Antimatter production in supernova remnants

TL;DR

This paper models cosmic ray acceleration and secondary antimatter production in supernova remnants, revealing lower antimatter yields than previously estimated and energy-dependent ratios.

Contribution

It introduces a time-dependent SNR model with Monte Carlo secondary production, providing more accurate estimates of antimatter ratios in cosmic rays.

Findings

Positron/electron ratio is a few percent and decreases with energy.

Antiproton/proton ratio is a few times 10^{-5} and rises slightly above 10 GeV.

SNRs produce less antimatter than previously suggested.

Abstract

We calculate the energy spectra of cosmic rays (CR) and their secondaries produced in a supernova remnant (SNR), taking into account the time-dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: The positron/electron ratio and the antiproton/proton ratio are a few percent and few $\times 10^{-5}$, respectively. Moreover, the obtained positron/electron ratio decreases with energy, while the antiproton/proton ratio rises at most by a factor of two above 10 GeV.