Shocks as a Secondary Source of Ionization in Diffuse Ionized Gas Halos

Using spectroscopic data for the edge-on spiral NGC 5775, discussed in a paper by Rand in these proceedings, we attempt to address the issue of how Diffuse Ionized Gas (DIG) halos are energized. Data are interpreted in the context of composite photo-ionization/shock models. We find that an increasing contribution from shocks with z is necessary to explain observed line ratios. In addition, the runs of [oiii]/Hα vs. z in NGC 5775 suggest that shocks make a greater contribution in regions where DIG is of a filamentary morphology.