Sazuna/UAT_keywords huggingface dataset:
Prospects for Gamma-Ray Emission from Magnetar Regions in CTAO Observations. Recent multiwavelength observations have highlighted magnetars as significant sources of cosmic rays, particularly through their gamma-ray emissions. This study examines three magnetar regions—CXOU J171405.7–31031, Swift J1834‑0846, and SGR 1806‑20—known for emitting detectable electromagnetic signals. We assess the detectability of these regions using the upcoming Cherenkov Telescope Array Observatory (CTAO) by conducting an ON/OFF spectral analysis and compare the expected results with existing observations. Our findings indicate that CTAO will detect gamma-ray emissions from these three magnetar regions with significantly reduced emission flux errors compared to current instruments. In particular, the study shows that the CXOUJ1714‑3810 and SwiftJ1834‑0846 magnetar regions can be observed by the full southern and northern CTAO arrays in just 5 hr of observation, with mean significances above 10σ and 30σ, respectively. This paper discusses the regions analyzed, presents key results, and concludes with insights drawn from the study.

Keywords: Gamma-ray observatories, Magnetars, Gamma-rays, Cosmic rays
Predictions of Dust Continuum Emission from a Potential Circumplanetary Disk: A Case Study of the Planet Candidate AB Aurigae b. Gas-accreting planets embedded in protoplanetary disks are expected to show dust thermal emission from their circumplanetary disks (CPDs). However, a recently reported gas-accreting planet candidate, AB Aurigae b, has not been detected in (sub)millimeter continuum observations. We calculate the evolution of dust in the potential CPD of AB Aurigae b and predict its thermal emission at 1.3 mm wavelength as a case study, where the obtained features may also be applied to other gas-accreting planets. We find that the expected flux density from the CPD is lower than the 3σ level of the previous continuum observation by the Atacama Large Millimeter/submillimeter Array with broad ranges of parameters, consistent with a nondetection. However, the expected planet mass and gas accretion rate are higher if the reduction of the observed near-infrared continuum and Hα line emission due to the extinction by small grains is considered, resulting in higher flux density of the dust emission from the CPD at (sub)millimeter wavelengths. We find that the corrected predictions of the dust emission are stronger than the 3σ level of the previous observation with the typical dust-to-gas mass ratio of the inflow to the CPD. This result suggests that the dust supply to the vicinity of AB Aurigae b is small if the planet candidate is not the scattered light of the star but is a planet and has a CPD. Future continuum observations at shorter wavelengths are required to obtain more robust clues to the question of whether the candidate is a planet or not.

Keywords: Millimeter astronomy, Exoplanet astronomy, Dust continuum emission, Protoplanetary disks, Planet formation
A Visibility-based Angular Bispectrum Estimator for Radio-interferometric Data. Considering radio-interferometric observations, we present a fast and efficient estimator to compute the binned angular bispectrum (ABS) from gridded visibility data. The estimator makes use of Fast Fourier Transform techniques to compute the ABS covering all possible triangle shapes and sizes. Here, we present the formalism of the estimator and validate it using simulated visibility data for the Murchison Widefield Array observations at ν = 154.25 MHz. We find that our estimator is able to faithfully recover the ABS of the simulated sky signal with ≈10%–15% accuracy for a wide variety of triangle shapes and sizes across the range of angular multipoles 46 ≤ ℓ ≤ 1320. In future work, we plan to apply this to actual data and also generalize it to estimate the three-dimensional redshifted 21 cm bispectrum.

Keywords: Diffuse radiation, Visibility function, Astronomy data analysis, Interferometric correlation, Radio interferometry
Ionized Gas Outflows in the Galaxy and Mass Assembly (GAMA) Survey: Signatures of AGN Feedback in Low-mass Galaxies. We present a sample of 398 galaxies with ionized gas outflow signatures in their spectra from the Galaxy and Mass Assembly Survey Data Release 4, including 45 low-mass galaxies with stellar masses M* &lt; 1010M⊙. We assemble our sample by systematically searching for the presence of a second velocity component in the [O III]λλ4959, 5007 doublet emission line in 39,612 galaxies with redshifts z &lt; 0.3. The host galaxies are classified using the Baldwin─Phillips─Terlevich diagram, with ~89% identified as active galactic nuclei (AGNs) and composites and 11% as star-forming (SF) galaxies. The outflows are typically faster in AGNs with a median velocity of 936 km s−1 compared to 655 km s−1 in the SF objects. Of particular interest are the 45 galaxies in the low-mass range, of which a third are classified as AGNs/composites. The outflows from the low-mass AGNs are also faster and more blueshifted compared to those in the low-mass SF galaxies. This indicates that black hole outflows can affect host galaxies in the low-mass range and that AGN feedback in galaxies with M* &lt; 1010M⊙ should be considered in galaxy evolution models.

Keywords: Supermassive black holes, Active galaxies, Galaxy dynamics, Dwarf galaxies, Stellar winds, Active galactic nuclei, Galaxy evolution, Galaxy winds, Galaxy kinematics
Photospheric Swirls in a Quiet-Sun Region. Swirl-shaped flow structures have been observed throughout the solar atmosphere, in both emission and absorption, at different altitudes and locations, and are believed to be associated with magnetic structures. However, the distribution patterns of such swirls, especially their spatial positions, remain unclear. Using the Automated Swirl Detection Algorithm, we identified swirls from the high-resolution photospheric observations, centered on Fe I 630.25 nm, of a quiet region near the Sun's central meridian by the Swedish 1-m Solar Telescope. Via a detailed study of the locations of the detected small-scale swirls with an average radius of ~300 km, we found that most of them are located in lanes between mesogranules (which have an average diameter of ~5.4 Mm) instead of the commonly believed intergranular lanes. The squared rotation, expansion/contraction and vector speeds, and proxy kinetic energy are all found to follow Gaussian distributions. Their rotation speed, expansion/contraction speed, and circulation are positively correlated with their radius. All these results suggest that photospheric swirls at different scales and locations across the observational 56 5 × 57 5 field of view could share the same triggering mechanism at preferred spatial and energy scales. A comparison with our previous work suggests that the number of photospheric swirls is positively correlated with the number of local magnetic concentrations, stressing again the close relation between swirls and local magnetic concentrations: the number of swirls should positively correlate with the number and strength of local magnetic concentrations.

Keywords: Solar observatories, Solar photosphere
Nebular and Nonthermal Radio Emissions for Young Stellar Populations with PARSEC v1.2s. In this paper, we compute, by means of the recently and thoroughly updated PARSE v1.2 s database of stellar nonrotating evolutionary tracks, the integrated stellar spectra, the ionizing photon budget, and the supernovae rates of young simple stellar populations (SSPs), for five metallicities between 0.0001 and 0.02 and four choices of stellar initial mass function (IMF) upper mass limits between 40 M⊙ and 350 M⊙. Using the photo-ionization code CLOUDY, we compute, at this same range of metallicities and limits, the intensities of some selected recombination and collisionally excited lines as a function of the age of the SSP. We account for the electron temperature dependence on IMF upper mass limit and metallicity while computing the thermal radio emission component, and also accounted for recent advances in core-collapse supernova explosion models while computing the nonthermal radio emission component. We self-consistently add the emission lines, nebular continuum, and nonthermal radio emission to the original SSP integrated photospheric spectra. Finally, from the resulting new suite of SSPs, we provide a consistent set of analytical relations between star formation rate (SFR) and ultraviolet, optical, and thermal radio luminosities that can be used to convert attenuation-corrected and dust-unaffected luminosities to SFR estimates. In a forthcoming paper, we will use our new SSP libraries as input to the state-of-the-art radiative transfer model GRAphites and SILicates to test the overall performance of these SSPs in reproducing the observed spectral energy distribution of young star-forming galaxies.

Keywords: Initial mass function, Core-collapse supernovae, Stellar populations, Radio continuum emission, Metallicity
Disk-locking Regulates Stellar Rotation in Young Clusters: Insights from NGC 2264. Many young clusters possess extended main sequences, a phenomenon commonly ascribed to stellar rotation. However, the mechanism behind their very wide stellar rotation distributions remains unclear. A proposed explanation is that magnetic star─disk interaction can regulate stellar rotation, i.e., protostars with longer disk lifetimes will eventually evolve into slow rotators, and vice versa. To examine this hypothesis, we took the star-forming region NGC 2264, as a test bed. We have studied its high-mass pre-main-sequence and zero-age main-sequence (ZAMS) stars. We find that, on average, diskless pre-main-sequence stars rotate faster than their disk-bearing counterparts. The stellar rotation distribution of the ZAMS stars is similar to evolved young clusters. We conclude that disk-locking may play a crucial role in the rotational velocity distribution of intermediate-mass early-type stars. We suggest that the observed wide stellar rotation distributions in many young clusters can occur in their early stages.

Keywords: Open star clusters, Stellar rotation, Stellar associations, Star clusters
Exploring Simple-population and Multiple-population Globular Clusters in the Outer Galactic Halo Using the Hubble Space Telescope. The pseudo two-color diagram, known as chromosome map (ChM), is a valuable tool for identifying globular clusters (GCs), which consist of single or multiple stellar populations (MPs). Recent surveys of Galactic GCs using ChMs have provided stringent observational constraints on the formation of GCs and their stellar populations. However, these surveys have primarily focused on GCs at moderate distances from the Galactic center and composed of MPs. In this paper, we present the first detailed study of the stellar composition of four GCs in the outer halo of the Milky Way: Arp 2, Ruprecht 106, Terzan 7, and Terzan 8. Our analysis is based on high-precision photometry obtained from images collected with the Hubble Space Telescope in the F275W, F336W, F438W, F606W, and F814W bands. We find that Ruprecht 106 and Terzan 7 are composed solely of a single stellar population, whereas Arp 2 and Terzan 8 host both first- and second-population stars. In these clusters, the second population comprises about half and one-third of the total number of GC stars, respectively. The results from this paper and the literature suggest that the threshold in the initial GC mass, if present, should be smaller than approximately 105 M⊙. The first-population stars of Arp 2 and Terzan 8, along with the stars of the simple-population GCs Ruprecht 106 and Terzan 7, exhibit intrinsic F275W – F814W color spreads, likely indicative of [Fe/H] variations of approximately 0.05–0.30 dex. This suggests that star-to-star metallicity variations are a common feature of star clusters, regardless of the presence of MPs.

Keywords: Globular star clusters, Stellar populations, Stellar abundances, Ultraviolet astronomy, Milky Way stellar halo
Deconstructing the Properties of Solar Super Active Region 13664 in the Context of the Historic Geomagnetic Storm of 2024 May 10–11. Active regions (ARs) are sites of strong magnetic fields on the solar surface whose size can be several times that of Earth. They spawn dynamic activity, sometimes resulting in severe space weather. Some ARs characterized by extraordinary magnetic properties and exhibiting extreme activity are termed as super active regions (SARs). Recently, solar AR 13664 produced 23 X-class flares and unleashed multiple coronal mass ejections, which triggered a severe geomagnetic storm during 2024 May 10–11—the strongest storm on record since 2003. Here, we put AR 13664 in historical context over the cumulative period of 1874 May–2024 June. We find that AR 13664 stands at the 99.95th percentile in the distribution of area over 1874 May–2024 June and at the 99.10th percentile in terms of flux content among all ARs over the period 1996 April–2024 June. Our analysis indicates that five of its magnetic properties rank at the 100.00th percentile among all ARs observed during 2010 May–2024 June by the Solar Dynamic Observatory. A total of 16 magnetic properties of AR 13664 are ranked higher than the 99.00th percentile when compared to other ARs recorded in Space-weather Helioseismic Magnetic Imager Active Region Patch data series, which includes all well-established flare relevant parameters. Furthermore, we demonstrate that AR 13664 reached its most dynamic flare productive state following a rapid rate of rise of its flare-relevant parameters and that the X-class flares were more frequent near their peak values. Our analyses establish AR 13644 to be an SAR and provide a paradigm for investigating their flare-relevant physical characteristics.

Keywords: Solar active region magnetic fields, Solar active regions, Stellar flares, Solar x-ray flares, Solar activity
Implication of Galaxy-scale Negative Feedback by One of the Most Powerful Multiphase Outflows in a Hyperluminous Infrared Galaxy at Intermediate Redshift. Powerful galactic outflows driven by active galactic nuclei (AGNs) are commonly considered as one of the main mechanisms to regulate star formation in massive galaxies. Ultra- and hyperluminous IR galaxies (U/HyLIRGs) are thought to represent a transition phase of galaxies from a rapidly growing period to a quiescent status as gas is swept out by outflows, providing a laboratory in which to investigate outflows and their feedback effects on hosts. In this paper we report recent Gemini and Atacama Large Millimeter/submillimeter Array (ALMA) observations of a HyLIRG, J1126, at z = 0.46842, which has been identified with a puzzling coexistence of a fast ionized outflow (&gt;2000 km s−1) and an intense starburst (star formation rate of 800 M ⊙ yr−1). The Gemini observation shows the fast ionized outflow is extended to several kiloparsecs with a mass-loss rate of 180 M ⊙ yr−1. A massive molecular outflow with a high mass-loss rate (2500 M ⊙ yr−1) is revealed by ALMA. The multiphase outflows show large factors of momentum boost and loading of kinetic power, indicating a driving by the thermal pressure of a nuclear hot wind and/or the radiation pressure of a highly obscured AGN. In addition to ejection of kinetic energy, it is also found that the powerful outflow can induce an ionizing shock in the galaxy disk and enhance the excitation and dissociation of molecular gas. The powerful outflow probably results in an instantaneous negative feedback and shows potential to regulate host growth in the long term.

Keywords: Ultraluminous infrared galaxies, Galaxy quenching, Active galactic nuclei, Galaxy winds
Red Stellar Populations and Dust Extinction toward W3. We explore red stellar populations toward the W3 giant molecular cloud through the use of optical-to-infrared (IR) photometry and Gaia DR 3 data, simultaneously characterizing stellar content and properties of dust in the molecular medium. We use a Rayleigh–Jeans color excess method modified to de-redden stellar observations of both red giants (RGs) and OB stars, and construct an IR Hertzsprung–Russell diagram validated against the Besançon Galactic model. Taking advantage of the near-universal IR interstellar extinction law and precise Gaia measurements, we develop a method for obtaining the spectral classification, foreground extinction, and distance moduli of stars, validated by spectroscopically confirmed OB stars. We constrain the observed parallax and proper motion of OB stars in W3, demonstrating the importance of considering systematic effects in the parallax bias, and assign parallax- and proper-motion-based cloud membership to our stellar samples. While it has been assumed that all spectroscopic OB stars are inside the W3 cloud, we find evidence of seven background B stars and three potential runaway OB stars. The methods developed here, which are based on known stellar populations, enable us to identify 82 new OB candidates that are confidently within the cloud. We quantify several dust-to-dust empirical correlations, in particular the IR color excess E(H ‑ [4.5]) and the optical depth τ 1 of submillimeter dust emission at 1 THz using RGs behind W3, measuring a best fit of  .

Keywords: Interstellar dust, Molecular gas, Early-type stars, Optical astronomy, Interstellar dust extinction, Infrared astronomy, Giant molecular clouds, Photometry, Late-type giant stars, Reddened stars
The Theory of Resonant Cosmic Ray–driven Instabilities—Growth and Saturation of Single Modes. Cosmic-ray (CR) feedback is critical for galaxy formation as CRs drive galactic winds, regularize star formation in galaxies, and escape from active galactic nuclei to heat the cooling cores of galaxy clusters. The feedback strength of CRs depends on their coupling to the background plasma and, as such, on the effective CR transport speed. Traditionally, this has been hypothesized to depend on the balance between the wave growth of CR-driven instabilities and their damping. Here, we study the physics of CR-driven instabilities from first principles, starting from a gyrotropic distribution of CR ions that stream along a background magnetic field. We develop a theory of the underlying processes that organize the particles' orbits and in particular their gyrophases, which provides an intuitive physical picture of (i) wave growth as the CR gyrophases start to bunch up lopsidedly toward the local wave magnetic field, (ii) instability saturation as a result of CRs overtaking the wave and damping its amplitude without isotropizing CRs in the wave frame, and (iii) CR backreaction onto the unstable plasma waves as the CR gyrophases follow a pendulum motion around the wave magnetic field. Using our new fluid-particle-in-cell code fluid-SHARP, we validate our theory on the evolution and excitation of individual unstable modes, such as forward- and backward-propagating Alfvén and whistler waves. We show that these kinetic simulations support our theoretical considerations, thus potentially foreshadowing a revision of the theory of CR transport in galaxies and galaxy clusters.

Keywords: Plasma astrophysics, Interstellar plasma, Particle astrophysics, Cosmic rays
PHAST. The Panchromatic Hubble Andromeda Southern Treasury. I. Ultraviolet and Optical Photometry of over 90 Million Stars in M31. The Panchromatic Hubble Andromeda Southern Treasury (PHAST) is a large 195-orbit Hubble Space Telescope program imaging ∼0.45 deg2 of the southern half of M31's star-forming disk at optical and near-ultraviolet (NUV) wavelengths. The PHAST survey area extends the northern coverage of the Panchromatic Hubble Andromeda Treasury (PHAT) down to the southern half of M31, covering out to a radius of ∼13 kpc along the southern major axis and in total ∼two-thirds of M31's star-forming disk. This new legacy imaging yields stellar photometry of over 90 million resolved stars using the Advanced Camera for Surveys in the optical (F475W and F814W), and the Wide Field Camera 3 (WFC3) in the NUV (F275W and F336W). The photometry is derived using all overlapping exposures across all bands, and achieves a 50% completeness-limited depth of F475W ∼ 27.7 in the lowest surface density regions of the outer disk and F475W ∼ 26.0 in the most crowded, high surface brightness regions near M31's bulge. We provide extensive analysis of the data quality, including artificial star tests to quantify completeness, photometric uncertainties, and flux biases, all of which vary due to the background source density and the number of overlapping exposures. We also present seamless population maps of the entire M31 disk, which show relatively well-mixed distributions for stellar populations older than 1–2 Gyr, and highly structured distributions for younger populations. The combined PHAST + PHAT photometry catalog of ∼0.2 billion stars is the largest ever produced for equidistant sources and is available for public download by the community.

Keywords: Local Group, Stellar populations, HST photometry, Andromeda Galaxy, Galaxies
Star-forming Nuclear Clusters in Dwarf Galaxies Mimicking Active Galactic Nucleus Signatures in the Mid-infrared. Effectively finding and identifying active galactic nuclei (AGNs) in dwarf galaxies is an important step in studying black hole formation and evolution. In this work, we examine four mid-infrared (IR)-selected AGN candidates in dwarf galaxies with stellar masses between M⋆ ~ 108 and 109 M⊙ and find that the galaxies are host to nuclear star clusters (NSCs) that are notably rare in how young and massive they are. We perform photometric measurements on the central star clusters in our target galaxies using Hubble Space Telescope optical and near-IR imaging and compare their observed properties to models of stellar population evolution. We find that these galaxies are host to very massive (~107 M⊙), extremely young (≲8 Myr), and dusty (0.6 ≲ Av ≲ 1.8) NSCs. Our results indicate that these galactic nuclei have ongoing star formation, are still at least partially obscured by clouds of gas and dust, and are most likely producing the extremely red AGN-like mid-IR colors. Moreover, prior work has shown that these galaxies do not exhibit X-ray or optical AGN signatures. Therefore, we recommend caution when using mid-IR color–color diagnostics for AGN selection in dwarf galaxies, since, as directly exemplified in this sample, they can be contaminated by massive star clusters with ongoing star formation.

Keywords: Young massive clusters, Stellar properties
Dynamics of Small, Constant-size Particles in a Protoplanetary Disk with an Embedded Protoplanet. Hydrodynamical simulations of protoplanetary disk dynamics are useful tools for understanding the formation of planetary systems, including our own. Approximations are necessary to make these simulations computationally tractable. A common assumption when simulating dust fluids is that of a constant Stokes number, a dimensionless number that characterizes the interaction between a particle and the surrounding gas. Constant Stokes number is not a good approximation in regions of the disk where the gas density changes significantly, such as near a planet-induced gap. In this paper, we relax the assumption of a constant Stokes number in the popular FARGO3D code using semianalytic equations for the drag force on dust particles, which enables an assumption of constant particle size instead. We explore the effect this change has on disk morphology and particle fluxes across the gap for both outward- and inward-drifting particles. The assumption of constant particle size, rather than constant Stokes number, is shown to make a significant difference in some cases, emphasizing the importance of the more accurate treatment.

Keywords: Hydrodynamical simulations, Circumstellar dust, Protoplanetary disks