Sazuna/UAT_keywords huggingface dataset:
Turbulence and Star Formation Suppression in Elliptical Galaxies: The Role of Active Galactic Nucleus Jet─Wind Interaction. Winds and jets are symbiotic when the accretion rate is low, according to black hole accretion theory. Both components are potentially important for active galactic nucleus (AGN) feedback, but previous works typically include only jets with free parameters. We perform hydrodynamical simulations of an isolated elliptical galaxy with both jets and winds included. The key features discriminating our simulations from others are that our simulations resolve the Bondi radius for reliable black hole accretion rate calculation and use parameters from GRMHD simulations. By selectively activating jets and winds, we examine their individual and combined effects. We find that effective AGN feedback, which is capable of generating strong turbulence and subsequently increasing central gas entropy and suppressing cool gas condensation and star formation, occurs only when both jets and winds operate simultaneously. The physical mechanism is the interaction between winds and jets; this interaction produces strong shear at their interface, leading to turbulence via the Kelvin─Helmholtz instability. In contrast, neither jets nor winds alone can generate strong turbulence due to the insufficient shear. The turbulence produced by wind─jet interaction is predominantly solenoidal in nature, giving rise to a broad energy spectrum approximately following a Kolmogorov-like power law and a dissipation rate of ∼10−27 erg cm−3 s−1 in the interstellar medium, consistent with observations. Our findings highlight the importance of simultaneously considering both jets and winds in studying the effects of AGN feedback in the evolution of elliptical galaxies.

Keywords: Hydrodynamical simulations, Hydrodynamics, Galaxy nuclei, Active galactic nuclei, Galaxy evolution, Interstellar medium, Galaxy quenching, Astronomical simulations
r-process Nucleosynthesis from Hyperaccreting Neutron Stars in Common Envelopes. We investigate nuclear reactions and feedback in hyperaccreting neutron star environments, considering accretion rates in the range 0.3─3 × 104 M⊙ yr−1, typical of short-period compact-object binaries in common envelopes. Our models account for weak reactions, neutrino energy loss, nuclear energy release, pair production, degenerate equations of state, and general relativistic hydrodynamics. Depending on the accretion rates, these systems can develop both proton- and neutron-rich atmospheres with strong convective instabilities linking the neutrino sphere to the outgoing accretion shock inside the radiation trapping zone. Convection drives nucleons through multiple heating and cooling cycles, with photodisintegration dominating during the heating phase and heavy element synthesis during the cooling phase, ejecting material with abundances that depend on the accretion rate and depth of the final decompression trajectory. The turbulent nature of convective currents is conducive to creating a wide range of nuclear products through a variety of effects, including nuclear statistical equilibrium freeze-out and the r-, p-, and γ-processes. We also observe a novel multistep process in reheated trajectories, consisting of proton-capture and photodissociation reactions operating on r-process seeds, producing overall neutron-deficient isotopes. A significant amount of infalling gas experiences high entropy and short (millisecond) freeze-out timescales capable of making r-process elements with high overabundances through a disequilibrium effect between neutrons and α-particles that does not require an excess of neutrons.

Keywords: R-process, Nuclear astrophysics, Common envelope binary stars
Chemical Evolution of Bulges of Active Galactic Nuclei in the Early Universe: Roles of Accreting Stars. JWST/NIRCam observations reveal dense stellar cores in high-redshift galactic bulges, indicative of sustained star formation and potential stellar accretion. We introduce accretion-modified stars (AMSs) as a new component in the chemical evolution of high-redshift bulges hosting active galactic nuclei (AGNs). The gas-phase chemical evolution of bulge environments containing AMSs is modeled within 1 Gyr by combining formalisms for population evolution and galactic chemical evolution, and observational signatures are tracked via photoionization modeling on Baldwin─Phillips─Terlevich (BPT) diagrams. Sustained high accretion onto AMSs leads to rapid gas-phase metal enrichment of the bulge, producing abundance peaks up to five times solar metallicity within 0.1 Gyr and significantly modifying elemental ratios in the gas phase. Atypical gas-phase abundance patterns occur during early high-accretion phases and gradually diminish as the accretion rate declines. In BPT diagrams, high-AMS-accretion scenarios shift the modeled emission-line sequence toward the local AGN branch and extend into the high-metallicity regime. Supersolar narrow-line regions observed in AGNs at z ≳ 15 may reflect such AMS-driven gas-phase enrichment of the host bulge under extreme gas densities. While direct detection of AMSs within AGN bulges remains challenging, the model provides testable predictions for future spectroscopic surveys and motivates further exploration of noncanonical stellar populations in AGN host bulges.

Keywords: Photoionization, Galaxy chemical evolution, Galaxy bulges, Chemical enrichment, Active galactic nuclei
Kinematics of Stellar Streams from Globular Clusters Depend on Black Hole Retention and Star Mass: A Selection Effect for Dark Matter Inference. Velocity dispersion (σ) in stellar streams from globular clusters (GCs) is sensitive to heating by Galactic substructure, including dark matter (DM) subhalos. Recent studies have compared σ in observed and modeled streams to probe DM properties, but have relied on stream models that neglect strong encounters, black holes (BHs), and mass segregation in GCs. Such phenomena may inflate stream σ or introduce selection effects—e.g., a σ that depends on star mass (m). We investigate this prospect using Monte Carlo N-body simulations of GCs under static Galactic tides to generate mock streams with realistic mass and velocity distributions. We find σ correlates with m, especially after core collapse (the GC's observable increase in central density upon ejecting its BHs), rising from 1.2 to 2.2 km s−1 between m = 0.3─0.8 M⊙, with typical kinematic cuts on stream membership. Similar in magnitude to heating by Galactic substructure, this enhancement occurs because the GC's loss of BHs allows its most-massive stars to occupy its dense center, raising their likelihood of strong ejection via binary interactions and adding broad, exponential wings to the stream's velocity distribution. Streams' kinematics thus probe properties (density, BH retention) of their progenitor GCs. Our results also imply observations of streams from some GCs, especially those not subject to highly episodic mass loss, may select for higher σ than predicted by models neglecting σ's m dependence. This would cause observed σ in streams—already on the low side of expectations for cold DM—to further favor alternatives such as warm or ultralight DM.

Keywords: Globular star clusters, Stellar streams, Stellar kinematics, Galactic archaeology, Dark matter, Stellar dynamics, Stellar mass black holes, Tidal tails, N-body simulations, Star clusters
A Submillimeter Survey of CS Excitation in Protoplanetary Disks: Evidence of X-Ray-driven Sulfur Chemistry. The sulfur chemistry in protoplanetary disks influences the properties of nascent planets, including potential habitability. Although the inventory of sulfur molecules in disks has gradually increased over the last decade, CS is still the most commonly observed sulfur-bearing species, and it is expected to be the dominant gas-phase sulfur carrier beyond the water snow line. Despite this, few dedicated multiline observations exist, and thus, the typical disk CS chemistry is not well constrained. Moreover, it is unclear how that chemistry—and in turn, the bulk volatile sulfur reservoir—varies with stellar and disk properties. Here, we present the largest survey of CS to date, combining both new and archival observations from the Atacama Large Millimeter/submillimeter Array, Submillimeter Array, and Northern Extended Millimeter Array of 12 planet-forming disks, covering a range of stellar spectral types and dust morphologies. Using these data, we derived disk-integrated CS gas excitation conditions in each source. Overall, CS chemistry appears similar across our sample with rotational temperatures of ≍10─40 K and column densities between 1012 and 1013 cm−2. CS column densities do not show strong trends with most source properties, which broadly suggests that CS chemistry is not highly sensitive to disk structure or stellar characteristics. We do, however, identify a positive correlation between stellar X-ray luminosity and CS column density, which indicates that the dominant CS formation pathway is likely via ion-neutral reactions in the upper disk layers, where X-ray-enhanced S+ and C+ drive abundant CS production. Thus, using CS as a tracer of gas-phase sulfur abundance requires a nuanced approach that accounts for its emitting region and dependence on X-ray luminosity.

Keywords: Protoplanetary disks, Planet formation, Astrochemistry
Spectroscopic r-process Abundance Retrieval for Kilonovae. III. Linking Spectral and Light-curve Modeling of the GW170817 Kilonova. The observed spectra and light curves of the kilonova produced by the GW170817 binary neutron star merger provide complementary insights, but modeling both the spectral and time domains has proven challenging. Here, we model the optical─infrared light curves of the GW170817 kilonova, using the properties and physical conditions of the ejecta as inferred from detailed modeling of its spectra. Using our software tool Spectroscopic r-Process Abundance Retrieval for Kilonovae (SPARK), we first infer the r-process abundance pattern of the kilonova ejecta from spectra obtained at 1.4, 2.4, 3.4, and 4.4 days postmerger. From these abundances, we compute time-dependent radioactive heating rates and the wavelength-, time-, and velocity-dependent opacities of the ejecta. We use these inferred heating rates and opacities to inform a kilonova light-curve model, to reproduce the observed early time light curves and to infer a total ejecta mass of Mej = 0.11 M⊙, towards the higher end of those inferred from previous studies. The combination of a large ejecta mass from our light-curve modeling and the presence of both red and blue ejecta from our spectral modeling suggests the existence of a highly magnetized hypermassive neutron star remnant that survives for ∼0.01─0.5 s and launches a blue wind, followed by fast, red, neutron-rich winds launched from a magnetized accretion disk. By modeling both spectra and light curves together, we demonstrate how combining information from both the spectral and time domains can more robustly determine the physical origins of the ejected material.

Keywords: Radiative transfer simulations, R-process, Nuclear abundances
Investigating the Role of Protostellar Variability with PRIMA Using Monte Carlo Simulations. Evidence suggests that protostellar outbursts likely play a critical role in the stellar mass assembly process, but the extent of this contribution is not well understood. Using the proposed observing program of PRIMA, a conceptual far-IR observatory (PRIMA GO Case #43 in A. Moullet et al 2023.), we examine the probe's ability to unambiguously determine whether or not variable accretion events dominate the stellar mass assembly process (Mburst ≥ 0.5M*). To do this, we construct multiple protostellar ensembles using Herschel 70 μm flux data and evolve them using a toy Monte Carlo simulation through steady-state and high-magnitude accretion events. Ensembles are observed at various epochs in the evolution process to conclude how many large-amplitude outbursts are observationally recoverable during the proposed program. Based on our synthetic observations and our simulation specifications, we determine that observing a protostellar ensemble of at least 2000 protostars using PRIMA's proposed program is sufficient for determining the importance of protostellar outbursts in the stellar mass assembly process.

Keywords: Accretion, Protostars, Star formation, Stellar evolution
Probing the Era of Giant Collisions: Millimeter Observations of the HD 166191 System. We present nonsimultaneous Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 and Submillimeter Array (SMA) observations of the HD 166191 disk, which was recently thought to have a collision in its terrestrial planet zone. Both observations detect dust continuum emission, and the ALMA observations detect the 12CO J = 3─2 line from the circumstellar disk. We do not detect SiO, a potential indicator of giant collisions, but place a limit on the total SiO mass in the system. Unlike as previously observed in the IR, we do not find evidence for variability at millimeter wavelengths when comparing the ALMA continuum observations from 2024 to the precollision SMA observations from 2014. We perform modeling of the CO and continuum visibilities, and find that both the CO and dust are marginally spatially resolved and are contained to within 20 au from the central star. The modeling of the CO suggests that the outer regions of the disk are gas-rich, although further observations are needed to confirm the total gas mass. The evolutionary state of this system has been debated in the literature, and our observations, while not definitive, are generally consistent with the idea that this disk is similar to an evolved protoplanetary or transition/hybrid disk. This could suggest that collisions in the terrestrial planet zone of HD 166191 are occurring while the disk is in a transitional phase, where the inner few au are depleted of gas. This makes HD 166191 an important object for understanding the transition between protoplanetary and debris disks and the stages at which collisions occur.

Keywords: Protoplanetary disks, Circumstellar disks, Submillimeter astronomy, Debris disks, Circumstellar gas
MAMMOTH-Grism: Revisiting the Mass─Metallicity Relation in Protocluster Environments at Cosmic Noon. We present one of the first measurements of the mass─metallicity relation (MZR) in multiple massive protoclusters at cosmic noon, using Hubble Space Telescope (HST) G141 slitless spectroscopy from the MAMMOTH-Grism survey. We identify 63 protocluster member galaxies across three overdense structures at z = 2─3 with robust detections of [O III], Hβ, and [O II] emission. The sample spans gas-phase metallicities of  12+log(O/H)=8.2−8.6 , dust-corrected Hβ-based star formation rates (SFRs) of 10─250 M⊙ yr−1, and stellar masses of M* ∼ 109.4─1010.5 M⊙, derived via spectral energy distribution fitting using deep HST and ground-based photometry. We stack spectra in five M* bins to obtain average metallicities and SFRs. Relative to field galaxies at similar redshifts, protocluster members show elevated SFRs at M* &lt; 1010.25 M⊙ and a systematically shallower MZR:  12+log(O/H)  =(6.96 ± 0.13) + (0.143 ± 0.017)  ×log(M*/M⊙) . We detect a mass-dependent environmental offset: massive protocluster galaxies are metal-poor compared to field counterparts of similar mass, whereas lower-mass systems exhibit comparable or mildly enhanced metallicities. This trend is consistent with a scenario where cold-mode accretion dilutes the interstellar medium (ISM) across the full mass range, while efficient recycling of feedback-driven outflows preferentially enriches the ISM in low-mass galaxies. Finally, we assess the dependence of metallicity offsets on local overdensity and find no significant trend, likely reflecting the survey's bias toward protocluster cores.

Keywords: Galaxy formation, Protoclusters, Galaxy abundances, Galaxy evolution, High-redshift galaxies
The Helium Common-envelope Wind Scenario for SN 2020eyj. SN 2020eyj is the first Type Ia supernova (SN Ia) showing the signature of compact helium-rich circumstellar material (CSM). Such a large amount of CSM is difficult to explain in a single-degenerate scenario where the donor star is a helium star. Here we show that, under certain conditions, it is possible that the transfer of helium leads to a common envelope (CE) engulfing the system, similar to the CE wind model proposed by X. Meng &amp; P. Podsiadlowski. If in such a helium CE wind model the initial white dwarf mass is larger than 1.1 M⊙ and the helium star is more massive than 1.8 M⊙, the mass of a helium CE can be larger than 0.3 M⊙ prior to supernova explosion. The CE mass heavily depends on the initial parameters of the binary system. A dynamical CE ejection event could occur shortly before the supernova, and then our model may naturally explain the properties of SN 2020eyj, specifically the massive He-rich CSM, and its dim peak brightness, low ejecta velocity, and low birth rate.

Keywords: Supernova remnants, White dwarf stars, Type Ia supernovae
High-precision Relativistic Timescales for Cislunar Navigation. We present a unified post-Newtonian framework for relativistic timing and coordinate transformations across the Barycentric, Geocentric, and Lunicentric Celestial Reference Systems (LCRS) and six timescales: Barycentric Coordinate Time (TCB), Geocentric Coordinate Time (TCG), Terrestrial Time (TT), Barycentric Dynamical Time (TDB), Lunicentric Coordinate Time (TCL), and Lunar Time (TL). Following IAU Resolution II (2024), we implement an LCRS metric with time coordinate TCL, linked to TCB via the IAU B1.5 prescription with lunar quantities. We truncate all series to retain contributions above a fractional threshold of 5 × 10−18 and timing terms exceeding 0.1 ps, expanding the lunar gravity to degree ℓ = 9 with Love number variations and including external tidal and inertial multipoles through the octupole. We derive closed-form mappings among TCB, TCG, TT, TDB, TCL, and TL, giving proper-to-coordinate time conversions and one-/two-way time-transfer corrections at subpicosecond accuracy. Secular rates and periodic perturbations from kinematic dilation, lunar monopole and multipoles, Earth tides, and gravitomagnetism are evaluated for clocks on the lunar surface in Very Low and Low Lunar Orbits, in elliptical lunar frozen orbits, at the Earth─Moon L1 point, and in Near-rectilinear Halo Orbits (NRHOs). Harmonics through ℓ = 9 and tides through ℓ = 8 suffice to meet 5 × 10−18 stability in deep cislunar regimes (e.g., NRHO, L1), supporting subpicosend synchronization and centimeter-level navigation, whereas near-surface and Very Low Lunar Orbits require much higher degree (typically  ℓmax≳300 ). The framework implements the IAU LCRS/TCL prescription and supplies accuracy budgets for high-precision time/frequency transfer, relativistic geodesy, quantum links, and fundamental tests beyond low Earth orbit.

Keywords: General relativity
CLASSY. XIII. Cutting through the Clouds—Comparing Indirect Tracers of Ionizing Photon Escape. The Epoch of Reionization (EoR) provides critical insights into the role of early galaxies in shaping the ionization state of the Universe. However, because of the opacity of the intergalactic medium, it is often not possible to make direct measurements of the ionizing photon escape fraction ( fescLyC ) of high-redshift (z ≳ 4) galaxies. To explore the agreement and systematics of common indirect approaches, we applied six empirically calibrated diagnostics to predict  fescLyC  for the 45 nearby star-forming galaxies from the COS Legacy Spectroscopic SurveY. These methods—based on ultraviolet (UV) absorption lines, the UV continuum slope, Lyα kinematics, a multivariate model, radiation-hydrodynamic simulations, and nebular emission-line ratios—enable us to explore systematic differences between predictions and assess how galactic properties influence inferred LyC escape. Despite significant variations in method predictions, there is broad consistency in the resulting weak and strong LyC leaker classifications, with approximately half exhibiting predicted escape fractions &gt;1%. We find evidence for two different pathways of LyC escape in nearby star-forming galaxies: (1) an early escape model driven by very young stellar populations, and (2) a delayed escape model that is consistent with supernova-driven outflows and time-dependent interstellar medium clearing. The early escape model is favored among galaxies with a single, intense burst of recent star formation. In contrast, the delayed escape model is common among galaxies with more extended starburst histories. To interpret ionizing photon escape during the EoR, it will be necessary to recognize and understand this diversity in LyC escape mechanisms.

Keywords: Stellar feedback, Interstellar line absorption, Ultraviolet spectroscopy, Galaxy stellar content, Lyman-alpha galaxies, Reionization, Galaxies
Stellar Populations with MaNGA: Iron Kink and Nitrogen Fuzz. Recent analysis of 2968 MaNGA early-type galaxies has yielded two notable trends with velocity dispersion (σ) not previously discussed in the literature. First, Fe abundance rises with σ but only until σ ≍ 100 km s−1, after which it falls. This kink is reproduced by TNG100 simulations, implying that hierarchical merger processes might explain it. Second, astrophysical scatter in N is high for galaxies with σ &lt; 100 km s−1. Due to the restricted list of nucleosynthetic sources for N, it is likely that asymptotic giant branch stars provide most of this N. A varied star formation history (compared to that of massive galaxies) along with variable retention and recycling of N-enriched gas might explain the fuzz of N abundance in low-σ galaxies. Because a timescale argument seems necessary to explain the nitrogen fuzz, and an initial mass function argument is ruled out, similar timescale arguments for the [Mg/Fe] trend as a function of velocity dispersion are supported.

Keywords: Galaxy chemical evolution, Galaxy stellar content, Galaxy ages, Galaxy abundances, Galaxy evolution
Systematic Analysis of Changing-Look Active Galactic Nucleus Variability Using ZTF Light Curves. Changing-look active galactic nuclei (CLAGNs) are a unique population of AGNs that exhibit the appearance (turn-on) or disappearance (turn-off) of broad emission lines. This study aims to explore the intrinsic mechanisms of CLAGNs by investigating their photometric variability using data from the Zwicky Transient Facility (ZTF), which has provided high-cadence observations over the past 6 yr. By visual inspections, we construct a sample of 152 CLAGNs from the literature, all of which show spectral transitions and large optical variability in their ZTF light curves. By analyzing 90 of these CLAGNs and the control samples of Type 1 AGNs, Type 2 AGNs, and extremely variable quasars (EVQs), matched in redshift (0.2 &lt; z &lt; 0.8) and supermassive black hole mass, we compare the color variability, structure function (SF), and variability metric σQSO, which quantifies how closely the light curves resemble a damped random walk model. We find that while CLAGNs and EVQs differ from typical Type 1 and Type 2 AGNs in bolometric luminosity and Eddington ratio, the on- and off-state CLAGNs share similar variability patterns with the overall CLAGN population, and distinct from EVQs and Type 1 and Type 2 AGNs. This suggests that "on" and "off" CLAGNs are not simply equivalent to Type 1 and Type 2 AGNs, respectively. Instead of undergoing genuine transitions between two AGN types, CLAGNs may inhabit a critical state where moderate fluctuations in the accretion rate lead to temporary spectral changes.

Keywords: Light curves, Active galactic nuclei, Photometry, Quasars