Sazuna/UAT_keywords huggingface dataset:
Comprehensive Laboratory Benchmark of K-shell Dielectronic Satellites of Fe XXV─XXI Ions. We report on comprehensive laboratory studies of the K-shell dielectronic recombination resonances of Fe XXV─XXI ions that prominently contribute to the hard X-ray spectrum of hot astrophysical plasmas. By scanning a monoenergetic electron beam to resonantly excite trapped Fe ions in an electron beam ion trap and achieving a high electron─ion collision energy resolution of ∼7 eV, we resolve their respective KLn satellites up to  n'=11 . By normalization to known radiative recombination cross sections, we also determine their excitation cross sections and that of the continuum with uncertainties below 15% and verify our results with an independent normalization based on previous measurements. Our experimental data excellently confirm the accuracy and suitability of distorted-wave calculations obtained with the Flexible Atomic Code for modeling astrophysical and fusion plasmas.

Keywords: X-ray astronomy, Atomic physics, Laboratory astrophysics, Experimental techniques, Dielectronic recombination, Atomic data benchmarking
The 2023 Outburst of the Gaia Alerted EXor Gaia23bab. Episodic accretion is a fundamental process in the build-up of the stellar mass. EX Lupi-type eruptive young stars (EXors) represent one of the main types of episodic accretion. We study the recently discovered EXor Gaia23bab during its 2023 outburst. We obtained optical and near-infrared photometry and spectroscopy to probe the variation of the physical properties of Gaia23bab during its recent outburst. We also collected archival photometry to study a previous outburst of the star. We used several accretion tracers, including the Ca II triplet, He I, and various hydrogen lines from the Paschen and Brackett series, to measure the accretion rate during the outburst. The accretion rate is consistent with ∼2.0 × 10‑7M⊙ yr‑1. Comparing the line fluxes of the hydrogen Brackett series to predictions of Case B theory suggests excitation temperatures of 5000–10,000 K and electron densities of 109–1010 cm‑3. Comparison to the predictions of a model for T Tauri stars revealed that the fluxes of the Balmer series are consistent with temperatures of 5000–12,500 K and a hydrogen density of 108 cm‑3, while the fluxes of the Paschen series are consistent with temperatures in the range between 10,000 and 12,500 K and a hydrogen density of 1011 cm‑3. The derived temperatures and densities confirm that Gaia23bab is a prototypical EXor, not only due to its accretion rate, but also based on the best-fit temperatures and densities revealed by the detected hydrogen lines.

Keywords: Eruptive variable stars, Classical T Tauri stars, Young stellar objects, Pre-main sequence stars, Star formation, Stellar accretion disks
A New Formation Mechanism of Counterstreaming Mass Flows in Filaments and the Doppler Bullseye Pattern in Prominences. The eruption of a solar prominence can eject substantial mass and magnetic field into interplanetary space and cause geomagnetic storms. However, various questions about prominences and their eruption mechanism remain unclear. In particular, what causes the intriguing Doppler bullseye pattern in prominences has not yet been solved, despite some preliminary studies proposing that they are probably associated with counterstreaming mass flows. Previous studies are mainly based on single-angle and short-timescale observations, making it difficult to determine the physical origin of Doppler bullseye patterns in prominences. Here, taking advantage of stereoscopic observations taken by the Solar Dynamics Observatory and the Solar Terrestrial Relations Observatory and a three-dimensional numerical simulation, we investigate the origin of the prominence Doppler bullseye pattern by tracing a long-lived transequatorial filament/prominence from 2012 July 23 to August 4. We find that the Doppler bullseye pattern can be launched by repeated coronal jets at one end of the prominence. It is evidenced in our observations and simulation that during the forward traveling of jet plasma along the helical magnetic field structure of the prominence, part of the ejecting plasma can not pass through the apex of the prominence due to the insufficient kinetic energy and therefore forms a backward-moving mass flow along the same or neighboring magnetic field lines. This process finally forms counterstreaming mass flows in on-disk filaments. When the on-disk filament rotates to the solar limb to be a prominence, the counterstreaming mass flows are naturally observed as a Doppler bullseye pattern.

Keywords: Solar activity, Solar chromosphere, Solar filaments, Solar magnetic fields
P-CORONA: A New Tool for Calculating the Intensity and Polarization of Coronal Lines in 3D Models of the Solar Corona. The critical need to study the magnetic field in the solar corona is highlighted by recent observational facilities, such as the Daniel K. Inouye Solar Telescope and Aditya-L1. A powerful tool for probing the magnetism of the solar corona is forward modeling of the intensity and polarization of coronal emission lines in three-dimensional (3D) magnetohydrodynamic models. Here we present P-CORONA, a new spectral synthesis code designed to calculate the intensity and polarization of coronal lines in 3D models of the solar corona, taking into account the symmetry breaking induced by magnetic and velocity fields. P-CORONA allows the calculation of the on-disk and off-limb intensity and polarization of forbidden and permitted coronal lines, thus facilitating a wide range of investigations. Applying the quantum theory of atom–photon interactions, P-CORONA accounts for the spectral line polarization caused by anisotropic radiation pumping and the Hanle and Zeeman effects, making it a valuable tool for investigating coronal magnetic fields. This paper details the code's theoretical formulation, implementation, and illustrative results of calculations in different 3D coronal models (MURaM and Predictive Science Inc.), including the impact of the Zeeman effect from the transverse magnetic field component on selected coronal forbidden lines. P-CORONA is now accessible to the research community on GitLab and Zenodo, providing a resource to facilitate research aimed at advancing our understanding of coronal magnetism and dynamics.

Keywords: Spectropolarimetry, Solar coronal lines, Solar physics, Solar magnetic fields, Solar corona
Tracing High-z Galaxies in X-Rays with JWST and Chandra. We leverage James Webb Space Telescope (JWST) data from the COSMOS-Web survey in order to provide updated measurements on the auto-power spectrum of the now resolved cosmic near-infrared background (CIB) and its coherence with the unresolved soft cosmic X-ray background (CXB) observed by Chandra at z &gt; 6. Maps of the CIB in the F277W and F444W NIRCam filters are constructed with sources fainter than mAB = 25 and cross-correlated with the CXB in the [0.5─2] keV band. We find that on scales between 1″ and 1000″ the CIB─CXB cross-power in both NIRCam filters is statistically significant, with signal-to-noise ratios (S/Ns) of 4.80 and 6.20, respectively, from redshifts 0 ≤ z ≤ 13. In our high-z (6 ≤ z ≤ 13) interval we find coherence in both filters, with S/Ns of 7.32 and 5.39, respectively. These results suggest that there are X-ray-emitting galaxies resolved by JWST, including star-forming galaxies and active galactic nuclei. We fit the large-scale biasing of the IR sources producing the CIB as a function of z with results consistent with prior measurements, and place constraints on the CXB flux and biasing at low and high z. The CXB flux measurements presented in this study suggest that approximately 94% of the [0.5─2] keV CXB is resolved, and this value is consistent within 2σ with the complete resolution of the [0.5─2] keV CXB.

Keywords: Star formation, Active galactic nuclei, Cosmic background radiation, Large-scale structure of the universe
Scaler Rates from the Pierre Auger Observatory: A New Proxy of Solar Activity. The modulation of low-energy galactic cosmic rays reflects interplanetary magnetic field variations and can provide useful information on solar activity. An array of ground-surface detectors can reveal the secondary particles, which originate from the interaction of cosmic rays with the atmosphere. In this work, we present an investigation of the low-threshold rate (scaler) time series recorded in 16 yr of operation by the Pierre Auger Observatory surface detectors in Malargüe, Argentina. Through an advanced spectral analysis, we detected highly statistically significant variations in the time series with periods ranging from the decadal to the daily scale. We investigate their origin, revealing a direct connection with solar variability. Thanks to their intrinsic very low noise level, the Auger scalers allow a thorough and detailed investigation of the galactic cosmic-ray flux variations in the heliosphere at different timescales and can, therefore, be considered a new proxy of solar variability.

Keywords: Solar activity, Cosmic ray detectors, Astronomy data analysis
Alfvén Wave Mode Conversion in Neutron Star Magnetospheres: A Semianalytic Approach. We write down the force-free electrodynamics equations in dipole coordinates and solve for axisymmetric normal modes corresponding to Alfvénic perturbations in the magnetosphere of a neutron star. We show that a single Alfvén wave propagating on dipole field lines spontaneously sources a fast magnetosonic (fms) wave at the next order in the perturbation expansion, without needing three-wave interaction. The frequency of the sourced fms wave is twice the original Alfvén wave frequency, and the wave propagates spherically outward. The properties of the outgoing fms wave can be computed exactly using the usual devices of classical electrodynamics. We extend the calculation to the closed zone of a rotating neutron star magnetosphere, and show that the Alfvén wave also sources a spherical fms wave but at the same frequency as the primary Alfvén wave.

Keywords: Neutron stars, Alfven waves, Perturbation methods, Plasma astrophysics
Frequency-dependent Emission of the Millisecond Pulsar B1937+21 with the Parkes Ultrawideband Receiver. In this study, we report on the broadband polarization behavior of the millisecond pulsar B1937+21 (J1939+2134), using high-quality observations made with the ultrawideband low receiver on Murriyang, the Parkes radio telescope. Observations spanning approximately 3 yr are carefully calibrated and integrated to produce high-signal-to-noise-ratio pulse profiles. Updated and accurate interstellar medium parameters toward the pulsar are obtained. The temporal variability of the dispersion measure, the Faraday rotation measure, and the flux density are analyzed from their corresponding structure functions. The frequency-and-longitude-dependent polarization evolutions are investigated. The spectra of the mean flux density follow a high-frequency cutoff power law, with the interpulse spectra being steeper than the main pulse. The fractional linear polarization of the main pulse decreases with increasing frequency, while the interpulse presents the opposite trend. Both the main pulse and interpulse exhibit increasing absolute circular polarization with increasing frequency. The peak intensity ratio of the main pulse to the interpulse increases with frequency, following a power-law spectrum with an index of 0.52 ± 0.02. The pulse width decreases with increasing frequency, further confirming that the emission height decreases with frequency, consistent with the results obtained from relativistic effects. These findings will contribute to a deeper understanding of the underlying emission mechanisms.

Keywords: Radio pulsars, Millisecond pulsars
Interpreting the Spectrotemporal Properties of the Black Hole Candidate Swift J151857.0-572147 during Its First Outburst in 2024. The transient Galactic black hole candidate Swift J151857.0-572147 went through an outburst in 2024 March for the first time. Using publicly archived Insight-HXMT data, we have analyzed the timing and spectral properties of the source. We have extracted the properties of the quasiperiodic oscillations (QPOs) by fitting the power density spectrum, which inferred that the QPOs are of type C. We have detected QPOs up to ∼48 keV using an energy dependence study of the QPOs. A high-frequency QPO was not observed during this period. We also conclude that the oscillations of the shock in transonic advective accretion flows may be the possible reason for the origin of the QPOs. In the broad energy band of 2–100 keV, simultaneous data from the three onboard instruments of Insight-HXMT were used to perform spectral analysis. Different combinations of models, including a broken power law, a multicolor disk blackbody, interstellar absorption, nonrelativistic reflection in both neutral and ionized medium, and relativistic reflection, were used to understand the spectral properties during the outburst. We discovered that at the beginning of the analysis period, the source was in an intermediate state and later transitioning toward the soft state based on the spectral parameters. It has a high hydrogen column density, which could be due to some local absorption by the source.

Keywords: X-ray binary stars, Black holes, Compact radiation sources, Compact objects, Stellar accretion disks, Shocks
Effects of Environment on the Size Evolution of Quiescent Galaxies: Comparing Galaxies in Clusters and in the Field at Two Rest-frame Wavelengths. We investigate the impact of environment on quiescent galaxy (QG) size evolution using the CLAUDS+HSC imaging covering 18.6 deg2 in five broad filters (Ugriz) and the effective radius of a single-Sérsic fit as a proxy for galaxy size. We estimate sizes in two rest-frame wavelengths—3000 Å (UV) and 5000 Å (optical)—for ∼86,000 massive (M* ≤ 109.5 M⊙) field QGs and for 1000 of their similarly massive counterparts from 47 clusters at 0.1 &lt; z &lt; 0.85. We fit the size–mass relation (SMR) for field and cluster QGs in five Δz = 0.15 redshift bins and use the characteristic size of M* = 5 × 1010 M⊙ QGs (SMR's zero-point) to trace the change in galaxy size over cosmic time and in two types of environment. Sizes of QGs are larger in the rest-frame UV than in the rest-frame optical in both clusters and the field, and this difference is more prominent in the field sample. However, QGs in clusters are systematically smaller than the field QGs, and this difference is significantly more pronounced if measured in the rest-frame UV light. Modeling of the redshift evolution in the characteristic QG size as Re ∝ (1 + z)β shows that the cluster QGs (β = ‑1.02 in UV and β = ‑1.00 in optical) grow in size as fast as the field QGs (β = ‑0.95 in UV and ‑1.22 in optical). This fast growth of cluster QGs is consistent with size increase driven by the accretion of two subpopulations onto clusters: (a) field QGs that are larger than their quiescent counterparts in clusters, and (b) environmentally quenched galaxies (newcomers) that are larger than the rest of the quiescent population.

Keywords: Galaxy clusters, Galaxy environments, Optical astronomy, Ultraviolet astronomy, Galaxy evolution
Identifying Compton-thick Active Galactic Nuclei with a Machine Learning Algorithm in Chandra Deep Field-South. Compton-thick active galactic nuclei (CT-AGNs), which are defined by column density NH ≥ 1.5 × 1024 cm‑2, emit feeble X-ray radiation, even undetectable by X-ray instruments. Despite this, the X-ray emissions from CT-AGNs are believed to be a substantial contributor to the cosmic X-ray background (CXB). According to synthesis models of AGNs, CT-AGNs are expected to make up a significant fraction of the AGN population, likely around 30% or more. However, only ∼11% of AGNs have been identified as CT-AGNs in the Chandra Deep Field-South (CDFS). To identify hitherto unknown CT-AGNs in the field, we used a random forest algorithm for identifying them. First, we build a secure classified subset of 210 AGNs to train and evaluate our algorithm. Our algorithm achieved an accuracy rate of 90% on the test set after training. Then, we applied our algorithm to an additional subset of 254 AGNs, successfully identifying 67 CT-AGNs within this group. This result significantly increased the fraction of CT-AGNs in the CDFS, which is closer to the theoretical predictions of the CXB. Finally, we compared the properties of host galaxies between CT-AGNs and non-CT-AGNs and found that the host galaxies of CT-AGNs exhibit higher levels of star formation activity.

Keywords: X-ray point sources, X-ray active galactic nuclei, Active galactic nuclei, Diffuse x-ray background
Blinded Mock Data Challenge for Gravitational-wave Cosmology. I. Assessing the Robustness of Methods Using Binary Black Hole Mass Spectrum. Gravitational wave sources are standard sirens that provide an independent way to map the cosmic expansion history by combining with an independent redshift measurement, either from an electromagnetic counterpart for a bright siren or using different statistical techniques for dark sirens. In this analysis, we perform the first Blinded Mock Data Challenge (Blinded-MDC) to test the robustness in inferring the value of Hubble constant H0 for a dark siren technique which depends on astrophysical mass distribution of binary black holes (BBHs). We have considered different analysis setups for the Blinded-MDC to test both statistical and systematic uncertainties and demonstrate the capabilities in inferring H0 with detector sensitivity as per the fourth observation run of LIGO-Virgo-KAGRA. We find that when the astrophysical population of BBHs matches with the underlying assumption of the model, a cosmological pipeline can recover the injected parameters using the observed mass distribution. However, when the mock mass distribution of the astrophysical population depends slightly on redshift and one is ignorant about it in analyzing the data, it can cause a systematic discrepancy in the inferred value of H0 by about 1.5σ, above the statistical fluctuations due to noise and a limited number of events. In the future, elaborate studies will be required to mitigate systematic uncertainties due to unknown astrophysical complexities. This MDC framework sets the road map for inspecting the precision and accuracy of standard siren cosmology and provides the first insight into the robustness of the population-dependent cosmology inference in a blinded analysis setup.

Keywords: Cosmology, Gravitational waves, Hubble constant
Iron-corrected Single-epoch Black Hole Masses of DESI Quasars at Low Redshift. We present a study on the possible overestimation of single-epoch supermassive black hole (SMBH) masses in previous works, based on more than 55,000 type 1 quasars at 0.25 &lt; z &lt; 0.8 from the Dark Energy Spectroscopic Instrument (DESI). We confirm that iron emission strength serves as a good tracer of the Eddington ratio, and estimate SMBH masses using an iron-corrected R–L relation for Hβ, where R is the broad-line region size and L is the continuum luminosity. Compared with our measurements, previous canonical measurements without the iron correction are overestimated by a factor of 1.5 on average. The overestimation can be up to a factor of 5 for super-Eddington quasars. The fraction of super-Eddington quasars in our sample is about 5%, significantly higher than 0.4% derived from the canonical measurements. Using a sample featuring both Hβ and Mg II emission lines, we calibrate Mg II-based SMBH masses using iron-corrected, Hβ-based SMBH masses and establish an iron-corrected R–L relation for Mg II. The revised relation features a flatter luminosity dependence with a slope of 0.36 and incorporates an additional term of ‑0.21RFe, where RFe denotes the relative iron strength. We use this formula to build a catalog of about 0.5 million DESI quasars at 0.6 &lt; z &lt; 1.6. If these iron-corrected R–L relations for Hβ and Mg II are valid at high redshift, current mass measurements of luminous quasars at z ≥ 6 would have been overestimated by a factor of 2.3 on average, alleviating the tension between SMBH mass and growth history in the early universe.

Keywords: Supermassive black holes, Active galactic nuclei, Quasars
Joint Survey Processing. III. Compact Oddballs in the COSMOS Field—Little Red Dots and Transients. We present the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) G800L grism spectroscopy observation of the faint active galactic nuclei (AGN) candidates in the Cosmic Evolution Survey field at redshift of 6 selected by the point-source morphology and the photometry drop-off at 8000 Å. Among the sample of seven objects, only one is detected by multiple bands and has a similar shape of spectral energy distribution as the so-called "little red dots" of James Webb Space Telescope (JWST)─selected AGN candidates, but our object is 3 mag brighter than the JWST sample. We draw the upper limit of the AGN luminosity function Φ = 1.1 × 10−7 Mpc3 mag−1 for MUV = −21 at redshift of 6. The rest of the sample shows inconsistent flux density when comparing magnitudes of HST ACS F814W to the Subaru i-band and z-band magnitudes combined. The HST ACS G800L grism observation shows that this inconsistency cannot be created from an emission line. Therefore, we speculate that these objects are transients with the light-curve decay timescale of at most 6 yr in the observed frame.

Keywords: Galaxy photometry, High-redshift galaxies
Mapping Galaxy Images across Ultraviolet, Visible, and Infrared Bands Using Generative Deep Learning. We demonstrate that generative deep learning can translate galaxy observations across ultraviolet, visible, and infrared photometric bands. Leveraging mock observations from the Illustris simulations, we develop and validate a supervised image-to-image model capable of performing both band interpolation and extrapolation. The resulting trained models exhibit high fidelity in generating outputs, as verified by both general image comparison metrics (mean absolute error, SSIM, PSNR) and specialized astronomical metrics (Gini coefficient, M20). Moreover, we show that our models can be used to predict real-world observations, using data from the DECaLS survey as a case study. These findings highlight the potential of generative learning to augment astronomical data sets, enabling efficient exploration of multiband information in regions where observations are incomplete. This work opens new pathways for optimizing mission planning, guiding high-resolution follow-ups, and enhancing our understanding of galaxy morphology and evolution.

Keywords: Convolutional neural networks, Astronomy data modeling, Galaxy photometry, Astronomy software