The Origin and Properties of X-ray-emitting Gas in the Halos of both Starburst and Normal Spiral Galaxies

Abstract

I discuss the empirical properties of diffuse X-ray emitting gas in the halos of both nearby starburst galaxies and normal spiral galaxies, based on high resolution X-ray spectral imaging with the Chandra X-ray Observatory. Diffuse thermal X-ray emission can provide us with unique observational probes of outflow and accretion processes occurring in star-forming galaxies, and their interaction with the inter-galactic medium. I consider both the spatial distribution of the diffuse X-ray emission in and around edge-on starburst galaxies with superwinds (e.g. surface brightness profiles, distribution with respect to H-alpha and radio emission), and its spectral properties (e.g. thermal or non-thermal nature, abundance ratios, temperatures and soft and hard X-ray luminosities). These results are discussed in the context of current theoretical models of supernova-driven superwinds, and compared to the more limited data on extra-planar hot gas around edge-on normal galaxies.