Sazuna/UAT_keywords huggingface dataset:
Not All Sub-Neptune Exoplanets Have Magma Oceans. The evolution and structure of sub-Neptunes may be strongly influenced by interactions between the outer gaseous envelope of the planet and a surface magma ocean. However, given the wide variety of permissible interior structures of these planets, it is unclear whether conditions at the envelope─mantle boundary will always permit a molten silicate layer or whether some sub-Neptunes might instead host a solid silicate surface. In this work, we use internal structure modeling to perform an extensive exploration of surface conditions within the sub-Neptune population across a range of bulk and atmospheric parameters. We find that a significant portion of the population may lack present-day magma oceans. In particular, planets with a high atmospheric mean molecular weight and large envelope mass fraction are likely to instead have a solid silicate surface, since the pressure at the envelope─mantle boundary is high enough that the silicates will be in solid postperovskite phase. This result is particularly relevant given recent inferences of high-mean molecular weight atmospheres from JWST observations of several sub-Neptunes. We apply this approach to a number of sub-Neptunes with existing or upcoming JWST observations and find that in almost all cases, a range of solutions exist that do not possess a present-day magma ocean. Our analysis provides critical context for interpreting sub-Neptunes and their atmospheres.

Keywords: Exoplanet atmospheric composition , Exoplanets, Exoplanet evolution, Exoplanet structure, Exoplanet atmospheres
Mystery behind the Peeling of a Filament and the Associated Sudden Disappearance of a Sunspot Penumbra. On 2024 July 25, while observing the solar active region NOAA 13762 with the high-resolution 1.6 m Goode Solar Telescope at the Big Bear Solar Observatory, we witnessed two mysterious phenomena: the partial detachment of filament strands from its main body in the chromosphere and the sudden disappearance of a sunspot penumbra in the photosphere, the former accompanied by small flares. Our analysis reveals a spatiotemporal correlation between the filament peeling process and the penumbral disappearance. To understand the above observations physically, we performed a magnetohydrodynamic simulation that successfully replicated the disappearance of the penumbra as a consequence of weakened horizontal magnetic field. The simulations demonstrate that both the filament peeling and the penumbral decay are driven by the same underlying process: the upward expansion of the magnetic flux rope induced by null point magnetic reconnection. These results suggest a novel mechanism by which the Sun sheds magnetic flux to interplanetary space in the form of filament peeling and penumbral disappearance.

Keywords: Sunspots, Solar filament eruptions, Solar magnetic reconnection
How Fast Could Supermassive Black Holes Grow at the Epoch of Reionization?. Utilizing cosmological hydrodynamic simulations, we show that there is a brief super-Eddington accretion phase in typical halos at high redshift, impervious to active galactic nucleus (AGN) self-regulation. However, once having attained a black hole mass of 104─105 M⊙, the AGN feedback process can self-regulate to guide the supermassive black holes (SMBHs) to grow at a significantly slower, sub-Eddington rate. By redshift z ∼ 10 the black hole mass with an initial super-Eddington jump-start is caught up by that of the steady Eddington-limited case. Thus, a continuous Eddington limit case represents the fastest possible route to maximally grow SMBHs. To account for the observed z = 7─10 quasars with SMHBs of billions of solar masses, our analysis establishes firmer ground for the need for seed masses of 104─105 M⊙ that are not grown via an earlier super-Eddington phase.

Keywords: AGN host galaxies, Stellar feedback, Quasars, Low-luminosity active galactic nuclei, Reionization, Astrophysical black holes
The Bigfoot: A Footprint of a Coma Cluster Progenitor at z = 3.98. Protoclusters, galaxy clusters' high-redshift progenitors, hold the key to understanding the formation and evolution of clusters and their member galaxies. However, their cosmological distances and spatial extensions (tens of Mpc) have inhibited complete mapping of their structure and constituent galaxies, which is key to robustly linking protoclusters to their descendants. Here we report the discovery of the Bigfoot, a tridimensional structure at z = 3.98 including 11 subgroups traced by 55 (700) spectroscopic (photometric) redshifts with JWST, extending over 15 × 37 × 49 cMpc3 in the PRIMER-UDS field. Bigfoot's large-scale and mass function of member galaxies closely match constrained simulations' predictions for the progenitors of today's most massive clusters (M0 &gt; 1015M⊙). All subgroups with Mh &gt; 1012.5M⊙ exhibit enhanced fractions of massive galaxies (&gt;1010.0M⊙) compared to lower-mass halos and fields, demonstrating the accelerated formation of massive galaxies in massive halos. The presence of this massive protocluster with a large central halo (1013.0M⊙) in a JWST deep field bears important cosmological implication that favors high σ8 of PLANCK cosmology over low-redshift probes.

Keywords: Protoclusters, Galaxies, High-redshift galaxy clusters
ELPIS: Accelerated Metal and Dust Enrichment in a Protocluster Core at z ≍ 8. We present a study of the metal, dust, and molecular gas content in galaxies within the A2744-z7p9OD protocluster at z ≍ 7.88. We focus on two galaxy groups—the Quintet and the Chain—which are covered by the Emission-Line Protocluster Imaging Survey (ELPIS) of the furthest overdensity beyond Pandora's Cluster A2744. [C II] 158 μm emission is detected in five galaxies, revealing molecular gas reservoirs with  log(Mgas/M⊙)∼9.0 ─9.6, while dust continuum at the observed frame of 1.26 mm is detected in three galaxies, yielding dust masses of  log(Mdust/M⊙)∼6.0 ─6.4, assuming a dust temperature of  Tdust=45−15+15  K. The derived properties—including stellar-to-dust mass ratios of  log(Mdust/M⋆)∼−3  to −2 at  log(M⋆/M⊙)≍9  and dust-to-gas mass ratios of  log(Mdust/Mgas)∼−4  to −3 at  12+log(O/H)≍8 —place these galaxies in an intermediate regime: higher than the very low ratios expected from supernova-driven dust production but still below the levels attained once efficient grain growth dominates. These values indicate a transition phase of dust mass assembly, likely reflecting the onset of grain growth via metal accretion under accelerated evolution in the protocluster core.

Keywords: Gas-to-dust ratio, Galaxy formation, Protoclusters, Dust formation, Reionization
Linking Electron Density with Elevated Star Formation Activity from z = 0 to z = 10. The interstellar medium in high-redshift galaxies exhibits significantly higher electron densities (ne) than in the local Universe. To investigate the origin of this trend, we analyze a sample of 9590 centrally star-forming galaxies with stellar masses greater than 109 M⊙ at redshifts 0.01 &lt; z &lt; 0.04, selected from the Dark Energy Spectroscopic Instrument Data Release 1. We derive ne from the [S II] λλ6716, 6731 doublet, measuring values of ne = 30─400 cm−3 at z ≍ 0. We find a tight correlation between ne and the star formation rate surface density (ΣSFR), which is well described by a broken power law. Above a threshold of  log(ΣSFR/M⊙yr−1kpc−2)≥−1.46 , the relation follows  ne=(233±13)×ΣSFR0.49±0.02 . Below this threshold, ne remains approximately at a constant value of 44 ± 3 cm−3. Remarkably, this relation remains consistent with measurements of galaxies at z = 0.9─10.2. By converting the observed redshift evolution of ΣSFR into ne evolution through our ne─ΣSFR relation, we obtain ne = 40 × (1 + z)1.4 cm−3, consistent with previous direct observations. The ne─ΣSFR relation arises likely because the high ΣSFR, fueled by dense cold gas or elevated efficiency, enhances radiative and mechanical feedback and produces dense ionized gas whose ne are further regulated by ambient pressure. We conclude that the redshift evolution of ne primarily reflects the evolution of the cold gas density and star formation activity over cosmic time.

Keywords: High-redshift galaxies, Star formation, Galaxy evolution, Interstellar medium
A Metal-free Galaxy at z = 3.19? Evidence of Late Population III Star Formation at Cosmic Noon. Star formation from metal-free gas, the hallmark of the first generation of Population III (Pop III) stars, was long assumed to occur only in the very early Universe. We report the discovery of Metal-Pristine Galaxy COSMOS Redshift 3 (MPG-CR3, hereafter CR3), an extremely metal-poor galaxy at redshift z = 3.193 ± 0.016. From JWST, Very Large Telescope, and Subaru observations, CR3 exhibits exceptionally strong Lyα, Hα, and He I λ10830 emissions. We measure rest-frame equivalent widths of EW0(Lyα) = 822 ± 101 Å and EW0(Hα) = 2814 ± 327 Å, among the highest seen in star-forming systems. No metal lines, e.g., [O III] λλ4959, 5007, C IV λλ1548, 1550, have statistically significant detections, placing a 2σ upper limit on the gas-phase metallicity of  12+log(O/H)&lt;6.52  (Z &lt; 7 × 10−3 Z⊙) with strong-line calibration established by JWST, making it the most metal-poor galaxy known at cosmic noon. Considering systematic uncertainties of ≳0.3 dex in the calibrations, the most conservative 2σ upper limit is set to  12+log(O/H)&lt;6.95 . The observed Lyα/Hα flux ratio is 13.9 ± 2.5, indicating negligible dust attenuation. Spectral energy distribution modeling with Pop III stellar templates indicates a very young (∼2 Myr), low-mass (M* ≍ 6.1 × 105M⊙) stellar population. Further, the photometric redshifts reveal that CR3 could reside in a slightly underdense environment (δ ≍ −0.12). CR3 provides evidence that first-generation star formation could persist well after the epoch of reionization, challenging the conventional view that pristine star formation ended by z ≳ 6.

Keywords: Star formation, Metallicity, Population III stars, High-redshift galaxies
Discovery of Powerful Multivelocity Ultrafast Outflows in the Starburst Merger Galaxy IRAS 05189─2524 with XRISM. We observed the X-ray-bright ultraluminous infrared galaxy IRAS 05189−2524 with XRISM during its performance verification phase. The unprecedented energy resolution of the onboard X-ray microcalorimeter revealed complex spectral features at ∼7─9 keV, which can be interpreted as blueshifted Fe XXV/XXVI absorption lines with various velocity dispersions, originating from ultrafast outflow (UFO) components with multiple bulk velocities of ∼0.076c, ∼0.101c, and ∼0.143c. In addition, a broad Fe─K emission line was detected around ∼7 keV, forming a P Cygni profile together with the absorption lines. The onboard X-ray CCD camera revealed a 0.4─12 keV broadband spectrum characterized by a neutrally absorbed power-law continuum with a photon index of ∼2.3 and intrinsic flare-like variability on timescales of ∼10 ks, both of which are likely associated with near-Eddington accretion. We also found potential variability of the UFO parameters on a timescale of ∼140 ks. Using these properties, we propose new constraints on the outflow structure and suggest the presence of multiple outflowing regions on scales of about tens to 100 Schwarzschild radii, located within roughly 2000 Schwarzschild radii. Since both the estimated momentum and energy outflow rates of the UFOs exceed those of galactic molecular outflows, our results indicate that powerful, multivelocity UFOs are already well developed during a short-lived evolutionary phase following a major galaxy merger, characterized by intense starburst activity and likely preceding the quasar phase. This system is expected to evolve into a quasar, sustaining strong UFO activity and suppressing star formation in the host galaxy.

Keywords: X-ray astronomy, Supermassive black holes, Ultraluminous infrared galaxies, Quasars
Spinning into the Gap: Direct-horizon Collapse as the Origin of GW231123 from End-to-end General-relativistic Magnetohydrodynamic Simulations. GW231123, the most massive binary black hole (BH) merger observed to date, involves component BHs with masses inside the pair-instability mass gap and unusually high spins. This challenges standard formation channels such as classical stellar evolution and hierarchical mergers. However, stellar rotation and magnetic fields, which have not been systematically incorporated in prior models, can strongly influence the BH properties. We present the first self-consistent simulations tracking a massive, low-metallicity helium star from helium core burning through collapse, BH formation, and post-BH formation accretion using 3D general-relativistic magnetohydrodynamic simulations. Starting from a 250 M⊙ helium core, we show that collapse above the pair-instability mass gap, aided by rotation and magnetic fields, drives mass loss through disk winds and jet launching. This enables the formation of highly spinning BHs within the mass gap and reveals a BH spin─mass correlation. Strong magnetic fields extract angular momentum from the BH through magnetically driven outflows, which in turn suppress accretion, resulting in slowly spinning BHs within the mass gap. In contrast, stars with weak fields permit nearly complete collapse and spin-up of the BH to a ≍ 1. We show that massive low-metallicity stars with moderate magnetic fields naturally produce BHs whose masses and spins match those inferred for GW231123, and are also consistent with those of GW190521. The outflows launched during collapse may impart a BH kick, which can induce spin─orbit misalignment and widen the postcollapse orbit, delaying the merger. These outflows could further drive short-lived, high-luminosity jets comparable to the most energetic γ-ray bursts, offering a potential observational signature of such events in the early Universe.

Keywords: Core-collapse supernovae, Stellar mass black holes, Gravitational wave sources, Gravitational wave astronomy, Supernova remnants, Gravitational waves, Gravitational collapse, Astrophysical black holes
The First RELHIC? Cloud-9 is a Starless Gas Cloud. Five-hundred-meter Aperture Spherical Telescope observations have recently identified a compact H I cloud (hereafter Cloud-9) in the vicinity of the spiral galaxy M94. This identification has been confirmed independently by Very Large Array and Green Bank Telescope observations. Cloud-9 has the same recession velocity as M94, and is therefore at a similar distance (∼4.4 Mpc). It is compact ( ∼1' radius, or ∼1.4 kpc), dynamically cold (W50 = 12 km s−1), nonrotating, and fairly massive, with an H I mass of ∼106 M⊙. Here we present deep Hubble Space Telescope/Advanced Camera for Surveys imaging designed to search for a luminous stellar counterpart. We visually rule out the presence of any dwarf galaxy with stellar mass exceeding 103.5 M⊙. A more robust color─magnitude diagram-based analysis conservatively rules out a 104 M⊙ stellar counterpart with  99.5−8.2+0.5 % confidence. The nondetection of a luminous component reinforces the interpretation that this system is a reionization-limited H I cloud (RELHIC); i.e., a starless dark matter halo filled with hydrostatic gas in thermal equilibrium with the cosmic ultraviolet background. Our results make Cloud-9 the leading RELHIC candidate of any known compact H I cloud. This provides strong support for a cornerstone prediction of the Lambda cold dark matter model, namely the existence of gas-filled starless dark matter halos on subgalactic mass scales, and constrains the present-day threshold halo mass for galaxy formation. *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 program 17712.

Keywords: Cosmology, Hubble Space Telescope, Galaxies
Induction Heating in Super-Earths: A Thermochemical Perspective. Electromagnetic induction heating has recently been proposed as an important internal heat source in the mantles of rocky exoplanets. However, its dependence on planetary interior properties remains poorly constrained. Here, we construct electrical conductivity profiles for super-Earth mantles considering different temperatures and compositions, and evaluate induction heating in super-Earth mantles in both solid and partially molten states. We find that high mantle temperature, iron content, and melt fraction all suppress the overall induction heating efficiency due to increased mantle conductivity and magnetic shielding. In GJ 486b, induction heating likely exceeds both radiogenic heating and tidal heating, driving persistent surface volcanism and early volatile depletion, whereas HD 3167b and GJ 357b experience insignificant induction heating due to weak stellar magnetic fields. Our findings highlight induction heating as a critical factor in the thermal and atmospheric evolution of close-in super-Earths around magnetically active stars.

Keywords: Exoplanet dynamics, Super Earths, Magnetic fields, Star-planet interactions, Planetary interior
Enhanced Localization of Dark Lensed Gravitational-wave Events Enables Host Galaxy Identification and Precise Cosmological Inference. Lensed gravitational-wave (GW) events are expected to be powerful new probes of cosmology, contingent on redshift measurement by electromagnetic observations. Host galaxy identification is thus crucial but challenging due to poor localization by GW signal alone. In this Letter, we show that the third-generation ground-based GW detectors will detect a population of lensed events with three or more detectable images (including the central one), each arriving at distinct times and Earth locations in space, forming an effective network that reduces the typical localization area to ∼0.01 deg2. For at least 90% (or 50%) of these events, the localization improves by more than a factor of 10 (or 30) compared with unlensed cases. Such precise localization and multiple-image detections enable robust host-galaxy identification and, through lens modeling, further yield subarcsecond position. As dark lensed sirens, these events become powerful probes of cosmological parameters. Using simulated lensed compact-binary mergers, we show that 2 yr or longer observations with third-generation GW detectors can measure the Hubble constant to ≲1% precision via "dark lensed sirens" (even when relying solely on lensed stellar-mass binary black hole events) while simultaneously constraining other cosmological parameters. This approach will provide an independent, complementary avenue for measuring cosmological parameters.

Keywords: Cosmological parameters, Compact binary stars, Gravitational wave sources, Gravitational wave astronomy, Gravitational lensing, Compact objects
A New Sample of Dwarf Galaxies with X-Ray-selected Active Galactic Nucleus Candidates from the eROSITA All-Sky Survey. To investigate the population of massive black holes in dwarf galaxies, we conduct a systematic search for active galactic nuclei (AGNs) using data from the first data release of the eROSITA All-Sky Survey (eRASS). We crossmatch dwarf galaxy positions in the NASA-Sloan Atlas with X-ray sources from eRASS and apply rigorous criteria to remove contaminants such as background sources, galaxies with dubious stellar masses, and X-ray binaries. Potential contamination from ultraluminous X-ray sources is also assessed. We ultimately assemble a sample of 27 X-ray-selected AGN candidates in dwarf galaxies with stellar masses M* = 107.5−9.5 M⊙ and redshifts z &lt; 0.15. An analysis of the host galaxy properties reveals that the AGN candidates are predominantly situated in systems with g − r colors, star formation rates, and concentrations typical of the broader dwarf galaxy population. Detailed examination of the X-ray sources indicates that most AGN candidates in our sample are consistent with being located in the nuclear regions of their host galaxies and exhibit Eddington ratios ranging between λEdd ∼ 10−3 and 10−1, with a few radiating at/above their Eddington limit. Notably, our methodology identifies 15 previously unreported AGNs candidates, highlighting the complementary nature of our approach to the existing literature.

Keywords: AGN host galaxies, Intermediate-mass black holes, Dwarf galaxies, Active galactic nuclei, X-ray active galactic nuclei, X-ray sources
Gran Telescopio Canarias/OSIRIS Deep Spectroscopy of Galactic Compact Planetary Nebulae: PN G048.5+04.2 and PN G068.7+14.8. We report deep long-slit spectroscopy of two compact Galactic planetary nebulae (PNe), PN G048.5+04.2 and PN G068.7+14.8, obtained using the 10.4 m Gran Telescopio Canarias (GTC). These spectra cover a broad wavelength range of ∼3630─10370 Å, enabling the detection of numerous emission lines critical for nebular analysis, including [O II] λ3727 and [O III] λ4363 in the blue and [S III] λ6312 and λ9069 in the red. Also detected in the spectrum of PN G068.7+14.8 are broad C III and C IV lines probably due to stellar emission, indicating that the central star of this PN is WC type. The GTC optical─near-IR spectra were analyzed in detail in conjunction with archival Spitzer Space Telescope Infrared Spectrograph mid-IR spectra, and the elemental abundances of the two PNe were determined. Photoionization models were established for the two PNe using CLOUDY, based on the ratios of line fluxes measured from the GTC spectra. Our best photoionization modeling, in combination with state-of-the-art post─asymptotic giant branch (AGB) evolutionary model tracks, shows that both PNe evolved from low-mass progenitors (&lt;2 M⊙) with relatively young ages (&lt;3 Gyr), although their central cores are probably in different evolutionary stages—the central star of PN G068.7+14.8 is still in the process of heating up, while that of PN G048.5+04.2 has already entered the white dwarf cooling track. A comparison with AGB model predictions also constrains the progenitors of both PNe to be of low mass. Moreover, the two PNe are in line with the radial oxygen gradients exhibited by Galactic PN populations, using the most up-to-date distances.

Keywords: Galaxy abundances, Planetary nebulae, Interstellar medium, Stellar evolution
An Intense Geomagnetic Storm Originated from Stealth Coronal Mass Ejection: Remote and In Situ Observations by Near Radially Aligned Spacecraft. We investigate the solar origin and heliospheric evolution of an intense geomagnetic storm that occurred on 2023 March 23─24. Despite multiple candidate coronal mass ejections (CMEs) observed between March 19 and 21, a weak CME detected on March 19 at 18:00 UT was identified as the cause, originating from the eruption of a longitudinal-filament channel near the center of the Sun. The channel underwent a smooth transition to the eruption phase without detectable low-coronal signatures. Wide-angle heliospheric imaging revealed asymmetric expansion and acceleration by solar wind drag, achieving an average CME velocity of ≍640 km s−1. The radial evolution of the interplanetary coronal mass ejection (ICME) was analyzed by three spacecraft in close radial alignment. Arrival times and propagation speeds were consistent across spacecraft, with a 21 hr delay between STEREO-A (STA) and WIND attributed to solar rotation and longitudinal separation. The ICME exhibits magnetic cloud (MC) signatures characterized by right-handed helicity, enhanced density at all three spacecraft. The MC underwent expansion (radial-size increases from 0.08 au at SolO to 0.18 au at STA), a decrease in magnetic field strength with distance;  Bav∝RH−1.97  (SolO-STA) and  Bav∝RH−1.53  (SolO-WIND). The MC axis is inclined with the ecliptic at −69° at SolO, −25° at STA, and −34° at WIND, indicating rotation during heliospheric transit. Importantly, the storm's main phase leads to a peak intensity (SYM-H= −169 nT) occurring at 24/02:40 UT, followed by a second peak (SYM-H = −170 nT) at 24/05:20 UT due to density enhancement toward MC's tail. The study emphasizes the significant geoeffectiveness of weak, stealth CMEs with southward Bz and density enhancements.

Keywords: Solar-terrestrial interactions, Solar storm, Solar coronal mass ejections, Heliosphere