Sazuna/UAT_keywords huggingface dataset:
VODKA-JWST: Synchronized Growth of Two Supermassive Black Holes in a Massive Gas Disk? A 3.8 kpc Separation Dual Quasar at Cosmic Noon with the NIRSpec Integral Field Unit. The search for dual supermassive black holes (SMBHs) is of immense interest in modern astrophysics. Galaxy mergers may fuel and produce SMBH pairs. Actively accreting SMBH pairs are observed as dual quasars, which are vital probes of SMBH growth. Dual quasars at cosmic noon are not well characterized. Gaia observations have enabled a novel technique to identify dual quasars at kiloparsec scales based on the small jitters of the light centroid as the two quasars vary stochastically. We present the first detailed study of a z = 2.17, 0 46, 3.8 kpc separation dual quasar, J0749+2255, using JWST/NIRSpec integral field unit spectroscopy. Identified by Gaia, J0749+2255 is one of the most distant small-separation dual quasars known. We detect the faint ionized gas of the host galaxy, traced by the narrow Hα emission. Line ratios indicate ionization from the two quasars and from intense star formation. Spectral analysis of the two quasars suggests that they have similar black hole properties, hinting at the possible synchronized accretion activity or lensed quasar images. Surprisingly, the ionized gas kinematics suggest a rotating disk rather than the disturbed system expected in a major gas-rich galaxy merger. Numerical simulations show that this is a plausible outcome of a major gas-rich galaxy merger several tens of Myr before coalescence. Whether J0749+2255 reflects an interesting phase of dual quasar evolution or is a lensed quasar remains unclear. Thus, this study underscores the challenges in definitively distinguishing between dual and lensed quasars, with observations supporting either scenario.

Keywords: Double quasars, Supermassive black holes, James Webb Space Telescope, Active galactic nuclei, Galaxy mergers
On the Significance of Rare Objects at High Redshift: The Impact of Cosmic Variance. The discovery of extremely luminous galaxies at ultra-high redshifts (z ≳ 8) has challenged galaxy formation models. Most analyses of this tension have not accounted for the variance due to field-to-field clustering, which causes the number counts of galaxies to vary greatly in excess of Poisson noise. This super-Poissonian variance is often referred to as cosmic variance. Since cosmic variance increases rapidly as a function of mass, redshift, and smaller observing areas, the most massive objects in deep JWST surveys are severely impacted by cosmic variance. We construct a simple model, including cosmic variance, to predict the distribution of the mass of the most massive galaxy for different surveys, which increases the tension with observations. The distributions differ significantly from previous predictions using the Extreme Value Statistics formalism, changing the position and shape of the distributions. We test our model using the UniverseMachine simulations, where the predicted effects of cosmic variance are clearly identifiable. We find that the high skew in the distributions of galaxy counts for typical deep surveys imply a high statistical variance on the cosmic variance itself. This impacts the calibration of the cosmic variance, as well as the expected mass of the most massive galaxy. We also find that the impact of cosmic variance dominates the impact of any realistic scatter in the stellar-to-halo-mass relation at z ≳ 12. It is therefore crucial to accurately account for the impact of cosmic variance in any analysis of tension between early extreme galaxies and galaxy formation models.

Keywords: Galaxy formation, High-redshift galaxies, Galaxies, Astrostatistics
The Molecular Cloud Life Cycle. I. Constraining H<SUB>2</SUB> Formation and Dissociation Rates with Observations. Molecular clouds (MCs) are the birthplaces of new stars in galaxies. A key component of MCs are photodissociation regions (PDRs), where far-ultraviolet radiation plays a crucial role in determining the gas's physical and chemical state. Traditional PDR models assume a chemical steady state (CSS), where the rates of H2 formation and photodissociation are balanced. However, real MCs are dynamic and can be out of CSS. In this study, we demonstrate that combining H2 emission lines observed in the far-ultraviolet or infrared with column density observations can be used to derive the rates of H2 formation and photodissociation. We derive analytical formulae that relate these rates to observable quantities, which we validate using synthetic H2 line emission maps derived from the SILCC-Zoom hydrodynamical simulation. Our method estimates integrated H2 formation and dissociation rates with an accuracy ≈30% (on top of the uncertainties in the observed H2 emission maps and column densities). Our simulations, valid for column densities N ≤ 2 × 1022 cm‑2, cover a wide dynamic range of H2 formation and photodissociation rates, showing significant deviations from CSS, with 74% of the MC's mass deviating from CSS by a factor greater than 2. Our analytical formulae can effectively distinguish between regions in and out of CSS. When applied to actual H2 line observations, our method can assess the chemical states of MCs, providing insights into their evolutionary stages and lifetimes. A NASA Small Explorer mission concept, Eos, will be proposed in 2025 and is specifically designed to conduct the types of observations outlined in this study.

Keywords: Molecular gas, Astrosphere interstellar medium interactions, Molecular clouds, Ultraviolet spectroscopy, Astrochemistry, Star formation, Interstellar medium, Diffuse interstellar clouds
Accretion-disk Reflection in the Seyfert 1 Galaxy NGC 3783 as Viewed by Chandra Grating Spectroscopy. In active galactic nuclei, X-ray illumination of the accretion disk around a supermassive black hole (SMBH) results in the production of the Kα fluorescent line of iron, which provides insights into accretion physics and SMBH spins. In this work, we studied X-ray reflection from the accretion disk in the Seyfert 1 galaxy NGC 3783 using all the data collected by the Chandra High Energy Transmission Grating Spectrometer. We used hardness-ratio diagrams to distinguish between different spectral states and conducted spectral analysis of all the multiepoch data sets, as well as the source in the observed spectral states. Our hardness analysis indicates that the source gradually evolved into a harder state (2013–2016) compared to the previous epochs (2000–2001). Our spectral modeling implies that the relativistically broadened iron emission from the innermost accretion disk is associated with a near-maximal SMBH spin ( ) in all the data sets, even though the hard state was present in 17% of them, and a consistent spin is also found in different spectral states. In addition, the narrow, bright Fe Kα line from distant regions has an excess velocity of   km s‑1 relative to the rest frame, implying that some distant layers of the disk could be twisted. Our results suggest that, despite long-term changes in the X-ray brightness of NGC 3783, likely caused by eclipsing material, the relativistic reflection can be constrained thanks to the substantial counts provided by the multiepoch observations, while a warped disk structure may be present.

Keywords: X-ray sources, Active galactic nuclei, Relativistic disks
The TRGB–SBF Project. II. Resolving the Virgo Cluster with JWST. The Virgo Cluster is the nearest substantial cluster of galaxies to the Milky Way and a cornerstone of the extragalactic distance scale. Here, we present JWST/NIRCam observations that simultaneously cover the cores and halos of 10 galaxies in and around the Virgo Cluster and are designed to perform simultaneous measurements of the tip of the red giant branch (TRGB) and surface brightness fluctuations (SBF). Seven of the targets are within the Virgo Cluster and where we are able to resolve some of the cluster's substructure, while an additional three provide important constraints on Virgo infall. The seven galaxies within Virgo itself all have SBF measurements from the Advanced Camera for Surveys Virgo Cluster Survey (ACSVCS). After adjusting the ACSVCS measurements for the offset from our new JWST TRGB measurements, we determine a distance to the Virgo Cluster of d = 16.17 ± 0.25 (stat) ± 0.47 (sys) Mpc. The work presented here is part of a larger program to develop a Population II distance scale through the TRGB and SBF that is completely independent of the prominent Cepheid + Type Ia supernova ladder. The TRGB distances to the galaxies presented here, when combined with future SBF measurements, will provide a crucial step forward for determining whether or not systematic errors can explain the well-known "Hubble tension" or if there is significant evidence for cracks in the ΛCDM model.

Keywords: Red giant tip, Galaxy distances, Virgo Cluster, Distance indicators, Stellar distance, Elliptical galaxies
The Physical Origin of Extreme Emission Line Galaxies at High Redshifts: Strong [O III] Emission Lines Produced by Obscured Active Galactic Nuclei. We present deep Subaru/FOCAS spectra for two extreme emission line galaxies (EELGs) at z ∼ 1 with strong [O III] λ5007 emission lines, exhibiting equivalent widths (EWs) of   Å and   Å, comparable to those of EELGs at high redshifts that are now routinely identified with JWST spectroscopy. Adding a similarly large [O III] EW (  Å) EELG found at z ∼ 2 in the JWST CEERS survey to our sample, we explore the physical origins of the large [O III] EWs of these three galaxies with the Subaru spectra and various public data including JWST/NIRSpec, NIRCam, and MIRI data. While there are no clear signatures of active galactic nuclei (AGNs) identified by the optical line diagnostics, we find that two out of two galaxies covered by the MIRI data show strong near-infrared excess in the spectral energy distributions (SEDs), indicating obscured AGNs. Because none of the three galaxies show clear broad Hβ lines, the upper limits on the flux ratios of broad Hβ to [O III] lines are small, ≲0.15 that are comparable with Seyfert 1.8–2.0 galaxies. We conduct Cloudy modeling with the stellar and AGN incident spectra, allowing a wide range of parameters, including metallicities and ionization parameters. We find that the large [O III] EWs are not self-consistently reproduced by the spectra of stars or unobscured AGNs, but obscured AGNs that efficiently produce O++ ionizing photons with weak nuclear and stellar continua that are consistent with the SED shapes.

Keywords: Active galactic nuclei, Emission line galaxies
Revisiting the Galactic Winds in M82. II. Development of Multiphase Outflows in Simulations. We performed a suit of three-dimensional hydrodynamical simulations with a resolution of ~10 pc to investigate the development of multiphase galactic wind in M82. The star formation and related feedback processes are solved self-consistently using a sink particle method, rather than relying on various assumptions that were used in previous studies. Our simulations produce a starburst event lasting around 25 Myr, which has a total stellar mass of 1.62─3.34 × 108 M⊙, consistent with observational estimates. The total injected supernova energy is between 1.14 × 1057 and 2.4 × 1057 erg. Supernova feedback heats portions of the cool gas in the central disk to warm and hot phases, and then drives the gas in all three phases out, eventually forming multiphase outflows. These outflows can replicate key properties of the winds observed in M82, such as morphology, mass outflow rates of cool and hot phases, and X-ray emission flux, provided the gas return from star-forming clumps to the diffuse interstellar medium is implemented appropriately. The maximum mass outflow rate of all gas (hot) is about 6─12 (2─3) M⊙ yr−1 at r ~ 4.0 kpc, corresponding to a mass loading factor of 2─4. However, the outflow velocities in our simulations are slower than observational estimates by ~20%─60%. The gas return process significantly influences the outflow properties, while the initial gas distribution in the nuclear region has a moderate effect. Yet, our results face some challenges in achieving convergence as the resolution increases. We discuss potential improvements to address these issues in future work.

Keywords: Galactic winds, Starburst galaxies, Hydrodynamical simulations, Stellar feedback, Galaxy evolution, Circumgalactic medium
The Response of Planetary Atmospheres to the Impact of Icy Comets. I. Tidally Locked Exo-Earths. Impacts by rocky and icy bodies are thought to have played a key role in shaping the composition of solar system objects, including the Earth's habitability. Hence, it is likely that they play a similar role in exoplanetary systems. We investigate how an icy cometary impact affects the atmospheric chemistry, climate, and composition of an Earth-like, tidally locked, terrestrial exoplanet, a prime target in the search for a habitable exoplanet beyond our solar system. We couple a cometary impact model, which includes thermal ablation and pressure driven breakup, with the 3D Earth system model WACCM6/CESM2 and use this model to investigate the effects of the water and thermal energy delivery associated with an R = 2.5 km pure water ice cometary impact on an Earth-like atmosphere. We find that water is the primary driver of longer timescale changes to the atmospheric chemistry and composition by acting as a source of opacity, cloud ice, and atmospheric hydrogen/oxygen. The water opacity drives heating at ∼5 × 10‑4 bar and cooling below, due to a decreased flux reaching the surface. The increase in atmospheric hydrogen and oxygen also drives an increase in the abundance of hydrogen/oxygen-rich molecules, with the exception of ozone, whose column density decreases by ∼10%. These atmospheric changes are potentially observable for ∼1–2 yr postimpact, particularly those associated with cloud ice scattering. They also persist, albeit at a much reduced level, to our quasi–steady state, suggesting that sustained bombardment or multiple large impacts have the potential to shape the composition and habitability of terrestrial exoplanets.

Keywords: Atmospheric composition, Computational astronomy, Atmospheric dynamics, Exoplanet atmospheres
Relight the Candle: What Happens to High-redshift Massive Quenched Galaxies. A puzzling population of extremely massive quiescent galaxies at redshifts beyond z = 3 has recently been revealed by JWST and the Atacama Large Millimeter/submillimeter Array, some of them with stellar ages that show their quenching times to be as high as z = 6, while their stellar masses are already above 5 × 1010 M ⊙. These extremely massive yet quenched galaxies challenge our understanding of galaxy formation at the earliest stages. Using the hydrodynamical cosmological simulation suite Magneticum Pathfinder, we show that such massive quenched galaxies at high redshifts can be successfully reproduced with similar number densities as observed. The stellar masses, sizes, formation redshifts, and star formation histories of the simulated quenched galaxies match those determined with JWST. Following these quenched galaxies at z = 3.4 forward in time, we find 20% to be accreted onto a more massive structure by z = 2, and from the remaining 80% about 30% rejuvenate up to z = 2, another 30% stay quenched, and the remaining 40% rejuvenate on a very low level of star formation. Stars formed through rejuvenation are mostly formed on the outer regions of the galaxies, not in the centers. Furthermore, we demonstrate that the massive quenched galaxies do not reside in the most massive nodes of the cosmic web, but rather live in side nodes of approximately Milky Way halo mass. Even at z = 0, only about 10% end up in small-mass galaxy clusters, while most of the quenched galaxies at z = 3.4 end up in group-mass halos, with about 20% actually not even reaching 1013 M ⊙ in halo mass.

Keywords: Quenched galaxies, Computational methods, Galaxy evolution, High-redshift galaxies, Galaxies
DDO 68-C: HST Confirms Yet Another Companion of the Isolated Dwarf Galaxy DDO 68. We present the results of deep Hubble Space Telescope photometry of the dwarf galaxy DDO 68-C, proposed as possibly associated with the isolated peculiar dwarf DDO 68. The new data resolve for the first time the stars of DDO 68-C down to well below the tip of the red giant branch (RGB), revealing a low-mass (M⋆ ≃ 1.5 × 107 M⊙) star-forming galaxy with a backbone of old stars. By means of a fully homogeneous analysis and using the RGB tip as a standard candle, we find that DDO 68 and DDO 68-C lie at the same distance from us, within the uncertainties (D = 12.6 ± 0.3 Mpc and D = 12.7 ± 0.4 Mpc, respectively), thus confirming that the two dwarfs are physically associated. While paired dwarf galaxies with a mutual projected distance similar to DDO 68 and DDO 68-C are not exceptional in the Lynx-Cancer void where they live, DDO 68 remains a unicum as, in addition to the newly confirmed companion, it records the evidence of at least two other satellites.

Keywords: Dwarf galaxies, Galaxy interactions
A Search for Low-frequency Radio Pulses from Long Gamma-Ray Bursts with the Murchison Widefield Array. It has been proposed that coherent radio emission could be emitted during or shortly following a gamma-ray burst (GRB). Here we present a low-frequency (170–200 MHz) search for radio pulses associated with long-duration GRBs using the Murchison Widefield Array (MWA). The MWA, with its rapid-response system, is capable of performing GRB follow-up observations within approximately 30 s. Our single pulse search, with temporal and spectral resolutions of 100 μs and 10 kHz, covers dispersion measures up to 5000 pc cm‑3. Two single pulse candidates are identified with significance greater than 6σ, surviving a friends-of-friends analysis. We rule out random fluctuations as their origin at a confidence level of 97% (2.2σ). We caution that radio frequency interference from digital TV (DTV) is most likely the origin of these pulses since the DTV frequency bands almost cover the entire observing frequency band. If they are astrophysical signals, we estimate the peak flux densities for our pulse candidates of 3.6 ± 0.6 and 10.5 ± 1.5 Jy, with corresponding fluences of 431 ± 74 and 211 ± 37 Jy ms, respectively. Based on these observations and the assumption of a magnetar origin for the pulse, we constrain the radio emission efficiency as ϵr ∼ 10‑3 for both candidates, which is consistent with pulsar observations. Our results highlight the promising potential of new-generation radio telescopes such as the MWA to probe the central engines of GRBs.

Keywords: Gamma-ray bursts, Radio bursts, Non-thermal radiation sources, Magnetars, Radio interferometry, Radio transient sources
Scylla. IV. Intrinsic Stellar Properties and Line-of-sight Dust Extinction Measurements toward 1.5 Million Stars in the SMC and LMC. By analyzing the spectral energy distributions (SEDs) of resolved stars in nearby galaxies, we can constrain their stellar properties and line-of-sight dust extinction. From the Scylla survey, we obtain ultraviolet to near-infrared photometry from Wide Field Camera 3 on board the Hubble Space Telescope for more than 1.5 million stars in the SMC and LMC. We use the Bayesian Extinction and Stellar Tool (BEAST) to analyze the multiband SEDs of these sources and characterize their initial masses, ages, metallicities, distances, and line-of-sight extinction properties (e.g., AV, RV). We apply quality cuts and perform validation simulations to construct a catalog of over 550,000 stars with high-reliability SED fits, which we use to analyze the stellar content and extinction properties of the SMC and LMC. We detect stars with masses as low as 0.6 M⊙. BEAST stellar age distributions show a jump in observed stars around 6 Gyr ago, which agrees with star formation histories. Extinctions (AV) in both galaxies follow a log-normal distribution. We compare AV with ancillary gas and dust tracers like H I, Hα, and far-infrared (FIR) dust emission and find positive correlations on a field-by-field basis. We convert observed AV to predicted dust surface densities using the Draine et al. model and find AV-based dust surface densities are a factor of ∼2.5 lower than observed FIR-based dust surface densities, a correction factor similar to other studies.

Keywords: Stellar populations, Hubble Space Telescope, Magellanic Clouds, Interstellar medium
Cyclic C<SUB>4</SUB><SUP>+</SUP> as the Carrier of the Diffuse Interstellar Band at 503.9 nm?. The diffuse interstellar bands (DIBs) have remained a mystery in astronomy since their discovery over a century ago. The only currently known carrier is  , responsible for five DIBs, while more than 550 are yet to be interpreted. The spectra of short carbon chain cations  , which are considered one of the most promising classes of species for the role of carriers of DIBs, are successfully recorded using He-tagging spectroscopy. The comparison of laboratory spectra with observations demonstrates a close match of two absorption bands of   with the broad DIB at 503.9 nm. This defines a high abundance of these ions in the interstellar medium (ISM), which should exceed those of other similar-sized carbon chain cations. It is anticipated that all other short carbon chain cations will exhibit linear geometry and, as a consequence, will have a long vibrational progression. However, the distinctive cyclic geometry of   is postulated to underpin the elevated abundance of these ions in the ISM, as well as the distinctive spectrum of this ion, which displays a single, strong, relatively narrow absorption band that exceeds in intensity all other absorption bands in the visible range.

Keywords: Diffuse interstellar bands
Estimation of Transit Time of CMEs from the Sun to Earth. Coronal mass ejections (CMEs) can cause severe geomagnetic storms on Earth, making it essential to forecast their arrival. However, predicting the transit time (TT) of Earth-directed CMEs is challenging due to the complex factors involved, such as CME dynamics, the state of the interplanetary medium, and CME interactions. Our goal is to predict the TT of Earth-directed CMEs without relying on computationally expensive methods. CMEs observed from L1 are significantly affected by projection effects, which underestimate their speed and overestimate their size and mass. To address this, we use the Solar TErrestrial RElations Observatory (STEREO) to study the kinematics of halo and partial halo CMEs in quadrature and near-quadrature configurations. We analyzed a data set of 44 Earth-directed CMEs, dividing it into two categories: 25 CMEs in STEREO's quadrature field of view (FOV) and 19 CMEs in the near-quadrature FOV. Three different proxies were used to prepare empirical models for estimating TT. Our findings indicate that, for the considered sample of events, the empirical model based on the maximum speed of CMEs observed in STEREO's FOV yields the most accurate TT estimates. Our model achieved a maximum error of 16.46 hr and a mean error of 7.25 hr in estimating the TT of 44 Earth-directed CMEs.

Keywords: Space weather