Constraints on the lepton content of PWN from the local CR positron spectrum

Abstract

Geminga is a nearby pulsar with an age of 3.42×105 yr and a spindown power of 3.2×1034 erg/s at present. B0656+14 has comparable spindown power, with an age of 1.11×105 yr and a distance of 290 pc. The winds of these pulsars had most probably powered PWN that broke up less than about 100 kyr after the birth of these pulsars. Assuming that leptonic particles accelerated by the pulsars were confined in the PWN and got released into the interstellar medium on breakup of the PWN, we calculate the contribution of these particles to the locally observed cosmic ray electron and positron spectra. Our calculations show that within the framework of our model, the local CR positron spectrum imposes constraints on pulsar parameters for Geminga and B0656+14, e.g. the pulsar period at birth, and also the local interstellar diffusion coefficient for CR leptons. Further, as both pulsars are located at almost the same position in the sky, we expect an anisotropy in the local cosmic ray positron flux