We present ROSAT PSPC and HRI observations of the galactic wind from the starburst galaxy M82 .
X-ray emission from the wind is detected to a distance of \sim 6 { \thinspace kpc } from the plane of the galaxy .
Making use of the PSPC ’ s mixture of good spatial and spectral characteristics , we separate point source and diffuse emission , and investigate the spectral variation of the diffuse emission through the wind .
The intrinsic X-ray luminosity of the wind in the 0.1-2.4 keV band is found to be approximately 1.9 \times 10 ^ { 40 } { \thinspace erg } { \thinspace s } ^ { -1 } outside the immediate vicinity of the nucleus .
The temperature of the diffuse emission is found to decrease weakly from \sim 0.6 { \thinspace keV } to \sim 0.4 { \thinspace keV } along the minor axis , whilst the inferred gas density drops as z ^ { -0.5 } and z ^ { -0.8 } along the northern and southern minor axes respectively .
We compare these results with those expected from two simple models for the emission : Chevalier & Clegg ’ s adiabatically expanding free wind and emission from shocked clouds in a wind , and find that the emission can not come from a free wind , but that shock heated clouds could be the source of the emission .