Sazuna/UAT_keywords huggingface dataset:
Accretion of Active Galactic Nucleus Stars Under the Influence of Disk Geometry. Massive stars can form within or be captured by active galactic nucleus disks, influencing both the thermal structure and metallicity of the disk environment. In a previous work, we investigated isotropic accretion onto massive stars from a gas-rich, high-entropy background. Here, we consider a more realistic scenario, by incorporating the stratified geometry of the background disk in our 3D radiation hydrodynamic simulations. We find that the accretion remains relatively isotropic when the disk is hot enough and the scale height is thicker than the accretion flow's nominal supersonic critical radius Rcrit (subthermal). However, when the disk becomes cold, the accretion flow becomes significantly anisotropic (superthermal). Escaping stellar and accretion luminosity can drive super-Eddington outflows in the polar region, while rapid accretion is sustained along the midplane. Eventually, the effective cross section is constrained by the Hill radius and the disk scale height rather than the critical radius when the disk is cold enough. For our setup (stellar mass ∼50 M⊙ and background density ρ ∼ 10−10 g cm−3), the accretion rate is capped below ∼0.02M⊙ yr−1 and the effective accretion parameter α ∼ 10−1 over the disk temperature range 3─7 × 104 K. Spiral arms facilitate inward mass flux by driving outward angular momentum transport. Gap-opening effects may further reduce the long-term accretion rate, although to confirm this would require global simulations evolved over much longer viscous timescales.

Keywords: Accretion, Radiative transfer simulations, Massive stars, Active galactic nuclei
The Burstiness of Star Formation at z ∼ 6: A Huge Diversity in the Recent Star Formation Histories of Very UV-faint Galaxies. IRAC data have long implied that early (z ≳ 6) galaxies often have very high specific star formation rates (sSFRs ≳ 30 Gyr−1), but JWST data have shown that at least some early galaxies are forming stars far less vigorously. Here, we systematically analyze the recent star formation histories (SFHs) of a large (N = 368) sample of z ∼ 6 Lyman-break galaxies (LBGs) spanning −22 ≲ MUV ≲ −16 assembled from Advanced Camera for Surveys+NIRCam imaging in the GOODS and A2744 fields. We find that very low Hα-to-UV luminosity ratios (LHα/LUV) and strong recent downturns in star formation rate (SFR) are ≍5× more common among the UV-faintest subset of our sample (&lt;MUV&gt; = −17.4) compared to the brightest subset (&lt;MUV&gt; = −20.0). The frequency of high LHα/LUV and strong recent SFR upturns is approximately constant with UV luminosity. We discuss how bursty SFHs naturally reproduce this much greater diversity in recent SFHs among very UV-faint galaxies. Using public NIRSpec/prism data, we newly confirm recent strong SFR downturns among three LBGs in our sample, and validate our photometric inferences on key SFH signatures among z ∼ 6 LBGs in general. Our results imply that early galaxies frequently cycle through phases of rapid stellar mass assembly and other periods of much slower growth. This yields huge (≳1─2 mag) fluctuations in MUV on rapid (∼10─30 Myr) timescales, helping explain the surprising abundance of z &gt; 10 galaxies. Finally, we caution that this burstiness causes all existing high-redshift samples (particularly line-selected samples) to be far less complete to galaxies with long recent phases of low sSFR compared to those currently undergoing a burst.

Keywords: Galaxy formation, High-redshift galaxies, Galaxy evolution
Cryogenic Differential Calorimetry: Exothermicity of Amorphous-to-crystalline Phase Transitions (ACPT) in Astrophysical and Cometary Ice Analogs. Amorphous ice is understood to be the predominant phase of water in cometary nuclei. A significant number of other volatiles can be trapped in amorphous H2O ice and released during the amorphous-to-crystalline phase transition (ACPT). This phase transition is an exothermic and is considered a potential cause of cometary outbursts, such as those observed in Comet 1P/Halley and Comet Hale–Bopp. However, only a single experimental study reported in the literature suggests that the presence of impurities (&gt;2%) in amorphous H2O ice suppresses the exothermic effect and results in an endothermic phase transition, which contradicts the hypothesis of exothermic-phase-transition-driven comet outbursts. To further explore this phenomenon, we conducted experiments on pure H2O, CO:H2O, and CO2:H2O ice mixtures with varying fractions (11%, 50%, and 80% CO, and 11%, 25%, and 50% CO2, both relative to H2O (100%)). Our experimental setup is a highly sensitive cryogenic differential scanning calorimeter with a μK noise floor and fifth-decimal resolution in temperature ratio of reference and ice. Our calorimetric data have been internally calibrated to ice sublimation endotherm to derive quantitative calorimetric data. We find that ACPT is exothermic in all CO:H2O mixtures and CO2:H2O mixtures with lower CO2 fractions. In mixtures with the highest CO2 content (50% relative to H2O (100%)) examined, the ACPT exotherm is weakened. Our results demonstrate that ACPT exothermicity persists throughout the CO and CO2 mixing ratios observed in a majority of comets, and it should play an important role in comet outbursts when CO and CO2 are the major volatiles trapped in amorphous H2O ice.

Keywords: Comets, Laboratory astrophysics
PKS J0805-0111: A Second Owens Valley Radio Observatory Blazar Showing Highly Significant Sinusoidal Radio Variability—The Tip of the Iceberg. Owens Valley Radio Observatory observations of the supermassive black hole binary (SMBHB) candidate PKS 2131‑021 revealed, for the first time, six likely characteristics of the phenomenology exhibited by SMBHBs in blazars, of which the most unexpected and critical is sinusoidal flux density variations. We have now identified a second blazar, PKS J0805‑0111, showing similar variations, with a period of 1.422 ± 0.005 yr in the rest frame of the z = 1.388 object. PKS J0805‑0111 displays five of the six characteristics observed in PKS 2131‑021. To estimate the significance of the sinusoidal variations, we generate 106 simulated light curves that reproduce the radio variability characteristics of PKS J0805‑0111 and show that the global probability that the periodicity we detect is due to the red-noise tail of the power spectral density is p = 6.7 × 10‑5 (3.82σ). This shows that PKS 2131‑021 is not a unique case. The discovery of these two objects in a sample of 1158 blazars allows us to reject, at a p-value ∼0.003, the null hypothesis that the sinusoidal variations in these two blazars are all due to a red-noise process. We estimate that the number of SMBHB candidates among blazars is ∼1 in 100.

Keywords: Blazars, Relativistic jets
A Numerical Model for the Dynamics of Pickup Ions Outside the Heliopause and IBEX "Ribbon" Observation. The leading mechanism for the origin of the Interstellar Boundary Explorer (IBEX) "ribbon" of enhanced energetic neutral atoms (ENAs) from the outer heliosphere is the so-called secondary ENA process. In this mechanism, neutralized ions escape the heliosphere, and after several times of charge exchange collision,s some propagate back toward Earth in directions nearly perpendicular to the local interstellar magnetic field. However, the physical processes governing the distribution of the pickup ions (PUIs) outside the heliopause are still unclear. In this study, we build a new global model of the IBEX ribbon, where a key component is to calculate the dynamics of the PUIs outside the heliopause by solving the gyrophase-averaged focused transport equations on top of the background magnetohydrodynamic-kinetic model for the heliosphere-interstellar medium interaction. We discuss how the properties of the simulated ribbon change with different scattering parameters and show simulation results of the ENA sky maps, ribbon centers, ribbon profiles at several azimuthal slices, the ribbon ENA source region, and the velocity distribution of PUIs in the ENA source region for different scattering frequencies. Our results show that the model can provide reasonable ribbon sky maps comparable to the observed ribbon when the PUI mean free path is on the order of several thousand astronomical units.

Keywords: Space plasmas, Heliosphere, Solar energetic particles, Solar wind, Interstellar magnetic fields, Pickup ions, Interstellar medium, Charge exchange ionization, Particle physics
Recurrent Jetlets Associated with the Disappearance of a Satellite Spot. Recurrent small-scale eruptions are fascinating phenomena in the solar atmosphere, characterized by repeated energy buildup and release over short time intervals. However, their underlying physical mechanisms remain unclear. On 2021 May 23, five recurrent jetlets (J1-J5) were observed continuously ejecting from a satellite spot located at the north edge of AR 12824. Using high-resolution, multiwavelength data from NVST, Solar Dynamics Observatory, and IRIS, we investigate the physical characteristics of these jetlets and their relationship with the satellite spot. The widths of these jetlets range from 1300 to 2900 km, their lifetimes range span 3–10 minutes, and their projection speeds vary from 152.8 to 406.0 km s‑1. During the eruptions, the satellite spot moved northwest at a low speed of 376 ± 12 m s‑1. Its area gradually decreased due to magnetic cancellation with the surrounding positive magnetic field, resulting in an average cancellation rate of 1.3 × 1018 Mx hr‑1. Dark lanes that separated from the satellite spot and small pores were observed to move toward nearby these features or dark lanes with opposite polarities, eventually disappearing during the magnetic cancellation process. J4 was driven by an eruption of a microfilament. Spectral observations revealed a redshift on the right side of J4 and a blueshift on the left side of its base, suggesting a counterclockwise rotation. The horizontal magnetic field of the satellite spot consistently exhibited a vortex structure throughout its evolution until it vanished. The nonlinear force-free field extrapolation confirms that the satellite spot serves as one footpoint of a mini-flux rope. These observations reveal that these jetlets might result from three-dimensional null-point magnetic reconnection, initiated by the continuous eruption of a mini-flux rope or multiple mini-flux ropes, driven by sustained magnetic cancellation.

Keywords: Solar filaments, Solar magnetic fields, Solar corona, Active solar chromosphere, Solar activity, Active solar corona, Solar chromosphere, Filamentary nebulae
COOL-LAMPS. VIII. Known Wide-separation Lensed Quasars and Their Host Galaxies Reveal a Lack of Evolution in M<SUB>BH</SUB>/M<SUB>⋆</SUB> Since z ∼ 3. Wide-separation lensed quasars (WSLQs) are a rare class of strongly lensed quasars, magnified by foreground massive galaxy clusters, with typically large magnifications of the multiple quasar images. They are a relatively unexplored opportunity for detailed study of quasar host galaxies. The current small sample of known WSLQs has a median redshift of z ≍ 2.1, larger than most other samples of quasar host galaxies studied to date. Here, we derive precise constraints on the properties of six WSLQs and their host galaxies, using parametric surface brightness fitting, measurements of quasar emission lines, and stellar population synthesis of host galaxies in six WSLQ systems. Our results, with significant uncertainty, indicate that these six hosts are a mixture of star-forming and quiescent galaxies. To probe for coevolution between active galactic nuclei (AGNs) and host galaxies, we model the offset from the "local" (z = 0) MBH─M⋆ relation as a simple power law in redshift. Accounting for selection effects, a WSLQ-based model for evolution in the MBH─M⋆ relation has a power-law index of γM = −0.42 ± 0.31, consistent with no evolution. Compared to several literature samples, which mostly probe unlensed quasars at z &lt; 2, the WSLQ sample shows less evolution from the local relation, at ∼4σ. We find that selection effects and choices of MBH calibration are the most important systematics in these comparisons. Given that we resolve host galaxy flux confidently even from the ground in some instances, our work demonstrates that WSLQs and highly magnified AGNs are exceptional systems for future AGN─host coevolution studies.

Keywords: AGN host galaxies, Supermassive black holes, Quasars, Strong gravitational lensing, Galaxy evolution
PECCARY: A Novel Approach for Characterizing Orbital Complexity, Stochasticity, and Regularity. Permutation Entropy and statistiCal Complexity Analysis for astRophYsics (PECCARY) is a computationally inexpensive, statistical method by which any time series can be characterized as predominantly regular, complex, or stochastic. Elements of the PECCARY method have been used in a variety of physical, biological, economic, and mathematical scenarios, but have not yet gained traction in the astrophysical community. This study introduces the PECCARY technique with the specific aims to motivate its use in and optimize it for the analysis of astrophysical orbital systems. PECCARY works by decomposing a time-dependent measure, such as the x-coordinate or orbital angular momentum time series, into ordinal patterns. Due to its unique approach and statistical nature, PECCARY is well suited for detecting preferred and forbidden patterns (a signature of chaos), even when the chaotic behavior is short-lived or when working with a relatively short-duration time series or small sets of time-series data. A variety of examples are used to demonstrate the capabilities of PECCARY. These include mathematical examples (sine waves, varieties of noise, well-known chaotic functions), a double pendulum system, and astrophysical tracer particle simulations with potentials of varying intricacies. Since the adopted timescale used to diagnose a given time series can affect the outcome, a method is presented to identify an ideal sampling scheme, constrained by the overall duration and the natural timescale of the system. The accompanying PECCARY Python package and its usage are discussed.

Keywords: Theoretical techniques, Astronomy software, Orbits, Galaxy dynamics, Astronomical methods, Orbit determination, Time series analysis
Reverberation Mapping Data of NGC 5548 Imply a Multicomponent Broad-line Region. Line broadening and variability are observational hallmarks of active galactic nuclei (AGN) which allow us to measure supermassive black hole masses as well as constrain the geometry and kinematics of the emitting gas, with the most precise measurements requiring a degree of modeling. Two popular models of the broad-line region (BLR) describe the emitting gas as either a distribution of puffed-up clouds or a thin disk with strong velocity gradients. As we show in this work, key features in the reverberation mapping data set obtained by the AGN-STORM team in NGC 5548 cannot be accounted for by either simple model. In several emission lines the observed broad-line profile has a single peak yet the delay profile has a distinct double peak, strongly motivating a BLR with emission from multiple components. We demonstrate a few possibilities that may alleviate the tension and better represent the true nature of the broad-line-emitting gas in NGC 5548 and beyond.

Keywords: Active galactic nuclei
The ALMA-ATOMS Survey: Exploring Protostellar Outflows in HC<SUB>3</SUB>N. We present the first systematic study of bipolar outflows using HC3N as a tracer in a sample of 146 massive star-forming regions from the Atacama Large Millimeter/submillimeter Array Three-millimeter Observations of Massive Star-forming Regions (ATOMS) survey. Protostellar outflows arise at the initial stage of star formation as a consequence of active accretion. In general, these outflows play a pivotal role in regulating the star formation processes by injecting energetic material in the parent molecular clouds. In this process, lower velocity components of outflows contain a significant portion of the energy. However, extraction of these components is difficult because the corresponding gas is often mixed with that of the ambient cloud. In our sample, we identified 44 bipolar outflows and one explosive outflow in HC3N (J = 11–10). The host clumps of these outflows are found to be at different evolutionary stages, suggesting that outflows in HC3N are detectable in different stages of star formation. In addition, the noncorrelation of HC3N outflows with clump evolutionary stages suggests that HC3N is an unbiased tracer of outflows. Analyses revealed that HC3N performs slightly better in detecting low-velocity components of outflows than traditionally employed tracers such as SiO. The derived outflow parameters (i.e., outflow mass, momentum, and energy) show moderate correlations with clump mass and luminosity. Our analysis of outflow opening angles and position–velocity diagrams across the outflow lobes show that, HC3N is not only a good tracer of low-velocity outflows but can also detect high-velocity collimated outflows. Overall, this study indicates that HC3N can be used as a complementary outflow tracer along with the traditionally known outflow tracers, particularly in the detection of the low-velocity components of outflows.

Keywords: Interstellar molecules, Submillimeter astronomy, Star forming regions, Protostars
Lyman-break Galaxies in the Megaparsec-scale Environments around Three z ∼ 7.5 Quasars with JWST Imaging. We study the megaparsec-scale environments of the three highest-redshift luminous quasars at z ≥ 7.5 (J031343.84-180636.40, J134208.11+092838.61, and J100758.27+211529.21) to understand their connection to large-scale structure. Cosmological simulations show that these early supermassive black holes are expected to form in the most massive dark matter halos. Therefore, it is expected that they are anchors of galaxy overdensities if luminous matter traces the underlying dark matter structure of the Universe. Using JWST NIRCam (F090W/F115W/F250M/F360M/F430M) imaging, we observe the large-scale structure out to ∼13 comoving Mpc (cMpc) around these quasars. We select F090W-dropout Lyman-break galaxies (LBGs) and F430M-excess [O III] emitters in the three fields. We find 18, 21, and 6 LBG candidates in the fields of J0313, J1342, and J1007, respectively, resulting in a wide range of overdensities (1 + δ ∼ 19, 24, and 7). The photometric redshifts indicate serendipitous foreground and background overdensities in the J0313 field. The joint angular autocorrelation of the combined LBG sample shows significant clustering on &lt;1.8 cMpc scales, demonstrating that the selected galaxies are likely associated with the large-scale structure surrounding the quasars. This first systematic study of z ∼ 7.5 quasars shows a diverse set of quasar environments at the onset of their formation, providing empirical data to help constrain theoretical predictions of early structure formation.

Keywords: Large-scale structure of the universe, High-redshift galaxy clusters, Quasars, Lyman-break galaxies, High-redshift galaxies
A Global Census of Metals in the Universe. We present a census of the mass density of metals and their evolution with cosmic time on a global scale throughout the Universe, synthesizing robust estimates of metals in stars, hot intracluster gas, and gaseous absorbers tracing neutral gas as well as ionized gas in the circumgalactic and intergalactic media. We observe an order of magnitude increase in the stellar metal mass density from z ∼ 2.5 to 0.7, over which time stars emerge as the most important metal reservoir at low redshifts, housing ∼30% of the total expected metal density at z ∼ 0.1. Hot virialized intracluster/intragroup gas accounts for ∼15% and 10% of metals at z ∼ 0.1 and 0.7, respectively. Using metallicity measurements from the COS CGM Compendium, KODIAQ-Z, and the HD-LLS surveys covering redshifts z &lt; 1 to z ∼ 2─3.5, we investigate the global distribution of metals in extragalactic cool ionized gas as a function of H I column density. During the period from z ≍ 3 to z &lt; 1, the global metal density of cool (T ∼ 104−5 K) gas has doubled. However, the fractional contribution of the ionized gas to the total expected metal density decreased from ∼20% at z ∼ 3 to ∼4% at z &lt; 1. The cosmic metal density of all gas phases has increased with cosmic time, reflecting an "inside-out" metal dispersion by feedback mechanisms and galactic outflows.

Keywords: Galaxy chemical evolution, Lyman limit systems, Quasar absorption line spectroscopy, Damped Lyman-alpha systems, Galaxy stellar content, Cool intergalactic medium, Chemical enrichment, Circumgalactic medium, Extragalactic astronomy, Metallicity
Varstrometry for Dual Active Galactic Nuclei Using Radio Interferometry: VaDAR with the VLBA. Multiple active galactic nuclei (multi-AGN) are a known result of galaxy mergers. Therefore, they are an important tool for studying the formation and dynamical evolution of galaxies and supermassive black holes. A novel method for the selection of multi-AGN leverages the exquisite positional accuracy of Gaia to detect astrometrically variable quasars. Previous work has paired this method with radio interferometry on subarcsecond scales. In this paper, we present a follow-up study of seven astrometrically variable quasars from the pilot sample using the Very Long Baseline Array (VLBA). We targeted these seven quasars with the VLBA at 2.0–2.4 GHz (S band) and 8.0–8.4 GHz (X band), reaching milliarcsecond resolutions, in order to study the radio properties at smaller scales and to constrain the origin of the astrometric variability. The new observations are also used to identify significant radio-optical offsets in all seven objects, suggesting that many astrometrically variable quasars also exhibit significant radio-optical offsets. We find that four of the seven sources are possible candidate multi-AGN based on their radio properties and radio-optical offsets. Overall, we use this follow-up study to constrain the smaller-scale radio properties of this sample of astrometrically variable quasars, and continue to explore the use of this method in the field of multi-AGN.

Keywords: Radio active galactic nuclei, Double quasars, Radio astronomy, Active galactic nuclei
An Investigation of the Evolution of Heliosheath Energetics Using a Pressure Enhancement Event Observed by IBEX. During solar cycle 24, an increase in the solar wind (SW) dynamic pressure in late 2014 caused a sharp increase in the heliospheric energetic neutral atom (ENA) flux that was seen by the Interstellar Boundary Explorer (IBEX) at 1 au in late 2016. We study the variation of the ENA energy spectra and temperature in the heliosheath (HS) and compare it with the changes in line-of-sight-integrated ENA pressure, SW number density, speed, and SW dynamic pressure to understand the detailed physics of the energetic evolution of the HS. We use an improved map-making method and a newly developed ribbon-separation technique to obtain these physical parameters from IBEX-Hi ENA data. We find that the pressure enhancement in SW dynamic pressure leads to an increase in HS pressure, which peaks in 2018 before decreasing. The temperature in the HS steadily rises due to the SW pressure enhancement and it does not show any signs of returning to the pre-enhancement value. This indicates that hot HS plasma persists even after the pressure in the HS has started to go down. After the pressure enhancement starts dissipating, a split in the 4.3 keV ENA maps is observed due to a decrease in flux close to equator. We find that this is probably caused by a decrease in SW speed near the equator, which seems to be due to the latitudinal ordering of the SW from the opening of polar coronal holes.

Keywords: Heliopause, Heliosheath, Solar wind, Heliosphere