The warm-hot gaseous halo of the Milky Way

Abstract

The circumgalactic region of the Milky Way contains a large amount of gaseous mass in the warm-hot phase. The presence of this warm-hot halo observed through $z=0$ X-ray absorption lines is generally agreed upon, but its density, path-length, and mass is a matter of debate. Here I discuss in detail why different investigations led to different results. The presence of an extended (over 100 kpc) and massive (over ten billion solar masses) warm-hot gaseous halo is supported by observations of other galaxies as well. I briefly discuss the assumption of constant density and end with outlining future prospects.

Based on an invited talk given at the "Half a century of X-ray astronomy" conference in Mykonos, Greece, September 2012. This is not intended to be a comprehensive review