Abstract :
Positrons (e+) in cosmic radiation are believed to be produced by the interactions of cosmic ray nuclei with interstellar space. e+ production spectrum had been calculated using a new set of invariant cross sections for the production of pions and kaons. In the case of e−, a primary component had been added to the secondary e− produced along with e+ in the galaxy. The equilibrium spectra of both e+ and e− were obtained and compared with the observations. An empirical relation is given for the energy loss rate due to inverse-Compton scattering, which connects smoothly the Thompson and Klein-Nishina regimes. It is found that a simple power law injection spectrum for e− can not explain the observed [e+ / (e+ + e−)] ratio, and one requires a spectral flattening below about 8 GeV. Flat e− spectrum similar to that in Crab supernova with a spectral break by one power around 5 GeV could explain both the observed spectrum and the [e+ / (e+ + e−)], suggesting that the sources of cosmic ray e− are supernovae energized by pulsars.
