Origin of energetic cosmic rays. II. The possibility of a contribution from pulsars

Abstract

For pt. I, see ibid., vol.7, 420 of 1974. The form of the primary cosmic ray spectrum expected from pulsars is derived using the model of Ostriker and Gunn for pulsar characteristics and experimental data on pulsar frequencies. It is found that in the energy range 10¹⁴ eV to 10¹⁶ eV (i.e. in the region covering the break in the primary spectrum) the majority of cosmic rays could come from pulsars. The shape of the spectrum is such as to go some way towards explaining the rapid change of slope which is found to occur at about 3*10¹⁵ eV. The pulsar contribution appears to cease above 3*10¹⁶ eV and some other source is necessary here; similarly other sources are needed below about 10¹⁴ eV.