Sazuna/UAT_keywords huggingface dataset:
Bridging Scales: How Much Do Supermassive Black Holes Grow in the Suppressed Bondi Regime?. The coevolution of supermassive black holes (SMBHs) and their host galaxies remains one of the central open questions in cosmology, rooted in the coupling between accretion, feedback, and the multiscale physics that links the event horizon to the circumgalactic medium. Here we bridge these scales by embedding a first-principles, GRMHD-informed prescription for black hole accretion and feedback—derived from multizone simulations that self-consistently connect inflows and outflows from the horizon to the Bondi radius—within cosmological magnetohydrodynamic zoom-in simulations of ∼1014M⊙ halos. These GRMHD results predict a "suppressed Bondi" regime in which magnetic stresses and relativistic winds strongly reduce effective accretion rates in a spin-dependent manner. We find that black holes cannot grow efficiently by accretion until they exceed ∼107M⊙, regardless of the feedback strength. Beyond this threshold, systems bifurcate: low-spin (η ∼ 0.02) black holes continue to accrete without quenching star formation, while high-spin (η ≳ 0.3) black holes quench effectively but become starved of further growth. Early, massive seeding partially alleviates this tension through merger-driven assembly, yet an additional cold or super-Eddington accretion mode appears essential to reproduce the observed SMBH population and the empirical black hole─galaxy scaling relations. Our results demonstrate that GRMHD-informed feedback models can account for the maintenance-mode behavior of low-luminosity active galactic nuclei like M87*, but cannot by themselves explain the full buildup of SMBH mass across cosmic time. A unified, multiregime framework is required to capture the evolving interplay between spin-dependent feedback, cold inflows, and mergers in driving coevolution.

Keywords: Accretion, Supermassive black holes, Bondi accretion, Schwarzschild radius, Active galactic nuclei, Magnetohydrodynamical simulations
On Schur Decomposition of Magnetic and Velocity Gradient Tensors in Space Plasma Turbulence. The study of the statistics of gradient tensors' invariants is useful to characterize the morphological/topological features of magnetic flux and plasma velocity flow lines in turbulent space plasmas. In the recent past, some studies of the statistics of the gradient tensors' invariants have been done to investigate the velocity and magnetic field flow lines topologies in turbulent heliospheric plasmas, thanks to the availability of multipoint missions. Here, we present a novel/complementary approach to the characterization of the gradient tensor properties of velocity and magnetic field in plasmas based on Schur decomposition of the field gradient tensors. This decomposition can be seen as an alternative to the standard decomposition into symmetric and skew-symmetric components, allowing for a decomposition of gradients into normal and nonnormal parts, separating eigenvalue and ideal pressure terms from the deviatoric and dissipative ones. The method is preliminarily applied to observations from the NASA Magnetospheric Multiscale space mission in the solar wind and the magnetosheath to show its potentiality.

Keywords: Interplanetary turbulence, Space plasmas, Solar wind, Heliosphere
Reexamining Evidence of a Pair-instability Mass Gap in the Binary Black Hole Population. The fourth Gravitational-Wave Transient Catalog (GWTC-4) has enabled empirical probes of the theorized pair-instability gap in the higher end of the binary black hole (BBH) mass spectrum. In this Letter, using flexibly parameterized models, we show that, at present, there is no evidence of a sharp drop-off in the spectrum of black hole masses near 40─50M⊙. We simultaneously characterize the transition in the distribution of BBH mass ratios and effective aligned and effective precessing spins using our flexible models. From the transitions in our inferred spin and mass-ratio distributions, we find that the high-mass broad-spin subpopulation has a significant fraction ( 52−23+18% ) of systems with mass ratios in the range 0.6─1. This suggests that alternatives to the hypothesis of 2G+1G hierarchical systems dominating BBH formation above ∼40─50M⊙ are more consistent with the GWTC-4 detection sample. By comparing with the predictions of star cluster simulations, we further show that contributions from (2G+2G) systems are not abundant enough to alleviate this discrepancy. We also demonstrate the effects of strong model assumptions on this inference, which can lead to biased astrophysical interpretation from restricted priors. We note that our results do not exclude that a high-mass gap may be identified as our sample size increases. We constrain the lower bound on the location of a possible PISN cutoff still allowed within measurement uncertainties to be  (57−10+17M⊙)  and discuss its implications on the S factor of 12C(α, γ)16O at 300 kev.

Keywords: Compact binary stars, Astrophysical black holes, Stellar evolution
Brightest Gamma-Ray-burst Flare Observed in GRB 221009A: Bridging the Last Gap between the Prompt Emission and Flare in Gamma-Ray Bursts. Flares are usually observed during the afterglow phases of Gamma-ray bursts (GRBs) in the soft-X-ray, optical, and radio bands—but rarely in the gamma-ray band. Despite its extraordinary brightness, GECAM-C has accurately measured both the bright prompt emission and flare emission of GRB 221009A without instrumental effects, offering a good opportunity to study the relation between them. In this work, we present a comprehensive analysis of the flare emission of GRB 221009A, which is composed of a series of flares. Among them, we identify an exceptionally bright flare with a record-breaking isotropic energy Eiso = 1.82 × 1053 erg for GRB flares. It exhibits the highest peak energy ever detected in GRB flares, Epeak ∼ 300 keV, making it a genuine gamma-ray flare. It also shows rapid rise and decay timescales, significantly shorter than those of typical X-ray flares observed in the soft-X-ray or optical bands but comparable to those observed in prompt emissions. Despite these exceptional properties, the flare shares several common properties with typical GRB flares. We note that this is the first observation of a GRB flare in the keV─MeV band with sufficiently high temporal resolution and high statistics, bridging the last gap between the prompt emission and flare.

Keywords: Gamma-ray bursts
Perihelion Asymmetry in the Water Production Rate of the Interstellar Object 3I/ATLAS. 3I/ATLAS is an interstellar object whose activity provides critical insights into its composition and origin. However, due to its orbital geometry, the object is too close to the Sun near perihelion to be observed from the ground, and space-based measurements are therefore required. Here we characterize the water production rate of 3I/ATLAS using Solar and Heliospheric Observatory/SWAN Lyα observations from 2025 November to December (heliocentric distances 1.4─2.2 au) with 3D Monte Carlo modeling. We report a peak postperihelion water production rate of  QH2O≍4×1028  molecules s−1, corresponding to a minimum active fraction of ∼30% (assuming a maximum nucleus radius of 2.8 km). Comparison of our postperihelion measurements with published preperihelion results reveals a heliocentric asymmetry, with an  r−5.9±0.8  scaling for the inbound rise, followed by a shallower  r−3.3±0.3  scaling during the outbound decline, where r is heliocentric distance. The postperihelion behavior indicates that the water production of 3I/ATLAS was driven primarily by the varying solar insolation acting on a stable active area. Combined with other evidence, including comparison with the hyperactive comet 103P/Hartley 2, our findings suggest that its water production is likely dominated by a distributed source of icy grains. Furthermore, it displayed remarkable stability in the activity with no signs of outbursts or rapid depletion of water production.

Keywords: Observational astronomy, Comae, Ultraviolet astronomy, Interstellar objects, Solar instruments, Comets, Solar system astronomy
Molecular Gas Morphological Analogs for the Milky Way. Complete catalogs of molecular clouds in the Milky Way allow analysis of the molecular medium and the star formation properties of the Milky Way that closely follows the method used for nearby galaxies. We explore whether the big dip in the radial distribution of molecular gas in the Milky Way is peculiar and find several other galaxies with similar patterns, all with similar morphological classifications of YClxxGnR, indicating a clearly defined, long bar leading to a grand-design spiral. This category is fairly rare among galaxies in the PHANGS sample, but all galaxies with this classification have some evidence for dips in the radial distribution of CO emission. The lengths of the bars correlate with the extents of the dips. The Milky Way and the other galaxies with dips have similar stellar masses and star formation rates, both lying near the high ends of the distributions for all PHANGS galaxies.

Keywords: Interstellar molecules, Galaxy structure, Interstellar clouds
A Possible "Too-many-satellites" Problem in the Isolated Dwarf Galaxy DDO 161. The abundance of satellite galaxies provides a direct test of ΛCDM and galaxy formation physics on small scales. While satellites of Milky Way-mass galaxies are well studied, those of dwarf galaxies remain largely unexplored. We present a systematic search for satellites around the isolated dwarf galaxy DDO 161 (M⋆ ≍ 108.4 M⊙) at a distance of 6 Mpc. We identify eight satellite candidates within the projected virial radius and confirm three new satellites through surface brightness fluctuation distance measurements from deep Magellan imaging data. Together with its confirmed satellite UGCA 319, DDO 161 has four confirmed satellites above  M⋆sat&gt;105.4M⊙ , making it the most satellite-rich dwarf galaxy known to date. We compare this system with predictions from the TNG50 cosmological simulation, combined with currently established galaxy─halo connection models calibrated on Milky Way satellites, and find that DDO 161 has a satellite abundance far exceeding all current expectations. The rich satellite system of DDO 161 offers new insight into how low-mass galaxies occupy dark matter halos in low-density environments and may provide new constraints on the nature of dark matter.

Keywords: Luminosity function, Distance measure, Dwarf galaxies, Galaxy groups
An Unexpected Population of Quenched Galaxies Harboring Undermassive SMBHs Revealed by Tidal Disruption Events. Restricted by event horizon suppression, tidal disruption events (TDEs) provide a unique window into otherwise hidden supermassive black holes (SMBHs) at the lower end of the mass spectrum, allowing the connection between star formation and SMBH mass to be explored across a broad stellar mass range. We derive stellar masses and specific star formation rates using PROSPECTOR fits to UV─mid-infrared broadband spectral energy distributions (SEDs) for 42 TDE hosts, together with a high-mass comparison sample, and combine these with SMBH mass estimates from the literature. We first verify our approach by reproducing the established result that quenched galaxies host more massive SMBHs than star-forming systems at fixed stellar mass, a result widely interpreted as evidence for SMBH growth driving the blue-to-red sequence transition. However, examining the TDE sample in isolation reveals a trend reversal at lower masses, uncovering a surprising population of low-mass (109.6 ≲ Mgal ≲ 1010.5 M⊙), quenched galaxies hosting SMBHs systematically less massive (MBH ≲ 106.5 M⊙) than those in star-forming galaxies of comparable stellar mass. After ruling out degeneracies in our SED fits, we conclude that this reflects a physical difference in the quenching mechanism between these TDE hosts and the more massive galaxies. This is unlikely to be driven by active galactic nucleus feedback, and could instead result from environmental processes, which can end star formation and hinder SMBH growth. We also show that the quenched and poststarburst population within the TDE sample is likely underrepresented due to selection biases, suggesting the true fraction could be even higher than observed.

Keywords: Supermassive black holes, Transient sources, Galaxy nuclei
WHALES. The Weighing Halos Accurately, Locally, and Efficiently with Supernovae Survey: Overview and Initial Data Release. We present an overview of the Weighing Halos Accurately, Locally, and Efficiently with Supernovae (WHALES) survey, the first to discover and measure Type Ia supernovae (SNe Ia) in and around galaxy superclusters. By building a sample of SNe Ia around these massive environments, we aim to provide new constraints on bulk-flow models while laying the groundwork for improved estimates of supercluster masses. Here, we present data from the first two seasons targeting the Shapley Supercluster (0.02 &lt; z &lt; 0.06), which is responsible for a large but unknown fraction of our Local Group's motion. Until now, no supernovae (SNe) had been analyzed in the direction of Shapley. Through the WHALES survey, we have identified 12 likely SNe Ia in this region using SkyMapper, including eight with spectroscopic confirmation. We present the first light curves of these SNe and combine our observations with data from the Asteroid Terrestrial-impact Last Alert System. We demonstrate that the low number of discovered SNe Ia per season is consistent with various rate calculations, highlighting the need for future surveys to monitor superclusters over a multiyear time span. Finally, we present simulations of SN Ia observations in the environments of massive galaxy clusters, demonstrating how the inferred peculiar velocities can constrain cluster masses, and highlighting the added complexity within superclusters. We find that a sample of 100 SNe Ia would enable a 25% precision measurement of the total mass of the Shapley Supercluster.

Keywords: Cosmology, Observational cosmology, Type Ia supernovae
JWST Confirmation of a Runaway Supermassive Black Hole via Its Supersonic Bow Shock. We present JWST/NIRSpec integral field unit observations of a candidate runaway supermassive black hole (SMBH) at the tip of a 62 kpc long linear feature at z = 0.96. The JWST data show a sharp kinematic discontinuity at the tip, with a radial velocity change of ≍600 km s−1 across  0.″1  (1 kpc). The velocity gradient, together with the projected postshock flow velocity of ≍300 km s−1, is well described by a simple shock-compression model of a supersonic object, with a velocity of  v∙=954−126+110  km s−1 and an inclination  i=29−3+6  deg. The previously puzzling kinematics along the linear feature, with the observed radial velocity decreasing from ≍300 km s−1 near the tip to ≍100 km s−1 closer to the former host galaxy, is naturally explained as gradual downstream mixing of shocked gas with the circumgalactic medium through turbulent entrainment. The bow shock interpretation is further supported by the morphology of the gas at the tip of the wake and an analysis of the [O III]/Hα, [N II]/Hα, [S II]/Hα, and [S III]/[S II] line ratios. The line ratios are consistent with fast radiative shocks and rapid cooling, with best-fit shock velocities that are in agreement with expectations from the black hole velocity and the shock geometry. Energy conservation over the lifetime of the wake suggests an SMBH mass of M∙ ≳ 107 M⊙. These results confirm that the wake is powered by a supersonic runaway SMBH, a long-predicted consequence of gravitational-wave recoil or multibody ejection from galactic nuclei.

Keywords: AGN host galaxies, Supermassive black holes
Stereoscopic Observations of Solar X-Ray Sources Explained by a Data-constrained Magnetohydrodynamic Simulation. We investigated the three-dimensional (3D) magnetic structures and dynamics responsible for particle acceleration in an X7.1-class flare that occurred on 2024 October 1, in NOAA active region 13842. We combined stereoscopic hard X-ray (HXR) observations from the Advanced Space-based Solar Observatory/Hard X-ray Imager and the Solar Orbiter/Spectrometer Telescope for Imaging X-rays (STIX) with a 3D magnetohydrodynamic (MHD) simulation constrained by observed photospheric magnetic fields. During the two main peaks of the impulsive phase, HXR footpoints appeared at different locations, indicating a migration of the primary reconnection site in the corona. Our data-constrained MHD simulation successfully reproduced the reconnected field lines linking the observed conjugate HXR footpoints. Furthermore, the simulation shows that these primary reconnections occur along a single quasi-separatrix layer (QSL) system. Therefore, the two main peaks of HXR can be interpreted as episodic energy release within the single QSL system. This study demonstrates that the data-constrained MHD model provides a realistic 3D magnetic context for interpreting HXR emission. Notably, STIX observations revealed a vertically distributed thermal HXR source, extending from the footpoints to the looptop, with its centroid migrating between the two peaks. This marks a first step toward understanding the particle acceleration processes in solar flares.

Keywords: Solar active region magnetic fields, Magnetohydrodynamics, Solar flares, Solar x-ray emission, Non-thermal radiation sources, Magnetohydrodynamical simulations
Testing the Association of Supermassive Black Hole Infrared Flares and High-energy Neutrinos. The physical origin of the observed cosmic neutrinos remains an open question and the subject of active research. While matter accretion onto supermassive black holes is long thought to accelerate particles to high energies, it has recently been suggested that tidal disruption events, and accretion flares in general, with prominent IR echoes can account for a fraction of the diffuse high-energy neutrino signal. Motivated by this result, we compile a sample of nearby accretion flares detected in the NEOWISE survey featuring strong IR echoes, and we cross-match it with the latest catalog of neutrino alerts, IceCat-1. We recover only a single spatial coincidence between the two catalogs, consistent with a chance coincidence. We find no temporal and spatial coincidences between the two samples, which, given the properties of our sample, appears to challenge previous conclusions. We discuss the physical implications of our results and potential future explorations.

Keywords: Accretion, Tidal disruption, Active galactic nuclei, Cosmological neutrinos
Preperihelion CN Production Rate of Interstellar Comet 3I/ATLAS. We present spectroscopic observations of the third interstellar comet 3I/ATLAS obtained with the DOLORES instrument on the 3.58 m Telescopio Nazionale Galileo on 2025 August 16 (rh = 2.98 au). The spectrum revealed a red slope of 12.68% ± 0.05%/1000 Å across the 5000─8000 Å range, consistent with previous findings. Observations show the CN outgassing violet band, which yields a production rate of (4.28 ± 0.83) · 1023 mol s−1. We derived upper limits for C2 and C3 production rates since no clear detection was possible and used those to compute C2/CN and C3/CN ratios. The resulting, notably low, values of −0.86 and −1.47, respectively, for C2/CN and C3/CN ratios classify 3I as a strongly carbon-chain depleted comet in the preperihelion orbit. Notably, recent postperihelion observations found a typical solar system cometary composition, probably suggesting new innermost material being exposed to solar radiation.

Keywords: Small Solar System bodies, Solar system, Interstellar objects, Spectroscopy, Comets, Comet origins
Hubble's Multiyear Search for Exospheres in the TRAPPIST-1 System Reveals Frequent Microflares. Lyα observations provide a powerful probe of stellar activity and atmospheric escape in exoplanetary systems. We present here an analysis of 109 Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) orbits monitoring the TRAPPIST-1 system between 2017 and 2022, covering three to five transits for each of its seven planets. We rule out transit depths ≳30%, prompting a revision of atmospheric escape rates, with upper limits  O(10)×  larger than previously reported (e.g.,  O(70)  Earth-ocean-equivalent hydrogen content per Gyr for planet b, consistent with claims that it is airless). The transit depth upper limits are ∼3 times larger than expected from the photon noise owing to a large baseline scatter, which we link to TRAPPIST-1's intrinsic Lyα variability from frequent "microflares." While JWST's near-infrared observations have shown that ∼1030 erg flares occur every ∼6 hr, we identify ∼1029 erg flares on subhour timescales in both HST/STIS and Very Large Telescope  g' observations. The far-UV and optical amplitudes (∼400% vs. ∼3%, respectively) for flares with similar waiting times indicate flare temperatures of 9700 −2400+1500  K over 0.017 −0.007+0.03 % of the stellar disk. Finally, our multiyear baseline reveals a variability with P = 3.27 ± 0.04 days—the first independent validation of TRAPPIST-1's 3.3-day rotation period.

Keywords: Exoplanet astronomy, Stellar surfaces, Stellar flares, Exoplanet dynamics
Evidence of Feedback Effects in Low-luminosity Active Galactic Nuclei Revealed by JWST Spectroscopy. This Letter presents an analysis of the infrared (∼3─28 μm) spectra extracted from the nuclear (r &lt; 150 pc) regions of four low-luminosity active galactic nuclei (AGN), observed by JWST NIRSpec/integral field unit and MIRI/Medium Resolution Spectroscopy as an extension of the Galaxy Activity, Torus, and Outflow Survey. We find that, compared to higher-luminosity AGN, these low-luminosity AGN exhibit distinct properties in their emission of ionized gas, polycyclic aromatic hydrocarbons (PAHs), and molecular hydrogen (H2). Specifically, the low-luminosity AGN exhibit relatively weak high ionization potential lines (e.g., [Ne V] and [O IV]), and the line ratios suggest that fast radiative shocks (with vs of ∼100s km s−1) are the primary excitation source of ionized gas therein. Under the low-excitation conditions of their nuclear regions, these low-luminosity AGN generally exhibit a higher fraction of PAHs with large size (NC ≳ 200), reflecting the preferential destruction of smaller PAH molecules by AGN feedback. Furthermore, the H2 transitions in these low-luminosity AGN are not fully thermalized, with slow, plausibly jet-driven molecular shocks (with vs ≤ 10 km s−1) likely being the extra excitation source. Taken together with results from the literature, these findings indicate that feedback operates in both low- and high-luminosity AGN, although its impact varies with AGN luminosity. In particular, systematic variations in PAH band ratios are found across AGN, demonstrating the differing influence of feedback in AGN of varying luminosities and highlighting the potential of PAH band ratios as diagnostics for distinguishing kinetic- and radiative-mode AGN feedback.

Keywords: Molecular gas, Interstellar line emission, Polycyclic aromatic hydrocarbons, Infrared spectroscopy, James Webb Space Telescope, Active galactic nuclei, Interstellar dust processes, Shocks