B/C ratio and the PAMELA positron excess

TL;DR

This paper models cosmic ray nuclei production and propagation from supernova remnants, predicting a flat B/C ratio at high energies, which can be tested by upcoming AMS-2 data.

Contribution

It introduces a detailed Monte Carlo simulation of secondary production in SNRs combined with Galactic propagation modeling to predict the B/C ratio behavior.

Findings

B/C ratio remains approximately constant near sources.

The B/C ratio at Earth flattens at high energies.

Prediction can be tested by AMS-2 observations.

Abstract

We calculate the diffuse intensity of cosmic ray (CR) nuclei and their secondaries in the Boron-Carbon group produced by supernova remnants (SNR). The trajectories of charged particles in the SNR are modeled as a random walk in the test particle approximation. Secondary production by CRs colliding with gas in the SNR is included as a Monte Carlo process, while we use Galprop to account for the propagation and interactions of CRs in the Galaxy. In the vicinity of a source, we find an approximately constant B/C ratio as a function of energy. As a result, the B/C ratio at Earth does not rise with energy, but flattens instead in the high energy limit. This prediction can be soon tested by the AMS-2 collaboration.