Sazuna/UAT_keywords huggingface dataset:
Evidence for a Hot Galactic Halo around the Andromeda Galaxy Using Fast Radio Bursts along Two Sightlines. Fast radio bursts (FRBs) are millisecond-duration radio transients that serve as unique probes of ionizedextragalactic matter. We report the discovery and localization of two FRBs piercing the Andromeda galaxy (M31) with the realfast transient-detection system at the Very Large Array. These unique sightlines enable constraints on M31's electron density distribution. We localized FRB 20230930A to a host galaxy at redshift z = 0.0925 and FRB 20230506C to a host galaxy at redshift z = 0.3896. After accounting for the dispersion contributions from the Milky Way, the host galaxies, and the intergalactic medium, we estimate M31's contribution to be 26─239 pc cm−3 toward FRB 20230930A and 51─366 pc cm−3 toward FRB 20230506C, within the 90% credible interval (CI). By modeling the M31 disk's contribution, we isolate the halo component and find that M31's halo contributes 7─169 pc cm−3 along FRB 20230930A (90% CI). The inferred values of DMM31,halo from the FRBs are consistent with predictions from a modified Navarro─Frenk─White profile at the corresponding impact parameter. The cool and warm phase gas is unlikely to account for the DMM31,halo unless the ionization fraction is as high as 90%. While limited to two sightlines, these results offer tentative evidence for the existence of a hot halo surrounding M31. We also discuss the potential contribution of other foreground structures, particularly in explaining the DM excess observed in FRB 20230506C. This work demonstrates how FRBs can be used to probe the circumgalactic medium of intervening galaxies.

Keywords: Radio bursts, Galaxies, Radio transient sources
Mergers and Recoil in Triple Massive Black Hole Systems from Illustris. Massive black hole binaries (MBHBs) form through galaxy mergers and are among the loudest sources of gravitational waves (GWs) in the Universe. If the binary inspiral time is long, a subsequent galaxy merger can introduce a third black hole, forming a triple system. In the Illustris cosmological simulation, 6% of MBHBs form such triples at parsec scales, where strong three-body interactions are likely. We apply results from numerical simulations of triple massive black holes (MBHs) to strong triples identified in Illustris to assess their impact on MBH mergers and recoils. We find that triple interactions raise the merger fraction, reduce the median merger timescales in strong triple systems, and increase the overall merger fraction slightly (by 4%). Furthermore, massive major mergers are over three times more likely to be facilitated by strong triple interactions than mergers in general. We also compare GW recoil kicks to gravitational slingshot kicks from triple interactions. Both mechanisms can produce kicks exceeding host escape speeds, ejecting MBHs and producing wandering or offset black holes. Although slingshots yield the kicks with the highest velocity, GW recoils dominate the ejected population when assuming random MBH spin orientations. Under this assumption, ejections from GW recoil and slingshot kicks reduce the total number of mergers by 6%. Our results highlight the impact of strong triple dynamics and GW recoils on MBH evolution and support their inclusion in cosmological simulations.

Keywords: Supermassive black holes, Interacting galaxies, Gravitational waves, Hydrodynamical simulations
A Multiwavelength View of the Multimessenger Sources NGC 1068 and PKS 1502+106. Multimessenger astronomy offers a powerful approach to studying high-energy radiative processes in astrophysical sources. A notable example was seen in 2017, when the IceCube Neutrino Observatory detected a high-energy neutrino event that was found to coincide with a gamma-ray flare from a blazar. Since then, numerous multimessenger studies combining neutrino and photon data have been conducted, yet the origin of neutrinos from active galactic nuclei (AGN) remains uncertain. In this work, we present the results of an X-ray observing program targeting two AGNs, NGC 1068 and PKS 1502+106. The multiwavelength dataset includes new observations from NICER and NuSTAR from the observing proposal, along with gamma-ray data collected using Fermi-LAT, and one archival observation from Chandra. Additionally, we derive the neutrino fluxes for both AGNs using 10 yr of IceCube data and neutrino spectra predicted by theoretical models. These results demonstrate the importance of combining multimessenger data in building and constraining theoretical models. They also highlight the importance of testing model predictions against observational data to refine measurements of both the neutrino flux and spectral shape.

Keywords: X-ray astronomy, High energy astrophysics, Blazars, Neutrino astronomy, Seyfert galaxies, Active galactic nuclei, Gamma-ray astronomy
Very Bright, Very Blue, and Very Red: JWST CAPERS Analysis of Highly Luminous Galaxies with Extreme Ultraviolet Slopes at z = 10. We present JWST/NIRSpec PRISM observations of three luminous (MUV &lt; −20) galaxies at z ∼ 10 observed with the CANDELS-Area Prism Epoch of Reionization Survey (CAPERS) Cycle 3 program. These galaxies exhibit extreme UV slopes compared to typical galaxies at z = 10. Of the three sources, two of them are a close pair (0 .″ 22) of blue galaxies at z = 9.800 ± 0.003 and z = 9.808 ± 0.002 with UV slopes of β = −2.87 ± 0.15 and β = −2.46 ± 0.10, respectively, selected from PRIMER COSMOS NIRCam imaging. We perform spectrophotometric modeling of the galaxies, which suggests extremely young stellar ages and a lack of dust attenuation. For the bluest galaxy, its UV slope also suggests significant Lyman continuum escape. In contrast, the third source (selected from CEERS NIRCam imaging) at z = 9.942 ± 0.002 exhibits a red UV slope with β = −1.51 ± 0.08. We rule out the possibility of a strong nebular continuum due to the lack of a Balmer jump and find no evidence to support the presence of an active galactic nucleus continuum due to a lack of strong UV emission lines and no broad component to Hγ or Hβ. Instead, it is most likely that the red UV slope is due to dust reddening (AV ≃ 0.9) implying a significant level of dust-obscured star formation only ≃480 Myr after the Big Bang. Under standard assumptions for dust attenuation, EGS-25297 would be the most intrinsically UV-luminous galaxy ( MUV,corr≃−22.4−1.1+0.7 ) yet spectroscopically confirmed at z ∼ 10. This work highlights that luminous galaxies at z ≳ 10 have a diversity of dust properties and that spectroscopy of these galaxies is essential to fully understand star formation at z ≳ 10.

Keywords: Early universe, Galaxy formation, High-redshift galaxies, Galaxy evolution
A High Incidence of Central Star Formation Inferred from the Color Gradients of Galaxies at z &gt; 4. We study the rest-frame ultraviolet-optical color gradients of 441 galaxies at 4 &lt; z &lt; 8 by characterizing the wavelength dependence of their structural parameters derived from simultaneously fitting the seven-band NIRCam images acquired with the James Webb Space Telescope. Distinct from trends observed at lower redshifts, where most galaxies exhibit negative color gradients whereby galaxy centers are redder than their outskirts, in high-redshift galaxies positive color gradients are just as common as or even outnumber negative color gradients. Varying stellar population, dust, and active galactic nuclei can contribute to the observed color gradient. We show that for the majority of our sample, the observed color gradients principally reflect radial variations in stellar population, without strong contribution from dust reddening or contamination from active galactic nuclei. The sign and magnitude of the color profile depend systematically on the global properties of the galaxy: positive color gradients, characteristic of centrally concentrated star formation or outside-in growth, are found preferentially in galaxies of lower stellar mass, smaller size, and bluer spectral energy distribution.

Keywords: Early universe, Galaxy formation, High-redshift galaxies, Galaxy evolution
Is Earendel a Star? Investigating the Sunrise Arc Using JWST Strong and Weak Gravitational Lensing Analyses. The galaxy cluster WHL J013719.8−08284 at z = 0.566 exhibits a strong-lensing feature known as the Sunrise Arc, which hosts Earendel, the most distant candidate star observed to date at z ≍ 6.2. If this object is a star, or a system of a few stars, its apparent magnitude implies both extreme gravitational lensing magnification and an unusually high luminosity. This study revisits Earendel's magnification, which, in previous literature, exhibits significant uncertainty across various lens models (2μ = 4000─35,000). We present an improved cluster mass reconstruction and a tighter constraint on Earendel's magnification using a joint strong- and weak-lensing analysis with JWST data. Our strong-lensing mass model, which incorporates newly identified multiple-image systems from JWST imaging data and modifies the existing multiple-image assignment scheme, yields an rms lens-plane scatter of less than  0.″3 . Additionally, our weak-lensing catalog achieves a source density of ∼100 galaxies arcmin−2, providing constraints on the mass profile beyond the strong-lensing regime. In our best-fit model, we estimate the magnification of Earendel to be μ = 43─67, significantly lower than previously proposed and thus calling into question its classification as a star.

Keywords: Weak gravitational lensing, Strong gravitational lensing, Galaxy clusters, James Webb Space Telescope
Cosmology with Voids from the Nancy Grace Roman Space Telescope. We provide an accurate forecast of the expected constraining power from the main void statistics—the void size function and the void-galaxy cross-correlation function—to be measured by the Roman reference High Latitude Spectroscopic Survey from the Nancy Grace Roman Space Telescope. Relying on a realistic galaxy mock lightcone, covering 2000 square degrees, we find more than 8 × 104 voids and explore their constraining power in the framework of three different cosmological models: ΛCDM, wCDM, and w0waCDM. This work confirms the strong complementarity of different void statistics and showcases the constraining power to be expected from Roman voids thanks to the combination of its high tracer density and large observed volume.

Keywords: Cosmology, Cosmological parameters, Large-scale structure of the universe, Voids, Dark energy
The Orbits of Isolated Dwarfs in the Local Group from New 3D Kinematics: Constraints on First Infall, Backsplash, and Quenching Mechanisms. It is commonly supposed that quenched field dwarfs near the edge of the Local Group (LG) are backsplash galaxies, having previously orbited within the Milky Way (MW) or M31's virial radius, whereas galaxies on first infall should still have gas and star formation. We measured proper motions (PMs) for six dwarf galaxies located 400─1000 kpc from the MW using the Hubble Space Telescope. For four galaxies (Aquarius, Cetus, Pisces, and Tucana), we report the first PMs. For the remaining two (Leo T and Pegasus), we measure PMs with order-of-magnitude precision improvement. We compute orbital histories to assess whether any of the six are backsplash galaxies. While some have nonzero likelihoods of past interaction with the MW or M31, these are weak and typically occur at large distances (i.e., &gt;2Rvir). The properties of Aquarius, Leo T, Pisces, and Pegasus are consistent with first passage through a massive halo. Cetus, which shows a low probability (∼4%─6%) of interacting with the MW or M31 in the last 6 Gyr, is more likely a backsplash galaxy resulting from an interaction with M31 over 6 Gyr ago, in the regime where rigid orbital models become less reliable. Tucana has been thought to be a backsplash galaxy, but our orbits indicate it cannot have interacted with a massive LG host. Our results highlight the diversity of evolutionary pathways for isolated, intermediate-mass dwarfs (M* ≍ 105─107 M⊙) and the need to reassess quenching mechanisms beyond environmental interactions with massive hosts.

Keywords: Local Group, Dwarf galaxies, Proper motions
A Census of Compact Elliptical Galaxies in the Coma Cluster. Compact elliptical (cE) galaxies are compact stellar systems with stellar masses of 108 ≤ M*/M⊙ ≤ 1010 and radii typically &lt;0.6 kpc. Here we investigate the properties of 13 cE galaxies in the Coma cluster, 6 of which are newly identified. Our goal in this paper is to explore whether these cEs form directly in the cluster environment or are preprocessed in small groups before infalling. We find that preprocessing in groups significantly contributes to the cE population in the Coma cluster. We analyze Hyper Suprime-Cam g-band Coma images and validate our photometric measurements through comparison with Hubble Space Telescope data. We also analyze spectroscopic data from the Dark Energy Spectroscopic Instrument. We significantly expand the known cE population in the Coma cluster through joint photometric and spectroscopic selection. We identify a subpopulation of cEs that likely formed in infalling groups, through their association with host galaxies, their positions on the caustic diagram, and their projected phase-space trajectories. We estimate that the central cE population will increase by up to 30% within the next 0.4 Gyr, highlighting the important role of preprocessing in cE evolution.

Keywords: Galaxy groups, Galaxy evolution, Coma Cluster, Compact galaxies
Marvelous Metals: Surveying the Circumgalactic Medium of Simulated Dwarf Galaxies. Dwarf galaxies are uniquely sensitive to feedback processes and known to experience substantial mass and metal loss from their disks. Here, we investigate the circumgalactic medium (CGM) of 64 isolated dwarf galaxies ( 6.0&lt;log(M*/M⊙)&lt;9.5 ) at z = 0 from the Marvel-ous Dwarfs and Marvelous Massive Dwarfs simulations. Our galaxies produce column densities broadly consistent with current observations. We investigate these column densities in the context of mass and metal retention rates, and CGM physical properties. We find 48% ± 11% of all baryons within R200c reside in the CGM, with ∼70% of CGM mass existing in a warm gas phase, 104.5 &lt; T &lt; 105.5 K, that dominates beyond r/R200c ∼ 0.5. The warm and cool (104.0 &lt; T &lt; 104.5 K) gas phases each retain 5%─10% of metals formed by the dwarf galaxy. The significant fraction of mass and metals residing in the warm CGM phase provides an interpretation for the lack of z ∼ 0 low ion detections beyond b/R200c ∼ 0.5, as the majority of mass in this region exists in higher ions. We find a weak correlation between galaxy mass and total CGM metal retention despite the fraction of metals lost from the halo increasing from ∼10% to &gt;40% toward lower masses. Our findings highlight the CGM (particularly its warm phase) as a key reservoir of mass and metals for dwarf galaxies across stellar masses, underscoring its importance in understanding the baryon cycle in the low-mass regime. Finally, we provide individual simulated galaxy properties and quantify the fraction of UV-observable mass to support future observational programs aimed at performing a metal budget around dwarf galaxies.

Keywords: Hydrodynamical simulations, Dwarf galaxies, Stellar feedback, Circumgalactic medium
MAMMOTH-MOSFIRE: Environmental Effects on Galaxy Interstellar Medium at z ∼ 2. The MAMMOTH-MOSFIRE program is a deep Keck/MOSFIRE K-band spectroscopic follow-up of emission-line galaxies identified in the MAMMOTH-Grism Hubble Space Telescope/wide-field camera 3 G141 slitless spectroscopic survey, targeting the core regions of the three most massive galaxy protoclusters at cosmic noon. To introduce this program, we present a comprehensive analysis of the [N II]λ6584, [S II]λλ6717,6731, and [O I]λ6300 Baldwin, Philips, and Terlevich (BPT) diagnostics for a unique sample of 43 protocluster member galaxies at z ∼ 2, investigating how the overdense environment influences their interstellar medium ionization conditions. We find that, similar to their field counterparts at z ∼ 2, protocluster galaxies exhibit a systematic offset in the [N II] BPT diagram relative to the local star-forming sequence, but no such offset in the [S II] BPT diagram. Notably, we detect significantly elevated [O I]/Hα ratios, which can be well reproduced by photoionization models incorporating both H II regions and low-velocity shocks (v ∼ 200 km s−1). We caution that neglecting shock excitation can bias abundance measurements, leading to an overestimation of nitrogen enrichment. This provides a potential explanation for the long-standing puzzle of enhanced [N II]/Hα ratios observed in z ∼ 2 galaxies. We further suggest that these shocks are likely environmentally driven, e.g., by ram pressure stripping or tidal interactions, which requires future confirmation through direct observations of features such as stripped gas tails.

Keywords: Protoclusters, Galaxy abundances, High-redshift galaxies, Galaxy evolution
Comprehensive Listing of 208 Nova White Dwarf Masses as the Primary Determinant of Spectral Class and Light-curve Class. For Galactic novae, I calculate and collect a comprehensive catalog of 208 measures of white dwarf (WD) masses (MWD) and 232 measures of average V magnitudes in quiescence (Vq). These are collected into a comprehensive catalog of most fundamental properties of all 402 known Galactic novae. The nova light curve and spectral classes are determined primarily by MWD. With an apparently clean cutoff, novae with light-curve shapes in the S, P, O, and C classes have &gt;0.95 M⊙, while the J, D, and F class novae have &lt;0.95 M⊙. The speed class of the light curves is t3 =  10(−1.73MWD)  × 1900 days. The spectral class of novae is Fe II below 1.15 M⊙, is He/N above 1.15 M⊙, and the hybrid novae are spread around this division. Neon novae have WD masses ranging from 0.53 to 1.37 M⊙, with 76% being measured to be below their minimum formation mass of 1.2 M⊙, demonstrating that most are losing mass over each eruption cycle. The FWHM velocity of the Balmer line profiles is close to 0.23 times the WD escape velocity, or roughly  10(MWD/2)  × 500 km s−1 for &lt;1.3 M⊙. And all the known Galactic recurrent novae are &gt;1.2 M⊙. For issues involving the late expansion of the ejecta, I find that the visibility of shells is strongly biased toward novae with orbital periods &lt;0.33 day, and that the visibility of γ-rays from the shells is strongly biased toward novae with fast declines, with t3 as a proxy for the γ-ray luminosity.

Keywords: Fast novae, Slow novae, Recurrent novae, Novae
An Analysis of the Radius Gap in a Sample of Kepler, K2, and TESS Exoplanets Orbiting M-dwarf Stars. Planetary radii are derived for 218 exoplanets orbiting 161 M dwarf stars. Stellar radii are based on an analysis of APOGEE high-resolution near-IR spectra for a subsample of the M dwarfs; these results are used to define a stellar radius-M Ks  calibration that is applied to the sample of M-dwarf planet hosts. The planetary radius distribution displays a gap over Rp ∼ 1.6─2.0 R⊕, bordered by two peaks at Rp ∼ 1.2─1.6 R⊕ (super-Earths) and 2.0─2.4 R⊕ (sub-Neptunes). The radius gap is nearly constant with exoplanetary orbital period (a power-law slope of m =  +0.01−0.04+0.03 ), which is different (2σ─3σ) from m ∼ −0.10 found previously for FGK dwarfs. This flat slope agrees with pebble accretion models, which include photoevaporation and inward orbital migration. The radius gap as a function of insolation is approximately constant over the range of Sp ∼ 20─250 S⊕. The Rp─Porb plane exhibits a sub-Neptune desert for Porb &lt; 2 days, which appears at Sp &gt; 120 S⊕, being significantly smaller than Sp &gt; 650 S⊕ found in the FGK planet-hosts, indicating that the appearance of the sub-Neptune desert is a function of host-star mass. Published masses for 51 exoplanets are combined with our radii to determine densities, which exhibit a gap at ρp ∼ 0.9ρ⊕, separating rocky exoplanets from sub-Neptunes. The density distribution within the sub-Neptune family itself reveals two peaks, at ρp ∼ 0.4ρ⊕ and ∼0.7ρ⊕. Comparisons to planetary models find that the low-density group are gas-rich sub-Neptunes, while the group at &lt;ρp&gt; ∼ 0.7ρ⊕ likely consists of volatile-rich water worlds.

Keywords: M dwarf stars, Exoplanets, Exoplanet evolution, Planet hosting stars, Near infrared astronomy
Low-frequency Probes of the Persistent Radio Sources Associated with Repeating Fast Radio Bursts. The discovery of persistent radio sources (PRSs) associated with three repeating fast radio bursts (FRBs) has provided insight into the local environments of these FRBs. Here, we present deep radio observations of the fields surrounding three highly active repeating FRBs, namely, FRB 20220912A, FRB 20240114A, and FRB 20240619D, using the upgraded Giant Metrewave Radio Telescope at low radio frequencies. Toward FRB 20240114A, we report the detection of compact source at 650 MHz with a flux density of 65.6 ± 8.1 μJy beam−1. Our measurements of the spectral index, star formation rate of the host galaxy, and recently reported constraints on the physical size strongly argue for our detected source to be a PRS associated with the FRB 20240114A. We investigate possible origins of the PRS associated with FRB 20240114A. Based on its brightness and age, we rule out central engines formed via accretion-induced collapse of a white dwarf, while superluminous supernovae, long gamma-ray bursts, and neutron star merger channels remain viable. An off-axis GRB afterglow could also explain the observed emission. For FRB 20220912A, we detect radio emission that is most likely due to star formation in the host galaxy. For FRB 20240619D, we provide upper limits on the radio emission from an associated PRS or the host galaxy. The detection of the PRS associated with FRB 20240114A is a useful addition to the PRSs known to be associated with only three other FRBs so far, and further supports the origin of the PRS in the form of magnetoionic medium surrounding the FRB sources.

Keywords: Compact objects, Radio transient sources
Terrestrial Exoplanet Internal Structure Constraints Enabled by Comprehensive Host Star Characterization Reveal That Terrestrial Planets in Mean Motion Resonances Are Water Rich. Exoplanet mass and radius inferences fundamentally rely on host star mass and radius inferences. Despite the importance of host star mass, radius, and elemental abundance inferences for the derivation of exoplanet internal structure constraints, published constraints have often been based on inferences that are not self-consistent. For 24 dwarf stars hosting terrestrial exoplanets, we use astrometric and photometric data plus high-resolution spectroscopy to infer accurate, precise, homogeneous, and physically self-consistent photospheric and fundamental stellar parameters, as well as elemental abundances. We infer updated planetary masses and radii using these data plus Doppler and transit observables and then use the complete data set to derive constraints on the CMFs of these terrestrial exoplanets. We find that the population of resonant or likely formerly resonant terrestrial exoplanets represented by Kepler-36 b and Kepler-105 c has a significantly lower mean CMF than the rest of the terrestrial exoplanets in our sample. Their resonant configurations suggest that they migrated inward from more distant formation locations, and we attribute their low densities to the incorporation and retention of significant amounts of water during their formation. We confirm that the ultra−short-period exoplanets 55 Cnc e and WASP-47 e have densities inconsistent with pure-rock compositions. We propose that they are both the stripped cores of mini-Neptunes, and we associate their low densities with the presence of significant amounts of hydrogen, helium, water, and/or other volatiles in their interiors. We verify that our results are independent of stellar parameter and elemental abundance inference approach and therefore robust.

Keywords: Exoplanet dynamics, Extrasolar rocky planets, Exoplanet migration, Exoplanets, Stellar abundances, Super Earths, Exoplanet systems, Exoplanet astronomy, Planet hosting stars, Exoplanet structure, Exoplanet formation