GALACTIC GAMMA-RAYS FROM THE INVERSE COMPTON PROCESS

The extent to which gamma rays from inverse Compton collisions contribute to the measured gamma-ray Bur in the satellite energy band (30-4000 MeV) is examined. The problems inherent in the estimate are discussed, not least the uncertainty in the scale height of cosmic-ray electrons and in the extent to which the local cosmic-ray intensity is spatially variable. Most of the paper refers to the derivation of the effective IC contribution, effective in the sense of being such as to account for the bulk of the large-scale gamma-ray intensity variations. It is found by demanding that the cosmic-ray intensity is constant over the region of space within similar to 1 kpc of the Sun. In this case, the ic contribution to the total Galactic diffuse intensity is 32 +/- 10% for the Galactic latitude range 10-20 degrees, increasing to 44 +/- 17% at the Galactic poles. The corresponding scale height of the electron component is z1/2 = (2.5 +/- 1) kpc. There are still CR intensity changes needed locally but these are on comparatively small scales; if later work should show that the CR intensity changes are, in fact, larger then the IC contribution will have to be reduced.