XMM-Newton, with its extraordinary sensitivity for faint extended X-ray emission, is used to derive spatial and spectral properties of the very hot extra-planar/ halo gas. For example, spectral models can be tested and hot gas properties like density, mass and energy can be estimated. Comparing the distribution of the halo X-ray emission with optical filaments and/or observed magnetic field structures uncovers interesting correlations on which work has just started.

Our study aims – in general – at assessing the importance of galactic halos as repositories of a metal-enriched hot medium and their significance in terms of galactic chemical evolution and possible metal enrichment of the intergalactic medium.

¹This work is based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).