Sazuna/UAT_keywords huggingface dataset:
The Radius Cliff is a Waterfall: Explaining Sub-Neptune Exoplanets with Steam Worlds. The demographics of Kepler planets provide a key testbed for models of planet formation and evolution, particularly for explaining the radius valley separating super-Earths and sub-Neptunes. A primordial interpretation based on differences in bulk densities—where rocky and water-rich planets form via migration pathways—offers an alternative to atmospheric loss scenarios. Updated interior structure models of water worlds with adiabatic steam atmospheres reproduce the observed valley near ∼2 R⊕ more accurately. Furthermore, migration models from our GENESIS library suggest that these formation pathways can also account for the distinct period distributions of super-Earths and sub-Neptunes, as well as the emergence of the hot Neptune desert. Motivated by this, we develop a Bayesian hierarchical mixture model for close-in Kepler planets (P &lt; 100 days), combining rocky planets and water worlds without H/He envelopes. The inferred mass distributions of rocky and water-rich planets peak at ∼2.6 and ∼7 M⊕, respectively, with the water mass fraction of water worlds peaking at ∼41%. Water worlds provide a good representation of the Kepler sub-Neptune population, with the radius cliff emerging as a "waterfall"—a sharp decline in their occurrence. However, our mass─radius analysis shows that water worlds alone cannot explain planets with R ≳ 3 R⊕, implying that at least ∼20% of sub-Neptunes in the sample are enriched in H/He gas.

Keywords: Exoplanet migration, Exoplanet catalogs, Exoplanet structure, Exoplanet formation, Exoplanet atmospheric structure
FEAST: Probing Hierarchical Star Formation with the Spatial Distributions of Young Star Clusters. We apply the angular two-point correlation function (TPCF) to the spatial distributions of young star clusters (YSCs) in four nearby star forming galaxies (NGC 628, NGC 4449, M51, and M83) in order to investigate their underlying hierarchical structuring. Using newly constructed catalogs of YSCs in the emerging phase (eYSCs), identified in the infrared with JWST, and optical YSCs detected in archival Hubble Space Telescope data, we compute the TPCFs for various cluster samples and age bins across the four galaxies, as part of the Feedback in Emerging extrAgalactic Star ClusTers (FEAST) program. We find clear evidence of hierarchical structuring, especially in eYSCs and YSCs with ages &lt;10 Myr (referred to as oYSCs), which show similar TPCFs within each galaxy. NGC 628 exhibits a clear distinction between the TPCFs of eYSCs and oYSCs, implying a shorter randomization timescale. In contrast, clusters aged 10─300 Myr exhibit progressively more random spatial distributions, becoming effectively random after ∼100 Myr, consistent with earlier studies. The two-dimensional fractal index D2 values of the YSCs' underlying distributions are calculated from model fits to the TPCFs. Our values of D2 derived from the youngest YSC populations align better with the expected value of D2 ∼ 1.3 for a universal star formation process compared to previous findings.

Keywords: Globular star clusters, Astrosphere interstellar medium interactions, Galaxy structure, Young star clusters, Star formation, Interstellar medium, Galaxies, Star clusters
Beyond Two Parameters: Revisiting Dark Energy with the Latest Cosmic Probes. Dark energy (DE) models with many free parameters are often considered excessive, as constraining all parameters poses a significant challenge. While such models offer greater flexibility to probe the DE sector in more detail. With the rapid advancement of astronomical surveys and the availability of diverse datasets, it is timely to examine whether current combined observations can effectively constrain an extended parameter space in DE models. This article investigates a four-parameter dynamical DE model that spans a broad region of the Universe's expansion history through four key parameters: present-day value of the DE equation of state (w0), its initial value (wm), scale factor depicting transition from wm to w0 (at), and steepness of this transition (∆de). We constrain the model using cosmic microwave background data from Planck, BAO from DESI DR2, and three distinct compilations of Type Ia Supernovae: PantheonPlus, DESY5, and Union3. Our results show that constraining all four parameters remains challenging: at is not constrained by any dataset, constraints on wm and ∆de remain weak, only w0 is well constrained across all datasets. The results further show that w0 &gt; −1, while wm is negative, indicating a phantom-like behavior at early times. Interestingly, despite its larger parameter space, the proposed model shows a preference over the ΛCDM and w0waCDM scenarios for certain combined datasets, according to both ∆χ2 and Bayesian evidence, although this preference is not strong.

Keywords: Cosmology, Cosmological models, Cosmological parameters, Hubble constant, Dark energy
Resonant Absorption and Fluctuations via Hybrid Simulations on Coronal Loops. II. Kinetic Description. The kinetic characteristics of resonant absorption of combined left- and right-hand polarized waves with finite amplitude are investigated. The plasma consists of a magnetized 2D slab with linearly inhomogeneous density layers. Using a 2D-3V particle-in-cell-hybrid code, we simulate this system with different layer thicknesses and different angles of the background magnetic field relative to the simulation plane. Resonant absorption excites counterpropagating kinetic Alfvén waves (KAWs) inside the layers, with frequencies consistent with large-scale kink modes. They are observed to interact nonlinearly to generate a parallel electric field, which subsequently produces density structures and accelerates protons. This causes strong heating and flat-topped distribution functions. We derive an analytical estimate for this parallel field that reproduces the most relevant signals of the dispersion relations during and after resonant absorption. The transverse particle dynamics are driven by the cross-field drift, causing the transverse temperature to oscillate and grow exponentially due to small-scale fluctuations. Therefore, the proton distribution functions are largely shaped nonresonantly by the KAW activity.

Keywords: Solar atmosphere, Solar physics, Alfven waves, Plasma physics
Radiative Transfer Modeling of Stripped-envelope Supernovae. I. A Grid for Ejecta Parameter Inference. We present 1800 multiwavelength Type Ib/c supernovae light-curve models obtained by running the radiation transport code Sedona and varying the mass distribution, velocity profile, and abundance ejecta profiles of helium star progenitors. To create a flexible but physically informed grid, we use autoencoders to construct a representation of ejecta profiles derived from stellar evolution models. We present simulated nearest-neighbor multiband light-curve matches to SN 1994I, SN 2007gr, and iPTF13bvn to demonstrate that realistic light curves can be generated in our grid. We show that the ejecta velocity distribution, in particular, strongly influences the light curve, while variation in 56Ni mixing alone has a limited impact on the bolometric light curve, even in extreme and unphysical mixing schemes; however, mixing can modestly impact color evolution. Finally, we show that the 56Ni mass, ejecta mass, and both the magnitude and structure of ejecta velocity distribution can be inferred from the multiband light curves, enabling improved inference over widely used semianalytical models.

Keywords: Type Ic supernovae, Neural networks, Type Ib supernovae, Light curves, Radiative transfer simulations
Digging into the Chemical Complexity in the Outer Galaxy: A Hot Molecular Core in Sh 2-283. The outer Galaxy (Galactocentric distance ≳13.5 kpc) serves as an excellent laboratory for investigating the chemical complexity in low-metallicity environments. Here we present the chemical analyses for the outer Galactic hot core Sh 2-283-1a SMM1 (DGC = 15.7 kpc and Z ∼ 0.3 Z⊙), recently detected by T. Ikeda et al. using the Atacama Large Millimeter/submillimeter Array. Toward this source, a variety of molecular species, including complex organic molecules (COMs; CH3OH, 13CH3OH, CH2DOH, and CH3OCH3), are detected. The molecular abundances relative to CH3OH are similar to those of another outer Galactic hot core, demonstrating that chemically rich hot cores exist in different regions of the outer Galaxy. We also compared molecular abundances among hot cores in the inner Galaxy, outer Galaxy, and Magellanic Clouds. This comparison revealed that the metallicity-corrected N(SO2)/N(H2) ratios of outer Galactic hot cores are significantly lower than those of the inner Galactic ones, while their N(CH3OH)/N(H2) ratios are similar. The Magellanic hot cores show different trends despite having metallicities similar to those of the outer Galaxy, indicating that the chemical complexity of hot cores is governed by environmental conditions (e.g., cosmic-ray intensity and dust temperature) rather than simple metallicity scaling. These environmental differences would also affect the production efficiency of COMs derived from CH3OH, as the N(CH3OCH3)/N(CH3OH) and N(C2H5OH)/N(CH3OH) ratios in the outer Galactic sources are moderately lower than those of inner Galactic sources. The N(CH2DOH)/N(CH3OH) ratio of Sh 2-283-1a SMM1 is 1.5 −1.2+3.9 %, comparable to that of inner Galactic high-mass sources.

Keywords: Interstellar molecules, Radio astronomy, Interstellar line emission, Chemical abundances, Astrochemistry, Dust continuum emission, Metallicity, Complex organic molecules
The Role of Gyrating Ions in Reformation of a Quasi-parallel Supercritical Shock. Collisionless shocks in space and astrophysical plasmas mediate energy exchange between charged particles and fields in two or more plasma flows. In this study we analyze the evolution of ion distributions around a reformation cycle of a quasi-parallel shock. We use multipoint in situ observations in the foreshock region of the Earth's bow shock of a transient foreshock structure as it generates a shock. We find that backstreaming ions in the foreshock create a density and magnetic field depletion known as caviton, which locally changes the shock geometry. Gyrating suprathermal ions that emerge within the caviton and reach the upstream edge of the core create a cross-field current imbalance that results in the nonlinear growth of a new shock layer. The new shock forms from the background foreshock fields over a distance of ∼6 ion inertial lengths (li) and within 4.5─11.2 li from the main bow shock. We find that plasma compression at the new thin shock layer is due to compactification of the cold upstream ion beam by high-amplitude magnetic field─aligned electrostatic fields. At later stages, the plasma compression expands to form a new sheath.

Keywords: Shocks
On the Thermal and Magnetic Properties of an Active Region Jet. Jets, as an essential manifestation of the release of the free magnetic energy, are ubiquitous in the solar atmosphere. We present a comprehensive analysis of a multithermal blowout jet that occurred in active region AR 13102 on 2022 September 20, using observations from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly, SDO/Helioseismic and Magnetic Imager (HMI), Interface Region Imaging Spectrograph, and Solar Upper Transition Region Imager. The jet is initiated by compact brightenings at its footpoints and exhibits a curtain-like spire with apparent rotational and weak lateral whipping motions. Time─distance analysis reveals a projected axial velocity ∼300 km s−1 and a rotational speed ∼30 km s−1. Differential emission measure analysis shows that the jet plasma spans a broad temperature range, with hot (≳10 MK) plasma concentrated near the flare loops and jet base and cooler components extending along the spire. Using the derived kinetic and thermal properties, we conclude that there is an equipartition between the jet's kinetic energy (5.4 ± 2.4) × 1020 J and thermal energy (7.0 ± 3.6) × 1020 J. HMI vector magnetograms and nonlinear force-free field extrapolations reveal that the jet originates from a compact mixed-polarity region at the edge of the active region, where flux emergence and cancellation, a low-lying twisted magnetic flux rope with a maximum twist number of ∼2.1, and a surrounding high-Q quasi-separatrix layer are present. The observed decrease in twist after the eruption, together with the jet's untwisting, indicates that the jet is driven by the eruption and the reconnection of the twisted flux rope, converting magnetic free energy into plasma heating and bulk motion. Our results highlight the importance of small-scale flux rope eruptions in driving blowout jets and releasing twist through magnetic reconnection and untwisting motions.

Keywords: Solar activity, Solar chromosphere, Solar corona, Solar magnetic reconnection
Cool-core Destruction in Merging Clusters with Active Galactic Nucleus Feedback and Radiative Cooling. The origin of the cool-core (CC) and non-cool-core (NCC) dichotomy of galaxy clusters remains uncertain. Previous simulations have found that cluster mergers are effective in destroying CCs but fail to prevent overcooling in cluster cores when radiative cooling is included. Feedback from active galactic nuclei (AGN) is a promising mechanism for balancing cooling in CCs; however, the role of AGN feedback in CC/NCC transitions remains elusive. In this work, we perform 3D binary cluster merger simulations incorporating AGN feedback and radiative cooling, aiming to investigate the heating effects from mergers and AGN feedback on CC destruction. We vary the mass ratio and impact parameter to examine the entropy evolution of different merger scenarios. We find that AGN feedback is essential in regulating the merging clusters, and that CC destruction depends on the merger parameters. Our results suggest three scenarios regarding CC/NCC transitions: (1) CCs are preserved in minor mergers or mergers that do not trigger sufficient heating, in which cases AGN feedback is crucial for preventing the cooling catastrophe; (2) CCs are transformed into NCCs by major mergers during the first core passage, and AGN feedback is subdominant; (3) in major mergers with a large impact parameter, mergers and AGN feedback operate in concert to destroy the CCs.

Keywords: Galaxy clusters, Hydrodynamical simulations, Active galactic nuclei
The DESI Single Fiber Lens Search. I. Four Thousand Spectroscopically Selected Galaxy─Galaxy Gravitational Lens Candidates. We present 4110 strong gravitational lens candidates, 3887 of which are new discoveries, selected from a sample of 5,837,154 luminous red galaxies (LRGs) observed with the Dark Energy Spectroscopic Instrument (DESI). Candidates are identified via the presence of background ionized oxygen [O II] nebular emission lines in the foreground LRG spectra, which may originate from the lensing of higher-redshift star-forming galaxies. Using the measured foreground redshift, background redshift, and integrated flux of the background [O II] doublet, we integrate over impact parameters to compute the probability that each candidate is a lens. We expect 53% of candidates to be true lenses with Einstein radii ranging from 0 .″ 1─4″, which can be confirmed with high-resolution imaging. Confirmed strong lenses from this sample will form a valuable cosmological data set, as strong gravitational lensing is the only method to directly measure dark matter halo substructure at cosmological distances. We independently recover the host of the multiply imaged gravitationally lensed type Ia supernova iPTF16geu. Monitoring these lenses for future multiply lensed transients will enable (a) H0 measurements via time-delay cosmography and (b) substructure measurements via flux ratios.

Keywords: Starburst galaxies, Strong gravitational lensing, Gravitational lensing, Einstein rings, Early-type galaxies
Insights into the Physical Nature of Polar-ring Galaxies from H I Observations. Polar-ring galaxies (PRGs) host an outer ring of gas and stars oriented nearly perpendicular to the main stellar body. They represent extreme examples of misaligned systems and provide valuable insights into galaxy interactions, gas accretion, and peculiar gas dynamics. We compile a complete sample of kinematically confirmed PRGs and collect their H I measurements. Combining literature data with new observations from the Five-hundred-meter Aperture Spherical Telescope, we detect H I emission in 22 sources, identify 1 potential H I absorption feature, and find 4 nondetections among 40 confirmed PRGs. Compared to galaxies in the ALFALFA and xGASS surveys, PRGs predominantly occupy the green valley or quenched regimes but exhibit higher gas fractions than typical early-type galaxies, suggesting gas accretion. The H I profile asymmetry and shape for PRGs are not consistent with those of the ALFALFA sample with p &lt; 0.05. We examine their Tully─Fisher relation (TFR) and baryonic TFR (bTFR), linking the systems' rotation velocities to their masses. The extreme outliers in TFRs for the control sample tend to display single-peaked H I profiles. PRGs do not follow a tight TFR or bTFR if the H I resides primarily in the host galaxy. But the scatter decreases significantly if we assume the gas is mainly distributed in the polar ring. Spatially resolved H I observations are essential to disentangling the gas distributions and kinematics in PRGs, which are key to understanding their formation mechanisms.

Keywords: Interstellar atomic gas, D galaxies, Scaling relations, Ring galaxies, Galaxy evolution
COSMOS-Web: Comprehensive Data Reduction for Wide-area JWST NIRCam Imaging. We present the data reduction methodology used for the COSMOS-Web survey JWST NIRCam data. Covering 0.54 deg2 with four broadband filters (F115W, F150W, F277W, F444W) and a total exposure time of approximately 270 hr, COSMOS-Web represents the largest contiguous field surveyed during JWST Cycle 1, posing unique data reduction challenges due to its extensive scale. By combining the official JWST Calibration Pipeline with custom improvements for noise removal, background subtraction, and astrometric alignment, we achieve high-fidelity science-ready mosaics. We detail the systematic approach employed in the three stages of the JWST Calibration Pipeline. The data, collected in three epochs from 2023 January to 2024 January, encompass 152 visits and have been processed into 20 mosaic tiles to optimize computational efficiency and data processing. The final data products achieve 5σ depths of 26.7─28.3 AB mag in 0 .″ 15 apertures. The processed and calibrated datasets are made available to the public.

Keywords: Surveys, James Webb Space Telescope, Astronomy data reduction, Near infrared astronomy
Small-scale Bright Point Characteristics at High-resolution with the Daniel K. Inouye Solar Telescope. Bright points (BPs) are small-scale, dynamic features that are ubiquitous across the solar disc and are often associated with the underlying magnetic field. Using broadband photospheric images obtained with the Visible Broadband Imager at the National Science Foundation's Daniel K. Inouye Solar Telescope (DKIST), the properties of BPs have been analyzed with DKIST for the first time at the highest spatial resolutions achievable. BPs were observed to have an average lifetime of 95 ± 29 s and a mean transverse velocity of 1.60 ± 0.41 km s−1. The BPs had a log-normal area distribution with a peak at 2300 km2. Transverse velocities and lifetimes across the DKIST images were comparable and consistent with previous studies. The area distribution of the DKIST data peaked in areas significantly lower than those from the literature. This was explored further and was observed to be due to an overestimation of BP areas due to the merging of close features when the spatial resolution is reduced, in tandem with possible oversplitting of features in the DKIST images. Furthermore, the effect of variable seeing in the data was determined. This showed that the average spatial resolution of the data was around  0.″034±0.″007 , in comparison to the theoretical diffraction limit of  0.″022 . Accounting for the influence of seeing, the peak of the area distribution of BPs in the DKIST data was estimated as 4800 km2, which is still significantly lower than previously observed.

Keywords: Solar magnetic fields, Solar photosphere, Solar granulation, Solar magnetic bright points
Quantifying the Impact of Selection Effects on FRB DM─z Relation Cosmological Inference. Fast radio bursts (FRBs) have emerged as powerful probes of baryonic matter in the Universe, offering constraints on cosmological and feedback parameters through their extragalactic dispersion measure─redshift (DMexgal─z) relation. However, the observed FRB population is shaped by complex selection effects arising from instrument sensitivity, DM-dependent search efficiency, and FRB source population redshift evolution. In this work, we quantify the impact of such observational and population selection effects on cosmological inference derived from the conditional distribution p(DMexgal∣z). Using forward-modeled FRB population simulations, we explore progressively realistic survey scenarios incorporating redshift evolution, luminosity function, and instrument DM selection function. To enable rapid likelihood evaluations, we build a neural network emulator for the variance in cosmic DM, σ2[DMcosmic(z)], trained on 5 × 104 baryonification halo model simulations, achieving ≤4% accuracy up to z = 4. We demonstrate that while redshift- and DM-dependent selection effects substantially alter the joint distribution p(DM, z), they have a negligible impact on the conditional distribution p(DMexgal∣z) for current sample sizes. The parameter biases are ≲0.8σ for 102 FRBs, indicating that conditional analyses are robust for present surveys. However, depending on the survey DM-dependent search efficiency, these biases may exceed 3σ for 104 FRBs, thus implying that explicit modeling of selection effects will be essential for next-generation samples.

Keywords: Radio transient sources, Observational cosmology, Cosmological parameters
Origin of the Lunar Inclination from Tidal Interaction of Multiple-Moon System. According to the giant impact theory, the Moon formed through accreting the debris disk produced by a collision between Theia and the proto-Earth, and the predicted lunar orbital inclination relative to the Earth's equatorial plane is about within 1° when the Moon formed. However, the current lunar orbital inclination with 5° relative to the Earth's orbital plane requires the Moon's orbital inclination relative to the Earth's equator to be about 10° when traced back to the time of lunar formation. Since two moons are also a natural outcome of simulations of lunar formation from a protolunar disk produced by a giant impact, here we show that, under solar perturbation, gravitational tidal interaction between Earth and its two moons with negligible orbital inclination relative to Earth's equatorial plane could lead to a merger of one moon with Earth, or a merger of the two moons or an ejection of one moon, resulting in the surviving moon's orbital inclination relative to Earth's equator exceeding 10°. The theory proposed here may provide a way of explaining the initial large lunar inclination relative to the Earth's equator.

Keywords: Tides, Inclination, Earth-moon system