adsabs/SciX_UAT_keywords huggingface dataset:
AGN-Host Interaction in IC 5063. I. Large-scale X-Ray Morphology and Spectral Analysis

We report the analysis of the deep (~270 ks) X-ray Chandra data of one of the most radio-loud, Seyfert 2 galaxies in the nearby universe (z = 0.01135), IC 5063. The alignment of the radio structure with the galactic disk and ionized bicone, enables us to study the effects of both radio jet and nuclear irradiation on the interstellar medium (ISM). The nuclear and bicone spectra suggest a low photoionization phase mixed with a more ionized or thermal gas component, while the cross-cone spectrum is dominated by shocked and collisionally ionized gas emission. The clumpy morphology of the soft (<3 keV) X-ray emission along the jet trails, and the large (≃2.4 kpc) filamentary structure perpendicular to the radio jets at softer energies (<1.5 keV), suggest a large contribution of the jet-ISM interaction to the circumnuclear gas emission. The hard X-ray continuum (>3 keV) and the Fe Kα 6.4 keV emission are both extended to kpc size along the bicone direction, suggesting an interaction of nuclear photons with dense clouds in the galaxy disk, as observed in other Compton Thick (CT) active nuclei. The northwest cone spectrum also exhibits an Fe XXV emission line, which appears spatially extended and spatially correlated with the most intense radio hot-spot, suggesting jet-ISM interaction.

Keywords: active galactic nuclei; x-ray active galactic nuclei
Spatial Distribution of O VI Covering Fractions in the Simulated Circumgalactic Medium

We use adaptive mesh refinement cosmological simulations to study the spatial distribution and covering fraction of ${\rm{O}}\,{\rm\small{VI}}$ absorption in the circumgalactic medium (CGM) as a function of projected virial radius and azimuthal angle. We compare these simulations to an observed sample of 53 galaxies from the Multiphase Galaxy Halos Survey. Using MOCKSPEC, an absorption-line analysis pipeline, we generate synthetic quasar absorption-line observations of the simulated CGM. To best emulate observations, we studied the averaged properties of 15,000 "mock samples," each of 53 sight lines having a distribution of $D/{R}_{\mathrm{vir}}$ and sight-line orientation statistically consistent with the observations. We find that the ${\rm{O}}\,{\rm\small{VI}}$ covering fraction obtained for the simulated galaxies agrees well with the observed value for the inner halo ( $D/{R}_{\mathrm{vir}}\leqslant 0.375$ ) and is within 1.1σ in the outer halo ( $D/{R}_{\mathrm{vir}}\gt 0.75$ ), but is underproduced within $0.375\lt D/{R}_{\mathrm{vir}}\leqslant 0.75$ . The observed bimodal distribution of the ${\rm{O}}\,{\rm\small{VI}}$ covering fraction with azimuthal angle, showing a higher frequency of absorption along the projected major and minor axes of galaxies, is not reproduced in the simulations. Further analysis reveals the spatial-kinematic distribution of ${\rm{O}}\,{\rm\small{VI}}$ -absorbing gas is dominated by outflows in the inner halo mixed with an inflowing gas that originates from farther out in the halo. Though the CGM of the individual simulated galaxies exhibits spatial structure, the flat azimuthal distribution occurs because the individual simulated galaxies do not develop a CGM structure that is universal from galaxy to galaxy.

Keywords: circumgalactic medium; extragalactic astronomy; quasar absorption line spectroscopy
Stochastic Turbulent Acceleration in a Fractal Environment

We analyze the stochastic acceleration of particles inside a fully developed turbulent plasma. It is well known that large-amplitude magnetic fluctuations and coherent structures in such an environment obey a fractal scaling, and our specific aim is to study for the first time the effects of the fractality of these environments on stochastic acceleration. We have shown that an injected Maxwellian energy distribution is heated and forms a high-energy tail in a very short time. Using standard parameters for the low solar corona, the injected Maxwellian distribution of electrons gets heated from the initial 100 eV to 10 KeV, and the power-law index of the high-energy tail is about -2.3. The high-energy tail starts around 100 keV, and reaches 10 MeV. The index of the power-law tail depends on the system size, and it is in good agreement with observed values for realistic system sizes. The heating and acceleration process is very fast (∼2 s). The reason why the acceleration time is so short is that the particles are trapped within small-scale parts of the fractal environment, and their scattering mean free path reduces drastically. The presence of small-scale activity also easily pulls particles from the thermal pool, so there is no need for a seed population. The mean square displacement in space and energy is superdiffusive for the high-energy particles.

Keywords: solar flares; particle astrophysics; plasma astrophysics; solar energetic particles; solar magnetic reconnection; solar magnetic fields
Dropping Anchor: Understanding the Populations of Binary Black Holes with Random and Aligned-spin Orientations

The relative spin orientations of black holes (BHs) in binaries encode their evolutionary history: BHs assembled dynamically should have isotropically distributed spins, while spins of BHs originating in the field should be aligned with the orbital angular momentum. In this article, we introduce a simple population model for these dynamical and field binaries that uses spin orientations as an anchor to disentangle these two evolutionary channels. We then analyze binary BH mergers in the Third Gravitational-Wave Transient Catalog (GWTC-3) and ask whether BHs from the isotropic-spin population possess different distributions of mass ratios, spin magnitudes, or redshifts from the preferentially aligned-spin population. We find no compelling evidence that binary BHs in GWTC-3 have different source-property distributions depending on their spin alignment, but we do find that the dynamical and field channels cannot both have mass-ratio distributions that strongly favor equal masses. We give an example of how this can be used to provide insights into the various processes that drive these BHs to merge. We also find that the current detections are insufficient in extracting differences in spin magnitude or redshift distributions of isotropic and aligned-spin populations.

Keywords: gravitational wave astronomy; gravitational waves; gravitational wave sources
Constraining the Gravitational Potential from the Projected Morphology of Extragalactic Tidal Streams

The positions and velocities of stellar streams have been used to constrain the mass and shape of the Milky Way's dark matter halo. Several extragalactic streams have already been detected, though it has remained unclear what can be inferred about the gravitational potential from only 2D photometric data of a stream. We present a fast method to infer halo shapes from the curvature of 2D projected stream tracks. We show that the stream curvature vector must point within 90° of the projected acceleration vector, in the absence of recent time-dependent perturbations. While insensitive to the total magnitude of the acceleration, and therefore the total mass, applying this constraint along a stream can determine halo shape parameters and place limits on disk-to-halo mass ratios. The most informative streams are those with sharp turns or flat segments, since these streams sample a wide range of curvature vectors over a small area (sharp turns) or have a vanishing projected acceleration component (flat segments). We apply our method to low surface brightness imaging of NGC 5907, and find that its dark matter halo is oblate. Our analytic approach is significantly faster than other stream modeling techniques, and indicates which parts of a stream contribute to constraints on the potential. The method enables a measurement of dark matter halo shapes for thousands of systems using stellar stream detections expected from upcoming facilities like Rubin and Roman.

Keywords: stellar streams; galaxy stellar halos; dark matter; tidal tails
Photochemistry of Anoxic Abiotic Habitable Planet Atmospheres: Impact of New H2O Cross Sections

We present a study of the photochemistry of abiotic habitable planets with anoxic CO2-N2 atmospheres. Such worlds are representative of early Earth, Mars, and Venus and analogous exoplanets. Photodissociation of H2O controls the atmospheric photochemistry of these worlds through production of reactive OH, which dominates the removal of atmospheric trace gases. The near-UV (NUV; >200 nm) absorption cross sections of H2O play an outsized role in OH production; these cross sections were heretofore unmeasured at habitable temperatures (<373 K). We present the first measurements of NUV H2O absorption at 292 K and show it to absorb orders of magnitude more than previously assumed. To explore the implications of these new cross sections, we employ a photochemical model; we first intercompare it with two others and resolve past literature disagreement. The enhanced OH production due to these higher cross sections leads to efficient recombination of CO and O2, suppressing both by orders of magnitude relative to past predictions and eliminating the low-outgassing "false-positive" scenario for O2 as a biosignature around solar-type stars. Enhanced [OH] increases rainout of reductants to the surface, relevant to prebiotic chemistry, and may also suppress CH4 and H2; the latter depends on whether burial of reductants is inhibited on the underlying planet, as is argued for abiotic worlds. While we focus on CO2-rich worlds, our results are relevant to anoxic planets in general. Overall, our work advances the state of the art of photochemical models by providing crucial new H2O cross sections and resolving past disagreement in the literature and suggests that detection of spectrally active trace gases like CO in rocky exoplanet atmospheres may be more challenging than previously considered.

Keywords: planetary theory; planetary atmospheres; exoplanet atmospheres; exoplanet atmospheric composition; extrasolar rocky planets; habitable planets; water vapor
Early Results from GLASS-JWST. XVI. Discovering a Bluer z 4-7 Universe through UV Slopes

We use the GLASS-JWST Early Release Science NIRCam parallel observations to provide a first view of the UV continuum properties of NIRCam/F444W selected galaxies at 4 < z < 7. By combining multiwavelength NIRCam observations, we constrain the UV continuum slope for a sample of 401 galaxies with stringent quality controls. We find that >99% of the galaxies are blue star-forming galaxies with very low levels of dust (Av β ~ 0.01 ± 0.33). We find no statistically significant correlation for UV slope with redshift or UV magnitude. However, we find that in general galaxies at higher redshifts and fainter UV magnitudes have steeper UV slopes. We find a statistically significant correlation for UV slope with stellar mass, with galaxies with higher stellar mass showing shallower UV slopes. Individual fits to some of our galaxies reach the bluest UV slopes of β ~ -3.1 allowed by stellar population models used in this analysis. Therefore, it is likely that stellar population models with a higher amount of Lyman continuum leakage, active galactic nucleus effects, and/or Population III contributions are required to accurately reproduce the rest-UV and optical properties of some of our bluest galaxies. This dust-free early view confirms that our current cosmological understanding of gradual mass + dust buildup of galaxies with cosmic time is largely accurate to describe the ~0.7-1.5 Gyr age window of the universe. The abundance of a large population of UV faint dust-poor systems may point to a dominance of low-mass galaxies at z > 6 playing a vital role in cosmic reionization.

Keywords: galaxy evolution; high-redshift galaxies
JWST Observations of the Enigmatic Y-Dwarf WISE 1828+2650. I. Limits to a Binary Companion

The Y-dwarf WISE 1828+2650 is one of the coldest known brown dwarfs with an effective temperature of ~300 K. Located at a distance of just 10 pc, previous model-based estimates suggest WISE1828+2650 has a mass of ~5-10 M J, making it a valuable laboratory for understanding the formation, evolution, and physical characteristics of gas giant planets. However, previous photometry and spectroscopy have presented a puzzle, with the near impossibility of simultaneously fitting both the short- (0.9-2.0 μm) and long-wavelength (3-5 μm) data. A potential solution to this problem has been the suggestion that WISE 1828+2650 is a binary system whose composite spectrum might provide a better match to the data. Alternatively, new models being developed to fit JWST/NIRSpec, and MIRI spectroscopy might provide new insights. This article describes JWST/NIRCam observations of WISE 1828+2650 in six filters to address the binarity question and to provide new photometry to be used in model fitting. We also report adaptive optics imaging with the Keck I0 m telescope. We find no evidence for multiplicity for a companion beyond 0.5 au with either JWST or Keck. Companion articles will present low- and high-resolution spectra of WISE 1828 obtained with both NIRSpec and MIRI.

Keywords: brown dwarfs; y dwarfs; visual binary stars; binary stars; james webb space telescope; theoretical models; infrared spectroscopy
Broadband X-Ray Spectral Analysis of the ULX NGC 1313 X-1 Using JeTCAF: Origin of the ULX Bubble

NGC 1313 X-1 is a mysterious ultraluminous X-ray (ULX) source whose X-ray-powering mechanism and bubble-like structure surrounding the source are topics of intense study. Here, we perform an X-ray spectroscopic study of the source using joint XMM-Newton and NuSTAR observations taken during 2012-2017. The combined spectra cover the energy band 0.3-20 keV. We use the accretion-ejection-based JeTCAF model for spectral analysis. The model-fitted disk mass accretion rate varies from 4.6 to 9.6 ${\dot{M}}_{\mathrm{Edd}}$ and the halo mass accretion rate varies from 4.0 to 6.1 ${\dot{M}}_{\mathrm{Edd}}$ with a dynamic Comptonizing corona of average size of ~15 r g . The data fitting is carried out for different black hole (BH) mass values. The goodness of the fit and uncertainties in model parameters improve while using higher BH masses, with the most probable mass of the compact object being 133 ± 33 M ⊙. We have estimated the mass outflow rate, its velocity and power, and the age of the inflated bubble surrounding the source. Our estimated bubble morphology is in accordance with the observed optical bubble and winds found through high-resolution X-ray spectroscopy, suggesting that the bubble was expanded by the outflows originating from the central source. Finally, we conclude that the super-Eddington accretion onto a nearly intermediate-mass BH may power a ULX when the accretion efficiency is low, though their efficiency increases when the jet/outflow is taken into account, in agreement with numerical simulations in the literature.

Keywords: accretion; x-ray astronomy; superbubbles; jets; astrophysical black holes; hydrodynamics; shocks
On Single-point Inversions of Magnetic Dipole Lines in the Corona

Prompted by a recent paper by Dima and Schad, we reconsider the problem of inferring magnetic properties of the corona using polarimetric observations of magnetic dipole (M1) lines. Dima and Schad point to a potential source of degeneracy in a formalism developed by Plowman, which under some circumstances can lead to the solution being under-determined. Here we clarify the nature of the problem. Its resolution lies in solving for the scattering geometry using the elongation of the observed region of the corona. We discuss some conceptual problems that arise when casting the problem for inversion in the observer's reference frame, and satisfactorily resolve difficulties identified by Plowman, Dima, and Schad.

Keywords: solar physics; solar e corona; solar corona; radiative processes; spectropolarimetry
Shaping the Envelope of the Asymptotic Giant Branch Star W43A with a Collimated Fast Jet

One of the major puzzles in the study of stellar evolution is the formation process of bipolar and multipolar planetary nebulae. There is growing consensus that collimated jets create cavities with dense walls in the slowly expanding (10-20 km s-1) envelope ejected in previous evolutionary phases, leading to the observed morphologies. However, the launching of the jet and the way it interacts with the circumstellar material to create such asymmetric morphologies have remained poorly known. Here we present for the first time CO emission from the asymptotic giant branch star W43A that traces the whole stream of a jet, from the vicinity of its driving stellar system out to the regions where it shapes the circumstellar envelope. We found that the jet has a launch velocity of 175 km s-1 and decelerates to a velocity of 130 km s-1 as it interacts with circumstellar material. The continuum emission reveals a bipolar shell with a compact bright dot in the center that pinpoints the location of the driving source of the jet. The kinematical ages of the jet and the bipolar shell are equal, τ ∼ 60 yr, indicating that they were created simultaneously, probably by a common underlying mechanism, and in an extremely short time. These results provide key initial conditions for the theoretical models that aim to explain the formation of bipolar morphologies in the circumstellar envelopes of low- and intermediate-mass stars.

Keywords: asymptotic giant branch stars; stellar jets
On the Interpretation of the Scalings of Density Fluctuations from In Situ Solar Wind Observations: Insights from 3D Turbulence Simulations

Solar wind turbulence is often perceived as weakly compressible and the density fluctuations remain poorly understood both theoretically and observationally. Compressible magnetohydrodynamic simulations provide useful insights into the nature of density fluctuations. We discuss a few important effects related to 3D simulations of turbulence and in situ observations. The observed quantities such as the power spectrum and variance depend on the angle between the sampling trajectory and the mean magnetic field due to anisotropy of the turbulence. The anisotropy effect is stronger at smaller scales and lower plasma beta. Additionally, in situ measurements tend to exhibit a broad range of variations, even though they could be drawn from the same population with the defined averages, so a careful averaging may be needed to reveal the scaling relations between density variations and other turbulence quantities such as turbulent Mach number from observations.

Keywords: magnetohydrodynamics; solar wind; interplanetary turbulence
The MASSIVE Survey. XVII. A Triaxial Orbit-based Determination of the Black Hole Mass and Intrinsic Shape of Elliptical Galaxy NGC 2693

We present a stellar dynamical mass measurement of a newly detected supermassive black hole (SMBH) at the center of the fast-rotating, massive elliptical galaxy NGC 2693 as part of the MASSIVE survey. We combine high signal-to-noise ratio integral field spectroscopy (IFS) from the Gemini Multi-Object Spectrograph with wide-field data from the Mitchell Spectrograph at McDonald Observatory to extract and model stellar kinematics of NGC 2693 from the central ~150 pc out to ~2.5 effective radii. Observations from Hubble Space Telescope WFC3 are used to determine the stellar light distribution. We perform fully triaxial Schwarzschild orbit modeling using the latest TriOS code and a Bayesian search in 6D galaxy model parameter space to determine NGC 2693's SMBH mass (M BH), stellar mass-to-light ratio, dark matter content, and intrinsic shape. We find ${M}_{\mathrm{BH}}=\left(1.7\pm 0.4\right)\times {10}^{9}\ {M}_{\odot }$ and a triaxial intrinsic shape with axis ratios p = b/a = 0.902 ± 0.009 and $q=c/a={0.721}_{-0.010}^{+0.011}$ , triaxiality parameter T = 0.39 ± 0.04. In comparison, the best-fit orbit model in the axisymmetric limit and (cylindrical) Jeans anisotropic model of NGC 2693 prefer ${M}_{\mathrm{BH}}=\left(2.4\pm 0.6\right)\times {10}^{9}\ {M}_{\odot }$ and ${M}_{\mathrm{BH}}=\left(2.9\pm 0.3\right)\times {10}^{9}\ {M}_{\odot }$ , respectively. Neither model can account for the non-axisymmetric stellar velocity features present in the IFS data.

Keywords: galaxy dynamics; galaxy masses; supermassive black holes; early-type galaxies; galaxies; galaxy dark matter halos; galaxy evolution; galaxy kinematics
The Double Asteroid Redirection Test (DART): Planetary Defense Investigations and Requirements

The Double Asteroid Redirection Test (DART) is a Planetary Defense mission, designed to demonstrate the kinetic impactor technique on (65803) Didymos I Dimorphos, the secondary of the (65803) Didymos system. DART has four level 1 requirements to meet in order to declare mission success: (1) impact Dimorphos between 2022 September 25 and October 2, (2) cause at least a 73 s change in its binary orbit period via the impact, (3) measure the change in binary period to an uncertainty of 7.3 s or less, and (4) measure the momentum transfer efficiency (β) of the impact and characterize the resulting effects of the impact. The data necessary to achieve these requirements will be obtained and analyzed by the DART Investigation Team. We discuss the rationales for the data to be gathered, the analyses to be undertaken, and how mission success will be achieved.

Keywords: asteroids; asteroid satellites; near-earth objects; impact phenomena
Element Abundance Analysis of the Metal-rich Stellar Halo and High-velocity Thick Disk in the Galaxy

Based on the second Gaia data release (DR2) and APOGEE (DR16) spectroscopic surveys, we define two kinds of star samples: high-velocity thick disk (HVTD) with vφ > 90 km s-1 and metal-rich stellar halo (MRSH) with vφ < 90 km s-1. Due to high-resolution spectra data from APOGEE (DR16), we can accurately analyze the element abundance distribution of HVTD and MRSH. These element abundances constitute a multidimensional data space, and we introduce an algorithm method for processing multidimensional data to give the result of dimensionality reduction clustering. According to chemical property analysis, we derive that some HVTD stars could originate from the thin disk and some MRSH stars could originate from dwarf galaxies, but those stars that have similar chemical abundance characteristics in both samples may form in situ.

Keywords: galaxy disks; galaxy kinematics; galaxy abundances; galaxy structure; galaxy stellar halos