Positrons and low energy cosmic rays from supernovae

Abstract

Burgeret al. (1970) calculated the positron flux from the decay of⁵⁶Co→⁵⁶Fe from cosmic rays injected from supernovae. The plasma properties of the ejected matter are determined in the present calculation in order to include the ionization loss of the positrons as the matter expands. It is found that using the matter velocity distribution of previous supernova model calculations that roughly 10% of the positrons escape. The average lifetime in the galaxy due to ionization loss is found to be relatively small, 1.5×10⁵ yr, and with the above injection results in ×3, the observed flux. The same matter velocity distribution is subjected to ionization loss in the galaxy and a steady state low energy, 10≤E≤200 MeV, differential flux spectrum is found,J(E)∼E ^−1.2. This removes the difficulty of the high galactic energy density resulting from a steeper spectrum.