Atomic Chemistry In Turbulent Astrophysical Media I: Effect of Atomic Cooling

Abstract

We carry out direct numerical simulations of turbulent astrophysical media that explicitly track ionizations, recombinations, and species-by-species radiative cooling. The simulations assume solar composition and follows the evolution of hydrogen, helium, carbon, oxygen, sodium, and magnesium, but they do not include the presence of an ionizing background. In this case, the medium reaches a global steady state that is purely a function of the one-dimensional turbulent velocity dispersion, ${\sigma }_{1D},$ and the product of the mean density and the driving scale of turbulence, $nL.$ Our simulations span a grid of models with ${\sigma }_{1D}$ ranging from 6 to 58 km s${}^{-1}$ and $nL$ ranging from 10${}^{16}$ to 10${}^{20}$ cm${}^{-2},$ which correspond to turbulent Mach numbers from $M=0.2$ to 10.6. The species abundances are well described by single-temperature estimates whenever $M$ is small, but local equilibrium models can not accurately predict the global equilibrium abundances when $M\gtrsim 1.$ To allow future studies to account for nonequilibrium effects in turbulent media, we gather our results into a series of tables, which we will extend in the future to encompass a wider range of elements, compositions, and ionizing processes.

17 Pages, 8 figures, Accepted to ApJ. Comments welcome

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• Modeling Photoionized Turbulent Material in the Circumgalactic Medium II: Effect of Turbulence within a Stratified Medium
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• Interpreting Observations of Absorption Lines in the Circumgalactic Medium with a Turbulent Medium
• Modeling Photoionized Turbulent Material in the Circumgalactic Medium III: Effects of Co-rotation and Magnetic Fields
• Catastrophic Cooling in Superwinds. II. Exploring the Parameter Space
• Non-equilibrium Photoionization and Hydrodynamic Simulations of Starburst-driven Outflows