Sazuna/UAT_keywords huggingface dataset:
The Gas and Stellar Content of a Metal-poor Galaxy at z = 8.496 as Revealed by JWST and ALMA. We present a joint analysis of the galaxy S04590 at z = 8.496 based on NIRSpec, NIRCam, and NIRISS observations obtained as part of the Early Release Observations program of the James Webb Space Telescope (JWST) and the far-infrared [C II] 158 μm emission line detected by dedicated Atacama Large Millimeter/submillimeter Array (ALMA) observations. We determine the physical properties of S04590 from modeling of the spectral energy distribution (SED) and through the redshifted optical nebular emission lines detected with JWST/NIRSpec. The best-fit SED model reveals a low-mass (M ⋆ = 107.2─108 M ⊙) galaxy with a low oxygen abundance of  12+log(O/H)=7.16−0.12+0.10  derived from the strong nebular and auroral emission lines. Assuming that [C II] effectively traces the interstellar medium, we estimate the total gas mass of the galaxy to be M gas = (8.0 ± 4.0) × 108 M ⊙ based on the luminosity and spatial extent of [C II]. This yields an exceptionally high gas fraction, f gas = M gas/(M gas + M ⋆) ≳ 90%, though one still consistent with the range expected for low metallicity. We further derive the metal mass of the galaxy based on the gas mass and gas-phase metallicity, which we find to be consistent with the expected metal production from Type II supernovae. Finally, we make the first constraints on the dust-to-gas (DTG) and dust-to-metal (DTM) ratios of galaxies in the epoch of reionization at z ≳ 6, showing overall low mass ratios of logDTG &lt; −3.8 and logDTM &lt; −0.5, though they are consistent with established scaling relations and in particular with those of the local metal-poor galaxy I Zwicky 18. Our analysis highlights the synergy between ALMA and JWST in characterizing the gas, metal, and stellar content of the first generation of galaxies.

Keywords: Galaxy formation, Star formation, Galaxy evolution, Interstellar medium, High-redshift galaxies, Galaxies
Observational Evidence for Cosmological Coupling of Black Holes and its Implications for an Astrophysical Source of Dark Energy. Observations have found black holes spanning 10 orders of magnitude in mass across most of cosmic history. The Kerr black hole solution is, however, provisional as its behavior at infinity is incompatible with an expanding universe. Black hole models with realistic behavior at infinity predict that the gravitating mass of a black hole can increase with the expansion of the universe independently of accretion or mergers, in a manner that depends on the black hole's interior solution. We test this prediction by considering the growth of supermassive black holes in elliptical galaxies over 0 &lt; z ≲ 2.5. We find evidence for cosmologically coupled mass growth among these black holes, with zero cosmological coupling excluded at 99.98% confidence. The redshift dependence of the mass growth implies that, at z ≲ 7, black holes contribute an effectively constant cosmological energy density to Friedmann's equations. The continuity equation then requires that black holes contribute cosmologically as vacuum energy. We further show that black hole production from the cosmic star formation history gives the value of ΩΛ measured by Planck while being consistent with constraints from massive compact halo objects. We thus propose that stellar remnant black holes are the astrophysical origin of dark energy, explaining the onset of accelerating expansion at z ~ 0.7.

Keywords: Black hole physics, Supermassive black holes, Star formation, Cosmological constant, Astrophysical black holes, Dark energy
Molecular Gas Properties in Young Stellar Clusters with a Suppressed Star Cluster Wind. In compact and dense star-forming clouds a global star cluster wind could be suppressed. In this case stellar feedback is unable to expel the leftover gas from the cluster. Young massive stars remain embedded in a dense residual gas and stir it by moving in the gravitational well of the system. Here we present a self-consistent model for the molecular gas distribution in such young, enshrouded stellar clusters. It is assumed that the cloud collapse terminates and the star formation ceases when a balance between the turbulent pressure and gravity and between the turbulent energy dissipation and regeneration rates is established. These conditions result in an equation that determines the residual gas density distribution that, in turn, allows one to determine the other characteristics of the leftover gas and the star formation efficiency. It is shown that our model predictions are in good agreement with several observationally determined properties of cloud D1 in the nearby dwarf spheroidal galaxy NGC 5253 and its embedded cluster.

Keywords: Star clusters
Probing the Milky Way Stellar and Brown Dwarf Initial Mass Function with Modern Microlensing Observations. We use recent microlensing observations toward the central bulge of the Galaxy to probe the overall stellar plus brown dwarf initial mass function (IMF) in these regions well within the brown dwarf domain. We find that the IMF is consistent with the same Chabrier IMF characteristic of the Galactic disk. In contrast, other IMFs suggested in the literature overpredict the number of short-time events, and thus of very low mass stars and brown dwarfs, compared with observations. This again supports the suggestion that brown dwarfs and stars predominantly form via the same mechanism. We show that claims for different IMFs in the stellar and substellar domains arise from an incorrect parameterization of the IMF. Furthermore, we show that the IMF in the central regions of the bulge seems to be bottom-heavy, as illustrated by the large number of short-time events compared with the other regions. This recalls our previous analysis of the IMF in massive early-type galaxies and suggests the same kind of two-phase formation scenario, with the central bulge initially formed under more violent, burst-like conditions than the rest of the Galaxy.

Keywords: Stellar mass functions, Initial mass function
Multi-messenger Model for the Prompt Emission from GRB 221009A. We present a multi-messenger model for the prompt emission from GRB 221009A within the internal shock scenario. We consider the time-dependent evolution of the outflow with its impact on the observed light curve from multiple collisions, as well as the self-consistent generation of the electromagnetic spectrum in synchrotron and inverse Compton-dominated scenarios. Our lepto-hadronic model includes UHE protons potentially accelerated in the outflow, and their feedback on spectral energy distribution and on the neutrino emission. We find that we can roughly reproduce the observed light curves with an engine with varying ejection velocity of ultrarelativistic material, which has an intermediate quiescent period of about 200 s and a variability timescale of ~1 s. We consider baryonic loadings of 3 and 30 that are compatible with the hypothesis that the highest-energetic LHAASO photons might come from UHECR interactions with the extragalactic background light, and the paradigm that energetic GRBs may power the UHECR flux. For these values and the high dissipation radii considered, we find consistency with the nonobservation of neutrinos and no significant signatures on the electromagnetic spectrum. Inverse Compton-dominated scenarios from the prompt emission are demonstrated to lead to about an order of magnitude higher fluxes in the HE range; this enhancement is testable via its spectral impact in the Fermi-GBM and LAT ranges.

Keywords: Gamma-ray bursts, High energy astrophysics, Non-thermal radiation sources, Cosmological neutrinos, Cosmic rays
A Second Earth-sized Planet in the Habitable Zone of the M Dwarf, TOI-700. We report the discovery of TOI-700 e, a 0.95 R ⊕ planet residing in the Optimistic Habitable Zone (HZ) of its host star. This discovery was enabled by multiple years of monitoring from NASA's Transiting Exoplanet Survey Satellite (TESS) mission. The host star, TOI-700 (TIC 150428135), is a nearby (31.1 pc), inactive, M2.5 dwarf (V mag = 13.15). TOI-700 is already known to host three planets, including the small, HZ planet, TOI-700 d. The new planet has an orbital period of 27.8 days, and based on its radius (0.95 R ⊕), it is likely rocky. TOI-700 was observed for 21 sectors over Years 1 and 3 of the TESS mission, including 10 sectors at 20 s cadence in Year 3. Using this full set of TESS data and additional follow-up observations, we identify, validate, and characterize TOI-700 e. This discovery adds another world to the short list of small, HZ planets transiting nearby and bright host stars. Such systems, where the stars are bright enough that follow-up observations are possible to constrain planet masses and atmospheres using current and future facilities, are incredibly valuable. The presence of multiple small, HZ planets makes this system even more enticing for follow-up observations.

Keywords: M dwarf stars, Astronomy data analysis, Exoplanet systems, Low mass stars, Transit photometry
Discovery of a Dusty, Chemically Mature Companion to a z ∼ 4 Starburst Galaxy in JWST ERS Data. We report the discovery of two companion sources to a strongly lensed galaxy SPT0418-47 ("ring") at redshift 4.225, targeted by the JWST Early Release Science program. We confirm that these sources are at a similar redshift to the ring based on Hα detected in the NIRSpec spectrum and [C II] λ158 μm line from the Atacama Large Millimeter/submillimeter Array (ALMA). Using multiple spectral lines detected in JWST/NIRSpec, the rest-frame optical to infrared images from NIRCam and MIRI and far-infrared dust continuum detected by ALMA, we argue that the newly discovered sources are actually lensed images of the same companion galaxy SPT0418-SE, hereafter referred to "SE," located within 5 kpc in the source plane of the ring. The star formation rate derived using [C II] and the dust continuum puts a lower limit of 17 M ☉ yr-1, while the SFRHα  is estimated to be &gt;2 times lower, thereby confirming that SE is a dust-obscured star-forming galaxy. Analysis using optical strong line diagnostics suggests that SE has near-solar elemental abundance, while the ring appears to have supersolar metallicity O/H and N/O. We attempt to reconcile the high metallicity in this system by invoking early onset of star formation with continuous high star-forming efficiency or by suggesting that optical strong line diagnostics need revision at high redshift. We suggest that SPT0418-47 resides in a massive dark-matter halo with yet-to-be-discovered neighbors. This work highlights the importance of joint analysis of JWST and ALMA data for a deep and complete picture of the early universe.

Keywords: Companion galaxies, James Webb Space Telescope, Gravitational lensing, Metallicity, High-redshift galaxies
Early Stages of Galilean Moon Formation in a Water-depleted Environment. A key feature of the Galilean satellite system is its monotonic decrease in bulk density with growing distance from Jupiter, indicating an ice mass fraction that is zero in the innermost moon Io and about half in the outer moons Ganymede and Callisto. Jupiter-formation models, and perhaps the Juno spacecraft water measurements, are consistent with the possibility that the Jovian system may have formed, at least partly, from ice-poor material. And yet, models of the formation of the Galilean satellites usually assume abundant water ice in the system. Here, we investigate the possibility that the Jovian circumplanetary disk was populated with ice-depleted chondritic minerals, including phyllosilicates. We show that the dehydration of such particles and the outward diffusion of the released water vapor allow condensation of significant amounts of ice in the formation region of Ganymede and Callisto in the Jovian circumplanetary disk. Our model predicts that Europa, Ganymede, and Callisto should have accreted little, if any, volatiles other than water ice, in contrast to the comet-like composition of Saturn's moon Enceladus. This mechanism allows for the presence of ice-rich moons in water-depleted formation environments around exoplanets as well.

Keywords: Planetary system formation, Galilean satellites, Natural satellites (Solar system), Natural satellite formation
Density Profiles of Collapsed Rotating Massive Stars Favor Long Gamma-Ray Bursts. Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows-jets-that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to propagate through and break out of. Most previous studies have used simple power laws or pre-collapse models for massive stars. However, the relevant stellar profile for lGRB models is in fact that of a star after its core has collapsed to form a compact object. To self-consistently compute such a stellar profile, we use the open-source code GR1D to simulate the core-collapse process for a suite of low-metallicity rotating massive stellar progenitors that have undergone chemically homogeneous evolution. Our models span a range of zero-age main-sequence (ZAMS) masses: M ZAMS = 13, 18, 21, 25, 35, 40, and 45M ☉. All of these models, at the onset of core-collapse, feature steep density profiles, ρ ∝ r -α , with α ≈ 2.5, which would result in jets that are inconsistent with lGRB observables. We follow the collapses of four of the seven models until they form black holes (BHs) and the other three models until they form proto-neutron stars (PNSs). We find, across all models, that the density profile outside the newly formed BH or PNS is well represented by a flatter power law with α ≈ 1.35-1.55. Such flat density profiles are conducive to the successful formation and breakout of BH-powered jets and are, in fact, required to reproduce observable properties of lGRBs. Future models of lGRBs should be initialized with shallower post-collapse stellar profiles, like those presented here, instead of the much steeper pre-collapse profiles that are typically used.

Keywords: Hydrodynamical simulations, Gamma-ray bursts, Core-collapse supernovae, Stellar mass black holes, General relativity
Hypervelocity Stars Track Back to the Galactic Center in Gaia DR3. Based on the proper motions and radial velocities from Gaia Data Release 3, we identify two hypervelocity stars (HVSs) that may originate from the Galactic center (GC). We select the candidates by first filtering for all Gaia stars with Galactocentric radial velocities &gt;500 km s-1. We also require the candidates cross the Galactic midplane only once at 80% confidence, as determined by backwards orbit integration in several models of the Galactic potential, given the uncertainties in the Gaia measurables. The final two HVS candidates are the only such stars in our sample whose backwards-integrated trajectories pass within 1 kpc of the GC, suggesting a potential GC origin. We discuss possible ejection scenarios for these HVSs, in particular, by finding that ejection via the Hills mechanism is unlikely unless the HVS trajectories were significantly altered by local or large-scale perturbations to the assumed Galactic potential, e.g., the Large Magellanic Cloud. Interestingly, one of the HVSs ejects in a direction that is curiously aligned with the clockwise stellar disk around Sgr A*, suggesting a possible connection. We also discuss that the two stars may be ejected by other mechanisms.

Keywords: Supermassive black holes, Galactic center, Stellar kinematics, Hypervelocity stars, Stellar dynamics
Discovery of an Isolated Dark Dwarf Galaxy in the Nearby Universe. Based on a new H I survey using the Five-hundred-meter Aperture Spherical radio Telescope (FAST), combined with the Pan-STARRS1 images, we identified an isolated H I cloud without any optical counterpart, named FAST J0139+4328. The newly discovered H I cloud appears to be a typical disk galaxy since it has a double-peak shape in the global H I profile and an S-like rotation structure in the velocity-position diagram. Moreover, this disk galaxy has an extremely low absolute magnitude (M B &gt; -10.0 mag) and stellar mass (&lt;6.9 ×105 M ⊙). Furthermore, we obtained that the H I mass of this galaxy is (8.3 ± 1.7) ×107 M ⊙, and the dynamical mass to total baryonic mass ratio is 47 ± 27, implying that dark matter dominates over baryons in FAST J0139+4328. These findings provide observational evidence that FAST J0139+4328 is an isolated dark dwarf galaxy with a redshift of z = 0.0083. This is the first time that an isolated dark galaxy has been detected in the nearby universe.

Keywords: Extragalactic astronomy
NEID Reveals That the Young Warm Neptune TOI-2076 b Has a Low Obliquity. TOI-2076 b is a sub-Neptune-sized planet (R = 2.39 ± 0.10 R ⊕) that transits a young (204 ± 50 MYr) bright (V = 9.2) K-dwarf hosting a system of three transiting planets. Using spectroscopic observations obtained with the NEID spectrograph on the WIYN 3.5 m Telescope, we model the Rossiter-McLaughlin effect of TOI-2076 b, and derive a sky-projected obliquity of $\lambda =-{3}_{-15}^{+16^\circ }$ . Using the size of the star (R = 0.775 ± 0.015 R ⊙), and the stellar rotation period (P rot = 7.27 ± 0.23 days), we estimate an obliquity of $\psi ={18}_{-9}^{+10^\circ }$ (ψ &lt; 34° at 95% confidence), demonstrating that TOI-2076 b is in a well-aligned orbit. Simultaneous diffuser-assisted photometry from the 3.5 m telescope at Apache Point Observatory rules out flares during the transit. TOI-2076 b joins a small but growing sample of young planets in compact multi-planet systems with well-aligned orbits, and is the fourth planet with an age ≲300 Myr in a multi-transiting system with an obliquity measurement. The low obliquity of TOI-2076 b and the presence of transit timing variations in the system suggest the TOI-2076 system likely formed via convergent disk migration in an initially well-aligned disk.

Keywords: Exoplanet dynamics, Exoplanets, Mini Neptunes, Exoplanet astronomy, Exoplanet evolution, Radial velocity, Transit photometry
Hydrodynamical Simulations of Black Hole Binary Formation in AGN Disks. We study close encounters between two single black holes (BHs) embedded in an AGN disk using a series of global 2D hydrodynamics simulations. We find that when the disk density is sufficiently high, bound BH binaries can be formed by the collision of their circum-single disks. Our analysis demonstrates that, after a BH pair passes the pericenter of their relative trajectory, post-collision gas drag may slow down the BHs, possibly forcing the two BHs to stay tightly bound. A binary formed by a close encounter can have a compact semimajor axis, large eccentricity, and retrograde orbital angular momentum. We provide a fitting formula that can accurately predict whether a close encounter can form a binary based on the gas mass and the incoming energy of the encounter. This fitting formula can be easily implemented in other long-term simulations that study the dynamical evolution of BHs in active galactic nucleus disks.

Keywords: Hydrodynamical simulations, Black holes, Galaxy accretion disks, Gravitational wave sources, Orbital evolution, Active galactic nuclei
Fractal Aggregates of Submicron-sized Grains in the Young Planet-forming Disk around IM Lup. Despite rapidly growing disk observations, it remains a mystery what primordial dust aggregates look like and what the physical and chemical properties of their constituent grains (monomers) are in young planet-forming disks. Confrontation of models with observations to answer this mystery has been a notorious task because we have to abandon a commonly used assumption, perfectly spherical grains, and take into account particles with complex morphology. In this Letter, we present the first thorough comparison between near-infrared scattered light of the young planet-forming disk around IM Lup and the light-scattering properties of complex-shaped dust particles. The availability of scattering observations at multiple wavelengths and over a significant range of scattering angles allows for the first determination of the monomer size, fractal dimension, and size of dust aggregates in a planet-forming disk. We show that the observations are best explained by fractal aggregates with a fractal dimension of 1.5 and a characteristic radius larger than ~2 μm. We also determined the radius of the monomer to be ~200 nm, and monomers much smaller than this size can be ruled out on the premise that the fractal dimension is less than 2. Furthermore, dust composition comprising amorphous carbon is found to be favorable to simultaneously account for the faint scattered light and the flared disk morphology. Our results support that planet formation begins with fractal coagulation of submicron-sized grains. All the optical properties of complex dust particles computed in this study are publicly available.

Keywords: Protoplanetary disks, Planet formation, Near infrared astronomy
A Comparative Study of Solar Active Region 12371 with Data-constrained and Data-driven Magnetohydrodynamic Simulations. We performed two data-based magnetohydrodynamic (MHD) simulations for solar active region 12371, which produced an M6.5 flare. The first simulation is a full data-driven simulation where the initial condition is given by a nonlinear force-free field (NLFFF). This NLFFF was extrapolated from photospheric magnetograms approximately 1 hr prior to the flare, and then a time-varying photospheric magnetic field is imposed at the bottom surface. The second simulation is also a data-driven simulation, but it stops driving at the bottom before the time of flare onset and then switches to the data-constrained simulation, where the horizontal component of the magnetic field varies according to an induction equation, while the normal component is fixed with time. Both simulations lead to an eruption, with both simulations producing highly twisted field lines before the eruption, which were not found in the NLFFF alone. After the eruption, the first simulation based on the time-varying photospheric magnetic field continues to produce sheared field lines after the flare without reproducing phenomena such as postflare loops. The second simulation reproduces the phenomena associated with flares well. However, in this case, the evolution of the bottom magnetic field is inconsistent with the evolution of the observed magnetic field. In this Letter, we report potential advantages and disadvantages in data-constrained and data-driven MHD simulations that need to be taken into consideration in future studies.

Keywords: Solar active region magnetic fields, Magnetohydrodynamics, Solar flares, Magnetohydrodynamical simulations