Cosmic-ray positrons from mature gamma-ray pulsars

Abstract

Abstract.We consider a possible contribution of mature γ-ray pulsars (with ages of ≥ 10 5 yrs) to cosmic ray positrons. Within the framework of the γ-ray pulsar outer gap model, e ± pairs in the pulsar magnetosphere are produced by the cascade of e ± pairs through synchrotron radiation of the return current from the outer gap. A good fraction of these cascade e ± pairs are reflected by the hard X-rays from the polar cap via resonant scattering and escape from the pulsar through the light cylinder. The escaped pairs are accelerated to relativistic energies in the pulsar wind driven by low-frequency electromagnetic waves. Using Monte Carlo simulations, we generate a sample of the mature γ-ray pulsars in our Galaxy and calculate the positron production rate from these pulsars. In a simple "leaky box" model, we calculate the ratio of cosmic-ray positrons to total electrons. Our result indicates that the pulsar contribution to the cosmic ray positrons peaks at about 60 GeV and the observed e + /(e − + e + ) ratio can be explained in this model.

Galactic electrons and positrons at the Earth: new estimate of the primary and secondary fluxes

“…Had we adopted alternative modeling with a shallower dependence on the age (see e.g. Chi et al 1996;Zhang & Cheng 2001;Profumo 2008), we would have placed more weight on younger objects, and thereby to the high energy part of the spectrum. As for the other measurements discussed Notes.…”

“…For instance, as discussed by Boulares (1989) (see also e.g. Aharonian et al 1995;Chi et al 1996;Zhang & Cheng 2001), pulsars could provide sizable contributions to the positron flux from pair conversions of γ-rays in the strong magnetic fields that they host. This has been recently revisited by several authors (e.g.…”

On possible interpretations of the high energy electron–positron spectrum measured by the Fermi Large Area Telescope

“…Shen 1970 [37]). For bright young pulsars the maximal acceleration energy can be as large as 10 3 TeV (see e.g.…”

Cosmic-ray electron anisotropies as a tool to discriminate between exotic and astrophysical sources

“…Although more refined models for electron production in pulsars can be considered, some of them produce an e ± output well below the observations (e.g. Harding-Ramaty model [12] or the one devised by Z hang and Cheng [20] ) or a comparable one (e.g. Chi et al [16]).…”