Sazuna/UAT_keywords huggingface dataset:
Constraining the Excitation of Molecular Gas in Two Quasar-starburst Systems at z ∼ 6. We present NOrthern Extended Millimeter Array observations of CO(8─7), (9─8), and (10─9) lines, as well as the underlying continuum for two far-infrared luminous quasars: SDSS J2054-0005 at z = 6.0389 and SDSS J0129-0035 at z = 5.7788. Both quasars were previously detected in CO (2─1) and (6─5) transitions, making them candidates for studying the CO spectral line energy distribution (SLED) of quasars at z ∼ 6. Utilizing the radiative transfer code CLOUDY, we fit the CO SLED with two heating mechanisms, including the photodissociation region (PDR) and X-ray-dominated region (XDR) for both objects. The CO SLEDs can be fitted by either a dense PDR component with an extremely strong far-ultraviolet radiation field (gas density n H ∼ 106 cm−3 and field strength G 0 ≳ 106) or a two-component model including a PDR and an XDR. However, the line ratios, including L TIR and previous [C II]158 μm and [C I]369 μm measurements, argue against a very high PDR radiation field strength. Thus, the results prefer a PDR+XDR origin for the CO SLED. The excitation of the high-J CO lines in both objects is likely dominated by the central active galactic nucleus (AGN). We then check the CO (9─8)-to-(6─5) line luminosity ratio r 96 for all z ∼ 6 quasars with available CO SLEDs (seven in total) and find that there are no clear correlations between r 96 and both L FIR and the AGN UV luminosities. This further demonstrates the complexity of the CO excitation powered by both the AGN and nuclear star formation in these young quasar host galaxies.

Keywords: AGN host galaxies, Molecular gas, Quasars, Submillimeter astronomy, Galaxies
Exact Nonlinear Decomposition of Ideal-MHD Waves Using Eigenenergies. II. Fully Analytical Equations and Pseudoadvective Eigenenergies. Physical insight into plasma evolution in the magnetohydrodynamic (MHD) limit can be revealed by decomposing the evolution according to the characteristic modes of the system. In this paper we explore aspects of the eigenenergy decomposition method (EEDM) introduced in an earlier study (ApJ, 967:80). The EEDM provides an exact decomposition of nonlinear MHD disturbances into their component eigenenergies associated with the slow, Alfvén, and fast eigenmodes, together with two zero-frequency eigenmodes. Here we refine the EEDM by presenting globally analytical expressions for the eigenenergies. We also explore the nature of the zero-frequency "pseudoadvective (PA) modes" in detail. We show that in evolutions with pure advection of magnetic and thermal energy (without propagating waves), a part of the energy is carried by the PA modes. Exact expressions for the error terms associated with these modes—commonly encountered in numerical simulations—are also introduced. The new EEDM equations provide a robust tool for the exact and unique decomposition of nonlinear disturbances governed by homogeneous quasi-linear partial differential equations, even in the presence of local or global degeneracies.

Keywords: Magnetohydrodynamics, Solar physics, Solar coronal waves, Alfven waves, Magnetohydrodynamical simulations
Investigating Differences in the Palomar-Green Blazar Population Using Polarization. We present polarization images with the Karl G. Jansky Very Large Array (VLA) in A- and B-array configurations at 6 GHz of seven radio-loud (RL) quasars and eight BL Lac objects belonging to the Palomar-Green (PG) "blazar" sample. This completes our arcsecond-scale polarization study of an optically selected volume-limited blazar sample comprising 16 radio-loud quasars and 8 BL Lac objects. Using the VLA, we identify kiloparsec-scale polarization in the cores and jets/lobes of all the blazars, with fractional polarization varying from around 0.8% ± 0.3% to 37% ± 6%. The kiloparsec-scale jets in PG RL quasars are typically aligned along their parsec-scale jets and show apparent magnetic fields parallel to jet directions in their jets/cores and magnetic field compression in their hot spots. The quasars show evidence of interaction with their environment as well as restarted active galactic nucleus activity through morphology, polarization, and spectral indices. These quasi-periodic jet modulations and restarted activity may be indicative of an unstable accretion disk undergoing transition. We find that the polarization characteristics of the BL Lacs are consistent with their jets being reoriented multiple times, with no correlation between their core apparent magnetic field orientations and parsec-scale jet directions. We find that the low synchrotron peaked BL Lacs show polarization and radio morphology features typical of "strong" jet sources as defined by E. T. Meyer et al. for the "blazar envelope scenario," which posits a division based on jet profiles and velocity gradients rather than total jet power.

Keywords: BL Lacertae objects, Radio jets, Quasars, Blazars, Active galaxies, Polarimetry
Realistic Outcomes of Moon–Moon Collisions in Lunar Formation Theory. The multiple impact hypothesis proposes that the Moon formed through a series of smaller collisions, rather than a single giant impact. This study advances our understanding of this hypothesis, as well as moon collisions in other contexts, by exploring the implications of these smaller impacts, employing a novel methodological approach that combines self-consistent initial conditions, hybrid hydrodynamic/N-body simulations, and the incorporation of material strength. Our findings challenge the conventional assumption of perfect mergers in previous models, revealing a spectrum of collision outcomes including partial accretion and mass loss. These outcomes are sensitive to collision parameters and the Earth's tidal influence, underscoring the complex dynamics of lunar accretion. Importantly, we demonstrate that incorporating material strength is important for accurately simulating moonlet-sized impacts. This inclusion significantly affects fragmentation, tidal disruption, and the amount of material ejected or accreted onto the Earth, ultimately impacting the Moon's growth trajectory. By accurately modeling diverse collision outcomes, our hybrid approach provides a powerful new framework for understanding the Moon's formation. We show that most collisions (≈90%) do not significantly erode the largest moonlet, supporting the feasibility of lunar growth through accretion. Moreover, we revise previous estimates of satellite disruption, suggesting a higher survival rate and further bolstering the multiple-impact scenario.

Keywords: Hydrodynamical simulations, Lunar theory, Lunar origin, The Moon, Lunar impacts, Earth-moon system, N-body simulations, Planet formation, Solar system astronomy
Radio Active Galactic Nuclei Activity in Low Redshift Galaxies Is Not Directly Related to Star Formation Rates. We examine the demographics of radio-emitting active galactic nuclei (AGN) in the local Universe as a function of host galaxy properties, most notably both stellar mass (M ⋆) and star formation rate (SFR). Radio AGN activity is theoretically implicated in helping reduce the SFR of galaxies, and therefore it is natural to investigate the relationship between these two galaxy properties. We use the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) optical IFU catalog in conjunction with the NVSS and Faint Images of the Radio Sky at Twenty radio catalogs. MaNGA's high precision determinations of SFR allow us to impose a clean cut to reliably identify radio AGN from star formers. Using this sample of AGN, the well-measured stellar velocity dispersions from MaNGA, and the black hole M–σ relationship, we examine the Eddington ratio distribution (ERD) and its dependence on M ⋆ and SFR. We find that the ERD depends strongly on M ⋆, with more massive galaxies having larger Eddington ratios (λ). Interpreting our model fit to the data leads to a completeness-corrected estimate of F AGN(λ &gt; 0.001), the fraction of galaxies with radio AGN with λ &gt; 0.001. At  , we estimate F AGN = 0.02. The AGN fraction increases rapidly with M ⋆, and at  , we estimate F AGN ∼ 0.24. We do not find any dependence on SFR, specific star formation rate, or velocity dispersion when controlling for stellar mass. We conclude that galaxy SFRs appear to be unrelated to the presence or absence of a radio AGN, which may be useful in constraining theoretical models of AGN feedback.

Keywords: Radio active galactic nuclei, Star formation, Stellar masses, AGN host galaxies
Rethinking Thorne–Żytkow Object Formation: The Fate of X-Ray Binary LMC X-4 and Implications for Ultra-long Gamma-Ray Bursts. We present a start-to-end simulation aimed at studying the long-term fate of high-mass X-ray binaries and whether a Thorne–Żytkow object (TŻO) might ultimately be assembled. We analyze results from a 3D hydrodynamical simulation that models the eventual fate of LMC X-4, a compact high-mass X-ray binary system, after the primary fills its Roche lobe and engulfs the neutron star companion. We discuss the outcome of this engulfment within the standard paradigm of TŻO formation. The post-merger angular momentum content of the stellar core is a key ingredient, as even a small amount of rotation can break spherical symmetry and produce a centrifugally supported accretion disk. Our findings suggest the inspiraling neutron star, upon merging with the core, can accrete efficiently via a disk at high rates (≈10‑2 M ⊙ s‑1), subsequently collapsing into a black hole and triggering a bright transient with a luminosity and duration typical of an ultra-long gamma-ray burst. We propose that the canonical framework for TŻO formation via common envelope needs to be revised, as the significant post-merger accretion feedback will unavoidably unbind the vast majority of the surrounding envelope.

Keywords: Hydrodynamical simulations, Stellar interiors, X-ray binary stars, Gamma-ray bursts, Late stellar evolution, Stellar mergers, Close binary stars, High mass x-ray binary stars, Transient sources, Interacting binary stars
GRB 211024B: An Ultra-long GRB Powered by Magnetar. Ultra-long gamma-ray bursts are characterized by exceptionally long-duration central engine activities, with characteristic timescales exceeding 1000 s. We present ground-based optical afterglow observations of the ultra-long gamma-ray burst GRB 211024B, detected by Swift. Its X-ray light curve exhibits a characteristic "internal plateau" with a shallow decay phase lasting approximately ∼15 ks, followed by a steep decline (α drop ∼ −7.5). Moreover, the early optical emission predicted by the late r-band optical afterglow is significantly higher than the observed value, indicating an external shock with energy injection. To explain these observations, we propose a magnetar central engine model. The magnetar collapses into a black hole due to spin-down or hyperaccretion, leading to the observed steep break in the X-ray light curve. The afterglow model fitting reveals that the afterglow injection luminosity varies with different assumptions of the circumburst medium density, implying different potential energy sources. For the interstellar medium case with a fixed injection end time, the energy may originate from the magnetar's dipole radiation. However, in other scenarios, relativistic jets produced by the magnetar/black hole system could be the primary energy source.

Keywords: Gamma-ray bursts, Transient sources
The SUPERCOLD-CGM Survey. II. [C I](1–0) Emission and the Physical Conditions of Cold Gas in Enormous Lyα Nebulae at z ∼ 2. We report Atacama Large Millimeter/submillimeter Array and Atacama Compact Array observations of atomic carbon ([C I](1–0)) and dust continuum in 10 enormous Lyα nebulae hosting ultraluminous Type-I QSOs at z = 2.2–2.5, as part of the Survey of Protocluster ELANe Revealing CO/C I in the Lyα Detected CGM. We detect [C I](1–0) and dust in all 10 QSOs and five companion galaxies. We find that the QSOs and companions have higher gas densities and more intense radiation fields than Luminous Infrared galaxies and high-z main sequence galaxies, with the highest values found in the QSOs. By comparing molecular gas masses derived from [C I](1–0), CO(4‑3), and dust continuum, we find that the QSOs and companions display a similar low CO conversion factor of α CO ∼ 0.8 M ☉  . After tapering our data to low resolution, the [C I](1–0) flux increases for nine QSOs, hinting at the possibility of [C I](1–0) in the circumgalactic medium (CGM) on a scale of 16‑40 kpc. However, the [C I](1–0) sensitivity is too low to confirm this for individual targets, except for a tentative (2.7σ) CGM detection in Q0050+0051 with   = (1.0–2.8) × 1010 M ☉. The 3σ mass limits of molecular CGM for the remaining QSO fields are (0.2–1.4) × 1010 M ☉. This translates into a baryon fraction of &lt;0.4%–3% in the molecular CGM relative to the total baryonic halo mass. Our sample also includes a radio-detected active galactic nuclei, Q1416+2649, which shows [C I](1–0) and CO(4‑3) luminosities an order of magnitude fainter for its far-infrared luminosity than other QSOs in our sample, possibly due to a lower molecular gas mass.

Keywords: Molecular gas, Quasars, Radio galaxies, Galaxy evolution, Interstellar medium, Circumgalactic medium, High-redshift galaxies
Astrometric Redshifts of Supernovae. Differential Chromatic Refraction (DCR) is caused by the wavelength dependence of our atmosphere's refractive index, which shifts the apparent positions of stars and galaxies and distorts their shapes depending on their spectral energy distributions. While this effect is typically mitigated and corrected for in imaging observations, we investigate how DCR can instead be used to our advantage to infer the redshifts of supernovae from multiband, time-series imaging data. We simulate Type Ia supernovae in the proposed Vera C. Rubin Observatory Legacy Survey of Space and Time Deep Drilling Field, and evaluate astrometric redshifts. We find that the redshift accuracy improves dramatically with the statistical quality of the astrometric measurements as well as with the accuracy of the astrometric solution. For a conservative choice of a 5 mas systematic uncertainty floor, we find that our redshift estimation is accurate at z &lt; 0.6. We then combine our astrometric redshifts with both host-galaxy photometric redshifts and supernovae photometric (light-curve) redshifts and show that this considerably improves the overall redshift estimates. These astrometric redshifts will be valuable, especially since Rubin will discover a vast number of supernovae for which we will not be able to obtain spectroscopic redshifts.

Keywords: Atmospheric refraction, Type Ia supernovae, Astrometry
Multizone Modeling of Black Hole Accretion and Feedback in 3D GRMHD: Bridging Vast Spatial and Temporal Scales. Simulating accretion and feedback from the horizon scale of supermassive black holes (SMBHs) out to galactic scales is challenging because of the vast range of scales involved. Elaborating on H. Cho et al., we describe and test a "multizone" technique, which is designed to tackle this difficult problem in three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations. While short-timescale variability should be interpreted with caution, the method is demonstrated to be well-suited for finding dynamical steady states over a wide dynamic range. We simulate accretion on a nonspinning SMBH (a * = 0) using initial conditions and the external galactic potential from a large-scale galaxy simulation and achieve a steady state over eight decades in radius. As found in H. Cho et al., the density scales with radius as ρ ∝ r ‑1 inside the Bondi radius R  B , which is located at R  B  = 2 × 105 r  g  (≈60 pc for M87), where r  g  is the gravitational radius of the SMBH; the plasma-β is ∼ unity, indicating an extended magnetically arrested state; the mass accretion rate   is ≈1% of the analytical Bondi accretion rate   and there is continuous energy feedback out to ≈100R  B  (or beyond &gt; kpc) at a rate  . Surprisingly, no ordered rotation in the external medium survives as the magnetized gas flows to smaller radii, and the final steady solution is very similar to when the exterior has no rotation. Using the multizone method, we simulate GRMHD accretion over a wide range of Bondi radii, R  B  ∼ 102‑107 r g, and find that  .

Keywords: Accretion, Supermassive black holes, Schwarzschild black holes, Bondi accretion, Active galactic nuclei, Magnetohydrodynamical simulations
Making the Invisible Visible: Magnetic Fields in Accretion Flows Revealed by X-Ray Polarization. Large-scale, strong magnetic fields are often evoked in black hole accretion flows, for jet launching in the low/hard state and to circumvent the thermal instability in the high/soft state. Here, we show how these ideas are strongly challenged by X-ray polarization measurements from the Imaging X-ray Polarimetry Explorer (IXPE). Quite general arguments show that equipartition large-scale fields in the accretion flow should be of order 106–8 G. These produce substantial Faraday rotation and/or depolarization. Since IXPE observes polarization in both spectral states, this sets upper limits to coherent large-scale (vertical, radial, or azimuthal) magnetic fields in the photosphere of B ≲ 5 × 106 G. While we stress that Faraday rotation should be calculated for each individual simulation (density, field geometry, and emissivity), it seems most likely that there are no equipartition-strength large-scale ordered fields inside the photosphere of the X-ray-emitting gas. Strong poloidal fields can still power a Blandford–Znajek jet in the low/hard state if they thread the black hole horizon rather than the X-ray-emitting flow, but this could also be challenged by (lack of) depolarization from vacuum birefringence. Instead, an alternative solution is that the low/hard state jet is dominated by pairs, so can be accelerated by lower fields. Strong toroidal fields could still stabilize the disk in the high/soft state if they are buried beneath the photosphere, though this seems unlikely due to magnetic buoyancy. Fundamentally, polarization data from IXPE mean that magnetic fields in black hole accretion flows are no longer invisible and unconstrained.

Keywords: X-ray astronomy, Accretion, Jets, Radio jets, High mass x-ray binary stars, Stellar mass black holes, Low-mass x-ray binary stars, Polarimetry, Astrophysical black holes
The Application of Manifold Learning to a Selection of Different Galaxy Populations and Scaling Relation Analysis. The growing volume of data produced by large astronomical surveys necessitates the development of efficient analysis techniques capable of effectively managing high-dimensional data sets. This study addresses this need by demonstrating some applications of manifold learning and dimensionality reduction techniques, specifically the self-organizing map (SOM), on the optical+near-infrared spectral energy distribution (SED) space of galaxies, with a focus on sample comparison, selection biases, and predictive power using a small subset. To this end, we utilize a large photometric sample from the five Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey fields and a subset with spectroscopic measurements from the KECK MOSDEF survey in two redshift bins at z ∼ 1.5 and z ∼ 2.2. We trained the SOM with the photometric data and mapped the spectroscopic data onto it as our study case. We found that MOSDEF targets do not cover all SED shapes existing in the SOM. Our findings reveal that active galactic nuclei within the MOSDEF sample are mapped onto the more massive regions of the SOM, confirming previous studies and known selection biases toward higher-mass, less dusty galaxies. Furthermore, SOMs were utilized to map measured spectroscopic features, examining the relationship between metallicity variations and galaxy mass. Our analysis confirmed that more massive galaxies exhibit lower [O III]/Hβ and [O III]/[O II] ratios and higher Hα/Hβ ratios, consistent with the known mass–metallicity relation. These findings highlight the effectiveness of SOMs in analyzing and visualizing complex, multidimensional data sets, emphasizing their potential in data-driven astronomical studies.

Keywords: AGN host galaxies, Galaxy colors, Astronomy data analysis, Galaxy evolution, Spectroscopy, Broad band photometry, Astronomy data visualization
Massive Star Cluster Formation with Binaries. I. Evolution of Binary Populations. We study the evolution of populations of binary stars within massive cluster-forming regions. We simulate the formation of young massive star clusters within giant molecular clouds with masses ranging from 2 × 104 to 3.2 × 105 M ⊙. We use TORCH, which couples stellar dynamics, magnetohydrodynamics, star and binary formation, stellar evolution, and stellar feedback through the AMUSE framework. We find that the binary fraction decreases during cluster formation at all molecular cloud masses. The binaries' orbital properties also change, with stronger and quicker changes in denser, more massive clouds. Most of the changes we see can be attributed to the disruption of binaries wider than 100 au, although the close binary fraction also decreases in the densest cluster-forming region. The binary fraction for O stars remains above 90%, but exchanges and dynamical hardening are ubiquitous, indicating that O stars undergo frequent few-body interactions early during the cluster formation process. Changes to the populations of binaries are a by-product of hierarchical cluster assembly: most changes to the binary population take place when the star formation rate is high, and there are frequent mergers between subclusters in the cluster-forming region. A universal primordial binary distribution based on observed inner companions in the Galactic field is consistent with the binary populations of young clusters with resolved stellar populations, and the scatter between clusters of similar masses could be explained by differences in their formation history.

Keywords: Binary stars, Young massive clusters, Star forming regions, Young star clusters, Star formation, Star clusters
Modeling the Multiwavelength Detection of Protoclusters. I. An Excess of Submillimeter Galaxies in Protocluster Cores. Studies of galaxy protoclusters yield insights into galaxy cluster formation complementary to those obtained via "archaeological" studies of present-day galaxy clusters. Submillimeter-selected galaxies (SMGs) are one class of sources used to find high-redshift protoclusters. However, due to the rarity of protoclusters (and thus the large simulation volume required) and the complexity of modeling dust emission from galaxies, the relationship between SMGs and protoclusters has not been adequately addressed in the theoretical literature. In this work, we apply the L-GALAXIES semianalytic model (SAM) to the Millennium N-body simulation. We assign submillimeter flux densities to the model galaxies using a scaling relation from previous work, in which dust radiative transfer was performed on high-resolution galaxy zoom simulations. We find that the fraction of model galaxies that are submillimeter-bright is higher in protocluster cores than in both protocluster "outskirts" and the field; the fractions for the latter two are similar. This excess is not driven by an enhanced starburst frequency. Instead, the primary reason is that overdense environments have a relative overdensity of high-mass halos and thus "oversample" the high-mass end of the star formation main sequence relative to less-dense environments. The fraction of SMGs that are optically bright is dependent on stellar mass and redshift but independent of the environment. The fraction of galaxies for which the majority of star formation is dust-obscured is higher in protocluster cores, primarily due to the dust-obscured fraction being correlated with stellar mass. Our results can be used to guide and interpret multiwavelength studies of galaxy populations in protoclusters.

Keywords: Galaxy clusters, High-redshift galaxy clusters, Infrared galaxies, Galaxy evolution, High-redshift galaxies