An interpretation of the galactic continuum radiation - II. A three-dimensional model of the radio emissivity

Abstract

The model of French & Osborne giving the distribution of synchrotron emissivity in the galactic plane is developed and extended to three dimensions. To account for the observed distribution over the whole celestial sphere a ‘thick disc’ of emission is required. In the preferred model the thickness of this disc decreases towards the Galactic Centre. A comparison of synchrotron and gamma-ray emission from the anticentre direction indicates that the sources of cosmic-ray nuclei and electrons must be different. The ‘closed galaxy’ model of Peters and Westergaard has great difficulty in accounting for the general level of synchrotron emissivity in the Galaxy.