Galactic -ray spectra, the flux of cosmic ray electrons and cosmic ray gradients

Abstract

Recent measurements of cosmic γ rays above 35 MeV give spectral shapes which indicate unexpectedly high fluxes of primary electrons in the cosmic ray flux in the producing regions. Coupled with the well known difficulty in explaining the observed flux of galactic synchrotron emission in terms of the local electron spectrum and likely magnetic fields in the Galaxy, the γ-ray data indicate that the electron/proton ratio in cosmic rays is probably much higher on average in the Galaxy than in the usual estimate for the solar vicinity. Consistency with the absolute gamma-ray intensities requires a simultaneous increase in electron flux and decrease in proton flux relative to solar values in directions away from the Galactic Centre, together with spatial variability.