The ‘bubbly’ interstellar medium as origin for the inhomogeneous internal metallicity distributions in large disc galaxies

Abstract

Resolved metallicity studies of local disc galaxies have revealed that their interstellar media (ISMs) are far from chemically homogeneous, displaying significant (${\sim} 0.05$dex) variations in the metallicity on characteristic scales of a few hundred parsecs. Such data is at odds with most analytical models, where the ISM is predicted to be more well-mixed. Here, we suggest that the observed small-scale features seen in galaxies may be superbubbles of metal-enriched gas created by a collection of core collapse supernovae with tight spatial (and temporal) correlation. In this scenario, the size of the metallicity fluctuations (superbubble radius, ϕ) is set by the disc scale height ..