers with third-generation ground-based detectors. To demonstrate this approach, we take six recently identified events in LIGO–Virgo–KAGRA (LVK) data, considered as potential previous mergers in hierarchical triple mergers, as examples. The use of escape velocities results in posterior spin distributions that are concentrated near zero, aligning with the expected birth spins of first-generation black holes formed from the collapse of stars. The uncertainty in the posterior primary mass distribution is significantly reduced comparing with the LVK distributions, especially for events modeled under the assumption of a globular cluster (GC) origin scenario. We rule out the possibility that GW190512, GW170729, and GW190708 originate from GCs as previous mergers in the hierarchical triple merger scenario.

Keywords: Gravitational wave astronomy
The Timing and Polarization of PSR J0002+6216. The combined timing analysis of data from the Five-hundred-meter Aperture Spherical radio Telescope (FAST) and the Fermi Large Area Telescope confirmed that PSR J0002+6216 is not a hyper-velocity (exceeding 1000 km s‑1) pulsar. From this analysis, we determined the total proper motion of PSR J0002+6216 to be μtot = 39.05 ± 15.79 mas yr‑1, which is consistent with Very Long Baseline Interferometry (VLBI) measurements to within 0.24 σ. Moreover, two glitches were detected for the first time, which occurred on MJD 58850(17) and MJD 60421(6), respectively. The second glitch exhibited an exponential recovery process, with Q = 0.0090(3) and τd = 45(3) days. Additionally, with FAST high-sensitivity observations, we measured the interstellar rotation measure (RM) and the 3D orientation of the spin axis for the first time, and updated the dispersion measure (DM) of PSR J0002+6216. Currently, no variations in RM or DM have been detected. By combining the measured RM with the observed position angle of the spin axis, we determined that the intrinsic position angle of the pulsar's spin axis is  . When we compared this with the proper motion position angle obtained from VLBI, we found a misalignment of approximately 23∘ between the spin and velocity angles of PSR J0002+6216. At present, pulsars with 2D spin–velocity angle measurements are unable to fully test the Janka et al. model. However, with more high-precision observational data in the future, we will be able to further test models related to pulsar birth.

Keywords: Proper motions, Radio pulsars
Asteroseismology of Long-period Variables with OGLE-IV Data: Using Global Seismic Parameters as Luminosity Indicators. Long-period variables (LPVs) are high-luminosity red giants or supergiants with pulsation periods ranging from days to years. Many LPVs in the Large Magellanic Cloud (LMC) and Galactic bulge (BLG) have been continuously observed over a time span of 26 yr by the Optical Gravitational Lensing Experiment (OGLE) survey. Using OGLE-IV data, we applied Gaussian processes with kernels tailored for solar-like oscillations to extract two global asteroseismic parameters—the frequency of maximum power ( ) and the large frequency separation (Δν)—for LPVs with primary mode periods (P1) between 10 and 100 days in the LMC and BLG. We found that the  -Δν relation for LPVs in this work aligns with that of lower-luminosity Kepler red giants, confirming that the pulsations of these LPVs are likely solar like. We found that   and Δν can serve as luminosity indicators. Compared to P1,   and Δν exhibit significantly tighter correlations with the absolute magnitude in the Two Micron All Sky Survey Ks band (MK), with corresponding scatter of 0.27 and 0.21 mag, respectively. Using the calibrated  –MK and Δν–MK relations for LPVs in the LMC, we determined the MK values for individual stars in the BLG. By accounting for extinction, we further calculated the distances to 4948 BLG stars. The peak of the resulting distance distribution corresponds to an estimated distance to the Galactic center of approximately 9.1 kpc, which appears to be overestimated, suggesting that the seismic luminosity relation calibrated from the LMC may not be directly applicable to BLG stars.

Keywords: Stellar pulsations, OGLE small amplitude red giant stars, Long period variable stars, Gaussian Processes regression, Asteroseismology
Orbital Phase Shifts of Type-I Outbursts in EXO 2030+375. EXO 2030+375 is a peculiar high-mass X-ray binary that has been exhibiting Type-I outburst activities consistently over the past decades. The phases of outburst peaks are generally stable and occur near the orbital periastron. However, significant orbital phase shifts have occasionally been observed in 1995, 2006, and 2016. In this paper, we report another orbital phase shift triggered by a giant outburst in 2021. During this event, the orbital phase of Type-I outburst peaks changed dramatically, moving from near periastron to 20 days after periastron, followed by a gradual recovery. Additionally, for several cycles after the 2021 giant outburst, some Type-I outbursts were missing, with subsequent outbursts occurring every two orbits. We discuss our observations in the frame of the precession of an eccentric Be disk.

Keywords: X-ray binary stars, High mass x-ray binary stars, B(e) stars
Six-hour Prediction of Interplanetary Magnetic Field B<SUB>z</SUB> Profiles for Strong Southward Cases by Deep Learning. In this study, we develop deep learning models to forecast the 6 hr interplanetary magnetic field (IMF) Bz component for southward cases. The models are based on a bidirectional long short-term memory method, and input parameters are solar wind data (V, N, T) and IMF components (Bt, Bx, By, Bz). The data are obtained from OMNI, whose period is from 2000 to 2022. We use the preceding 12 hr of data as input and the subsequent 6 hr of Bz data as target. To focus on strong geomagnetic conditions, we consider periods where Bz values drop below the negative standard deviation (approximately ‑3 nT) for at least 6 hr. The models are trained and validated using a 12-fold cross-validation process, with each model trained over 8 months of data and tested over 4 months. The ensemble model, which averages 12-fold model results, achieves an RMSE ranging from 1.75 (30 minutes prediction) to 2.55 nT (6 hr prediction), significantly outperforming two baseline methods: multilayer perceptron and multiple linear regression. Our model can capture both decreasing and increasing phases of Bz, showing reliable performance across varying geomagnetic conditions. Our results suggest a sufficient possibility for predicting Bz under noticeable southward conditions. We expect that our model can be used for subsequent space weather predictions, such as global magnetohydrodynamic simulations in the magnetosphere.

Keywords: Neural networks, Space weather, The Sun, Solar wind, Interplanetary magnetic fields
CWTHF: Identifying Dark Matter Halos with Continuous Wavelet Transform. Cosmological simulations are an important method for investigating the evolution of the Universe. In order to gain further insight into the processes of structure formation, it is necessary to identify isolated bound objects within the simulations, namely, the dark matter halos. The continuous wavelet transform (CWT) is an effective tool used as a halo finder due to its ability to extract clustering information from the input data. In this study, we introduce the continuous wavelet transform halo finder (CWTHF), the first wavelet-based, MPI-parallelized halo finder, marking a novel approach in the field of cosmology. We calculate the CWT from the cloud-in-cell grid and segment the grid based on the local CWT maxima. We then investigate the effects of the parameters that influence our program and identify the default settings. A comparison with the conventional friends-of-friends (FOF) method demonstrates the viability of CWT for halo finding. Although the actual performance is not faster than FOF, the linear time complexity of   of our identification scheme indicates its significant potential for future optimization and application.

Keywords: Galaxy dark matter halos, N-body simulations, Wavelet analysis, Large-scale structure of the universe
Velocity and Density Fluctuations in the Quiet Sun Corona. We investigate the properties and relationship between Doppler velocity fluctuations and intensity fluctuations in the off-limb quiet Sun corona. These are expected to reflect the properties of Alfvénic and compressive waves, respectively. The data come from the Coronal Multichannel Polarimeter (COMP). These data were studied using spectral methods to estimate the power spectra, amplitudes, perpendicular correlation lengths, phases, trajectories, dispersion relations, and propagation speeds of both types of fluctuations. We find that most velocity fluctuations are due to Alfvénic waves but that intensity fluctuations come from a variety of sources, likely including fast and slow mode waves, as well as aperiodic variations. The relation between the velocity and intensity fluctuations differs depending on the underlying coronal structure. On short closed loops, the velocity and intensity fluctuations have similar power spectra and speeds. In contrast, on longer nearly radial trajectories, the velocity and intensity fluctuations have different power spectra, with the velocity fluctuations propagating at much faster speeds than the intensity fluctuations. Considering the temperature sensitivity of COMP, these longer structures are more likely to be closed fields lines of the quiet Sun rather than cooler open field lines. That is, we find the character of the interactions of Alfvénic waves and density fluctuations depends on the length of the magnetic loop on which they are traveling.

Keywords: Quiet sun, Atomic spectroscopy, Solar physics, Solar coronal waves, Quiet solar corona, Time series analysis
Estimating the Bulk Velocity of Energetic Particle Populations Using IS⊙IS/EPI-Lo Measurements. We introduce a method to derive the bulk velocity of the solar energetic particle population, given intensity measurements for a set of apertures viewing half of the sky, as is the case for energetic particle measurements from IS⊙IS/EPI-Lo on the Parker Solar Probe spacecraft. In the comoving frame, intensity distribution is modeled as an isotropic power-law energy spectrum multiplied by an arbitrary pitch angle distribution. This distribution is shifted by an arbitrary bulk velocity vector, then converted to expectation values for the particle counts that would be observed by the instrument. By assuming that the observed particle counts are Poisson-distributed samples of the model, a maximum likelihood bulk velocity is found. To test the method, we used simulated measurements to explore the reliability of the method. We found that, even with half-sky measurements, the method can provide nearly unbiased estimates of the bulk velocity within the uncertainty as long as the pitch angle distribution is resolved. We also took advantage of a period during which the spacecraft was rolling for calibration purposes, effectively giving EPI-Lo full-sky viewing. By comparing the result obtained from different segments of the sky, we found that those obtained from different half-sky fields of view are generally compatible within the uncertainty, especially when the pitch angle distribution is resolved. We also compared the perpendicular part of the bulk energetic velocity to the perpendicular part of the bulk solar wind velocity, finding a strong correlation (∼0.78), as expected.

Keywords: Regression, Solar energetic particles, Solar wind, Nonlinear regression, Poisson distribution
The Immediate, Exemplary, and Fleeting Echelle Spectroscopy of SN 2023ixf: Monitoring Acceleration of Slow Progenitor Circumstellar Material Driven by Shock Interaction. We present high-resolution WIYN/NEID echelle spectroscopy (R ≍ 70,000) of the supernova (SN) 2023ixf in M101, obtained 1.51 to 18.51 days after explosion over nine epochs. Daily monitoring for the first 4 days after explosion shows narrow emission features (≤200 km s−1), exhibiting predominantly blueshifted velocities that rapidly weaken, broaden, and vanish in a manner consistent with radiative acceleration and the SN shock eventually overrunning or enveloping the full extent of the dense circumstellar medium (CSM). The most rapid evolution is in the He I emission, which is visible on day 1.51 but disappears by day 2.62. We measure the maximum pre-SN speed of He I to be 25   km s−1, where the error is attributable to the uncertainty in how much the He I had already been radiatively accelerated and to measurement of the emission-line profile. The radiative acceleration of CSM is likely driven by the shock─CSM interaction, and the CSM is accelerated to ≥200 km s−1 before being completely swept up by the SN shock to ∼2000 km s−1. We compare the observed spectra with spherically symmetric r1w6b HERACLES/CMFGEN model spectra and find the line evolution to generally be consistent with radiative acceleration, optical depth effects, and evolving ionization state. The progenitor of SN 2023ixf underwent an enhanced mass-loss phase ≳4 yr prior to core collapse, creating a dense, asymmetric CSM region extending out to approximately rCSM = 3.7 × 1014 (vshock/9500 km s−1) cm.

Keywords: Hydrodynamical simulations, Core-collapse supernovae, Type II supernovae, Stellar mass loss, Circumstellar matter, Radiative transfer simulations, Supernovae
Dust Destruction in Shock Waves in the Cygnus Loop. Supernova remnant (SNR) shock waves are known to be important sources of dust destruction in the interstellar medium. Models of dust destruction in shocks have made various predictions of the destruction efficiency, but have generally been difficult to test in detail due to the uncertainties in the physical parameters in observed shocks and the required assumptions in the models. In this paper we present new Hubble Space Telescope data on shocks in the Cygnus Loop SNR that have been observed with enough precision over time to allow determination of their proper motions and thus the shock speeds. The observed UV emission comes from various ions from elements that are prevalent in dust. We present results of new models for these radiative shocks that include dust destruction, including the liberation of elements into the gas phase. The inclusion of sputtered grain material substantially alters the predicted cooling and spectra and gives us a better estimate of the effects of dust on the shock emission. The observed line ratios strongly support the predictions that radiative shocks with speeds vs = 90–160 km s‑1 destroy dust with an efficiency that increases with shock speed approximately with the predicted rates.

Keywords: Supernova remnants, Interstellar medium, Interstellar dust processes
Central Velocity Dispersion as the Primary Driver of Abundance Patterns in Quenched Galaxies. The element abundances of galaxies provide crucial insights into their formation and evolution. Using high-resolution integral field unit data from the Mapping Nearby Galaxies at Apache Point Observatory survey, we analyze the central spectra (0–0.5 Re) of 1185 quenched galaxies (z = 0.012‑0.15) to study their element abundances and stellar populations. We employ the full-spectrum fitting code alf to derive stellar ages and element abundances from synthetic spectra and empirical libraries. Our key findings are: (1) the central velocity dispersion (σ*) is the most effective parameter correlating with the (relative) element abundances, especially [Na/Fe], [Mg/Fe], [C/Fe], and [N/Fe], outperforming M* and M*/Re; (2) when binned by σ*, the relative abundances of Na, Mg, C, and N remain stable across different formation times (Tform), suggesting these elements are primarily influenced by the burstiness of star formation (traced by σ*) rather than prolonged evolutionary processes; and (3) Fe and Ca show little variation with σ*, indicating weaker sensitivity to σ*-driven processes. However, Tform has a global influence on all elements, contributing to their overall chemical evolution, although this is secondary to σ* for most elements. These results support the primary role of σ* in shaping the abundance patterns, likely stemming from the connection with central massive black holes and possibly also that with dark matter halos, which influences the burstiness of star formation histories.

Keywords: Stellar populations, Galaxy evolution, Chemical abundances, Early-type galaxies
The Diversity of Cold Worlds: A Blended-light Binary Straddling the T/Y Transition in Brown Dwarfs. We present the first brown dwarf spectral binary characterized with JWST: WISE J014656.66+423410.0, the coldest blended-light brown dwarf binary straddling the T/Y transition. We obtained a moderate resolution (R ∼ 2700) G395H spectrum of this unresolved binary with JWST/NIRSpec and we fit it to late T and Y dwarf spectra from JWST/NIRSpec, and model spectra of comparable temperatures, both as individual spectra and pairs mimicking an unresolved binary system. We find that this tightly separated binary is likely composed of two unequal-brightness sources with a magnitude difference of 0.50 ± 0.08 mag in IRAC [4.5] and a secondary 1.01 ± 0.13 mag redder than the primary in [3.6]–[4.5]. Despite the large color difference between the best-fit primary and secondary, their temperature difference is only 92 ± 23 K, a feature reminiscing of the L/T transition. Carbon disequilibrium chemistry strongly shapes the mid-infrared spectra of these sources, as a complex function of the metallicity and surface gravity. While a larger library of JWST/NIRSpec spectra is needed to conclusively examine the peculiarities of blended-light sources, this spectral binary is a crucial pathfinder to both understand the spectral features of planetary-mass atmospheres and detect binarity in unresolved, moderate-resolution spectra of the coldest brown dwarfs.

Keywords: Brown dwarfs, Binary stars, Y dwarfs, James Webb Space Telescope, Spectroscopy