Sazuna/UAT_keywords huggingface dataset:
Investigating the Drivers of Electron Temperature Variations in H II Regions with Keck-KCWI and VLT-MUSE. H II region electron temperatures are a critical ingredient in metallicity determinations, and recent observations have revealed systematic variations in the temperatures measured using different ions. We present electron temperatures (T  e ) measured using the optical auroral lines ([N II]λ5756, [O II]λ λ7320, 7330, [S II]λ λ4069, 4076, [O III]λ4363, and [S III]λ6312) for a sample of H II regions in seven nearby galaxies. We use observations from the Physics at High Angular resolution in Nearby Galaxies survey (PHANGS) obtained with integral field spectrographs on Keck (Keck Cosmic Web Imager) and the Very Large Telescope (Multi-Unit Spectroscopic Explorer). We compare the different T  e  measurements with H II region and ISM environmental properties such as electron density, ionization parameter, molecular gas velocity dispersion, and stellar association/cluster mass and age obtained from PHANGS. We find that the temperatures from [O II] and [S II] are likely overestimated due to the presence of electron density inhomogeneities in H II regions. We measure high [O III] temperatures in a subset of regions with high molecular gas velocity dispersion and low ionization parameter, which may be explained by the presence of low-velocity shocks. In agreement with previous studies, the T e─T e between [N II] and [S III] temperatures have the lowest observed scatter and follow predictions from photoionization modeling, which suggests that these tracers reflect H II region temperatures across the various ionization zones better than [O II], [S II], and [O III].

Keywords: Spiral galaxies, H II regions, Interstellar medium
Dissipative Dark Matter on FIRE. II. Observational Signatures and Constraints from Local Dwarf Galaxies. We analyze the first cosmological baryonic zoom-in simulations of galaxies in dissipative self-interacting dark matter (dSIDM). The simulations utilize the FIRE-2 galaxy formation physics with the inclusion of dissipative dark matter self-interactions modeled as a constant fractional energy dissipation (f diss = 0.75). In this paper, we examine the properties of dwarf galaxies with M * ∼ 105–109 M ⊙ in both isolation and within Milky Way–mass hosts. For isolated dwarfs, we find more compact galaxy sizes and promotion of disk formation in dSIDM with (σ/m) ≤ 1 cm2 g‑1. On the contrary, models with (σ/m) = 10 cm2 g‑1 produce puffier stellar distributions that are in tension with the observed size–mass relation. In addition, owing to the steeper central density profiles, the subkiloparsec circular velocities of isolated dwarfs when (σ/m) ≥ 0.1 cm2 g‑1 are enhanced by about a factor of 2, which are still consistent with the kinematic measurements of Local Group dwarfs but in tension with the H I rotation curves of more massive field dwarfs. Meanwhile, for satellites of Milky Way–mass hosts, the median circular velocity profiles are marginally affected by dSIDM physics, but dSIDM may help promote the structural diversity of dwarf satellites. The number of satellites is slightly enhanced in dSIDM, but the differences are small compared with the large host-to-host variations. In conclusion, the dSIDM models with (σ/m) ≳ 0.1 cm2 g‑1, f diss = 0.75 are in tension in massive dwarfs (M halo ∼ 1011 M ⊙) due to circular velocity constraints. However, models with lower effective cross sections (at this halo mass/velocity scale) are still viable and can produce nontrivial observable signatures.

Keywords: Cosmology, Hydrodynamical simulations, Local Group, Dwarf galaxies, Dark matter
Gas-dynamical Mass Measurements of the Supermassive Black Holes in the Early-type Galaxies NGC 4786 and NGC 5193 from ALMA and HST Observations. We present molecular gas-dynamical mass measurements of the central black holes in the giant elliptical galaxies NGC 4786 and NGC 5193, based on CO (2‑1) observations from the Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope near-infrared imaging. The central region in each galaxy contains a circumnuclear disk that exhibits orderly rotation with projected line-of-sight velocities of ∼270 km s‑1. We build gas-dynamical models for the rotating disk in each galaxy and fit them directly to the ALMA data cubes. At 0.″31 resolution, the ALMA observations do not fully resolve the black hole sphere of influence (SOI), and neither galaxy exhibits a central rise in rotation speed, indicating that emission from deep within the SOI is not detected. As a result, our models do not tightly constrain the central black hole mass in either galaxy, but they prefer the presence of a central massive object in both galaxies. We measure the black hole mass to be   $({M}_{\mathrm{BH}}/{10}^{8}\,{M}_{\odot })=5.0\pm 0.2\,[1\sigma \,\mathrm{statistical}]{\,}_{-1.3}^{+1.4}\,[\mathrm{systematic}]$   in NGC 4786 and   $({M}_{\mathrm{BH}}/{10}^{8}\,{M}_{\odot })=1.4\pm 0.03\,[1\sigma \,\mathrm{statistical}{]}_{-0.1}^{+1.5}\,[\mathrm{systematic}]$   in NGC 5193. The largest component of each measurement's error budget is from the systematic uncertainty associated with the extinction correction in the host galaxy models. This underscores the importance of assessing the impact of dust attenuation on the inferred M BH. *Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with programs 15226 and 15909.

Keywords: Supermassive black holes, Molecular gas, Astronomy data modeling, Millimeter astronomy, Galaxy kinematics, Submillimeter astronomy, Early-type galaxies
Constraints on the z ∼ 5 Star-forming Galaxy Luminosity Function From Hubble Space Telescope Imaging of an Unbiased and Complete Sample of Long Gamma-Ray Burst Host Galaxies. We present rest-frame UV Hubble Space Telescope imaging of the largest and most complete sample of 23 long-duration gamma-ray burst (GRB) host galaxies between redshifts 4 and 6. Of these 23, we present new WFC3/F110W imaging for 19 of the hosts, which we combine with archival WFC3/F110W and WFC3/F140W imaging for the remaining four. We use the photometry of the host galaxies from this sample to characterize both the rest-frame UV luminosity function (LF) and the size─luminosity relation of the sample. We find that when assuming the standard Schechter-function parameterization for the UV LF, the GRB host sample is best fit with   $\alpha =-{1.30}_{-0.25}^{+0.30}$   and   ${M}_{* }=-{20.33}_{-0.54}^{+0.44}$   mag, which are consistent with results based on z ∼ 5 Lyman-break galaxies. We find that ∼68% of our size─luminosity measurements fall within or below the same relation for Lyman-break galaxies at z ∼ 4. This study observationally confirms expectations that at z ∼ 5 Lyman-break and GRB host galaxies should trace the same population and demonstrates the utility of GRBs as probes of hidden star formation in the high-redshift Universe. Under the assumption that GRBs unbiasedly trace star formation at this redshift, our nondetection fraction of 7/23 is consistent at the 95% confidence level with 13%─53% of star formation at redshift z ∼ 5 occurring in galaxies fainter than our detection limit of M 1600Å ≍ −18.3 mag.

Keywords: Gamma-ray bursts, High-redshift galaxies, Galaxies
Identifying H I Emission and UV Absorber Associations near the Magellanic Stream. We present a new technique to identify associations of H I emission in the Magellanic Stream (MS) and ultraviolet (UV) absorbers from 92 QSO sight lines near the MS. We quantify the level of associations of individual H I elements to the main H I body of the Stream using Wasserstein distance-based models, and derive characteristic spatial and kinematic distances of the H I emission in the MS. With the emission-based model, we further develop a comparison metric, which identifies the dominant associations of individual UV absorbers with respect to the MS and nearby galaxies. For ionized gas associated with the MS probed by C II, C IV, Si II, Si III, Si IV, we find that the ion column densities are generally ∼0.5 dex higher than those that are not associated, and that the gas is more ionized toward the tail of the MS as indicated by the spatial trend of the C II/C IV ratios. For nearby galaxies, we identify potential new absorbers associated with the circumgalactic medium of M33 and NGC 300, and affirm the associations of absorbers with IC 1613 and the Wolf–Lundmark–Mellote galaxy. For M31, we find the previously identified gradient in column densities as a function of the impact parameter, and that absorbers with higher column densities beyond M31's virial radius are more likely to be associated with the MS. Our analysis of absorbers associated with the Magellanic Clouds reveals the presence of continuous and blended diffuse ionized gas between the Stream and the Clouds. Our technique can be applied to future applications of identifying associations within physically complex gaseous structures.

Keywords: Magellanic Clouds, Magellanic Stream, Milky Way Galaxy, Circumgalactic medium
Ground-based and JWST Observations of SN 2022pul. II. Evidence from Nebular Spectroscopy for a Violent Merger in a Peculiar Type Ia Supernova. We present an analysis of ground-based and JWST observations of SN 2022pul, a peculiar "03fg-like" (or "super-Chandrasekhar") Type Ia supernova (SN Ia), in the nebular phase at 338 days postexplosion. Our combined spectrum continuously covers 0.4–14 μm and includes the first mid-infrared spectrum of a 03fg-like SN Ia. Compared to normal SN Ia 2021aefx, SN 2022pul exhibits a lower mean ionization state, asymmetric emission-line profiles, stronger emission from the intermediate-mass elements (IMEs) argon and calcium, weaker emission from iron-group elements (IGEs), and the first unambiguous detection of neon in a SN Ia. A strong, broad, centrally peaked [Ne II] line at 12.81 μm was previously predicted as a hallmark of "violent merger" SN Ia models, where dynamical interaction between two sub-M Ch white dwarfs (WDs) causes disruption of the lower-mass WD and detonation of the other. The violent merger scenario was already a leading hypothesis for 03fg-like SNe Ia; in SN 2022pul it can explain the large-scale ejecta asymmetries seen between the IMEs and IGEs and the central location of narrow oxygen and broad neon. We modify extant models to add clumping of the ejecta to reproduce the optical iron emission better, and add mass in the innermost region (&lt;2000 km s‑1) to account for the observed narrow [O I] λ λ6300, 6364 emission. A violent WD–WD merger explains many of the observations of SN 2022pul, and our results favor this model interpretation for the subclass of 03fg-like SNe Ia.

Keywords: White dwarf stars, Type Ia supernovae, Supernovae
ASASSN-18ap: A Dusty Tidal Disruption Event Candidate with an Early Bump in the Light Curve. We reexamined the classification of the optical transient ASASSN-18ap, which was initially identified as a supernova (SN) upon its discovery. Based on newly emerged phenomena, such as a delayed luminous infrared outburst and the emergence of luminous coronal emission lines, we suggest that ASASSN-18ap is more likely a tidal disruption event (TDE) in a dusty environment, rather than an SN. The total energy in the infrared outburst is 3.1 × 1051 erg, which is an order of magnitude higher than the total energy in the optical-to-UV range, indicating a large dust extinction, an extra-extreme ultraviolet component, or anisotropic continuum emission. A bumpy feature appeared in the optical light curve at the start of brightening, which was reported in a couple of TDEs very recently. This early bump may have been overlooked in the past, due to the lack of sufficient sampling of the light curves of most TDEs during their ascending phase, and it could provide insight into the origin of optical emission.

Keywords: Supermassive black holes, High energy astrophysics, Tidal disruption, Time domain astronomy, Supernovae
Search for Gravitational-wave Transients Associated with Magnetar Bursts in Advanced LIGO and Advanced Virgo Data from the Third Observing Run. Gravitational waves are expected to be produced from neutron star oscillations associated with magnetar giant flares and short bursts. We present the results of a search for short-duration (milliseconds to seconds) and long-duration (∼100 s) transient gravitational waves from 13 magnetar short bursts observed during Advanced LIGO, Advanced Virgo, and KAGRA's third observation run. These 13 bursts come from two magnetars, SGR 1935+2154 and Swift J1818.0‑1607. We also include three other electromagnetic burst events detected by Fermi-GBM which were identified as likely coming from one or more magnetars, but they have no association with a known magnetar. No magnetar giant flares were detected during the analysis period. We find no evidence of gravitational waves associated with any of these 16 bursts. We place upper limits on the rss of the integrated incident gravitational-wave strain that reach 3.6 × 10‑23   $/\sqrt{\mathrm{Hz}}$   at 100 Hz for the short-duration search and 1.1 × 10‑22   $/\sqrt{\mathrm{Hz}}$   at 450 Hz for the long-duration search. For a ringdown signal at 1590 Hz targeted by the short-duration search the limit is set to 2.3 × 10‑22   $/\sqrt{\mathrm{Hz}}$  . Using the estimated distance to each magnetar, we derive upper limits on the emitted gravitational-wave energy of 1.5 × 1044 erg (1.0 × 1044 erg) for SGR 1935+2154 and 9.4 × 1043 erg (1.3 × 1044 erg) for Swift J1818.0‑1607, for the short-duration (long-duration) search. Assuming isotropic emission of electromagnetic radiation of the burst fluences, we constrain the ratio of gravitational-wave energy to electromagnetic energy for bursts from SGR 1935+2154 with the available fluence information. The lowest of these ratios is 4.5 × 103.

Keywords: Magnetars, Stellar oscillations, Gravitational waves, X-ray bursts
The Atacama Cosmology Telescope: Mitigating the Impact of Extragalactic Foregrounds for the DR6 Cosmic Microwave Background Lensing Analysis. We investigate the impact and mitigation of extragalactic foregrounds for the cosmic microwave background (CMB) lensing power spectrum analysis of Atacama Cosmology Telescope (ACT) data release 6 (DR6) data. Two independent microwave sky simulations are used to test a range of mitigation strategies. We demonstrate that finding and then subtracting point sources, finding and then subtracting models of clusters, and using a profile bias-hardened lensing estimator together reduce the fractional biases to well below statistical uncertainties, with the inferred lensing amplitude, A lens, biased by less than 0.2σ. We also show that another method where a model for the cosmic infrared background (CIB) contribution is deprojected and high-frequency data from Planck is included has similar performance. Other frequency-cleaned options do not perform as well, either incurring a large noise cost or resulting in biased recovery of the lensing spectrum. In addition to these simulation-based tests, we also present null tests on the ACT DR6 data for sensitivity of our lensing spectrum estimation to differences in foreground levels between the two ACT frequencies used, while nulling the CMB lensing signal. These tests pass whether the nulling is performed at the map or bandpower level. The CIB-deprojected measurement performed on the DR6 data is consistent with our baseline measurement, implying that contamination from the CIB is unlikely to significantly bias the DR6 lensing spectrum. This collection of tests gives confidence that the ACT DR6 lensing measurements and cosmological constraints presented in companion papers to this work are robust to extragalactic foregrounds.

Keywords: Cosmology, Cosmic microwave background radiation, Weak gravitational lensing, Large-scale structure of the universe
From out of the Blue: Swift Links 2002es-like, 2003fg-like, and Early Time Bump Type Ia Supernovae. We collect a sample of 42 Type Ia supernovae (SNe Ia) with Swift UV photometry and well-measured early time light-curve rises and find that 2002es-like and 2003fg-like SNe Ia have different prepeak UV color evolutions compared to normal SNe Ia and other spectroscopic subtypes. Specifically, 2002es-like and 2003fg-like SNe Ia are cleanly separated from other SNe Ia subtypes by UVM2 ‑ UVW1 ≳ 1.0 mag at t = ‑ 10 days relative to B-band maximum. Furthermore, the SNe Ia that exhibit nonmonotonic bumps in their rising light curves, to date, consist solely of 2002es-like and 2003fg-like SNe Ia. We also find that SNe Ia with two-component power-law rises are more luminous than SNe Ia with single-component power-law rises at prepeak epochs. Given the similar UV colors, along with other observational similarities, we discuss a possible progenitor scenario that places 2002es-like and 2003fg-like SNe Ia along a continuum and may explain the unique UV colors, early time bumps, and other observational similarities between these objects. Ultimately, further observations of both subtypes, especially in the near-infrared, are critical for constraining models of these peculiar thermonuclear explosions.

Keywords: Type Ia supernovae
Massive Debris Disks May Hinder Secular Stirring by Planetary Companions: An Analytic Proof of Concept. Debris disks or exo-Kuiper belts, detected through their thermal or scattered emission from their dusty components, are ubiquitous around main-sequence stars. Since dust grains are short-lived, their sustained presence is thought to require dynamical excitation, i.e., "stirring," of a massive reservoir of large planetesimals, such that mutual collisions are violent enough to continually supply fresh dust. Several mechanisms have been proposed to explain debris disk stirring, with the commonly accepted being long-term, secular planet–debris disk interactions. However, while effective, existing planet-stirring models are rudimentary; namely, they ignore the (self-)gravity of the disk, treating it as a massless reservoir of planetesimals. Here, using a simple analytical model, we investigate the secular interactions between eccentric planets and massive, external debris disks. We demonstrate that the disk gravity drives fast apsidal precession of both planetesimal and planetary orbits, which, depending on the system parameters, may well exceed the planet-induced precession rate of planetesimals. This results in strong suppression of planetesimal eccentricities and thus relative collisional velocities throughout the disk, often by more than an order of magnitude when compared to massless disk models. We thus show that massive debris disks may hinder secular stirring by eccentric planets orbiting near, e.g., the disk's inner edge, provided the disk is more massive than the planet. We provide simple analytic formulae to describe these effects. Finally, we show that these findings have important implications for planet inferences in debris-bearing systems, as well as for constraining the total masses of debris disks (as done for β Pic).

Keywords: Exoplanet dynamics, Planetary system evolution, Celestial mechanics, Circumstellar disks, Debris disks, Planetary dynamics
A Narrow Uniform Core with a Wide Structured Wing: Modeling the TeV and Multiwavelength Afterglows of GRB 221009A. The TeV afterglow of the BOAT GRB 221009A was interpreted as arising from a narrow jet, while the radio-to-X-ray afterglows were interpreted as arising from a wide structured jet. However, there is no model explaining the TeV and lower-energy multiwavelength afterglows simultaneously. We here investigate a two-component jet model, including a narrow uniform core with a wide structured wing, to explain both the multiwavelength afterglows that last up to 100 days. We find that to explain the early TeV afterglow with the inverse-Compton process, we need a circumburst density higher than ≳0.1 cm‑3, while the radio afterglow and the H.E.S.S. upper limit combine to constrain the density to be lower at larger radii. Thus, a decreasing density profile with radius is favored. Considering that the rising TeV light curve during the afterglow onset favors a constant-density medium, we invoke a stratified density profile, including a constant-density profile at small radii and a wind density profile at large radii. We find that the two-component jet model with such a stratified density profile can explain the TeV, X-ray, and optical afterglows of GRB 221009A, although the radio fluxes exceed the observed ones by a factor of 2 at later epochs. The discrepancy in the radio afterglow could be resolved by invoking some nonstandard assumption about the microphysics of afterglow shocks. The total kinetic energy of the two components in our model is ≲1052 erg, significantly smaller than that in the single structured jet models.

Keywords: Gamma-ray astronomy, Gamma-ray bursts, High energy astrophysics
Modeling of the Polytropic Index and Temperature Anisotropy in the Solar Wind. The polytropic index is a fundamental physical parameter related to the thermodynamic processes present in space and astrophysical plasmas. This paper investigates the theoretical relationship between the polytropic index and the temperature anisotropy for flow parameters relevant to space plasmas. The derivation is based on the Chew–Goldberger–Low double-adiabatic equations of state and the finite Larmor radius correction. On the basis of this, we present the polytropic index relation, taking into account the temperature anisotropy, flow speed, and magnetic field of the plasma. This relation was further analyzed for the limit of the quasi-parallel and quasi-transversal cases. The quasi-transversal limit gives a polytropic index as a function of the anisotropic temperature γ = 1 + 2[2T ⊥ ‑ T ∥]/[2T ⊥ + T ∥]. Using this result, we analyze the polytropic index for the bulk proton parameters derived from Ulysses spacecraft data spanning the interval from 1992 January 1 to 2009 June 30, and we find an average polytropic index of γ ∼ 1.43. This value is close to that of recently published results. However, unlike previous statistical studies, this research computes the polytropic index without relying on power-law fitting, and its variation is now associated with the anisotropic temperature.

Keywords: Space plasmas, Theoretical techniques, Heliosphere, Solar energetic particles, Solar wind, Polytropes
Photon Rings and Shadow Size for General Axisymmetric and Stationary Integrable Spacetimes. There are now multiple direct probes of the region near black hole horizons, including direct imaging with the Event Horizon Telescope (EHT). As a result, it is now of considerable interest to identify what aspects of the underlying spacetime are constrained by these observations. For this purpose, we present a new formulation of an existing broad class of integrable, axisymmetric, stationary spinning black hole spacetimes, specified by four free radial functions, that makes manifest which functions are responsible for setting the location and morphology of the event horizon and ergosphere. We explore the size of the black hole shadow and higher-order photon rings for polar observers, approximately appropriate for the EHT observations of M87*, finding analogous expressions to those for general spherical spacetimes. Of particular interest, we find that these are independent of the properties of the ergosphere, but do directly probe the free function that defines the event horizon. Based on those expressions, we extend the nonperturbative, nonparametric characterization of the gravitational implications of various near-horizon measurements to spinning spacetimes. Finally, we demonstrate this characterization for a handful of explicit alternative spacetimes.

Keywords: Spacetime metric, Black holes, Non-standard theories of gravity, Rotating black holes, General relativity