Sazuna/UAT_keywords huggingface dataset:
Constraints on Cosmological Coupling from the Accretion History of Supermassive Black Holes. Coupling of black hole mass to the cosmic expansion has been suggested as a possible path to understanding the dark energy content of the Universe. We test this hypothesis by comparing the supermassive black hole (SMBH) mass density at z = 0 to the total mass accreted in active galactic nuclei (AGN) since z = 6, to constrain how much of the SMBH mass density can arise from cosmologically coupled growth, as opposed to growth by accretion. Using an estimate of the local SMBH mass density of ≈1.0 × 106 M ⊙ Mpc‑1, a radiative accretion efficiency, η, in the range 0.05 &lt; η &lt; 0.3, and the observed AGN luminosity density at z ≈ 4, we constrain the value of the coupling constant between the scale size of the Universe and the black hole mass, k, to lie in the range 0 &lt; k ≲ 2, below the value of k = 3 needed for black holes to be the source term for dark energy. Initial estimates of the gravitational-wave background (GWB) using pulsar timing arrays, however, favor a higher SMBH mass density at z = 0. We show that if we adopt such a mass density at z = 0 of ≈7.4 × 106 M ⊙ Mpc‑1, this makes k = 3 viable even for low radiative efficiencies, and may exclude nonzero cosmological coupling. We conclude that, although current estimates of the SMBH mass density based on the black hole mass–bulge mass relation probably exclude k = 3, the possibility remains open that, if the GWB is due to SMBH mergers, k &gt; 2 is preferred.

Keywords: Luminosity function, Supermassive black holes, Active galactic nuclei, Gravitational waves
Sub-GeV Gamma Rays from Nearby Seyfert Galaxies and Implications for Coronal Neutrino Emission. Recent observations of high-energy neutrinos by IceCube and gamma rays by the Fermi Large Area Telescope (LAT) and the MAGIC telescope have suggested that neutrinos are produced in gamma-ray opaque environments in the vicinity of supermassive black holes. In this work, we present 20 MeV–1 TeV spectra of three Seyfert galaxies whose nuclei are predicted to be active in neutrinos, NGC 4151, NGC 4945, and the Circinus galaxy, using 14.4 yr of Fermi LAT data. In particular, we find evidence of sub-GeV excess emission that can be attributed to gamma rays from NGC 4945, as was also seen in NGC 1068. These spectral features are consistent with predictions of the magnetically powered corona model, and we argue that NGC 4945 is among the brightest neutrino active galaxies detectable for KM3Net and Baikal-GVD. On the other hand, in contrast to other reported results, we do not detect gamma rays from NGC 4151, which constrains neutrino emission from the accretion shock model. Future neutrino detectors such as IceCube-Gen2 and MeV gamma-ray telescopes such as AMEGO-X will be crucial for discriminating among the theoretical models.

Keywords: Supermassive black holes, Neutrino astronomy, Active galactic nuclei, Gamma-ray astronomy, Particle astrophysics
The ALMA-QUARKS Survey: Detection of Two Extremely Dense Substructures in a Massive Prestellar Core. Only a handful of massive starless core candidates have been discovered so far, but none of them have been fully confirmed. Within the MM1 clump in the filamentary infrared dark cloud G34.43+0.24 that was covered by the Atacama Large Millimeter/submillimeter Array (ALMA) ATOMS survey at Band 3 (∼2″, 6000 au) and the ALMA-QUARKS survey at Band 6 (∼0.″3, 900 au), two prestellar core candidates MM1-C and E1 with masses of 71 and 20 M ⊙ and radii of 2100–4400 au were discovered. The two cores show no obvious sign of star formation activities. In particular, MM1-C is a very promising massive prestellar core candidate with a total gas mass of 71 M ⊙. Within MM1-C, we detected two extremely dense substructures, C1 and C2, as characterized by their high densities of ${n}_{{{\rm{H}}}_{2}}\sim {10}^{8\mbox{--}9}\,{\mathrm{cm}}^{-3}$ . Moreover, evidence of further fragmentation in C2 was also revealed. We have detected the primordial fragmentation in the earliest stage of massive star formation, and we speculate that MM1-C would be the birthplace of a massive multiple system. However, we cannot fully rule out the possibility that the massive prestellar core MM1-C will just form a cluster of low-mass stars if it undergoes further fragmentation.

Keywords: Dark interstellar clouds, Star forming regions, Star formation, Interstellar medium
Exploiting Machine Learning and Disequilibrium in Galaxy Clusters to Obtain a Mass Profile. We use 3D k-means clustering to characterize galaxy substructure in the A2146 cluster of galaxies (z = 0.2343). This method objectively characterizes the cluster's substructure using projected position and velocity data for 67 galaxies within a 2.305 Mpc circular region centered on the cluster's optical center. The optimal number of substructures is found to be four. Four distinct substructures with rms velocity typical of galaxy groups or low-mass subclusters, when compared to cosmological simulations of galaxy cluster formation, suggest that A2146 is in the early stages of formation. We utilize this disequilibrium, which is so prevalent in galaxy clusters at all redshifts, to construct a radial mass distribution. Substructures are bound but not virialized. This method is in contrast to previous kinematical analyses, which have assumed virialization, and ignored the ubiquitous clumping of galaxies. The best-fitting radial mass profile is much less centrally concentrated than the well-known Navarro–Frenk–White profile, indicating that the dark-matter-dominated mass distribution is flatter pre-equilibrium, becoming more centrally peaked in equilibrium through the merging of the substructure.

Keywords: Galaxy clusters, Astroinformatics, Dark matter distribution, Large-scale structure of the universe
PEARLS: A Potentially Isolated Quiescent Dwarf Galaxy with a Tip of the Red Giant Branch Distance of 30 Mpc. A wealth of observations have long suggested that the vast majority of isolated classical dwarf galaxies (M * = 107–109 M ⊙) are currently star forming. However, recent observations of the large abundance of "ultra-diffuse galaxies" beyond the reach of previous large spectroscopic surveys suggest that our understanding of the dwarf galaxy population may be incomplete. Here we report the serendipitous discovery of an isolated quiescent dwarf galaxy in the nearby Universe, which was imaged as part of the JWST PEARLS Guaranteed Time Observation program. Remarkably, individual red-giant branch stars are visible in this near-IR imaging, suggesting a distance of 30 ± 4 Mpc, and a wealth of archival photometry point to an sSFR of 2 × 10‑11 yr‑1 and star formation rate of 4 × 10‑4 M ⊙ yr‑1. Spectra obtained with the Lowell Discovery Telescope find a recessional velocity consistent with the Hubble Flow and &gt;1500 km s‑1 separated from the nearest massive galaxy in Sloan Digital Sky Survey suggesting that this galaxy was either quenched from internal mechanisms or had a very high-velocity (≳1000 km s‑1) interaction with a nearby massive galaxy in the past. This analysis highlights the possibility that many nearby quiescent dwarf galaxies are waiting to be discovered and that JWST has the potential to resolve them.

Keywords: Stellar populations, Dwarf galaxies, James Webb Space Telescope, Galaxy evolution, Low surface brightness galaxies
New Horizons Venetia Burney Student Dust Counter Observes Higher than Expected Fluxes Approaching 60 au. The NASA New Horizons Venetia Burney Student Dust Counter (SDC) measures dust particle impacts along the spacecraft's flight path for grains with mass ≥10‑12 g, mapping out their spatial density distribution. We present the latest SDC dust density, size distribution, and flux measurements through 55 au and compare them to numerical model predictions. Kuiper Belt objects (KBOs) are thought to be the dominant source of interplanetary dust particles in the outer solar system due to both collisions between KBOs and their continual bombardment by interstellar dust particles. Continued measurements through 55 au show higher than model-predicted dust fluxes as New Horizons approaches the putative outer edge of the Kuiper Belt (KB). We discuss potential explanations for the growing deviation: radiation pressure stretches the dust distribution to further heliocentric distances than its parent body distribution; icy dust grains undergo photosputtering that rapidly increases their response to radiation pressure forces and pushes them further away from the Sun; and the distribution of KBOs may extend much further than existing observations suggest. Ongoing SDC measurements at even larger heliocentric distances will continue to constrain the contributions of dust production in the KB. Continued SDC measurements remain crucial for understanding the Kuiper Belt and the interpretation of dust disks around other stars.

Keywords: Small Solar System bodies, Interplanetary dust, Kuiper belt
Which Came First: Supermassive Black Holes or Galaxies? Insights from JWST. Insights from JWST observations suggest that active galactic nuclei feedback evolved from a short-lived, high-redshift phase in which radiatively cooled turbulence and/or momentum-conserving outflows stimulated vigorous early star formation ("positive" feedback), to late, energy-conserving outflows that depleted halo gas reservoirs and quenched star formation. The transition between these two regimes occurred at z ∼ 6, independently of galaxy mass, for simple assumptions about the outflows and star formation process. Observational predictions provide circumstantial evidence for the prevalence of massive black holes at the highest redshifts hitherto observed, and we discuss their origins.

Keywords: Active galactic nuclei, Black holes, Quasars
Starburst-induced Gas–Star Kinematic Misalignment. A kinematic misalignment of the stellar and gas components is a phenomenon observed in a significant fraction of galaxies. However, the underlying physical mechanisms are not well understood. A commonly proposed scenario for the formation of a misaligned component requires any preexisting gas disk to be removed, via flybys or ejective feedback from an active galactic nucleus. In this Letter, we study the evolution of a Milky Way mass galaxy in the FIREbox cosmological volume that displays a thin, counterrotating gas disk with respect to its stellar component at low redshift. In contrast to scenarios involving gas ejection, we find that preexisting gas is mainly removed via the conversion into stars in a central starburst, triggered by a merging satellite galaxy. The newly accreted, counterrotating gas eventually settles into a kinematically misaligned disk. About 4% (8 out of 182) of FIREbox galaxies with stellar masses larger than 5 × 109 M ⊙ at z = 0 exhibit gas–star kinematic misalignment. In all cases, we identify central starburst-driven depletion as the main reason for the removal of the preexisting corotating gas component, with no need for feedback from, e.g., a central active black hole. However, during the starburst, the gas is funneled toward the central regions, likely enhancing black hole activity. By comparing the fraction of misaligned discs between FIREbox and other simulations and observations, we conclude that this channel might have a non-negligible role in inducing kinematic misalignment in galaxies.

Keywords: Hydrodynamical simulations, Starburst galaxies, Galaxy structure, Galaxy evolution
Spectacular Nucleosynthesis from Early Massive Stars. Stars that formed with an initial mass of over 50 M ⊙ are very rare today, but they are thought to be more common in the early Universe. The fates of those early, metal-poor, massive stars are highly uncertain. Most are expected to directly collapse to black holes, while some may explode as a result of rotationally powered engines or the pair-creation instability. We present the chemical abundances of J0931+0038, a nearby low-mass star identified in early follow-up of the SDSS-V Milky Way Mapper, which preserves the signature of unusual nucleosynthesis from a massive star in the early Universe. J0931+0038 has a relatively high metallicity ([Fe/H] = ‑1.76 ± 0.13) but an extreme odd–even abundance pattern, with some of the lowest known abundance ratios of [N/Fe], [Na/Fe], [K/Fe], [Sc/Fe], and [Ba/Fe]. The implication is that a majority of its metals originated in a single extremely metal-poor nucleosynthetic source. An extensive search through nucleosynthesis predictions finds a clear preference for progenitors with initial mass &gt;50 M ⊙, making J0931+0038 one of the first observational constraints on nucleosynthesis in this mass range. However, the full abundance pattern is not matched by any models in the literature. J0931+0038 thus presents a challenge for the next generation of nucleosynthesis models and motivates the study of high-mass progenitor stars impacted by convection, rotation, jets, and/or binary companions. Though rare, more examples of unusual early nucleosynthesis in metal-poor stars should be found in upcoming large spectroscopic surveys.

Keywords: Population III stars, Nucleosynthesis, Core-collapse supernovae, Hypernovae, Stellar abundances, Galactic archaeology, Nuclear astrophysics, Population II stars, Chemically peculiar stars
The First Polarimetric View on Quasiperiodic Oscillations in a Black Hole X-Ray Binary. We present the first polarimetric analysis of quasiperiodic oscillations (QPOs) in a black hole binary utilizing IXPE data. Our study focuses on Swift J1727.8–1613, which experienced a massive outburst that was observed by various telescopes across different wavelengths. The IXPE observation we studied was conducted during the hard-intermediate state. The polarization degree (PD) and polarization angle (PA) were measured at 4.28% ± 0.20% and 1.°9 ± 1.°4, respectively. Remarkably, significant QPO signals were detected during this observation, with a QPO frequency of approximately 1.34 Hz and a fractional rms amplitude of about 12.3%. Furthermore, we conducted a phase-resolved analysis of the QPO using the Hilbert–Huang transform technique. The photon index showed a strong modulation with respect to the QPO phase. In contrast, the PD and PA exhibit no modulations in relation to the QPO phase, which is inconsistent with the expectation of the Lense–Thirring precession of the inner flow. Further theoretical studies are needed to conform with the observational results.

Keywords: Low-mass x-ray binary stars, Accretion, Polarimetry
Does or Did the Supernova Remnant Cassiopeia A Operate as a PeVatron?. For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE; E  γ  ≥ 100 TeV) γ-rays. In this context, the historical SNR Cassiopeia A (Cas A) is considered one of the most promising targets for UHE observations. This paper presents the observation of Cas A and its vicinity by the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE band, combined with the young age of Cas A, enabled us to derive stringent model-independent limits on the energy budget of UHE protons and nuclei accelerated by Cas A at any epoch after the explosion. The results challenge the prevailing paradigm that Cas A–type SNRs are major suppliers of PeV CRs in the Milky Way.

Keywords: Supernova remnants, Gamma-rays, Galactic cosmic rays
GJ 367b Is a Dark, Hot, Airless Sub-Earth. We present the mid-infrared (5–12 μm) phase curve of GJ 367b observed by the Mid-Infrared Instrument on the James Webb Space Telescope (JWST). GJ 367b is a hot (T eq = 1370 K), extremely dense (10.2 ± 1.3 g cm‑3) sub-Earth orbiting an M dwarf on a 0.32 day orbit. We measure an eclipse depth of 79 ± 4 ppm, a nightside planet-to-star flux ratio of 4 ± 8 ppm, and a relative phase amplitude of 0.97 ± 0.10, all fully consistent with a zero-albedo planet with no heat recirculation. Such a scenario is also consistent with the phase offset of 11°E ± 5° to within 2.2σ. The emission spectrum is likewise consistent with a blackbody with no heat redistribution and a low albedo of A  B  ≈ 0.1, with the exception of one anomalous wavelength bin that we attribute to unexplained systematics. The emission spectrum puts few constraints on the surface composition but rules out a CO2 atmosphere ≳1 bar, an outgassed atmosphere ≳10 mbar (under heavily reducing conditions), or an outgassed atmosphere ≳0.01 mbar (under heavily oxidizing conditions). The lack of day–night heat recirculation implies that 1 bar atmospheres are ruled out for a wide range of compositions, while 0.1 bar atmospheres are consistent with the data. Taken together with the fact that most of the dayside should be molten, our JWST observations suggest that the planet must have lost the vast majority of its initial inventory of volatiles.

Keywords: Extrasolar rocky planets, James Webb Space Telescope, Exoplanet atmospheres, Exoplanet surface composition
The First TESS Self-lensing Pulses: Revisiting KIC 12254688. We report the observations of two self-lensing pulses from KIC 12254688 in Transiting Exoplanet Survey Satellite (TESS) light curves. This system, containing an F2V star and white-dwarf companion, was among the first self-lensing binary systems discovered by the Kepler Space Telescope over the past decade. Each observed pulse occurs when the white dwarf transits in front of its companion star, gravitationally lensing the star's surface, thus making it appear brighter to a distant observer. These two pulses are the very first self-lensing events discovered in TESS observations. We describe the methods by which the data were acquired and detrended, as well as the best-fit binary parameters deduced from our self-lensing+radial velocity model. We highlight the difficulties of finding new self-lensing systems with TESS, and we discuss the types of self-lensing systems that TESS may be more likely to discover in the future.

Keywords: Gravitational microlensing, White dwarf stars, Compact binary stars
A Floor in the Sun's Photospheric Magnetic Field: Implications for an Independent Small-scale Dynamo. Clette recently showed that F 10.7 systematically approaches a quiet Sun daily value of 67 solar flux units (sfu) at solar minima as the number of spotless days on the Sun increases. Previously, a floor of ∼2.8 nT had been proposed for the solar wind (SW) magnetic field strength (B). F 10.7, which closely tracks the Sun's unsigned photospheric magnetic flux, and SW B exhibit different relationships to their floors at 11 yr solar minima during the last ∼50 yr. While F 10.7 approaches 67 sfu at each minimum, the corresponding SW B is offset above ∼2.8 nT by an amount approximately proportional to the solar polar field strength—which varied by a factor of ∼2.5 during this interval. This difference is substantiated by ∼130 yr of reconstructed F 10.7 (via the range of the diurnal variation of the East-component (rY) of the geomagnetic field) and SW B (based on the interdiurnal variability geomagnetic activity index). For the last ∼60 yr, the contribution of the slow SW to SW B has exhibited a floor-like behavior at ∼2 nT, in contrast to the contributions of coronal mass ejections and high-speed streams that vary with the solar cycle. These observations, as well as recent SW studies based on Parker Solar Probe and Solar Dynamics Observatory data, suggest that (1) the Sun has a small-scale turbulent dynamo that is independent of the 11 yr sunspot cycle; and (2) the small-scale magnetic fields generated by this nonvarying turbulent dynamo maintain a constant open flux carried to the heliosphere by the Sun's floor-like slow SW.

Keywords: Solar cycle, Slow solar wind, Quiet sun, Solar dynamo, Solar radio emission, Solar magnetic fields, Solar-terrestrial interactions
Whither or Wither the Sulfur Anomaly in Planetary Nebulae?. We present a thorough investigation of the long-standing sulfur anomaly enigma. Our analysis uses chemical abundances from the most extensive data set available for 126 planetary nebulae (PNs) with improved accuracy and reduced uncertainties from a 10° × 10° Galactic bulge region. By using argon as a superior PN metallicity indicator, the anomaly is significantly reduced and better constrained. For the first time in PNs we show sulfur α-element lockstep with both oxygen and argon. We dispel hypotheses that the anomaly originates from underestimation of higher sulfur ionization stages. Using a machine-learning approach, we show that earlier ionization correction factor schemes contributed significantly to the anomaly. We find a correlation between the sulfur anomaly and the age/mass of PN progenitors, with the anomaly either absent or significantly reduced in PNs with young progenitors. Despite inherent challenges and uncertainties, we link this to PN dust chemistry, noting those with carbon-dust chemistry show a more pronounced anomaly. By integrating these findings, we provide a plausible explanation for the residual, reduced sulfur anomaly and propose its potential as an indicator of relative galaxy age compositions based on PNs.

Keywords: Planetary nebulae nuclei, Galactic abundances, Planetary nebulae
The Hidden Companion in J1527: A 0.69 Solar-mass White Dwarf?. Finding nearby neutron stars can probe the supernova and metal-enrichment histories near our solar system. Recently, Lin et al. reported an exciting neutron star candidate, Two Micron All Sky Survey J15274848+3536572 (hereafter J1527), with a small Gaia distance of 118 pc. They claim that J1527 harbors an unseen neutron star candidate with an unusually low mass of 0.98 ± 0.03 M ⊙. In this work, we use the Canada–France–Hawaii Telescope high-resolution spectrum to measure J1527's orbital inclination independently. Our spectral fitting suggests an orbital inclination of 63° ± 2°. Instead, by fitting a complex hybrid variability model consisting of the ellipsoidal-variation component and the starspot modulation to the observed light curve, Lin et al. obtain an orbital inclination of ${45.2}_{-0.20}^{+0.13}$ degrees. We speculate that the orbital inclination obtained by the light-curve fitting is underestimated since J1527's light curves are obviously not pure ellipsoidal variations. According to our new inclination (i ∼ 63°), the mass of the unseen compact object is reduced to 0.69 ± 0.02 M ⊙, which is as massive as a typical white dwarf.

Keywords: Close binary stars, Inclination, Compact objects
Molecular Outflow in the Reionization-epoch Quasar J2054-0005 Revealed by OH 119 μm Observations. Molecular outflows are expected to play a key role in galaxy evolution at high redshift. To study the impact of outflows on star formation at the epoch of reionization, we performed sensitive Atacama Large Millimeter/submillimeter Array observations of OH 119 μm toward J2054-0005, a luminous quasar at z = 6.04. The OH line is detected and exhibits a P-Cygni profile that can be fitted with a broad blueshifted absorption component, providing unambiguous evidence of an outflow, and an emission component at near-systemic velocity. The mean and terminal outflow velocities are estimated to be v out ≈ 670 and 1500 km s‑1, respectively, making the molecular outflow in this quasar one of the fastest at the epoch of reionization. The OH line is marginally spatially resolved for the first time in a quasar at z &gt; 6, revealing that the outflow extends over the central 2 kpc region. The mass outflow rate is comparable to the star formation rate ( ${\dot{M}}_{\mathrm{out}}/\mathrm{SFR}\sim 2$ ), indicating rapid (∼107 yr) quenching of star formation. The mass outflow rate in a sample of star-forming galaxies and quasars at 4 &lt; z &lt; 6.4 exhibits a positive correlation with the total infrared luminosity, although the scatter is large. Owing to the high outflow velocity, a large fraction (up to ∼50%) of the outflowing molecular gas may be able to escape from the host galaxy into the intergalactic medium.

Keywords: Galactic winds, High-redshift galaxies, Stellar feedback, Quasars