paper

Modeling Emission-Line Surface Brightness in a Multiphase Galactic Wind: An O VI Case Study

arXiv:2510.02443 · doi:10.1093/mnras/stag617

Abstract

We present a fast and robust analytic framework for predicting surface brightness (SB) of emission lines in galactic winds as a function of radius up to kpc out in the circum-galactic medium. We model multiphase structure in galactic winds by capturing emission from both the volume-filling hot phase (T K) and turbulent radiative mixing layers that host intermediate temperature gas at the boundaries of cold clouds (T K). Our multiphase framework makes significantly different predictions of emission signatures compared to traditional single-phase models and explains the paucity of OVI SB measurements in the literature. After accounting for ram pressure equilibrium between the cold clouds and hot wind in supersonic outflows, non-equilibrium ionization effects, and energy budgets other than mechanical energy from core-collapse supernovae, our OVI SB predictions qualitatively match observational results. Our framework provides constraints on the optimal galactic wind properties that facilitate OVI emission observations, including star formation rate surface density, hot phase mass loading factor, and thermalization efficiency factor. These constraints are consistent with existing observations and can help inform future target selections.

19 pages, 15 figures. Accepted for publication in MNRAS, 27 March 2026. Zirui Chen and Zixuan Peng are co-first authors who made equal contributions to this work

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