Sazuna/UAT_keywords huggingface dataset:
The Impact of Orbital Anisotropy Assumptions in Lensing-dynamics Modeling. We investigate potential systematic biases introduced by assumptions regarding stellar orbital anisotropy in joint lensing-dynamics modeling. Using massive early-type galaxies from the TNG100 simulation at redshifts z = 0.2, 0.5, and 0.7, we generate a self-consistent mock data set containing lensing and stellar kinematic observables. This is achieved through taking the potential from both dark matter and baryons of the galaxies, plus the radial variation of the orbit anisotropy depicted by a logistic function. By integrating constraints from strong lensing, weak lensing, and stellar kinematics, we disentangle the contributions of stars and dark matter inside the galaxies. Under commonly adopted stellar anisotropy assumptions (isotropic orbits, constant anisotropy, and the Osipkov─Merritt profile), we find no significant systematic bias in key inferred parameters at the population level: the stellar mass bias  ∆logM⋆/M⊙=−0.03±0.10dex , the dark matter fraction bias ∆fdm = 2% ± 10%, and the dark matter inner density slope bias ∆ηdm = 0.15 ± 0.2. In other words, the inferences on stellar mass, dark matter fraction, and on the inner dark matter slopes are consistent with no bias within a 1σ error. Additionally, this lack of significant biases is insensitive to the discrepancies between the assumed anisotropy in modeling and the real orbital anisotropy of the mock sample. Our results suggest that conventional assumptions regarding stellar orbital anisotropy do not introduce a significant bias when inferring galaxy mass density distribution at the population level.

Keywords: Strong gravitational lensing, Galaxy dynamics, Elliptical galaxies
Simulating Image Coaddition with the Nancy Grace Roman Space Telescope. IV. Hyperparameter Optimization and Experimental Features. For weak gravitational lensing cosmology with the forthcoming Nancy Grace Roman Space Telescope, image coaddition (or construction of oversampled images from undersampled ones) is a critical step in the image processing pipeline. In the previous papers in this series, we re-implemented the IMCOM algorithm, which offers control over point-spread functions (PSFs) in coadded images, and applied it to state-of-the-art image simulations for Roman. In this work, we systematically investigate the impact of IMCOM hyperparameters on the quality of measurement results. We re-coadd the same 16 blocks ( 1.75×1.75arcmin2 , 2688 × 2688 pixels each) from OpenUniverse2024 simulations with 26 different configurations in each of five bands. We then compare the results in terms of 12 objective evaluation criteria, including internal diagnostics of IMCOM, properties of coadded noise frames, measurements of injected point sources, and time consumption. We demonstrate that: (i) the Cholesky kernel is the best-known linear algebra strategy for IMCOM, (ii) for our measurements, a wide Gaussian target output PSF outperforms a smoothed Airy disk or a narrow Gaussian, (iii) kernel-specific settings are worth considering for future coaddition, and (iv) IMCOM experimental features studied in this work are either inconsequential or detrimental. We end this paper by discussing current and next steps of IMCOM-related studies in the context of Roman shear and clustering measurements.

Keywords: Weak gravitational lensing, Astronomy image processing
Next-generation Improvements in Giant-exoplanet Evolutionary and Structural Models. Many evolutionary models of giant exoplanets still rely on simplifying assumptions that are no longer adequate, given detailed constraints from Jupiter, Saturn, and modern exoplanet observations. Here, we identify the key physical improvements required for next-generation planetary evolution models using our code APPLE, which enables the systematic emulation and extension of legacy studies. We quantify the effects of updated equations of state, helium rain, fuzzy cores, nonadiabatic and compositionally inhomogeneous envelopes, and improved atmospheric boundary conditions, by first isolating the impact of each physical ingredient and then constructing combined baseline models for planets with masses between 0.3 and 4 MJup, to assess their collective influence on planetary structure and observable properties. We find that the adoption of modern equations of state and realistic heavy-element distributions leads to systematic but sometimes subtle differences (∼5% to 10%) in radius evolution, while helium rain and the treatment of convection can significantly alter thermal histories and atmospheric compositions (by ∼5% to 20%). These updated physical processes must be incorporated into the next-generation exoplanet evolutionary models to achieve physically consistent interpretations of planetary observations.

Keywords: Exoplanets, Exoplanet evolution, Exoplanet structure, Planetary interior, Planetary structure
A JWST Paα Calibration of the Radio Luminosity─Star Formation Rate Relation at z ∼ 1.3. As radio emission from normal galaxies is a dust-free tracer of star formation, tracing the star formation history of the Universe is a key goal of the Square Kilometre Array and the Next-Generation Very Large Array. In order to investigate how well radio luminosity traces star formation rate (SFR) in the early Universe, we have examined the radio properties of a JWST Paα sample of galaxies at 1.0 ≲ z ≲ 1.8. In the GOODS-S field, we cross-matched a sample of 506 FRESCO Paα emitters with the 1.23 GHz radio continuum data from the MeerKAT MIGHTEE survey, finding 47 detections. After filtering for active galactic nuclei (via X-ray detections, hot mid-infrared dust, and extended radio emission), as well as blended sources, we obtained a sample of star-forming galaxies comprising 11 cataloged radio detections, 18 noncataloged detections (at ≍3σ─5σ), and 298 undetected sources. Stacking the 298 undetected sources, we obtain a 3.3σ detection in the radio. This sample, along with a local sample of Paα emitters, lies along previous radio luminosity/SFR relations from local (&lt;0.2) to high redshift (z ∼ 1). Fitting the FRESCO data at 1.0 ≲ z ≲ 1.8, we find  log(L1.4GHz)=  (1.31 ± 0.17) ×  log(SFRPaα)+  (21.36 ± 0.17), which is consistent with other literature relations. We can explain some of the observed scatter in the L1.4GHz/SFRPaα correlation by a toy model in which the synchrotron emission is a delayed/averaged tracer of the instantaneous Paα SFR by ∼10/75 Myr.

Keywords: Extragalactic radio sources, Starburst galaxies, Galaxy evolution
An Enhanced Sample of Galactic Red Supergiants Reveals Spiral Structures. Red supergiants (RSGs), representing a kind of massive young stellar population, have rarely been used to probe the structure of the Milky Way, mainly due to the long-standing scarcity of Galactic RSG samples. The Gaia BP/RP spectra (hereafter XP), which cover a broad wavelength range, provide a powerful tool for identifying RSGs. In this work, we develop a feedforward neural network classifier that assigns to each XP spectrum a probability of being an RSG, denoted as P(RSG). We perform 10 independent runs with randomly divided training and validation sets, and apply each run to all XP spectra of stars with G &lt; 12 mag. By selecting sources with P(RSG) ≥ 0.9, 10 high-confidence candidate samples are obtained. A star is considered a true Galactic RSG only if it appears in at least eight of these samples, yielding a final catalog of 2436 objects. These RSGs show a clear spatial correlation with OB stars and trace the Galactic spiral arms well, confirming the reliability of our classification, and highlighting their potential to serve as powerful tracers of the Milky Way's structure.

Keywords: Red supergiant stars, Neural networks, Galaxy structure, Spiral arms, Stellar classification
Tracing Pebble Drift History in Two Protoplanetary Disks with CO Enhancement. Pebble drift is an important mechanism for supplying the materials needed to build planets in the inner region of protoplanetary disks. Thus, constraining pebble drift's timescales and mass flux is essential to understanding planet formation history. Current pebble drift models suggest pebble fluxes can be constrained from the enhancement of gaseous volatile abundances when icy pebbles sublimate after drifting across key snowlines. In this work, we present Atacama Large Millimeter/submillimeter Array observations of spatially resolved 13C18O J = 2─1 line emission inside the midplane CO snowline of the HD 163296 and MWC 480 protoplanetary disks. We use radiative transfer and thermochemical models to constrain the spatial distribution of CO gas column density. We find that both disks display centrally peaked CO abundance enhancement of up to 10 times of the Interstellar Medium (ISM) abundance levels. For HD 163296 and MWC 480, the inferred enhancements require 250─350 and 480─660 M⊕ of pebbles to have drifted across their CO snowlines, respectively. These ranges fall within cumulative pebble mass flux ranges to grow gas giants in the interior to the CO snowline. The centrally peaked CO enhancement is unexpected in current pebble drift models, which predict CO enhancement peaks at the CO snowline, or is uniform inside the snowline. We propose two hypotheses to explain the centrally peaked CO enhancement, including a large CO desorption distance and CO trapped in water ice. By testing both hypotheses with the 1D gas and dust evolution code chemcomp, we find that volatile trapping (about 30%) best reproduces the centrally peaked CO enhancement observed.

Keywords: Protoplanetary disks
A Physics Informed Neural Network for Deriving MHD State Vectors from Global Active Regions Observations. Solar active regions (ARs) do not appear randomly but cluster along longitudinally warped toroidal bands ("toroids") that encode information about magnetic structures in the tachocline, where global-scale organization likely originates. Global MagnetoHydroDynamic Shallow-Water Tachocline (MHD-SWT) models have shown potential to simulate such toroids, matching observations qualitatively. For week-scale early prediction of flare-producing AR emergence, forward-integration of these toroids is necessary. This requires model initialization with a dynamically self-consistent MHD state-vector that includes magnetic, flow fields, and shell-thickness variations. However, synoptic magnetograms provide only geometric shape of toroids, not the state-vector needed to initialize MHD-SWT models. To address this challenging task, we develop PINNBARDS, a novel physics-informed neural network (PINN)—Based AR Distribution Simulator, that uses observational toroids and MHD-SWT equations to derive initial state-vector. Using 2024 February 14 Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) synoptic map, we show that PINN converges to physically consistent, predominantly antisymmetric toroids, matching observed ones. Although surface data provides north and south toroids' central latitudes, and their latitudinal widths, they cannot determine tachocline field strengths, connected to AR emergence. We explore here solutions across a broad parameter range, finding hydrodynamically dominated structures for weak fields (∼2 kG) and overly rigid behavior for strong fields (∼100 kG). We obtain best agreement with observations for 20─30 kG toroidal fields, and ∼10° bandwidth, consistent with low-order longitudinal mode excitation. To our knowledge, this framework provides the first plausible method for reconstructing state-vectors for hidden tachocline magnetic structures from surface patterns; this could potentially lead to accurate prediction of flare-producing AR-emergence weeks ahead.

Keywords: Magnetohydrodynamics, Solar magnetic flux emergence, Solar photosphere, Solar interior, Neural networks, Solar active regions
Discovery of a 21 cm Absorption System at z = 2.327 with CHIME. We report the detection of a new 21 cm absorption system associated with the radio source NVSS J164725 + 375218 at a redshift of z = 2.327, identified through a pilot survey conducted by the Canadian Hydrogen Intensity Mapping Experiment (CHIME). This is the fifth detection of an associated system at z &gt; 2. By analyzing a subset of available data, we conduct a spectrally blind survey for 21 cm absorption systems within the redshift range of 0.78─2.55 along 202 lines of sight toward known sources in the declination range of 35° to 60°. We detect three 21 cm absorbers: two previously known intervening systems and one newly discovered associated system. By fitting the absorption profiles with models containing one to three Gaussian components and selecting the best model using the Bayesian information criterion, we estimate the optical depth, velocity-integrated optical depth, and the ratio between the H I column density and the spin temperature of the absorption systems. These results demonstrate CHIME's ability to discover new absorbers, even in a small subset of its full dataset.

Keywords: Interstellar absorption, Damped Lyman-alpha systems, Redshift surveys
The Most Luminous Hβ Reverberation Mapping of E1821+643 Indicates the Lower Boundary of the Radius─Luminosity Relation. The radius─luminosity (RBLR─L5100) relation is fundamental to active galactic nucleus (AGN) studies, enabling supermassive black hole (SMBH) mass estimates and AGN-based cosmology applications. However, its high-luminosity end remains poorly calibrated due to insufficient reliable reverberation mapping (RM) data. We present a four-year RM campaign of the luminous quasar E1821+643 using the Lijiang 2.4 m telescope, supplemented by archival multiwavelength data. E1821+643 is the most luminous AGN with an Hβ RM measurement to date. The measured time lag of  83.2−18.7+17.5  days is a factor of 5.6 shorter than predicted by the canonical RBLR─L5100 relation. By compiling the full Hβ RM sample, we find that such deviation defines a lower envelope (0.2RBLR) of measured lags across the entire luminosity range, while the upper envelope lies near 2RBLR, implying that the scatter for individual AGNs can reach 1 dex. Spectral decomposition reveals two distinct Hβ components: a core component with a lag of  267.0−17.6+16.6  days closer to the RBLR─L5100 relation, and a redshifted tail with a much shorter lag of −49.0 −34.5+50.5  days. The short-lag component not only accounts for the significantly shortened overall lag but also leads to an opposite interpretation of the intrinsic broad-line region (BLR) kinematics. These effects can introduce systematic uncertainties in black hole mass estimates by factors of up to tens. Our findings demonstrate that shortened lags in high-accretion-rate AGNs arise from multicomponent BLR structures, posing substantial challenges to single-epoch mass estimates and impacting SMBH demographics and cosmological applications.

Keywords: Supermassive black holes, Reverberation mapping, Quasars
Radio Near-infrared Imaging of Dual Active Galactic Nuclei Candidates. We report the results of a pilot study that searched for dual active galactic nuclei (AGN) in local (z &lt; 0.25) galaxies hosting double-peaked narrow emission lines in their optical spectra. We present high-resolution L-band (1.5 GHz or 18 cm) continuum images from the Very Long Baseline Array as well as WFC3/IR F160W images from the Hubble Space Telescope of two candidate dual AGN systems: J0948+6848 and J1223+5409. In both targets, we detected compact nonthermal radio emission that is approximately cospatial with the near-infrared AGN. Both systems host two high brightness temperature (&gt;108 K) radio sources that indicate the presence of either a parsec-scale-separation dual AGN (dsep ∼ 90 and ∼56 pc, respectively) or a radio jet. Matched-resolution multiband radio observations are necessary to further characterize the AGN activity in these systems.

Keywords: Supermassive black holes, Active galaxies, Active galactic nuclei
Single-pulse Correlations in PSR B0329+54: Implications for Radio Emission Zones. Individual radio pulses from a pulsar are directly linked to the underlying emission processes and the associated magnetic field geometry within its magnetosphere. Thus, single-pulse studies across frequencies can provide crucial insights into the physics of radio emission. Multiple studies have investigated single-pulse correlations in PSR B0329+54 with widely separated discrete frequencies, reporting the broadband nature of pulsar emission. However, understanding the frequency evolution of these correlations has been limited by poor frequency sampling, and the physical origin of these correlations remains unexplored. We present a detailed study of single-pulse correlations in PSR B0329+54 at low radio frequencies using the upgraded Giant Meterwave Radio Telescope, with well-sampled time series spanning 300─1460 MHz. We derived an inverted flux spectrum for this pulsar, with a turnover near 470 MHz. We used flux-calibrated and scintillation-corrected single pulses to study correlations across frequencies. Our results show that maximum correlations consistently occur near the longitude of the central component, with correlation strength exceeding 69% for all frequency combinations, while outer components exhibit correlations above 46%. These findings indicate very strong interfrequency correlations, with no anticorrelations detected. No cross-component correlations were observed; only corresponding components correlate across frequencies. The longitudes of maximum correlation do not coincide with the intensity peaks of the average profile. We also examine how correlations vary with frequency at selected fiducial longitudes. The observations reported in this work favor curvature radiation from relativistic charge bunches in the pulsar plasma; however, reproducing the correlation curves along with spectra remains an open challenge.

Keywords: Astronomical techniques, Radio pulsars
The Impact of Diffusion and Turbulent Mixing on Chemical Abundance Variations in the Open Cluster NGC 2420. The mixing of material in stellar envelopes critically determines surface elemental abundances. A well-established tension remains between theoretical models and observational data for stars near the main-sequence turn-off. Resolving this issue requires developing a more physically complete treatment of material mixing, likely arising from processes inadequately represented in standard stellar models. This paper discusses four mixing mechanisms, including convection, convective overshooting, radiative diffusivity, and atomic diffusion, with particular focus on their combined impact on the surface elemental abundances of stars in the open cluster NGC 2420 during stellar evolution. We find that changes in the surface elemental abundances depend on the initial mass of the star and its evolutionary stage. The addition of extra mixing (radiative diffusivity) can resolve the issue of pure hydrogen atmospheres that arises for stars with masses greater than 1.35 M⊙. Our best-fitting model (Con+Ov+Diff) with a moderate overshoot parameter fov ∼ 0.0174 reproduces the observed abundance dip in NGC 2420, confirming atomic diffusion as the key mechanism and supporting a cluster age of ∼2.5 Gyr.

Keywords: Stellar abundances, Stellar convection envelopes, Stellar evolution
NuSTAR and TESS Discovery of an Intermediate Polar IGR J19173+0747. IGR J19173+0747 was discovered as an X-ray source by the INTEGRAL satellite and was initially classified as either a high-mass X-ray binary (HMXB) or a magnetic cataclysmic variable. Here, we report the detection of a coherent X-ray pulsation with a period of 792.9 ± 1.1 s in recent NuSTAR data, which we interpret as the spin period of the central compact object. Based on TESS optical photometry, we have also identified a periodic modulation of 793.38 ± 0.02 s, a value consistent, within uncertainties, with that determined from the X-ray data. This period lies outside the typical orbital period range for polars but falls within the characteristic spin-period range of intermediate polars (IPs). Furthermore, the X-ray spectrum exhibits a clear emission-line feature dominated by a fluorescent Fe Kα line at 6.4 keV. We derive an X-ray luminosity of  LX=1.31−0.56+0.88×1034ergs−1  and an absolute G-band magnitude of  MG=5.69−0.56+0.61  for IGR J19173+0747, both of which are consistent with typical values for IPs. Based on these findings, we rule out both the HMXB and polar scenarios and classify IGR J19173+0747 as an IP. Spectral fitting yields a white dwarf mass estimate of 0.948 ± 0.044 M⊙ for this source.

Keywords: X-ray binary stars, White dwarf stars, X-ray sources, Compact objects, Cataclysmic variable stars
The Spectral Features of Single-band Type III-like Radio Bursts Observed by PSP during Its First Nine Orbital Encounters. The spectral features of 1122 single-band type III-like radio bursts were analyzed statistically using data from the Parker Solar Probe (PSP) during the first nine orbital encounters. After excluding overlapping events, 923 bursts were classified into 706 complete-spectrum (CS) bursts and 217 incomplete-spectrum (IS) bursts depending on radiation completeness. The distribution of start frequency fst for IS events (20─54 MHz) was predicted by a lognormal fit. The higher cutoff frequency (flo ∼ 1.2─1.6 MHz) than previous results may be attributed to the limitation of exciting conditions or the radial expansion of guiding magnetic flux tubes. Short durations (1─4 minutes) and low peak fluxes (∼103 sfu) indicate that most events are short-time weak bursts. The spectral index of duration versus frequency is near −1, which reflects the influence of velocity dispersion and radio-wave scattering. For the denoised spectra of CS events, the peak frequency of maximal flux (∼4.5 MHz) is obviously higher than those from STEREO (∼1 MHz) and WIND (∼ 2 MHz). This implies that the radiation may be the second or third harmonic wave rather than the fundamental wave. Statistical frequency drift rates follow the classical power-law relation (Dabs ∝ f1.84) and are consistent with simulation results of typical type III radio bursts. CS and IS bursts show similarities in flo, duration, and drift features, but obviously differ in the peak frequency of maximal flux. These results can provide a useful reference for further exploring the emission mechanisms of single-band type III-like radio bursts and the associated energetic electron acceleration processes.

Keywords: Space plasmas, Radio bursts, Solar radio emission, Solar physics, Interplanetary physics
Variability Study and Searching for Quasiperiodic Oscillations with Day-like Periods in the Blazar S5 0716+714 with TESS. Using an unprecedented cadence of 30 minutes provided by the Transiting Exoplanet Survey Satellite, we have examined the optical light curves (LCs) of the blazar S5 0716+714 obtained from its Sectors 40, 47, and 53 over a period of about 75 days. This source exhibited flux variability in each of those sectors, reaching a maximum variability amplitude of 5.6%. The power spectral density shapes were tested with a simple power law and two distinct bending power laws and were found to be better fit by bending power laws than simple power laws for all but one of the segments. To look for any periodicities in these LCs, we used weighted wavelet Z transform analysis and generalized Lomb─Scargle periodograms. We identified one possible quasiperiodic oscillation signature in a portion of sector 40 (period of ∼6.5 hr), having ∼95% global significance. A statistical approach to assess the LCs involving continuous autoregressive moving average was implemented, and the LCs were found to follow more complex processes than the simplest and typical damped random walk process. We briefly discuss the statistical properties of the LCs along with the general variability features and physical processes that could cause these types of fluctuations.

Keywords: BL Lacertae objects, Jets, Active galactic nuclei, Blazars