Non-equilibrium Ionization States Within Galactic Outflows: Explaining Their O VI and N V Column Densities
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.
Keywords
Cite
@article{arxiv.1903.06183,
title = {Non-equilibrium Ionization States Within Galactic Outflows: Explaining Their O VI and N V Column Densities},
author = {William J Gray and Evan Scannapieco and Matthew D. Lehnert},
journal= {arXiv preprint arXiv:1903.06183},
year = {2019}
}
Comments
16 pages, 11 figures, accepted to ApJ. Comments welcome