High velocity clouds interacting with galactic halo plasma as a source of X-ray emission

Kellett, B.J. and Bingham, R. (2005) High velocity clouds interacting with galactic halo plasma as a source of X-ray emission. Journal of Plasma Physics, 71 (2). pp. 111-118. ISSN 0022-3778

Abstract

Several high velocity clouds (HVCs) are now known to be soft X-ray sources. In this paper we suggest that all interaction between the HVCs and the galactic halo is leading to plasma instabilities that generate energetic electrons which in turn generate X-ray emission. This process is essentially analogous to the interaction process between cornets and non-magnetized planets with the solar wind which is also known to lead to the generation of X-rays. We show that for reasonable assumptions about the galactic halo magnetic field, the X-ray emission can be converted into an estimate of the mean galactic halo density it the position of the cloud. This provides a method for estimating the baryonic mass of the plasma halo provided that we call obtain a good estimate for the distance to the HVC.

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