Secondary antinuclei from supernova remnants and background for dark matter searches

TL;DR

This paper investigates the production of secondary antinuclei in supernova remnants and assesses their impact as background signals in dark matter detection, concluding that SNR contributions are minor at energies relevant for dark matter searches.

Contribution

It provides the first detailed calculation of SNR-induced antinuclei fluxes and compares them with standard secondary production, constraining their significance for dark matter experiments.

Findings

SNR-produced antinuclei are significant above ~10 GeV/n but negligible at lower energies.

The SNR component cannot explain the AMS antiproton/proton ratio without conflicting with B/C data.

Total antinuclei flux is tightly constrained, minimally affecting dark matter search backgrounds.

Abstract

We compute the spectra of cosmic-ray (CR) nuclei and antinuclei under a scenario where hadronic interaction processes inside supernova remnants (SNRs) can produce a diffusively-shock-accelerated "source component" of secondary particles. This scenario is able to explain the recent measurements reported by AMS on the antiproton/proton ratio, that is found to be remarkably constant at ~60-450 GeV of kinetic energy. However, as we will show, this explanation is ruled out by the new AMS data on the B/C ratio, which is found to decrease steadily up to TeV/n energies. With the constraints provided by the two ratios, we calculate conservative (B/C driven) and speculative (pbar/p driven) SNR-induced flux contribution for the spectra of antideuteron and antihelium in CRs, along with their standard secondary component expected from CR collisions in the interstellar gas. We found that the SNR component of anti-nuclei can be significantly large at high-energy, above a few ~10 GeV/n, but it is always sub-dominant at sub-GeV/n energies, that is, the energy region where dark-matter induced signals may exceed the standard astrophysical background. Furthermore, the total antinuclei flux from insterstellar spallation plus SNR-component is tightly bounded by the data, so that hadronic production in SNRs has a minor impact on the astrophysical background for dark matter searches.