Sazuna/UAT_keywords huggingface dataset:
How Does Feedback Affect the Star Formation Histories of Galaxies?. Star formation in galaxies is regulated by the interplay of a range of processes that shape the multiphase gas in the interstellar and circumgalactic media. Using the Cosmology and Astrophysics with MachinE Learning Simulations (CAMELS) suite of cosmological simulations, we study the effects of varying feedback and cosmology on the average star formation histories (SFHs) of galaxies at z ∼ 0 across the IllustrisTNG, SIMBA, and ASTRID galaxy formation models. We find that galaxy SFHs in all three models are sensitive to changes in stellar feedback, which affect the efficiency of baryon cycling and the rates at which central black holes grow, whereas the effects of varying active galactic nucleus (AGN) feedback depend on model-specific implementations of black hole seeding, accretion, and feedback. We also find strong interaction terms that couple stellar and AGN feedback, usually by regulating the amount of gas available for the central black hole to accrete. Using a double power law to describe the average SFHs, we derive a general set of equations relating the shape of the SFHs to physical quantities like baryon fraction and black hole mass across all three models. We find that a single set of equations (albeit with different coefficients) can describe the SFHs across all three CAMELS models, with cosmology dominating the SFH at early times, followed by halo accretion, and feedback and baryon cycling at late times. Galaxy SFHs provide a novel, complementary probe to constrain cosmology and feedback, and can connect the observational constraints from current and upcoming galaxy surveys with the physical mechanisms responsible for regulating galaxy growth and quenching.

Keywords: Cosmology, Galactic winds, Supermassive black holes, Stellar feedback, Galaxy physics, Star formation, Extragalactic astronomy, Astronomical simulations
Second-timescale Glints from Satellites and Space Debris Detected with Tomo-e Gozen. A search for second-timescale optical transients is one of the frontiers of time-domain astronomy. However, it has been pointed out that reflections of sunlight from Earth-orbiting objects can also produce second-timescale "glints." We conducted wide-field observations at 2 frames per second using Tomo-e Gozen on the 1.05 m Kiso Schmidt telescope. We identified 1554 point-source glints that appeared in only one frame (0.5 s). Their brightness ranges from 11 to 16 mag, with fainter glints being more numerous. These glints are likely caused by satellites and space debris in high-altitude orbits such as the geosynchronous Earth orbit or highly elliptical orbits. Many glints brighter than 14 mag are associated with known satellites or debris with large apogees (&gt;30,000 km). In contrast, most fainter glints are not associated with cataloged objects and may be due to debris with sizes of 0.3─1 m. The event rate of second-timescale glints is estimated to be 4.7 ± 0.2 deg−2 hr−1 (average) and 9.0 ± 0.3 deg−2 hr−1 (near the equator) at 15.5 mag. Our results demonstrate that high-altitude debris can represent a significant foreground in searches for second-timescale optical transients. They also imply that deep surveys such as Rubin/LSST will detect many of these glints in single-exposure images.

Keywords: Artificial satellites, Sky surveys, Transient sources
The Stellar Content of NGC 3603 Revisited: Is the IMF Top Heavy?. Studies of the resolved stellar populations of young massive clusters have shown that the slope of the initial mass function (IMF) appears to be the same everywhere, with no dependence on stellar density or metallicity. At the same time, studies of integrated properties of galaxies usually conclude that the IMF does vary and must be top-heavy in starburst regions. In order to investigate this, we have carried out a long-term project to characterize the massive-star content of NGC 3603, the nearest giant H II region, known to have a rich population of massive stars. We used both ground-based and Hubble Space Telescope (HST) imaging to obtain photometry, and we employed Gaia to establish membership. We obtained spectra of 128 stars using the Magellan 6.5 m telescope and HST, and we combine these data to produce a reddening map. After analyzing the data in the same way as we have for 25 other star-forming regions in the Milky Way and the Magellanic Clouds, we find that the IMF slope of NGC 3603 is quite normal compared to other clusters, with Γ = −0.9 ± 0.1. If anything, there are fewer very high mass (&gt;65M⊙) stars than one would expect by extrapolation from lower masses. This slope is also indistinguishable from what several studies have shown for R136 in the LMC, an even richer region. We speculate that the depreciation of the highest-mass bins in NGC 3603, but not in R136, may indicate that it is harder to form extremely massive stars at the higher metallicity of the Milky Way compared to that of the LMC. ∗This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile. It also uses observations made with the NASA/ESA Hubble Space Telescope (HST), obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations were made under proposals GO-10602 (PI: Maiz Apellaniz) and GO-11626 (PI: Massey).

Keywords: Massive stars, Initial mass function, Stellar evolution
Black Hole Dragging: A New Mechanism for Forming Nuclear Star Clusters in Giant Elliptical Galaxies. It has long been thought that nuclear star clusters (NSCs) cannot coexist with the most massive supermassive black holes (SMBHs), since SMBH mergers—unavoidable for the most massive systems—would scatter away NSC stars. However, central concentrations of light have now been reported in up to one-third of all massive ellipticals. We present a new mechanism for forming NSCs in giant elliptical galaxies, arising naturally from SMBH mergers, which could explain these observations. We call this "black hole dragging." After a major merger of two galaxies and their SMBHs, the newly merged SMBH can receive a gravitational-wave recoil kick. We show that recoiling SMBHs induce two competing effects on the galaxy's background stars. First, some stars become bound to the SMBH and comove with it, an effect strongest at low recoil velocities. Second, background stars are ejected as the recoiling SMBH falls back due to dynamical friction, an effect strongest at high recoil velocities. At intermediate recoil velocities (500─1000 km s−1), both effects become important, and the density of bound stars can exceed that of the background stellar core. This yields a central dense NSC that is clearly visible in the galaxy's surface brightness profile. We show that NSCs formed in this way have realistic sizes, masses, and velocity dispersions when measured similarly to observed systems. This provides a route for even giant ellipticals containing SMBHs to host an NSC. We predict such NSCs should have indistinguishable colors, ages, and chemistry from non-NSC central stars, combined with low ellipticities.

Keywords: Black hole physics, Computational astronomy, Galaxy dynamics, Galaxy nuclei, Giant elliptical galaxies, Gravitational waves
Type Ia Supernova Growth-rate Measurement with LSST Simulations: Intrinsic Scatter Systematics. Measurement of the growth rate of structures (fσ8) with Type Ia supernovae (SNe Ia) will improve our understanding of the nature of dark energy and enable tests of general relativity. In this paper, we generate simulations of the 10 yr SN Ia data set of the Rubin-LSST survey, including a correlated velocity field from an N-body simulation and realistic models of SNe Ia properties and their correlations with host-galaxy properties. We find, similar to SN Ia analyses that constrain the dark energy equation-of-state parameters w0wa, that constraints on fσ8 can be biased depending on the intrinsic scatter of SNe Ia. While for the majority of intrinsic scatter models we recover fσ8 with a precision of ∼13%─14%, for the most realistic dust-based model, we find that the presence of non-Gaussianities in Hubble diagram residuals leads to a bias on fσ8 of ∼ −20%. When trying to correct for the dust-based intrinsic scatter, we find that the propagation of the uncertainty on the model parameters does not significantly increase the error on fσ8. We also find that while the main component of the error budget of fσ8 is the statistical uncertainty (&gt;75% of the total error budget), the systematic error budget is dominated by the uncertainty on the damping parameter, σu, that gives an empirical description of the effect of redshift space distortions on the velocity power spectrum. Our results motivate a search for new methods to correct for the non-Gaussian distribution of the Hubble diagram residuals, as well as an improved modeling of the damping parameter.

Keywords: Cosmology, Type Ia supernovae, Large-scale structure of the universe, Cosmological parameters from large-scale structure
New Measures of STEREO CME Masses and Directions. Coronal mass ejections (CMEs) propagate away from the Sun throughout interplanetary space. The CME mass influences its evolution and interaction with the background solar wind; however, accurate CME masses are not routinely measured. We combine the CORSET catalog, which identifies CME regions in coronal images, with the standard mass estimation method based on excess brightness to create the first multiviewpoint catalog of CME masses. This catalog spans from 2007 through 2014 when both STEREO satellites were available for stereoscopic reconstructions. We determine a projected mass for each CORSET region, providing reconstructions at multiple times and perspectives for most CMEs. For a subset of events with paired CORSET STEREO A and B regions, we determine a deprojected CME mass and direction. Given a CME longitude, we can convert the projected mass to a "true" mass. By assuming the true mass should be the same from all viewpoints, we can combine the multiple perspectives to infer the "true" longitude, as done in R. C. Colaninno &amp; A. Vourlidas. Additionally, we consider a revised technique where we assume the deprojected height and latitude should also be consistent from both perspectives. We compare our results with GCS CME reconstructions from LLAMACoRe and find our mostly automated deprojection techniques yield results comparable to those obtained through manual GCS reconstructions. The catalog contains over 35,000 masses corresponding to 1174 unique events in STEREO A, 688 in STEREO B, and 456 events with deprojected masses and directions.

Keywords: Coronagraphic imaging, Solar physics, Solar coronal mass ejections
Solar Eruption Onset and Particle Acceleration in Nested-null Topologies. The magnetic breakout model explains a variety of solar eruptions, ranging from small-scale jets to large-scale coronal mass ejections (CMEs). Most of our previous studies are focused on jets and CMEs in single null-point topologies. Here, we investigate the initiation of CMEs and associated particle acceleration in a double null-point (or nested fan-spine) topology during multiple homologous M- and X-class flares from an active region. The initiation of the flare and associated eruption begins with inflow structures moving toward the inner null of the closed fan-spine topology. Simultaneous slow flare reconnection below a small filament formed a hot flux rope along with expansion of the overlying flux during slow breakout reconnection at the inner null. The first explosive breakout reconnection of the flux rope at the inner null produced a circular and a remote ribbon along with successful eruption of the flux rope and associated fast EUV (shock) wave. Simultaneous flare reconnection beneath the erupting flux rope produced a typical two-ribbon flare along with two hard X-ray footpoint sources. When the flux rope (with shock) reaches the outer null, a second explosive breakout reconnection produces another large-scale remote ribbon. The radio observations reveal quasiperiodic Type III bursts (period = 100 s) and a Type II burst during the breakout reconnection near the inner and outer nulls, along with gradual solar energetic particles observed at 1 au for magnetically connected events. This study highlight the importance of two successive breakout reconnections in the initiation of CMEs in nested-null topologies and associated particle acceleration and release into the interplanetary medium. The particles are accelerated by the shock ahead of the flux rope, which formed during the inner breakout reconnection. These findings have significant implications for particle acceleration and escape processes in multiscale null-point topologies that produce jets and CMEs.

Keywords: Solar energetic particles, Solar radio emission, Solar coronal mass ejections, Solar magnetic reconnection
BASS. LIV. Physical Properties of AGN-hosting Galaxy Mergers from Multiwavelength SED Fitting. Galaxy mergers are believed to play an important role in triggering rapid supermassive black hole (SMBH) growth. As merging nuclei approach each other, the physical properties of the participating galaxies and the associated SMBH growth are expected to evolve significantly. This study measures and characterizes these physical properties throughout the merger sequence. We constructed multiwavelength spectral energy distributions (SEDs) from hard X-rays to the far-IR for a sample of 72 nearby active galactic nucleus (AGN) host galaxies. The sample comprises 64 interacting systems, including single AGN in mergers and dual AGN, with nuclear separations ≤30 kpc, as well as eight isolated active galaxies with merging features. We carefully adapted available photometric measurements at each wavelength to account for their complex morphologies and varying spatial resolutions, to perform SED fitting using CIGALE, aimed to derive critical physical properties. Our results reveal that merging galaxies hosting AGN(s) show deviations from the star-forming main sequence and a wide range of star formation rates (SFRs). Both AGN activity and star formation are significantly influenced by the merger process, but these effects are more prominent in major (mass ratios &lt; 4:1) interactions. We find that the projected nuclear separation is not a good tracer of the merger stage. Instead, morphological classification accurately assesses the merger progression. Based on this morphological analysis, late-stage mergers exhibit elevated SFRs (5.1×), AGN luminosities (2.4×), and nuclear obscuration (2.8×) compared to earlier stages, supporting previous findings and reinforcing the link between merger-driven galaxy evolution and SMBH growth.

Keywords: AGN host galaxies, Spectral energy distribution, Galaxy mergers
Near-Sun Characteristics of a CME Inferred from Observations in the 5303 Å Coronal Emission Line. Using observations of the solar corona in the 5303 Å (Fe XIV) emission line with the Visible Emission Line Coronagraph (VELC) on board Aditya-L1, we estimated the electron density (Ne), thermal energy (ECME), and mass (MCME) of a coronal mass ejection (CME) very close to the Sun at heliocentric distance r ≍ 1.06R⊙. The corresponding values are Ne ≍ 3.7 × 108 cm−3, ECME ≍ 9.4 × 1028 erg, and MCME ≍ 2.7 × 1014 g, respectively. The procedure adopted suggests a possibility to understand the properties of the CMEs in the visible wavelength range, particularly during the temporal phase close to their onset. The widths and Doppler velocities of the line are nearly constant in the VELC field of view (FoV ≍ 1.06─1.50R⊙). The values are ≍0.85 Å and ≍+2 km s−1, respectively.

Keywords: The Sun, Solar coronal lines, Solar coronal mass ejections, Solar corona, Spectroscopy, Solar activity
The Responsivity of Mg II, C IV, Hα, and Hβ Emission Lines in SDSS Quasars. This study systematically investigates the responsivity (α) of broad emission-line (BEL) variations (Mg II λ2798, C IV λ1549, Hα λ6563 and Hβ λ4861) to continuum variations in 24,847 quasars using matched spectroscopic data from Sloan Digital Sky Survey Data Releases 7 and 16. For these four types of BELs, we find a correlation between the variations in emission lines and in the continuum, and we measure average α values of 0.45 (Mg II), 0.35 (C IV), 0.78 (Hα), and 0.60 (Hβ). Our results also show that the α of Mg II, Hα, and Hβ exhibit a negative correlation with continuum luminosity, while C IV shows no statistically significant continuum luminosity dependence. Our results align with photoionization models and prior studies. These findings may provide new observational constraints on the structure and dynamics of the broad-line region across different ionization states.

Keywords: Surveys, Black hole physics, Active galactic nuclei, Quasars
Mapping the SO<SUB>2</SUB> Shoreline in Gas Giant Exoplanets. JWST has revealed sulfur chemistry in giant exoplanet atmospheres, where molecules such as sulfur dioxide (SO2) trace photochemistry, metallicity, and formation and migration. To ascertain the conditions that determine whether (or how much) SO2, H2S, and other sulfur-bearing species are present in exoplanet atmospheres, we present a grid of planetary atmospheres covering metallicities from 0.3 to 1000× solar and temperatures from 250 to 2050 K. These models map out the "SO2 shoreline," the region of metallicity and irradiation for which SO2 may be sufficiently abundant to be detectable. SO2 is a sensitive indicator of metallicity; expected SO2 abundances also depend strongly on overall temperature and C/O ratio; the SO2 abundance depends surprisingly weakly on X-ray and ultraviolet irradiation, also weakly on Kzz (for Teq ≳ 600 K), and is essentially independent of internal temperature. Despite its detection in a growing number of giant planets, SO2 is never the dominant sulfur-bearing molecule: depending on temperature and metallicity, H2S, S2, NS, SO, SH, and even S8 or atomic S are frequently as common (or more so) as SO2. Nonetheless SO2 remains the most easily detectable sulfur-bearing species, followed by H2S, though perhaps SO and SH could be detectable in some gas giants. Aside from a pressing need for additional observational constraints on sulfur, we also identify the need for future work to account for the effects of clouds and hazes, fully self-consistent atmospheric models, 2D and 3D models, a wider range of planetary masses and radii, and studies to measure and refine reaction rates and molecular opacities of sulfur-bearing species.

Keywords: Exoplanet atmospheric composition , Infrared spectroscopy, Chemical abundances, Astrochemistry, Spectroscopy, Molecular reactions, Exoplanet atmospheres
Probing Evolution of Long GRB Properties through their Cosmic Formation History Aided by Machine Learning─predicted Redshifts. Gamma-ray bursts (GRBs) are valuable probes of cosmic star formation reaching back into the epoch of reionization, and a large dataset with known redshifts (z) is an important ingredient for these studies. Usually, z is measured using spectroscopy or photometry, but ∼80% of GRBs lack such data. Prompt and afterglow correlations can provide estimates in these cases, though they suffer from systematic uncertainties due to assumed cosmologies and due to detector threshold limits. We use a sample with z estimated via machine learning models, based on prompt and afterglow parameters, without relying on cosmological assumptions. We then use an augmented sample of GRBs with measured and predicted z, forming a larger dataset. We find that the predicted z are a crucial step forward in understanding the evolution of GRB properties. We test three cases: no evolution, an evolution of the beaming factor, and an evolution of all terms captured by an evolution factor (1 + z)δ. We find that these cases can explain the density rate in the z range between 1 and 2, but neither of the cases can explain the derived rate densities at smaller and higher z, which may point toward an evolution term different than a simple power law. Another possibility is that this mismatch is due to the nonhomogeneity of the sample, e.g., a noncollapsar origin of some long GRB within the sample.

Keywords: Cosmology, Gamma-ray bursts, Star formation
The Evolution of Jupiter and Saturn as a Function of the R<SUB>ρ</SUB> Parameter. Computed using the APPLE planetary evolution code, we present updated evolutionary models for Jupiter and Saturn that incorporate helium rain, nonadiabatic thermal structures, and "fuzzy" extended heavy-element cores. Building on our previous Ledoux-stable models, we implement improved atmospheric boundary conditions that account for composition-dependent effective temperatures and systematically explore the impact of varying the parameter Rρ, which allows one to explore in an approximate way the efficiency of semiconvection. For both Jupiter and Saturn, we construct models spanning from Rρ = 1 (Ledoux) to Rρ = 0 (Schwarzschild), and identify best-fit solutions that match each planet's effective temperature, equatorial radius, lower-order gravitational moments, and atmospheric composition at 4.56 Gyr. We find that lower Rρ values lead to stronger convective mixing, resulting in higher surface metallicities and lower deep interior temperatures, while requiring reduced heavy-element masses and lower initial entropies to stabilize the dilute inner cores. Our Saturn models also broadly agree with the observed Brunt─Väisälä frequency profile inferred from Cassini ring seismology, with stable layers arising from both the helium rain region and the dilute core. These findings support the presence of complex, compositionally stratified interiors in both gas giants.

Keywords: Saturn, Solar system gas giant planets, Jupiter, Solar system evolution, Extrasolar gaseous giant planets
Symbiotic Stars (Including T Corona Borealis) Are Not Immediate Progenitors of Normal Type Ia Supernovae. A popular solution to the Type Ia supernova (SN Ia) progenitor problem is that the immediate progenitors are symbiotic star systems. This solution requires that the companion star of the exploding white dwarf must be a red giant star with a heavy stellar wind. This has been tested for 189 normal SN Ia, with all tested systems being proven to not have the required red giant: (A) Zero-out-of-nine normal type Ia supernova remnants have any red giant ex-companion star near the center with limits of MV &gt; 0.0. (B) Zero-out-of-two normal SN Ia in nearby galaxies have any red giant at the position as seen in archival pre-eruption images by HST to limits of MV &gt; 0.0. (C)─(D) Zero-out-of-111 normal SN Ia have any detected hydrogen or helium emission lines in their eruption spectra, with limits on entrained gas of MH &lt; 0.22 and MHe &lt; 0.07 M⊙, which is the minimum mass lost by a red giant in a nearby blastwave. (E)─(F) Zero-out-of-nine nearby normal SN Ia were detected in the radio or X-rays, as required from the ejecta/wind impact, to limits of  Ṁwind&lt;3×10−9  M⊙yr−1. (G) Zero-out-of-∼69 normal SN Ia display any brightening in the first few days to limits of MV &gt; −18, as required for a red giant companion when we are looking down its shadowcone. With zero-out-of-189 normal SN Ia having any possibility of having a red giant companion, the fraction of SN Ia with symbiotic progenitors is &lt;0.53%. The overwhelming conclusion is that normal SN Ia are not from symbiotic-progenitors in any measurable fraction.

Keywords: Supernova remnants, Type Ia supernovae, Symbiotic novae, Symbiotic binary stars, Supernovae