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arXiv · 1903.06183

Non-equilibrium Ionization States Within Galactic Outflows: Explaining Their O VI and N V Column Densities

William J Gray·Evan Scannapieco·Matthew D. Lehnert
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Abstract

We present a suite of one-dimensional spherically-symmetric hydrodynamic simulations that study the atomic ionization structure of galactic outflows. We track the ionization state of the outflowing gas with a non-equilibrium atomic chemistry network that includes photoionization, photo-heating, and ion-by-ion cooling. Each simulation describes a steady-state outflow that is defined by its mass and energy input rates, sonic radius, metallicity, and UV flux from both the host galaxy and meta-galactic background. We find that for a large range of parameter choices, the ionization state of the material departs strongly from what it would be in photo-ionization equilibrium, in conflict with what is commonly assumed in the analysis of observations. In addition, nearly all the models reproduce the low N V to O VI column density ratios and the relatively high O VI column densities that are observed.

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William J Gray, Evan Scannapieco, Matthew D. Lehnert. 2019-03-14. Non-equilibrium Ionization States Within Galactic Outflows: Explaining Their O VI and N V Column Densities. https://doi.org/10.3847/1538-4357%2Fab1004

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