Sazuna/UAT_keywords huggingface dataset:
Suppressing the Thermal SZ-induced Variance in CMB-cluster Lensing Estimators. Accurate galaxy cluster mass measurements from the gravitational lensing of the cosmic microwave background temperature maps depend on mitigating potential biases from the cluster’s own thermal Sunyaev-Zel’dovich (SZ) effect signal. Quadratic lensing estimators use a pair of maps to extract the lensing signal: a large-scale gradient map and a small-scale lensing map. The SZ bias can be eliminated by using an SZ-free map in the pair, with the gradient map being favored for signal-to-noise reasons. However, while this approach eliminates the bias, the SZ power in small-scale lensing map adds extra variance that can become significant for high-mass clusters and low-noise surveys. In this work, we propose projecting out an SZ template to reduce the SZ variance. Any residual SZ signal after template fitting is uncorrelated with the SZ-free gradient map, and thus does not bias the mass measurements. For massive clusters above 4× {10}14 {M}⊙  observed by the upcoming CMB-S4 and Simons Observatory experiments, we find that the template fitting approach would increase the cluster lensing signal-to-noise by a factor of 1.4.

Keywords: Galaxy clusters, Weak gravitational lensing, Observational cosmology, Cosmic microwave background radiation, Sunyaev-Zeldovich effect
Collision and Radiative Parameters for Cr II Lines Observed in Stellar and Nebular Spectra. Electron excitation collision strengths (Ω) and transition probabilities (A-values) for the iron-peak element Cr II lines are of high importance for the stellar and nebular abundance studies. Collision and radiative parameters are presented for all possible inelastic transitions between the Cr II 512 fine-structure levels covering infrared to extreme ultraviolet lines. These parameters should allow a detailed modeling and analysis of the available measured stellar and nebular spectra from different astrophysical objects. Accurate target wave functions have been generated using the multiconfiguration Hartree-Fock method together with term-dependent one-electron orbitals and well-chosen configuration expansions. The wave functions are then used in the calculations of transition probabilities and collision rates. The B-spline Breit-Pauli R-matrix method has been employed for the calculation of electron excitation collision strengths. The semiempirical fine-tuning procedure has been applied to the energies of the local supercluster (LS) terms prior to transformation of the Hamiltonian matrices to intermediate coupling. The Hamiltonian matrices for the calculation of collision rates also include spin-orbit interaction. The 512 fine-structure levels of the Cr II 3d 5, 3d 44s, 3{d}34{s}2, 3d 44p, and 3d 34s4p configurations have been considered in our work. The thermally averaged collision strengths have been determined using a Maxwellian distribution for a wide range of temperatures from 102 to 105 K. The accuracy of our results has been estimated by comparison with other calculated collision rates and available measured radiative rates.

Keywords: Atomic spectroscopy, Laboratory astrophysics
PIC Simulation of a Shock Tube: Implications for Wave Transmission in the Heliospheric Boundary Region. A shock tube problem is solved numerically by using one-dimensional full particle-in-cell simulations under the condition that a relatively tenuous and weakly magnetized plasma is continuously pushed by a relatively dense and strongly magnetized plasma having supersonic relative velocity. A forward and a reverse shock and a contact discontinuity are self-consistently reproduced. The spatial width of the contact discontinuity increases as the angle between the discontinuity normal and ambient magnetic field decreases. The inner structure of the discontinuity shows different profiles between magnetic field and plasma density, or pressure, which is caused by a non-MHD effect of the local plasma. The region between the two shocks is turbulent. The fluctuations in the relatively dense plasma are compressible and propagating away from the contact discontinuity, although the fluctuations in the relatively tenuous plasma contain both compressible and incompressible components. The source of the compressible fluctuations in the relatively dense plasma is in the relatively tenuous plasma. Only compressible fast mode fluctuations generated in the relatively tenuous plasma are transmitted through the contact discontinuity and propagate in the relatively dense plasma. These fast mode fluctuations are steepened when passing the contact discontinuity. This wave steepening and probably other effects may cause the broadening of the wave spectrum in the very local interstellar medium plasma. The results are discussed in the context of the heliospheric boundary region or heliopause.

Keywords: Space plasmas, Heliosphere, Interstellar magnetic fields, Interplanetary magnetic fields, Solar transition region
Multiwavelength Polarimetry of the Filamentary Cloud IC 5146. II. Magnetic Field Structures. The IC 5146 cloud is a nearby star-forming region in Cygnus, consisting of molecular gas filaments in a variety of evolutionary stages. We used optical and near-infrared polarization data toward the IC 5146 cloud, reported in the first paper of this series, to reveal the magnetic fields in this cloud. Using the newly released Gaia data, we found that the IC 5146 cloud may contain two separate clouds: a first cloud, including the densest main filament at a distance of ∼600 pc, and a second cloud, associated with the Cocoon Nebula at a distance of ∼800 pc. The spatially averaged H-band polarization map revealed a well-ordered magnetic field morphology, with the polarization segments perpendicular to the main filament but parallel to the nearby subfilaments, consistent with models assuming that the magnetic field is regulating cloud evolution. We estimated the magnetic field strength using the Davis-Chandrasekhar-Fermi method and found that the magnetic field strength scales with volume density with a power-law index of ∼0.5 in the density range from {N}{{{H}}2}∼ 10 to 3000 cm-3, which indicates an anisotropic cloud contraction with a preferred direction along the magnetic field. In addition, the mass-to-flux ratio of the cloud gradually changes from subcritical to supercritical from the cloud envelope to the deep regions. These features are consistent with strong magnetic field star formation models and suggest that the magnetic field is important in regulating the evolution of the IC 5146 cloud.

Keywords: Interstellar filaments, Molecular clouds, Interstellar magnetic fields, Starlight polarization, Collapsing clouds
Resolving 3D Disk Orientation Using High-resolution Images: New Constraints on Circumgalactic Gas Inflows. We constrain gas inflow speeds in star-forming galaxies with color gradients consistent with inside-out disk growth. Our method combines new measurements of disk orientation with previously described circumgalactic absorption in background quasar spectra. Two quantities, a position angle and an axis ratio, describe the projected shape of each galactic disk on the sky, leaving an ambiguity about which side of the minor axis is tipped toward the observer. This degeneracy regarding the 3D orientation of disks has compromised previous efforts to measure gas inflow speeds. We present Hubble Space Telescope and Keck/LGSAO imaging that resolves the spiral structure in five galaxies at redshift z ≈ 0.2. We determine the sign of the disk inclination for four galaxies, under the assumption that spiral arms trail the rotation. We project models for both radial infall in the disk plane and circular orbits onto each quasar sightline. We compare the resulting line-of-sight velocities to the observed velocity range of Mg II absorption in spectra of background quasars, which intersect the disk plane at radii between 69 and 115 kpc. For two sightlines, we constrain the maximum radial inflow speeds as 30-40 km s-1. We also rule out a velocity component from radial inflow in one sightline, suggesting that the structures feeding gas to these growing disks do not have unity covering factor. We recommend appropriate selection criteria for building larger samples of galaxy-quasar pairs that produce orientations sensitive to constraining inflow properties.

Keywords: Galaxy formation, Quasar absorption line spectroscopy, Laser guide stars, Galaxy evolution, Circumgalactic medium, Extragalactic astronomy
3D MHD Modeling of the Impact of Subsurface Stratification on the Solar Dynamo. Various models of solar subsurface stratification are tested in the global EULAG-MHD solver to simulate diverse regimes of near-surface convective transport. Sub- and superadiabacity are altered at the surface of the model (r &gt; 0.95R ⊙) to either suppress or enhance convective flow speeds in an effort to investigate the impact of the near-surface layer on global dynamics. A major consequence of increasing surface convection rates appears to be a significant alteration of the distribution of angular momentum, especially below the tachocline where the rotational frequency predominantly increases at higher latitudes. These hydrodynamic changes correspond to large shifts in the development of the current helicity in this stable layer (r &lt; 0.72R ⊙), significantly altering its impact on the generation of poloidal and toroidal fields at the tachocline and below, acting as a major contributor toward transitions in the dynamo cycle. The enhanced near-surface flow speed manifests in a global shift of the toroidal field (B  ϕ ) in the butterfly diagram, from a north-south symmetric pattern to a staggered antisymmetric emergence.

Keywords: Solar physics, Solar dynamo, Magnetohydrodynamical simulations
Coulomb Explosion of Polycyclic Aromatic Hydrocarbons Induced by Heavy Cosmic Rays: Carbon Chains Production Rates. Cosmic rays (CRs) process the matter of the interstellar medium (ISM), not only modifying the interstellar matter but also injecting chemical species in the gas phase. In this work, we study the effect of CRs on astrophysical polycyclic aromatic hydrocarbons (PAHs). For events in which many electrons are stripped out from the PAHs, coulomb explosion takes place and carbon chains are produced. We computed PAH multi-ionization cross sections with a collisional model. We used another model to predict the fragmentation pattern following coulomb explosion. Experimental measurements were used to assess the validity of the calculations. The production rates of carbon chains were calculated using different CR fluxes and elemental compositions, to account for the variations expected in different astrophysical environments. PAHs with a range of sizes and levels of compactness were explored. As an average over the explored PAHs, the PAH lifetime with respect to a standard interstellar CR flux is found to be on the order of a few billion years. The production rates of chains (5-15 carbons) are slightly below the H2 ionization rate ζ. In the diffuse ISM, with 10% of the available cosmic carbon locked in PAHs, this process leads to carbon chain fractional abundances at steady state, in the range of 10-15-10-14, with a confidence interval of 1 order of magnitude. It reaches 10-13 in quiescent dense clouds. This is not sufficient to explain the observed abundances of carbon chains and complex organic molecules in dense clouds.

Keywords: Interstellar molecules, Polycyclic aromatic hydrocarbons, Astrochemistry, Galactic cosmic rays, Interstellar medium
Radio, EUV, and X-Ray Observations during a Filament Rise in the 2011 June 7 Solar Flare. The most energetic flares start with a filament rise followed by magnetic reconnection below this filament. The start of the reconnection corresponds to the beginning of the flare impulsive phase. In this paper we study processes before this phase. During the filament rise we recognize an unusual radio continuum with a starting boundary drifting toward lower frequencies. The estimated velocity of the agent generating this continuum boundary is about 400 km s-1, similar to that of the rising filament. In association with this filament rise, transient X-ray sources and extreme ultraviolet (EUV) brightenings are found near the filament footpoint and outside the locations where later two parallel flare ribbons appear. Moreover, oscillations with a ∼30 s period are found simultaneously in radio, EUV, and X-ray observations. Around the end of these oscillations the flare impulsive phase starts as seen in observations of the drifting pulsation structure and X-ray source located at the upper part of the rising filament. We interpret the unusual radio continuum and transient X-ray sources, which are located outside the two parallel flare ribbons, as those generated during an interaction of the rising filament with the above-lying magnetic loops. The EUV brightening at the filament footpoint could be a signature of the magnetic reconnection inside the magnetic rope carrying the filament. Possible scenarios of the ∼30 s period oscillations in radio, X-ray, and EUV are discussed.

Keywords: Solar flares, Solar ultraviolet emission, Solar x-ray flares, Solar oscillations, Solar radio flares
Surprisingly Strong K-band Emission Found in Low-luminosity Active Galactic Nuclei. We examine the near-infrared (NIR) emission from low-luminosity active galactic nuclei (LLAGNs). Our galaxy sample includes 15 objects with detected 2-10 keV X-ray emission, dynamical black hole mass estimates from the literature, and available Gemini/NIFS integral field spectroscopy data. We find evidence for red continuum components at the center of most galaxies, consistent with the hot dust emission seen in higher-luminosity AGNs. We decompose the spectral data cubes into a stellar and continuum component, assuming the continuum component comes from thermal emission from hot dust. We detect nuclear thermal emission in 14 out of 15 objects. This emission causes weaker CO absorption lines and redder continuum (2.05-2.28 μm) in our K-band data, as expected from hot dust around an AGN. The NIR emission is clearly correlated with the 2-10 keV X-ray flux, with a Spearman coefficient of r spearman = 0.69 suggesting a &gt;99% significance of correlation, providing further evidence of an AGN origin. Our sample has typical X-ray and NIR fluxes 3-4 orders of magnitude less luminous than previous work studying the NIR emission from AGNs. We find that the ratio of NIR to X-ray emission increases toward lower Eddington ratios. The NIR emission in our sample is often brighter than the X-ray emission, with our K-band AGN luminosities comparable to or greater than the 2-10 keV X-ray luminosities in all objects with Eddington ratios below 0.01%. The nature of this LLAGN NIR emission remains unclear, with one possibility being an increased contribution from jet emission at these low luminosities. These observations suggest the James Webb Space Telescope will be a useful tool for detecting the lowest-luminosity AGNs.

Keywords: Near infrared astronomy, Low-luminosity active galactic nuclei, Active galactic nuclei, Interferometry
Point-spread Function Estimation for Adaptive Optics Imaging of Astronomical Extended Objects. This paper focuses on point-spread function (PSF) estimation for astronomical images containing only single extended objects captured by adaptive optics systems. The problem is very different from, and much more challenging than, PSF estimation with point-like source images. We propose a new PSF estimation framework based on deep-learning technology. In this framework, PSFs can be estimated “end-to-end” using the original degraded images. Moreover, such a framework can precisely address different sources of blur without requiring accurate prior information about the PSF, image or imaging system. Therefore, the method is practical. We test the proposed method on both simulated and real data, and the favorable results show that the method is valid and performs much better than classical methods do.

Keywords: Optical telescopes
Identifiable Acetylene Features Predicted for Young Earth-like Exoplanets with Reducing Atmospheres Undergoing Heavy Bombardment. The chemical environments of young planets are assumed to be largely influenced by the impacts of bodies lingering on unstable trajectories after the dissolution of the protoplanetary disk. We explore the chemical consequences of impacts within the context of reducing planetary atmospheres dominated by carbon monoxide, methane, and molecular nitrogen. A terawatt high-power laser was selected in order to simulate the airglow plasma and blast wave surrounding the impactor. The chemical results of these experiments are then applied to a theoretical atmospheric model. The impact simulation results in substantial volume mixing ratios within the reactor of 5% hydrogen cyanide (HCN), 8% acetylene (C2H2), 5% cyanoacetylene (HC3N), and 1% ammonia (NH3). These yields are combined with estimated impact rates for the early Earth to predict surface boundary conditions for an atmospheric model. We show that impacts might have served as sources of energy that would have led to steady-state surface quantities of 0.4% C2H2, 400 ppm HCN, and 40 ppm NH3. We provide simulated transit spectra for an Earth-like exoplanet with this reducing atmosphere during and shortly after eras of intense impacts. We predict that acetylene is as observable as other molecular features on exoplanets with reducing atmospheres that have recently gone through their own “heavy bombardments,” with prominent features at 3.05 and 10.5 μm.

Keywords: Impact phenomena, Extrasolar rocky planets, Plasma physics, Laboratory astrophysics, Planetary atmospheres, Molecular spectroscopy, Exoplanet atmospheres
Evidence of Dust Grain Evolution from Extinction Mapping in the IC 63 Photodissociation Region. Photodissociation regions (PDRs) are parts of the ISM consisting of predominantly neutral gas, located at the interface between H II regions and molecular clouds. The physical conditions within these regions show variations on very short spatial scales, and therefore PDRs constitute ideal laboratories for investigating the properties and evolution of dust grains. We have mapped IC 63 at high resolution from the UV to the NIR (275 nm to 1.6 μm), using the Hubble Space Telescope WFC3. Using a Bayesian SED fitting tool, we simultaneously derive a set of stellar (T eff, {log}(g), distance) and extinction (A  V , R  V ) parameters for 520 background stars. We present maps of A  V  and R  V  with a resolution of 25 arcsec based on these results. The extinction properties vary across the PDR, with values for A  V  between 0.5 and 1.4 mag, and a decreasing trend in R  V , going from 3.7 at the front of the nebula to values as low as 2.5 further in. This provides evidence for evolution of the dust optical properties. We fit two modified blackbodies to the MIR and FIR SED, obtained by combining the A  V  map with data from Spitzer and Herschel. We derive effective temperatures (30 and 227 K) and the ratio of opacities at 160 μm to V band κ 160/κ  V  (7.0 × 10-4 and 2.9 × 10-9) for the two dust populations. Similar fits to individual pixels show spatial variations of κ 160/κ  V . The analysis of our HST data, combined with these Spitzer and Herschel data, provides the first panchromatic view of dust within a PDR. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program GO-14186.

Keywords: Photodissociation regions, Interstellar dust extinction, Interstellar medium
Shear Measurement Bias Due to Spatially Varying Spectral Energy Distributions in Galaxies. Galaxy color gradients (CGs)—I.e., spectral energy distributions that vary across the galaxy profile—will impact galaxy shape measurements when the modeled point-spread function (PSF) corresponds to that for a galaxy with spatially uniform color. This paper describes the techniques and results of a study of the expected impact of galaxy CGs on weak lensing measurements with the Large Synoptic Survey Telescope (LSST) when the PSF size depends on wavelength. The bias on cosmic shear measurements from CGs is computed both for parametric bulge+disk galaxy simulations and for more realistic chromatic galaxy surface brightness profiles based on Hubble Space Telescope V- and I-band images in the All-Wavelength Extended Groth Strip International Survey (AEGIS). For the parametric galaxies, and for the more realistic galaxies derived from AEGIS galaxies with a sufficient signal-to-noise ratio that CG bias can be isolated, the predicted multiplicative shear biases due to CGs are found to be at least a factor of two below the LSST full-depth requirement on the total systematic uncertainty in the redshift-dependent shear calibration. The analysis code and data products are publicly available (https://github.com/sowmyakth/measure_cg_bias).

Keywords: Weak gravitational lensing, Cosmology, Observational cosmology, Astronomical techniques, Gravitational lensing shear
On the Sensitivity of Heliosphere Models to the Uncertainty of the Low-energy Charge Exchange Cross-section. Models play an important role in our understanding of the global structure of the solar wind and its interaction with the interstellar medium. A critical ingredient in many types of models is the charge-exchange collisions between ions and neutrals. Some ambiguity exists in the charge-exchange cross-section for protons and hydrogen atoms, depending on which experimental data is used. The differences are greatest at low energies, and for the plasma-neutral interaction in the outer heliosheath may exceed 50%. In this paper we assess a number of existing data sets and formulae for proton-hydrogen charge exchange. We use a global simulation of the heliosphere to quantify the differences between the currently favored cross-section, and we suggest a formulation that more closely matches the majority of available data. We find that in order to make the resulting two heliospheres the same size, the interstellar proton and hydrogen densities need to be adjusted by 10%-15%, which provides a way to link the uncertainty in the cross-section to the uncertainty in the parameters of the pristine interstellar plasma.

Keywords: Heliosheath, Astrosphere interstellar medium interactions, Heliosphere, Charge exchange ionization
Laboratory Observation of Radiative Shock Deceleration and Application to SN 1987A. The first laboratory evidence of a radiative shock (RS) decelerating during its free expansion phase in an optically thick medium is presented. A shock is generated in a multilayer solid target under the irradiation of a high-power laser at the GEKKO XII laser facility. The rear surface of the target is connected to a gas cell filled with Xe. Upon breakout, an RS, characterized by low Boltzmann number Bo ≪ 1 and Mihalas number R ≈ 10, is generated. Experimental results reveal that radiative losses through the radiative precursor cause the shock to lose energy and decelerate. A model is developed that describes the shock propagation as a function of time. The model is in agreement with both numerical simulations and experimental results. These results have tremendous consequences for astrophysical systems, such as SN 1987A, where radiative deceleration may play a role in the formation of the observed hotspots in the circumstellar ring.

Keywords: Shocks, Laboratory astrophysics, Experimental techniques