Sazuna/UAT_keywords huggingface dataset:
Formation of CO<SUB>2</SUB> Driven by Photochemistry of Water Ice Mixed with Carbon Grains. We present results on photochemistry of carbon-grains/water-ice mixtures at temperatures from 10 to 150 K. Such a temperature range corresponds to the physical conditions found in molecular clouds, hot cores and corinos, protostellar envelopes, and planet-forming and debris disks. We demonstrate that UV irradiation of carbon-grains/water-ice mixtures leads to the formation of CO2, which, beyond the desorption temperature of CO2 partly escapes into the gas phase, and partly remains trapped on the surface of grains. Thus, we present the first direct evidence of the efficient formation of CO2 on carbon surfaces covered by water ice at high temperatures (up to 150 K) leading to a conclusion that the known low-temperature formation route of CO2 remains valid at high temperatures as long as H2O is present on carbon grains. Moreover, we demonstrate an improved capability of the dust-surface/crystalline-water-ice interface (as compared to amorphous water ice) to trap CO2 in the solid state well above the CO2 desorption temperature. The high-temperature chemical pathway to CO2 may lead to the chemical erosion of carbonaceous grains in planet-forming disks, providing an alternative explanation of the loss of solid carbon in the innermost disk regions that resulted in the formation of carbon-poor Earth and other terrestrial planets in the solar system.

Keywords: Interstellar dust, Laboratory astrophysics, Astrochemistry
Near-Sun In Situ and Remote-sensing Observations of a Coronal Mass Ejection and its Effect on the Heliospheric Current Sheet. During the thirteenth encounter of the Parker Solar Probe (PSP) mission, the spacecraft traveled through a topologically complex interplanetary coronal mass ejection (ICME) beginning on 2022 September 5. PSP traversed through the flank and wake of the ICME while observing the event for nearly two days. The Solar Probe ANalyzer and FIELDS instruments collected in situ measurements of the plasma particles and magnetic field at ~13.3 R  S  from the Sun. We observe classical ICME signatures, such as a fast-forward shock, bidirectional electrons, low proton temperatures, low plasma β, and high alpha particle to proton number density ratios. In addition, PSP traveled through two magnetic inversion lines, a magnetic reconnection exhaust, and multiple sub-Alfvénic regions. We compare these in situ measurements to remote-sensing observations from the Wide-field Imager for Solar PRobe Plus instrument on board PSP and the Sun Earth Connection Coronal and Heliospheric Investigation on the Solar Terrestrial Relations Observatory. Based on white-light coronagraphs, two CMEs are forward modeled to best fit the extent of the event. Furthermore, Air Force Data Assimilative Flux Transport magnetograms modeled from Global Oscillation Network Group magnetograms and Potential Field Source Surface modeling portray a global reconfiguration of the heliospheric current sheet (HCS) after the CME event, suggesting that these eruptions play a significant role in the evolution of the HCS.

Keywords: Solar cycle, Heliosphere, Solar coronal mass ejection shocks, Interplanetary magnetic fields, Solar coronal mass ejections, Solar magnetic fields
Ho'oleilana: An Individual Baryon Acoustic Oscillation?. Theory of the physics of the early hot universe leads to a prediction of baryon acoustic oscillations (BAOs) that has received confirmation from the pairwise separations of galaxies in samples of hundreds of thousands of objects. Evidence is presented here for the discovery of a remarkably strong individual contribution to the BAO signal at z = 0.068, an entity that is given the name Ho'oleilana. The radius of the 3D structure is $155\,{{\rm{h}}}_{75}^{-1}$ Mpc. At its core is the Boötes supercluster. The Sloan Great Wall, Center for Astrophysics Great Wall, and Hercules complex all lie within the BAO shell. The interpretation of Ho'oleilana as a BAO structure with our preferred analysis implies a value of the Hubble constant of ${76.9}_{-4.8}^{+8.2}\,\mathrm{km}\,{{\rm{s}}}^{-1}\,{\mathrm{Mpc}}^{-1}.$

Keywords: Large-scale structure of the universe
Discovery of a Variable Multiphase Outflow in the X-Ray-emitting Tidal Disruption Event ASASSN-20qc. Tidal disruption events (TDEs) are exotic transients that can lead to temporary super-Eddington accretion onto a supermassive black hole. Such an accretion mode is naturally expected to result in powerful outflows of ionized matter. However, to date such an outflow has only been directly detected in the X-ray band in a single TDE, ASASSN-14li. This outflow has a low velocity of just a few 100 km s-1, although there is also evidence for a second, ultrafast phase. Here we present the detection of a low-velocity outflow in a second TDE, ASASSN-20qc. The high-resolution X-ray spectrum reveals an array of narrow absorption lines, each blueshifted by a few 100 km s-1, which cannot be described by a single photoionization phase. For the first time, we confirm the multiphase nature of a TDE outflow, with at least two phases and two distinct velocity components. One highly ionized phase is outflowing at ${910}_{-80}^{+90}$ km s-1, while a lower ionization component is blueshifted by ${400}_{-120}^{+100}$ km s-1. We perform a time-resolved analysis of the X-ray spectrum and detect that, surprisingly, the ionization parameter of the mildly ionized absorber strongly varies over the course of a single 60 ks observation, indicating that its distance from the black hole may be as low as 400 gravitational radii. We discuss these findings in the context of TDEs and compare this newly detected outflow with that of ASASSN-14li.

Keywords: Accretion, Supermassive black holes, Tidal disruption
Three-dimensional Simulations of Massive Stars. II. Age Dependence. We present 3D full star simulations, reaching up to 90% of the total stellar radius, for three 7 M ⊙ stars of different ages: zero-age main sequence (ZAMS), mid-main sequence (midMS), and terminal-age main sequence (TAMS). A comparison with several theoretical prescriptions shows that the generation spectra for all three ages are dominated by convective plumes. Two distinct overshooting layers are observed, with most plumes stopped within the layer situated directly above the convective boundary; overshooting to the second, deeper layer becomes progressively more infrequent with increasing stellar age. Internal gravity wave (IGW) propagation is significantly impacted in the midMS and TAMS models as a result of some IGWs getting trapped within their Brunt-Väisälä frequency spikes. A fundamental change in the wave structure across radius is also observed, driven by the effect of density stratification on IGW propagation causing waves to become evanescent within the radiative zone, with older stars being affected more strongly. We find that the steepness of the frequency spectrum at the surface increases from ZAMS to the older models, with older stars also showing more modes in their spectra.

Keywords: Internal waves, Stellar convective zones, Stellar properties, Stellar ages, Stellar dynamics, Stellar evolution
Constraints on the Abundance of Primordial Black Holes from X-Ray Quasar Microlensing Observations: Substellar to Planetary Mass Range. We use X-ray observations of quasar microlensing (sensitive to smaller compact objects than in the optical) to study the possible presence of a population of low mass black holes (BHs; from ~10-3 M ⊙ to 10-1 M ⊙) in lens galaxies. We compare these observations with microlensing magnification simulations of a mixed population of stars and BHs plus a smooth matter component. We estimate the individual mass fractions of both stars and BHs for three different BH masses in the range of substellar to planetary masses. Our Bayesian analysis indicates that the contribution of BHs is negligible in the substellar mass range but that a population of BHs of planetary mass (M ≲ 10-3 M ⊙) could pass unnoticed to X-ray microlensing. We provide new upper limits to the contribution of BHs to the fraction of dark matter based on both, the quasar microlensing data in the X-ray band, and our previous estimates in the optical of intermediate-mass BHs with an additional upper limit at M = 3M ⊙.

Keywords: X-ray quasars, Gravitational lensing, Gravitational microlensing, Quasar microlensing, Dark matter, Primordial black holes
The Sloan Digital Sky Survey Reverberation Mapping Project: The Black Hole Mass-Stellar Mass Relations at 0.2 ≲ z ≲ 0.8. We measure the correlation between black hole mass M BH and host stellar mass M * for a sample of 38 broad-line quasars at 0.2 ≲ z ≲ 0.8 (median redshift z med = 0.5). The black hole masses are derived from a dedicated reverberation mapping program for distant quasars, and the stellar masses are derived from two-band optical+IR Hubble Space Telescope imaging. Most of these quasars are well centered within ≲1 kpc from the host galaxy centroid, with only a few cases in merging/disturbed systems showing larger spatial offsets. Our sample spans two orders of magnitude in stellar mass (~109-1011 M ⊙) and black hole mass (~107-109 M ⊙) and reveals a significant correlation between the two quantities. We find a best-fit intrinsic (i.e., selection effects corrected) M BH-M *,host relation of $\mathrm{log}({M}_{\mathrm{BH}}/{M}_{\odot })={7.01}_{-0.33}^{+0.23}+{1.74}_{-0.64}^{+0.64}\mathrm{log}({M}_{* ,\mathrm{host}}/{10}^{10}{M}_{\odot })$ , with an intrinsic scatter of ${0.47}_{-0.17}^{+0.24}$ dex. Decomposing our quasar hosts into bulges and disks, there is a similar M BH-M *,bulge relation with slightly larger scatter, likely caused by systematic uncertainties in the bulge-disk decomposition. The M BH-M *,host relation at z med = 0.5 is similar to that in local quiescent galaxies, with negligible evolution over the redshift range probed by our sample. With direct black hole masses from reverberation mapping and the large dynamical range of the sample, selection biases do not appear to affect our conclusions significantly. Our results, along with other samples in the literature, suggest that the locally measured black hole mass-host stellar mass relation is already in place at z ~ 1.

Keywords: AGN host galaxies, Black hole physics, Quasars, Surveys, Active galaxies
SCUBA-2 High Redshift Bright Quasar Survey. II. The Environment of z   6 Quasars at Submillimeter Band. The formation of the first supermassive black holes is expected to have occurred in some most pronounced matter and galaxy overdensities in the early universe. We have conducted a submillimeter wavelength continuum survey of 54 z ~ 6 quasars using the Submillimeter Common-User Bolometre Array-2 on the James Clerk Maxwell Telescope to study the environments around z ~ 6 quasars. We identified 170 submillimeter galaxies (SMGs) with above 3.5σ detections in 450 or 850 μm maps. Their far-IR luminosities are (2.2-6.4) × 1012 L ☉, and their star formation rates are ~400-1200 M ☉ yr-1. We also calculated the SMGs' differential and cumulative number counts in a combined area of ~620 arcmin2. To a 4σ detection (at ~5.5 mJy), SMGs' overdensity is ${0.68}_{-0.19}^{+0.21}$ (±0.19), exceeding the blank-field source counts by a factor of 1.68. We find that 13/54 quasars show overdensities (at ~5.5 mJy) of δ SMG ~ 1.5-5.4. The combined area of these 13 quasars exceeds the blank-field counts with the overdensity to 5.5 mJy of δ SMG ~ ${2.46}_{-0.55}^{+0.64}$ (±0.25) in the regions of ~150 arcmin2. However, the excess is insignificant on the bright end (e.g., 7.5 mJy). We also compare results with previous environmental studies of Lyα emitters and Lyman break galaxies on a similar scale. Our survey presents the first systematic study of the environment of quasars at z ~ 6. The newly discovered SMGs provide essential candidates for follow-up spectroscopic observations to test whether they reside in the same large-scale structures as the quasars and search for protoclusters at an early epoch.

Keywords: Submillimeter astronomy, Active galaxies, Quasars
A New Photoionization Model of the Narrow-line Region in Active Galactic Nuclei. The photoionization model of narrow-line regions in active galactic nuclei (AGNs) has been investigated for decades. Many published models are restricted to simple linear scaling abundance relations, dust-free assumption, uniform AGN radiation field, and using one specific photoionization code, which restricts them from providing a satisfactory prediction on a broad range of AGN observations. Through a comprehensive investigation, here we present how the choice of abundance scaling relations, dust inclusion, AGN radiation fields, and different photoionization codes CLOUDY and MAPPINGS affect the predictions on the strength of strong UV, optical, and infrared emission lines. We find the dust-depleted radiation-pressure-dominated AGN model built with the latest nonlinear abundance sets and photoionization code MAPPINGS V are consistent with AGN observations across a broad range of wavelengths. We also assess new potential H II-AGN separation diagrams in the optical and UV wavelengths.

Keywords: Photoionization, Emission line galaxies, Seyfert galaxies, Active galactic nuclei, Interstellar medium
Hydrodynamics and Survivability during Post-main-sequence Planetary Engulfment. The engulfment of substellar bodies (SBs), such as brown dwarfs and planets, by giant stars is a possible explanation for rapidly rotating giants, lithium-rich giants, and the presence of SBs in close orbits around subdwarfs and white dwarfs. We perform three-dimensional hydrodynamical simulations of the flow in the vicinity of an engulfed SB. We model the SB as a rigid body with a reflective surface because it cannot accrete. This reflective boundary changes the flow morphology to resemble that of engulfed compact objects with outflows. We measure the drag coefficients for the ram-pressure and gravitational drag forces acting on the SB, and use them to integrate its trajectory inside the star. We find that engulfment can increase the luminosity of a 1 M ⊙ star by up to a few orders of magnitude. The time for the star to return to its original luminosity is up to a few thousand years when the star has evolved to ≈10 R ⊙ and up to a few decades at the tip of the red giant branch (RGB). No SBs can eject the envelope of a 1 M ⊙ star before it evolves to ≈10 R ⊙ if the orbit of the SB is the only energy source contributing to the ejection. In contrast, SBs as small as ≈10 M Jup can eject the envelope at the tip of the RGB. The numerical framework we introduce here can be used to study planetary engulfment in a simplified setting that captures the physics of the flow at the scale of the SB.

Keywords: Exoplanet dynamics, Hydrodynamical simulations, Brown dwarfs, Exoplanets, Evolved stars, Hydrodynamics, Exoplanet systems, Exoplanet evolution, Lithium stars, Star-planet interactions, Common envelope evolution, Stellar evolution
Ram Pressure Stripping in the EAGLE Simulation. Ram pressure stripping of satellite galaxies is thought to be a ubiquitous process in galaxy clusters, and a growing number of observations reveal satellites at different stages of stripping. However, in order to determine the fate of any individual galaxy, we turn to predictions from either simulations or analytic models. It is not well determined whether simulations and analytic models agree in their predictions, nor the causes of disagreement. Here we investigate ram pressure stripping in the reference EAGLE hydrodynamical cosmological simulation, and compare the results to predictions from analytic models. We track the evolution of galaxies with stellar mass M * &gt; 109 M ⊙ and initial bound gas mass M gas &gt; 109 M ⊙ that fall into galaxy clusters (M 200c  &gt; 1014 M ⊙) between z = 0.27 and z = 0. We divide each galaxy into its neutral gas disk and hot ionized gas halo and compare the evolution of the stripped gas fraction in the simulation to that predicted by analytic formulations for the two gas phases, as well as to a toy model that computes the motions of gas particles under the combined effects of gravity and a spatially uniform ram pressure. We find that the analytic models generally underpredict the stripping rate of neutral gas and overpredict that of ionized gas, with significant scatter between the model and simulation stripping timescales. This is due to opposing physical effects: the enhancement of ram pressure stripping by stellar feedback, and the suppression of stripping by the compaction of galactic gas.

Keywords: Hydrodynamical simulations, Ram pressure stripped tails, Galaxy structure, Galaxy physics, Galaxy evolution
A New Insight into the Linear Theory of Magnetoacoustic Waves in the Homogeneous Flux Tubes with an Abrupt Boundary. An important and interesting issue is brought to notice in the standard linear theory of the magnetoacoustic waves in the homogeneous magnetic flux tubes with an abrupt magnetic boundary, which are representative of the coronal, chromospheric, and photospheric loops of the solar atmosphere. It is shown that the dispersion relation given for the magnetoacoustic waves of such flux tubes by the linear standard theory is generally inapplicable because it does not take into account the electrodynamic boundary condition and the applicability is only restricted to the case β = 0, where β is the usual plasma parameter given by the ratio of the thermodynamic gas pressure to the magnetic pressure. This issue is then addressed, which gives us new insight into the standard linear theory of such modes, and a new dispersion relation is obtained, which is generally applicable i.e., for all β and would reduce to the earlier expression as a special case for β = 0. Finally a comparison is drawn between the dispersion curves described by the newly derived dispersion relation and its previous counterpart.

Keywords: Solar corona
Fast Radio Bursts as Probes of Magnetic Fields in Galaxies at z &lt; 0.5. We present a sample of nine fast radio bursts (FRBs) from which we derive magnetic field strengths of the host galaxies represented by normal, z &lt; 0.5 star-forming galaxies with stellar masses M * ≈ 108-1010.5 M ⊙. We find no correlation between the FRB rotation measure (RM) and redshift, which indicates that the RM values are due mostly to the FRB host contribution. This assertion is further supported by a significant positive correlation (Spearman test probability P  S  &lt; 0.05) found between the RM and the estimated host dispersion measure (DMhost; with Spearman rank correlation coefficient r  S  = +0.75). For these nine galaxies, we estimate their magnetic field strengths projected along the sight line ∣B ∥∣, finding a low median value of 0.5 μG. This implies the magnetic fields of our sample of hosts are weaker than those characteristic of the solar neighborhood (≈6 μG), but relatively consistent with a lower limit on the observed range of ≈2-10 μG for star-forming disk galaxies, especially as we consider reversals in the B-field, and that we are only probing B∥. We compare to RMs from simulated galaxies of the Auriga project-magneto-hydrodynamic cosmological zoom simulations-and find that the simulations predict the observed values to within a 95% confidence interval. Upcoming FRB surveys will provide hundreds of new FRBs with high-precision localizations, RMs, and imaging follow-up to support further investigation into the magnetic fields of a diverse population of z &lt; 1 galaxies.

Keywords: Extragalactic magnetic fields, Galaxy evolution, Radio transient sources
Simple Convective Accretion Flows (SCAFs): Explaining the ≈ -1 Density Scaling of Hot Accretion Flows around Compact Accretors. Recent simulations find that hot gas accretion onto compact accretors is often highly turbulent and diskless, and shows a power-law density profile with slope α  ρ  ≈ -1. These results are consistent with observational constraints, but do not match existing self-similar solutions of radiatively inefficient accretion flows. We develop a theory for this new class of accretion flows, which we dub simple convective accretion flows (SCAFs). We use a set of hydrodynamic simulations to provide a minimalistic example of SCAFs, and develop an analytic theory to explain and predict key flow properties. We demonstrate that the turbulence in the flow is driven locally by convection, and argue that radial momentum balance, together with an approximate up-down symmetry of convective turbulence, yields α  ρ  = -1 ± few 0.1. Empirically, for an adiabatic hydrodynamic flow with γ ≈ 5/3, we get α  ρ  ≈ -0.8; the resulting accretion rate (relative to the Bondi accretion rate), $\dot{M}/{\dot{M}}_{{\rm{B}}}\sim {({r}_{\mathrm{acc}}/{r}_{{\rm{B}}})}^{0.7}$ , agrees very well with the observed accretion rates in Sgr A*, M87*, and a number of wind-fed supergiant X-ray binaries. We also argue that the properties of SCAFs are relatively insensitive to additional physical ingredients such as cooling and magnetic field; this explains their common appearance across simulations of different astrophysical systems.

Keywords: Accretion, Hydrodynamical simulations, Compact objects
Capturing Statistical Isotropy Violation with Generalized Isotropic Angular Correlation Functions of Cosmic Microwave Background Anisotropy. The exquisitely measured maps of fluctuations in the cosmic microwave background (CMB) present the possibility of systematically testing the principle of statistical isotropy of the Universe. A systematic approach based on strong mathematical formulation allows any nonstatistical isotropic (nSI) feature to be traced to the nature of physical effects or observational artifacts. Bipolar spherical harmonics (BipoSH) representation has emerged as an overarching general formalism for quantifying the departures from statistical isotropy for a field on a 2D sphere. We adopt a little-known reduction of the BipoSH functions, dubbed minimal harmonics in the original paper by Manakov et al. We demonstrate that this reduction technique of BipoSH leads to a new generalized set of isotropic angular correlation functions referred to here as minimal BipoSH functions that are observable quantifications of nSI features in a sky map. This paper presents a novel observable quantification of deviation from statistical isotropy in terms of generalized angular correlation functions that are compact and complementary to the BipoSH spectra that generalize the angular power spectrum of CMB fluctuations.

Keywords: Cosmic microwave background radiation, Two-point correlation function
On the Decline of Star Formation during the Evolution of Galaxies. Cosmological simulations predict that during the evolution of galaxies, the specific star formation rate continuously decreases. In a previous study we showed that generally this is not caused by the galaxies running out of cold gas but rather a decrease in the fraction of gas capable of forming stars. To investigate the origin of this behavior, we use disk galaxies selected from the cosmological hydrodynamical simulation Magneticum Pathfinder and follow their evolution in time. We find that the mean density of the cold gas regions decreases with time. This is caused by the fact that during the evolution of the galaxies the star-forming regions move to larger galactic radii, where the gas density is lower. This supports the idea of inside-out growth of disk galaxies.

Keywords: Galaxies, Late-type galaxies, Galaxy evolution, Disk galaxies