Impact of the spectral hardening of TeV cosmic rays on the prediction of the secondary positron flux

Abstract

The rise in the cosmic-ray positron fraction measured by the PAMELA satellite is likely due to the presence of astrophysical sources of positrons, for example, pulsars, on kpc scales around the Earth. Nevertheless, assessing the properties of these sources from the positron data requires a good knowledge of the secondary positron component generated by the interaction of cosmic rays with the interstellar gas. In this paper, we investigate the impact of the spectral hardening in the cosmic-ray proton and helium fluxes recently reported by the ATIC2 and CREAM balloon experiments on the predictions of the secondary positron flux. We show that the effect is not negligible, leading to an increase in the secondary positron flux by up to ∼60 per cent above ∼100GeV. We provide fitting formulae that allow a straightforward utilization of our results, which can help in deriving constraints on one's favourite primary positron source, for example, pulsars or dark matter. © 2011 The Author Monthly Notices of the Royal Astronomical Society © 2011 RAS.