Production and acceleration of antinuclei in supernova shockwaves

TL;DR

This paper models the production of antinuclei in supernova remnants and assesses their impact on cosmic ray backgrounds, finding that SNR contributions are sub-dominant at energies relevant for dark matter detection.

Contribution

It introduces a detailed calculation of secondary antinuclei production within SNRs constrained by recent AMS data, providing upper limits on their flux contributions.

Findings

SNR-produced antinuclei are significant above ~10 GeV/n but negligible below a few GeV/n.

Total secondary antinuclei flux is tightly constrained by current cosmic ray data.

SNR interactions do not significantly alter the background for dark matter searches.

Abstract

We compute the energy spectra of antideuterons and antihelium in cosmic rays (CRs) in a scenario where hadronic interactions inside supernova remnants (SNRs) can produce a diffusively-shock-accelerated "source component" of secondary antinuclei. The key parameters that specify the SNR environment and the interstellar CR transport are tightly constrained with the new measurements provided by the AMS experiment on the B/C ratio and on the antiproton/proton ratio. The best-fit models obtained from the two ratios are found to be inconsistent with each other, as the antiproton/proton data require enhanced secondary production. Thus, we derive conservative (i.e., B/C-driven) and speculative (antiproton/proton-driven) upper limits to the SNR flux contributions for the d and He spectra spectra in CRs, along with their standard secondary component expected from CR collisions in the interstellar gas. We find that the source component of antinuclei can be appreciable at kinetic energies above a few ~10 GeV/n, but it is always sub-dominant below a few GeV/n, that is the energy window where dark matter (DM) annihilation signatures are expected to exceed the level of secondary production. We also find that the total (standard + SNR) flux of secondary antinuclei is tightly bounded by the data. Thus the presence of interaction processes inside SNRs does not critically affect the total background for DM searches.