Sazuna/UAT_keywords huggingface dataset:
Unravelling the Asphericities in the Explosion and Multifaceted Circumstellar Matter of SN 2023ixf. We present a detailed investigation of photometric, spectroscopic, and polarimetric observations of the Type II SN 2023ixf. Earlier studies have provided compelling evidence for a delayed shock breakout from a confined dense circumstellar matter (CSM) enveloping the progenitor star. The temporal evolution of polarization in the SN 2023ixf phase revealed three distinct peaks in polarization evolution at 1.4 days, 6.4 days, and 79.2 days, indicating an asymmetric dense CSM, an aspherical shock front and clumpiness in the low-density extended CSM, and an aspherical inner ejecta/He-core. SN 2023ixf displayed two dominant axes, one along the CSM-outer ejecta and the other along the inner ejecta/He-core, showcasing the independent origin of asymmetry in the early and late evolution. The argument for an aspherical shock front is further strengthened by the presence of a high-velocity broad absorption feature in the blue wing of the Balmer features in addition to the P-Cygni absorption post-16 days. Hydrodynamical light-curve modeling indicated a progenitor mass of 10 M ⊙ with a radius of 470 R ⊙ and explosion energy of 2 × 1051 erg, along with 0.06 M ⊙ of 56 Ni, though these properties are not unique due to modeling degeneracies. The modeling also indicated a two-zone CSM: a confined dense CSM extending up to 5 × 1014 cm with a mass-loss rate of 10‑2 M ⊙ yr‑1 and an extended CSM spanning from 5 × 1014 to at least 1016 cm with a mass-loss rate of 10‑4 M ⊙ yr‑1, both assuming a wind-velocity of 10 km s‑1. The early-nebular phase observations display an axisymmetric line profile of [O I], redward attenuation of the emission of Hα post 125 days, and flattening in the Ks-band, marking the onset of dust formation.

Keywords: Spectropolarimetry, Red supergiant stars, Core-collapse supernovae, Type II supernovae, Polarimetry, Supernova dynamics
Chromospheric Modeling of the Active M3V Star G 80–21 with RH1.5D. This study investigates the active regions of the M3.0V star G 80–21 using the observed data from the CARMENES project with synthetic spectra generated by the RH1.5D radiative transfer code. The CARMENES project aims to search for exoplanets around M dwarfs using high-resolution near-infrared and optical echelle spectrographs. By comparing the observed data and models for the chromospheric lines of H α  and the bluest Ca II infrared triplet line, we obtain the best-fit models for this star. The optimal fitting for the observed spectrum of G 80–21 is achieved by employing two active areas in conjunction with an inactive region, with a calcium abundance of [Ca/H] = ‑0.4. This combination successfully fits all the observed data across varying ratios. The minor active component consistently comprises approximately 18% of the total (ranging from 14% to 20%), which suggests that the minor active component is likely located in the polar regions. Meanwhile, the major active component occupies a variable proportion, ranging from 51% to 82%. Our method allows for the determination of the structure and size of stellar chromospheric active regions by analyzing high-resolution observed spectra.

Keywords: Stellar atmospheres, Stellar activity
The Diffusion Tensor of Protons at 1 au: Comparing Simulation, Observation, and Theory. The natural variation in plasma parameters observed at 1 au can lead to a variation in transport parameters, such as diffusion and drift coefficients, for energetic charged particles of solar and galactic origin. Given the importance of these parameters to particle transport studies, this variation is investigated through test particle simulations over a range of energies in the presence of simulated turbulence with properties corresponding to an ensemble of observed turbulence conditions at Earth. The resulting transport coefficients are then compared with observational estimates from the literature, as well as the predictions of several scattering theories. Parallel and perpendicular mean free paths are shown to vary widely, for the former in agreement with prior observational estimates, but not for the latter. Furthermore, a large disparity between the predictions of theory and the simulation results is noted for the perpendicular mean free path. As such, these results indicate that particle transport studies, particularly predictive ones, need to take into account this natural variation in transport coefficients.

Keywords: Heliosphere, Interplanetary turbulence, Solar energetic particles, Solar wind, Galactic cosmic rays
Star Stream Velocity Distributions in Cold Dark Matter and Warm Dark Matter Galactic Halos. The dark matter subhalos orbiting in a galactic halo perturb the orbits of stars in thin stellar streams. Over time, the random velocities in the streams develop non-Gaussian wings. The rate of velocity increase is approximately a random walk at a rate proportional to the number of subhalos, primarily those in the mass range ≈106‑7 M ⊙. The distribution of random velocities in long streams is measured in simulated Milky Way–like halos that develop in representative warm dark matter (WDM) and cold dark matter (CDM) cosmologies. The radial velocity distributions are well modeled as the sum of a Gaussian and an exponential. The resulting Markov Chain Monte Carlo fits find Gaussian cores of 1‑2 km s‑1 and exponential wings that increase from 3 km s‑1 for 5.5 keV WDM, 4 km s‑1 for 7 keV WDM, to 6 km s‑1 for a CDM halo. The observational prospects to use stream measurements to constrain the nature of galactic dark matter are discussed.

Keywords: Warm dark matter, Milky Way dark matter halo, Cold dark matter, Stellar streams
The Search for Disk Perturbing Planets Around the Asymmetrical Debris Disk System HD 111520 Using REBOUND. Debris disks, which are optically thin, dusty disks around main-sequence stars, are often found to have structures and/or asymmetries associated with planet–disk interactions. Debris disk morphologies can hence be used as probes for planets in these systems, which are unlikely to be detected with other current exoplanet detection methods. In this study we take a look at the very asymmetrical debris disk around HD 111520, which harbours several signs of perturbation such as a "fork"-like structure in the NW, as well as a 4° warp from the midplane on either side of the disk. We simulate the complicated disk morphology using the code REBOUND, with the goal of constraining the possible mass and orbit of the planet responsible for the observed structures. We find that an ∼1 M jup, eccentric planet that is inclined relative to the disk and is orbiting outside the warp location is able to reproduce the majority of disk features including the warp, fork, and radial extent asymmetry. To create the surface brightness asymmetry, a second eccentric planet is required inside the disk inner edge (50 au), although we are unable to produce the 2:1 brightness asymmetry observed, suggesting that a second mechanism may be required. Our work demonstrates how debris disk morphologies alone can be used to learn more about the architecture and evolution of a system as a whole, and can provide planet constraints to determine potential targets for current/future instruments such as JWST/NIRCam and the Gemini Planet Imager 2.0.

Keywords: Exoplanet dynamics, Planetary-disk interactions, Exoplanet evolution, Debris disks, N-body simulations
Cascading Dark Energy. The standard cosmological model is in the midst of a stress test, thanks to the tension between supernova-based measurements of the Hubble constant H 0 and inferences of its values from cosmic microwave background (CMB) anisotropies. Numerous explanations for the present-day cosmic acceleration require the presence of a new fundamental scalar field, as do early dark energy solutions to the Hubble tension. This raises the possibility that multiple fields cooperatively contribute to the dark energy component in bursts throughout cosmic time due to distinct initial conditions and couplings. Here, this cascading dark energy scenario is illustrated through a realization that effectively reduces to a two-field model, with two epochs in which dark energy is cosmologically significant. The model is compared to measurements of the CMB and baryon acoustic oscillations, as well as both PANTHEON and SH0ES observations of Type Ia supernovae. Neglecting the linear perturbations, it is found that this scenario ameliorates the Hubble tension, improving over purely late-time models of dark energy and the agreement between the galaxy survey measurements of baryon acoustic oscillations.

Keywords: Cosmology, Cosmological parameters, Dark energy
HST Proper Motion of Andromeda III. Another Satellite Coorbiting the M31 Satellite Plane. We measure the absolute proper motion of Andromeda III (And III) using Advanced Camera for Surveys/Wide Field Channel and WFPC2 exposures spanning an unprecedented 22 yr time baseline. The WFPC2 exposures have been processed using a deep-learning centering procedure recently developed as well as an improved astrometric calibration of the camera. The absolute proper motion zero point is given by 98 galaxies and 16 Gaia EDR3 stars. The resulting proper motion is (μ  α , μ  δ ) = (‑10.5 ± 12.5, 47.5 ± 12.5) μas yr‑1. We perform an orbit analysis of And III using two estimates of M31's mass and proper motion. We find that And III's orbit is consistent with dynamical membership to the Great Plane of Andromeda system of satellites although with some looser alignment compared to the previous two satellites NGC 147 and NGC 185. And III is bound to M31 if M31's mass is M vir ≥ 1.5 × 1012 M ⊙.

Keywords: Local Group, Andromeda Galaxy, Space astrometry
How Do Primordial Black Holes Change the Halo Mass Function and Structure?. We examine the effects of massive primordial black holes (PBHs) on cosmic structure formation, employing both a semianalytical approach and cosmological simulations. Our simulations incorporate PBHs with a monochromatic mass distribution centered around 106 M ⊙, constituting a fraction of 10‑2 to 10‑4 of the dark matter (DM) in the Universe, with the remainder being collisionless particle DM. Additionally, we conduct a ΛCDM simulation for comparative analysis with runs that include PBHs. At smaller scales, halos containing PBHs exhibit similar density and velocity dispersion profiles to those without PBHs. Conversely, at larger scales, PBHs can expedite the formation of massive halos and reside at their centers owing to the "seed effect." To analyze the relative distribution of PBH host halos compared to non-PBH halos, we apply nearest neighbor statistics. Our results suggest that PBH host halos, through gravitational influence, significantly impact the structure formation process, compared to the ΛCDM case, by attracting and engulfing nearby newly formed minihalos. Should PBHs constitute a fraction of DM significantly larger than ∼10‑3, almost all newly formed halos will be absorbed by PBH-seeded halos. Consequently, our simulations predict a bimodal feature in the halo mass function, with most of the massive halos containing at least one PBH at their core and the rest being less massive non-PBH halos.

Keywords: Large-scale structure of the universe, Early universe, Dark matter, Cosmological perturbation theory
The Interplay between the Disk and Corona of the Changing-look Active Galactic Nucleus 1ES 1927+654. Time-domain studies of active galactic nuclei (AGNs) offer a powerful tool for understanding black hole accretion physics. Prior to the optical outburst on 2017 December 23, 1ES 1927+654 was classified as a "true" type 2 AGN, an unobscured source intrinsically devoid of broad-line emission in polarized spectra. Through our 3 yr monitoring campaign spanning X-ray to ultraviolet/optical wavelengths, we analyze the post-outburst evolution of the spectral energy distribution (SED) of 1ES 1927+654. Examination of the intrinsic SED and subsequent modeling using different models reveal that the post-outburst spectrum is best described by a combination of a disk, blackbody, and corona components. We detect systematic SED variability and identify four distinct stages in the evolution of these components. During the event the accretion rate is typically above the Eddington limit. The correlation between ultraviolet luminosity and optical to X-ray slope (α OX) resembles that seen in previous studies of type 1 AGNs, yet exhibits two distinct branches with opposite slopes. The optical bolometric correction factor (κ 5100) is ∼10 times higher than typical AGNs, again displaying two distinct branches. Correlations among the corona optical depth, disk surface density, and α OX provide compelling evidence of a disk─corona connection. The X-ray corona showcases systematic variation in the compactness-temperature plot. Between 200 and 650 days, the corona is "hotter when brighter," whereas after 650 days, it becomes "cooler when brighter." This bimodal behavior, in conjunction with the bifurcated branches of α OX and κ 5100, offers strong evidence of a transition from a slim disk to a thin disk ∼650 days after the outburst.

Keywords: Accretion, Active galactic nuclei, Astrophysical black holes
Circumbinary Disk Spectra Irradiated by Two Central Accretion Disks in a Binary Black Hole System. We study the effect of irradiation from two accretion disks (minidisks) around respective black holes of stellar-to-intermediate masses in a circular binary on the spectrum of a circumbinary disk (CBD) surrounding them. We assume the CBD to be a standard disk and adopt the orbit-averaged irradiation flux because the viscous timescale is much longer than the orbital period. We then solve the energy equation both analytically and numerically to compute the CBD temperature distribution and the corresponding disk spectrum. We find that the analytically calculated spectra are in good agreement with the numerical ones. The CBD spectrum is almost independent of the binary mass ratio. We also find that the combined spectra of two minidisks and the CBD have double peaks, one peak in the soft X-ray band and the other in the infrared (IR) band. The former peak comes from the two minidisks, while the latter peak from the CBD. The observed flux density increases with frequency as ν 1/3 toward the soft X-ray peak, while it decreases with frequency away from the IR peak as ν ‑5/3. The latter feature is testable with near-IR observations with Subaru and JWST.

Keywords: Accretion, Black holes, High energy astrophysics, Galaxy accretion disks, Compact objects, Stellar accretion disks, Astrophysical black holes
Pulling Back the Curtain on Shocks and Star Formation in NGC 1266 with Gemini-NIFS. We present Gemini near-infrared integral field spectrograph K-band observations of the central 400 pc of NGC 1266, a nearby (D ≍ 30 Mpc) post-starburst galaxy with a powerful multiphase outflow and a shocked interstellar medium. We detect seven H2 rovibrational emission lines excited thermally to T ∼ 2000 K, and weak Brγ emission, consistent with a fast continuous shock (or C-shock). With these bright H2 lines, we observe the spatial structure of the shock with an unambiguous tracer for the first time. The Brγ emission is concentrated in the central ≲100 pc, indicating that any remaining star formation in NGC 1266 is in the nucleus, while the surrounding cold molecular gas has little ongoing star formation. Though it is unclear what fraction of this Brγ emission is from star formation or the active galactic nuclei (AGN), assuming it is entirely due to star formation we measure an instantaneous star formation rate of 0.7 M ⊙ yr−1, though the star formation rate may be significantly higher in the presence of additional extinction. NGC 1266 provides a unique laboratory to study the complex interactions between AGN, outflows, shocks, and star formation, all of which are necessary to unravel the evolution of the post-starburst phase.

Keywords: AGN host galaxies, Shocks, Galaxy quenching, Near infrared astronomy
Exploring the Magnetic and Thermal Evolution of a Coronal Jet. Coronal jets are the captivating eruptions that are often found in the solar atmosphere and primarily formed due to magnetic reconnection. Despite their short-lived nature and lower energy compared to many other eruptive events, e.g., flares and coronal mass ejections, they play an important role in heating the corona and accelerating charged particles. However, their generation in the ambience of nonstandard flare regime is not fully understood, and warrant a deeper investigation, in terms of their onset, growth, eruption processes, and thermodynamic evolution. Toward this goal, this paper reports the results of a data-constrained three-dimensional magnetohydrodynamics (MHD) simulation of an eruptive jet; initialized with a non-force-free-field (NFFF) extrapolation and carried out in the spirit of implicit large eddy simulation (ILES). The simulation focuses on the magnetic and dynamical properties of the jet during its onset, and eruption phases, that occurred on 2015 February 5 in an active region NOAA AR12280, associated with a seemingly three-ribbon structure. In order to correlate its thermal evolution with computed energetics, the simulation results are compared with differential emission measurement analysis in the vicinity of the jet. Importantly, this combined approach provides an insight to the onset of reconnection in transients in terms of emission and the corresponding electric current profiles from MHD evolutions. The presented study captures the intricate topological dynamics, finds a close correspondence between the magnetic and thermal evolution in and around the jet location. Overall, it enriches the understanding of the thermal evolution due to MHD processes, which is one of the broader aspects to reveal the coronal heating problem.

Keywords: Magnetohydrodynamics, Solar corona, Solar activity, Magnetic fields, Magnetohydrodynamical simulations
Resolved UV and Optical Color Gradients Reveal Environmental Influence on Galaxy Evolution at Redshift z ∼ 1.6. The changes in colors across a galaxy are intimately connected to the galaxy's formation, growth, quenching history, and dust content. A particularly important epoch in the growth of galaxies is near z ∼ 2, often referred to as "cosmic noon," where galaxies on average reach the peak of their star formation. We study a population of 125 cluster galaxies at z ∼ 1.6 in three Hubble Space Telescope filters, F475W, F625W, and F160W, roughly corresponding to the rest-frame far-ultraviolet, near-ultraviolet, and r band, respectively. By comparing to a control sample of 200 field galaxies at similar redshift, we reveal clear, statistically significant differences in the overall spatially resolved colors and color gradients in galaxies across these two different environments. On average, cluster galaxies have redder ultraviolet colors in both the inner and outer regions bounded by r 50, as well as an overall wider dispersion of outside-in color gradients. The presence of these observed differences, along with evidence from ancillary data from previous studies, strongly suggests that the environment drives these population-level color differences, by affecting the stellar populations and/or dust content.

Keywords: Galaxy clusters, Ram pressure stripped tails, High-redshift galaxy clusters, Star formation, Galaxy evolution, Ultraviolet photometry, Galaxy quenching
pop-cosmos: Scaleable Inference of Galaxy Properties and Redshifts with a Data-driven Population Model. We present an efficient Bayesian method for estimating individual photometric redshifts and galaxy properties under a pretrained population model (pop-cosmos) that was calibrated using purely photometric data. This model specifies a prior distribution over 16 stellar population synthesis (SPS) parameters using a score-based diffusion model, and includes a data model with detailed treatment of nebular emission. We use a GPU-accelerated affine-invariant ensemble sampler to achieve fast posterior sampling under this model for 292,300 individual galaxies in the COSMOS2020 catalog, leveraging a neural network emulator (Speculator) to speed up the SPS calculations. We apply both the pop-cosmos population model and a baseline prior inspired by Prospector-α, and compare these results to published COSMOS2020 redshift estimates from the widely used EAZY and LePhare codes. For the ∼12,000 galaxies with spectroscopic redshifts, we find that pop-cosmos yields redshift estimates that have minimal bias (∼10−4), high accuracy (σ MAD = 7 × 10−3), and a low outlier rate (1.6%). We show that the pop-cosmos population model generalizes well to galaxies fainter than its r &lt; 25 mag training set. The sample we have analyzed is ≳3× larger than has previously been possible via posterior sampling with a full SPS model, with average throughput of 15 GPU-sec per galaxy under the pop-cosmos prior, and 0.6 GPU-sec per galaxy under the Prospector prior. This paves the way for principled modeling of the huge catalogs expected from upcoming Stage IV galaxy surveys.

Keywords: Bayesian statistics, Astrostatistics techniques, Affine invariant, Galaxy photometry, Spectral energy distribution, Redshift surveys
Probing Cold-to-temperate Exoplanetary Atmospheres: The Role of Water Condensation on Surface Identification with JWST. Understanding the surface temperature and interior structure of cold-to-temperate sub-Neptunes is critical for assessing their habitability, yet direct observations are challenging. In this study, we investigate the impact of water condensation on the atmospheric compositions of sub-Neptunes, focusing on the implications for James Webb Space Telescope (JWST) spectroscopic observations. By modeling the atmospheric photochemistry of two canonical sub-Neptunes, K2-18 b and LHS 1140 b, both with and without water condensation and with and without thick atmospheres, we demonstrate that water condensation can significantly affect the predicted atmospheric compositions. This effect is driven by oxygen depletion from the condensation of water vapor and primarily manifests as an increase in the C/O ratio within the photochemically active regions of the atmosphere. This change in composition particularly affects planets with thin H2-dominated atmospheres, leading to a transition in dominant nitrogen and carbon carriers from N2 and oxygen-rich species like CO/CO2 toward heavier hydrocarbons and nitriles. While our models do not fully account for the loss mechanisms of these higher-order species, such molecules can go on to form more refractory molecules or hazes. Planets with thin H2-rich atmospheres undergoing significant water condensation are thus likely to exhibit very hazy atmospheres. The relatively flat JWST spectra observed for LHS 1140 b could be consistent with such a scenario, suggesting a shallow surface with extensive water condensation or a high atmospheric C/O ratio. Conversely, the JWST observations of K2-18 b are better aligned with a volatile-rich mini-Neptune with a thick atmosphere.

Keywords: Extrasolar rocky planets, Exoplanet atmospheric composition , Exoplanets, Exoplanet surfaces, Extrasolar gaseous planets, Exoplanet surface characteristics, Exoplanet atmospheres