Sazuna/UAT_keywords huggingface dataset:
Ultramassive Black Holes Formed by Triple Quasar Mergers at z   2. The origin of rare and elusive ultramassive black holes (UMBH; with M BH &gt; 1010 M ⊙) is an open question. Using the large volume cosmological hydrodynamic simulation ASTRID, we report on the formation of an extremely massive UMBH with M BH ~ 1011 M ⊙ at z ~ 2. The UMBH is assembled as a result of two successive mergers of massive galaxies each with stellar mass M * &gt; 3 × 1011 M ⊙ that also produces a bright, rare triple quasar system powered by three ~109 M ⊙ black holes. The second merger of supermassive black holes (SMBHs) follows the first after 150 Myr. The merger events lead to sustained Eddington accretion onto the central SMBH, forming a UMBH in the center of a massive compact stellar core with M * &gt; 2 × 1012 M ⊙. The strong feedback of the UMBH quenches the surrounding star formation to &lt;10 M ⊙ yr-1 in the inner 50 h -1 kpc region. There are two more UMBHs with M BH &gt; 5 × 1010 M ⊙ at z &gt; 2 in ASTRID that are also produced by major mergers of galaxies, and their progenitors can be observed as quasar triplets of lower luminosity. The rarely observed quasar multiples can be the cradle of UMBHs at high redshift, and likely end up in the center of the most massive clusters.

Keywords: Hydrodynamical simulations, Supermassive black holes
Confinement of the Solar Tachocline by Dynamo Action in the Radiative Interior. A major outstanding problem in solar physics is the confinement of the solar tachocline, the thin shear layer that separates nearly solid-body rotation in the radiative interior from strong differential rotation in the convection zone. Here, we present the first 3D, global solar simulation that displays a magnetically confined tachocline. The nonaxisymmetric magnetism is initially built in the convection zone and then diffusively imprints downward, similar to the proposed fast magnetic confinement scenario by the Sun's cyclic dynamo field. Additionally, the field is locally amplified throughout the radiative interior by vigorous horizontal motions that seem to arise from a combination of equatorial Rossby waves and shear, magnetic, and buoyancy instabilities. Our work thus supports prior studies proposing dynamo action in the radiative interior, and suggests that horizontal motions could play a key role in driving this deep dynamo.

Keywords: Internal waves, Magnetohydrodynamics, Solar radiative zone, Solar differential rotation, Solar interior, Solar convective zone, Solar dynamo, Astrophysical fluid dynamics, Magnetohydrodynamical simulations
A New Era of Intracluster Light Studies with JWST. Still largely unexplored, the diffuse light in clusters of galaxies traces the past and ongoing buildup of these massive structures. Here we present the first comprehensive study of the intracluster light (ICL) of the cluster SMACS J0723.3-7327 (z = 0.39) using the JWST Early Release Observations. These deep and high spatial resolution images allow the study of the ICL with a high signal-to-noise ratio up to a radial distance of ~400 kpc, twice as far with respect to previous HST studies of intermediate-redshift clusters. This opens up the possibility of exploring the rich mixture of processes that are building the ICL. We find that the inner parts of this cluster (R &lt; 100 kpc) are built through a major merger, while the outer parts (R &gt; 100 kpc) are mainly produced by the tidal stripping of Milky Way-like satellites. We also find that the slope of the stellar mass density radial profile of the ICL of this cluster (α 3D = -2.47 ± 0.13) closely follows the predicted dark matter halo slope (α 3D,DM = -2.6 to -2), supporting the idea that both components have a similar shape and thus the potential of using the ICL as a tracer of the dark matter distribution in clusters of galaxies. Future JWST studies of the ICL are set to revolutionize our understanding of cluster formation and will be crucial to improve the gravitational lensing mass maps of these structures and thus accurately characterize the properties of the first galaxies.

Keywords: Galaxy clusters, James Webb Space Telescope, Dark matter distribution
Early Results from GLASS-JWST. VI. Extreme Rest-optical Equivalent Widths Detected in NIRISS Wide Field Slitless Spectroscopy. Wide Field Slitless Spectroscopy (WFSS) provides a powerful tool for detecting strong line emission in star-forming galaxies (SFGs) without the need for target preselection. As part of the GLASS-JWST Early Release Science (ERS) program, we leverage the near-infrared wavelength capabilities of NIRISS (1-2.2 μm) to observe rest-optical emission lines out to z ~ 3.4, to a depth and with a spatial resolution higher than ever before (Hα to z &lt; 2.4; [O III]+Hβ to z &lt; 3.4). In this Letter we constrain the rest-frame [O III]λ5007 equivalent width (EW) distribution for a sample of 76 1 &lt; z &lt; 3.4 SFGs in the A2744 Hubble Frontier Field and determine an abundance fraction of extreme emission line galaxies with EW &gt; 750Å in our sample to be 12%. We determine a strong correlation between the measured Hβ and [O III]λ5007 EWs, supporting that the high [O III]λ5007 EW objects require massive stars in young stellar populations to generate the high-energy photons needed to doubly ionize oxygen. We extracted spectra for objects up to 2 mag fainter in the near-infrared than previous WFSS studies with the Hubble Space Telescope. Thus, this work clearly highlights the potential of JWST/NIRISS to provide high-quality WFSS data sets in crowded cluster environments.

Keywords: Starburst galaxies, James Webb Space Telescope, Emission line galaxies
Early Results from GLASS-JWST. VII. Evidence for Lensed, Gravitationally Bound Protoglobular Clusters at z = 4 in the Hubble Frontier Field A2744. We investigate the blue and optical rest-frame sizes (λ ≃ 2300-4000 Å) of three compact star-forming regions in a galaxy at z = 4 strongly lensed (×30, ×45, and ×100) by the Hubble Frontier Field galaxy cluster A2744 using GLASS-ERS James Webb Space Telescope (JWST)/NIRISS imaging at 1.15 μm, 1.50 μm, and 2.0 μm with a point-spread function ≲0.″1. In particular, the Balmer break is probed in detail for all multiply imaged sources of the system. With ages of a few tens of Myr, stellar masses in the range (0.7-4.0) ×106 M ☉ and optical/ultraviolet effective radii spanning the interval 3 &lt; R  eff  &lt; 20 pc, such objects are currently the highest-redshift (spectroscopically confirmed) gravitationally bound young massive star clusters (YMCs), with stellar mass surface densities resembling those of local globular clusters. Optical (4000 Å, JWST-based) and ultraviolet (1600 Å, Hubble Space Telescope-based) sizes are fully compatible. The contribution to the ultraviolet underlying continuum emission (1600 Å) is ~30%, which decreases by a factor of 2 in the optical for two of the YMCs (~4000 Å rest-frame), reflecting the young ages (&lt;30 Myr) inferred from the spectral energy distribution fitting and supported by the presence of high-ionization lines secured with the Very Large Telescope/MUSE. Such bursty forming regions enhance the specific star formation rate of the galaxy, which is ≃10 Gyr-1. This galaxy would be among the extreme analogs observed in the local universe having a high star formation rate surface density and a high occurrence of massive stellar clusters in formation. *Based on observations collected with JWST under the ERS program 1324 (PI T. Treu).

Keywords: Young star clusters, High-redshift galaxies
Early Results from GLASS-JWST. VIII. An Extremely Magnified Blue Supergiant Star at Redshift 2.65 in the A2744 Cluster Field. We report the discovery of an extremely magnified star at redshift z = 2.65 in the James Webb Space Telescope (JWST) NIRISS pre-imaging of the A2744 galaxy-cluster field. The star's background host galaxy lies on a fold caustic of the foreground lens, and the cluster creates a pair of images of the region close to the lensed star. We identified the bright transient in one of the merging images at a distance of ~0.″15 from the critical curve by subtracting the JWST F115W and F150W imaging from coadditions of archival Hubble Space Telescope (HST) F105W and F125W images and F140W and F160W images, respectively. Since the time delay between the two images should be only hours, the transient must be the microlensing event of an individual star, as opposed to a luminous stellar explosion that would persist for days to months. Analysis of individual exposures suggests that the star's magnification is not changing rapidly during the observations. From photometry of the point source through the F115W, F150W, and F200W filters, we identify a strong Balmer break, and modeling allows us to constrain the star's temperature to be approximately 7000-12,000 K.

Keywords: Gravitational microlensing, Galaxy clusters, Gravitational lensing
A Long Time Ago in a Galaxy Far, Far Away: A Candidate z ∼ 12 Galaxy in Early JWST CEERS Imaging. We report the discovery of a candidate galaxy with a photo-z of z ~ 12 in the first epoch of the James Webb Space Telescope (JWST) Cosmic Evolution Early Release Science Survey. Following conservative selection criteria, we identify a source with a robust z phot = ${11.8}_{-0.2}^{+0.3}$ (1σ uncertainty) with m F200W = 27.3 and ≳7σ detections in five filters. The source is not detected at λ &lt; 1.4 μm in deep imaging from both Hubble Space Telescope (HST) and JWST and has faint ~3σ detections in JWST F150W and HST F160W, which signal a Lyα break near the red edge of both filters, implying z ~ 12. This object (Maisie's Galaxy) exhibits F115W - F200W &gt; 1.9 mag (2σ lower limit) with a blue continuum slope, resulting in 99.6% of the photo-z probability distribution function favoring z &gt; 11. All data-quality images show no artifacts at the candidate's position, and independent analyses consistently find a strong preference for z &gt; 11. Its colors are inconsistent with Galactic stars, and it is resolved (r  h  = 340 ± 14 pc). Maisie's Galaxy has log M */M ⊙ ~ 8.5 and is highly star-forming (log sSFR ~ -8.2 yr-1), with a blue rest-UV color (β ~ -2.5) indicating little dust, though not extremely low metallicity. While the presence of this source is in tension with most predictions, it agrees with empirical extrapolations assuming UV luminosity functions that smoothly decline with increasing redshift. Should follow-up spectroscopy validate this redshift, our universe was already aglow with galaxies less than 400 Myr after the Big Bang.

Keywords: Early universe, Galaxy formation, Galaxy evolution
The Periodic Signals of Nova V1674 Herculis (2021). We present time-series photometry during the early decline phase of the extremely fast nova V1674 Herculis. The 2021 light curve showed periodic signals at 0.152921(3) days and 501.486(5) s, which we interpret as respectively the orbital and white dwarf spin periods in the underlying binary. We also detected a sideband signal at the difference frequency between these two clocks. During the first 15 days of outburst, the spin period appears to have increased by 0.014(1)%. This increase probably arose from the sudden loss of high-angular-momentum gas ("the nova explosion") from the rotating, magnetic white dwarf. Both periodic signals appeared remarkably early in the outburst, which we attribute to the extreme speed with which the nova evolved (and became transparent to radiation from the inner binary). After that very fast initial period increase of 71 ms, the period subsequently decreased-at 182(18) ms yr-1 in 2021, and 88(18) ms yr-1 in 2022. These rates are ~100× faster than typically seen in intermediate polars. This could be due to high accretion torques from very high mass-transfer rates, which might be common when low-mass donor stars are strongly irradiated by a nova outburst.

Keywords: Close binary stars, Interacting binary stars, Novae, Recurrent novae, Stellar accretion, Stellar accretion disks, Cataclysmic variable stars, Classical novae
Solar Flare Forecast Using 3D Convolutional Neural Networks. Solar flares are immense energy explosions in the solar atmosphere and severely influence space weather. So, forecasting solar flare eruptions is extremely important. Spatial distribution and evolution of active region (AR) magnetic fields are closely related to flare eruptions. In this paper, we simultaneously utilized the two characteristics to build two flare-forecast models using three-dimensional convolutional neural networks (3D CNNs). The two models forecast whether an AR would erupt a ≥C- or ≥M-class flare within the next 24 hr, respectively. The magnetogram sequences provided by the Space-weather Helioseismic and Magnetic Imager Active Region Patches are selected to train our models. We used several performance metrics, such as true skill statistics (TSS), to evaluate our models. The TSS scores of the ≥C and ≥M models reach 0.756 and 0.826, respectively, indicating that our models have superior forecast performance. We used the the gradient-weighted class activation mapping (Grad-CAM) method to visually explain our flare-forecast models. The Grad-CAM illustrates that the 3D CNNs may extract the spatial distribution and evolution of AR magnetic fields simultaneously for flare forecasts. So, the 3D CNN method is valid for flare forecasts, and it utilizes the characteristics related to flare eruptions.

Keywords: Solar flares
Constraining Sterile Neutrino Dark Matter in the Milky Way Halo with Swift-XRT. We present a search for sterile neutrino dark matter decay signals in the Milky Way's dark matter halo by considering the entirety of the Swift X-ray Telescope (Swift-XRT) data archive. After filtering the raw archive, we analyze a ~77 Ms data set containing the full field of view, as well as a ~41 Ms data set with point sources excised using the Swift-XRT Point Source catalog. We report nondetections of emission lines across the 3-6 keV continuum in both data sets, including at and around 3.5 keV. The point-source-excised data set is found to have higher sensitivity to faint dark matter decay signals due to its freedom from point-source contamination and is thus used to set constraints. Nondetections across the total data set's continuum are used to constrain the sterile neutrino dark matter parameter space, marginally strengthening existing X-ray constraints. Nondetections at ~3.5 keV in data subsets grouped by angular distance from the galactic center are used to constrain the 3.5 keV line's galactic intensity profile, providing the strongest constraints to date across ~1/4 of the galaxy.

Keywords: Warm dark matter, Milky Way dark matter halo, X-ray astronomy, Cosmology, High energy astrophysics, Neutrino astronomy, Observational cosmology, Dark matter density, Cosmological neutrinos, Diffuse x-ray background, Dark matter, Particle astrophysics
First Detection of the Molecular Cloud Population in the Extended Ultraviolet Disk of M83. We report a CO(J = 3‑2) detection of 23 molecular clouds in the extended ultraviolet (XUV) disk of the spiral galaxy M83 with the Atacama Large Millimeter/submillimeter Array. The observed 1 kpc2 region is at about 1.24 times the optical radius (R 25) of the disk, where CO(J = 2–1) was previously not detected. The detection and nondetection, as well as the level of star formation (SF) activity in the region, can be explained consistently if the clouds have the mass distribution common among Galactic clouds, such as Orion A—with star-forming dense clumps embedded in thick layers of bulk molecular gas, but in a low-metallicity regime where their outer layers are CO-deficient and CO-dark. The cloud and clump masses, estimated from CO(3‑2), range from 8.2 × 102 to 2.3 × 104 M ⊙ and from 2.7 × 102 to 7.5 × 103 M ⊙, respectively. The most massive clouds appear similar to Orion A in star formation activity as well as in mass, as expected if the cloud mass structure is common. The overall low SF activity in the XUV disk could be due to the relative shortage of gas in the molecular phase. The clouds are distributed like chains up to 600 pc (or longer) in length, suggesting that the trigger of cloud formation is on large scales. The common cloud mass structure also justifies the use of high-J CO transitions to trace the total gas mass of clouds, or galaxies, even in the high-z universe. This study is the first demonstration that CO(3‑2) is an efficient tracer of molecular clouds even in low-metallicity environments.

Keywords: Spiral galaxies, Molecular clouds, Star formation, Galaxy evolution, Interstellar medium
Repeated Mergers of Black Hole Binaries: Implications for GW190521. The gravitational wave event GW190521 involves the merger of two black holes of ~85 M ⊙ and ~66 M ⊙ forming an intermediate-mass black hole (IMBH) of mass ~142 M ⊙. Both progenitors are challenging to explain within standard stellar evolution as they are within the upper black hole mass gap. We propose a dynamical formation pathway for this IMBH based on multiple mergers in the core of a globular cluster. We identify such scenarios from analysis of a set of 58 N-body simulations using NBODY6-gpu. In one of our simulations, we observe a stellar black hole undergoing a chain of seven binary mergers within 6 Gyr, attaining a final mass of 97.8 M ⊙. We discuss the dynamical interactions that lead to the final IMBH product, as well as the evolution of the black hole population in that simulation. We explore statistically the effects of gravitational recoil on the viability of such hierarchical mergers. From the analysis of all 58 simulations we observe additional smaller chains, tentatively inferring that an IMBH formation through hierarchical mergers is expected in the lifetime of a median-mass globular cluster with probability 0.01 ≲ p ≲ 0.1 without gravitational merger recoil. Using this order-of-magnitude estimate we show that our results are broadly consistent with the rate implied by GW190521, assuming that gravitational recoil ejection of progenitors has a low probability. We discuss implications for future gravitational wave detections, emphasizing the importance of studying such formation pathways for black holes within the upper mass gap as a means to constrain such modeling.

Keywords: Globular star clusters, Black hole physics, Intermediate-mass black holes, Stellar mergers, Gravitational wave sources, N-body simulations
Star Formation History and Transition Epoch of Cluster Galaxies Based on the Horizon-AGN Simulation. Cluster galaxies exhibit substantially lower star formation rates than field galaxies today, but it is conceivable that clusters were sites of more active star formation in the early universe. Herein, we present an interpretation of the star formation history (SFH) of group/cluster galaxies based on the large-scale cosmological hydrodynamic simulation, Horizon-AGN. We find that massive galaxies in general have small values of e-folding timescales of star formation decay (i.e., "mass quenching") regardless of their environment, while low-mass galaxies exhibit prominent environmental dependence. In massive host halos (i.e., clusters), the e-folding timescales of low-mass galaxies are further decreased if they reside in such halos for a longer period of time. This "environmental quenching" trend is consistent with the theoretical expectation from ram pressure stripping. Furthermore, we define a "transition epoch" as where cluster galaxies become less star-forming than field galaxies. The transition epoch of group/cluster galaxies varies according to their stellar and host-cluster halo masses. Low-mass galaxies in massive clusters show the earliest transition epoch of ~7.6 Gyr ago in lookback time. However, this decreases to ~5.2 Gyr for massive galaxies in low-mass clusters. Based on our findings, we can describe a cluster galaxy's SFH with regard to the cluster halo-to-stellar mass ratio.

Keywords: Galaxy clusters, Galaxy quenching, Galaxy evolution
Discovery of a Filamentary Synchrotron Structure Connected to the Coherent Magnetic Field in the Outer Galaxy. Using data from the Galactic Arecibo L-band Feed Array Continuum Transit Survey, we report the discovery of two previously unidentified, very compressed, thin, and straight polarized filaments approximately centered at Galactic coordinates, (l, b) = (182.°5, - 4.°0), which we call G182.5-4.0. Using data from the Isaac Newton Telescope Galactic Plane Survey, we also find straight, long, and extremely thin Hα filaments coincident with the radio emission. These filaments are positioned in projection at the edge of the Orion-Eridanus superbubble and we find evidence indicating that the filaments align with the coherent magnetic field of the outer Galaxy. We find a lower limit on the total radio flux at 1.4 GHz to be 0.7 ± 0.3 Jy with an average linearly polarized fraction of ${40}_{-20}^{+30} \% $ . We consider various scenarios that could explain the origin of these filaments, including a shell-type supernova remnant (SNR), a bow shock nebula associated with a pulsar, or relic fragments from one or more supernova explosions in the adjacent superbubble, with a hybrid scenario being most likely. This may represent an example of a new class of objects that is neither an SNR nor a bow shock. The highly compressed nature of these filaments and their alignment with the Galactic plane suggests a scenario where this object formed in a magnetic field that was compressed by the expanding Orion-Eridanus superbubble, suggesting that the object is related to this superbubble and implying a distance of ~400 pc.

Keywords: Supernova remnants, Interstellar medium, Radio continuum emission
Mangrove: Learning Galaxy Properties from Merger Trees. Efficiently mapping baryonic properties onto dark matter is a major challenge in astrophysics. Although semianalytic models (SAMs) and hydrodynamical simulations have made impressive advances in reproducing galaxy observables across cosmologically significant volumes, these methods still require significant computation times, representing a barrier to many applications. Graph neural networks have recently proven to be the natural choice for learning physical relations. Among the most inherently graph-like structures found in astrophysics are the dark matter merger trees that encode the evolution of dark matter halos. In this paper, we introduce a new, graph-based emulator framework, Mangrove, and show that it emulates the galactic stellar mass, cold gas mass and metallicity, instantaneous and time-averaged star formation rate, and black hole mass-as predicted by an SAM-with an rms error up to 2 times lower than other methods across a (75 Mpc/h)3 simulation box in 40 s, 4 orders of magnitude faster than the SAM. We show that Mangrove allows for quantification of the dependence of galaxy properties on merger history. We compare our results to the current state of the art in the field and show significant improvements for all target properties. Mangrove is publicly available: https://github.com/astrockragh/Mangrove.

Keywords: Hydrodynamical simulations, Algorithms, Neural networks, Astrostatistics, N-body simulations, Galaxies