Production and Acceleration of Antinuclei in Supernova Shockwaves

Abstract

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 / ratio. The best-fit models obtained from the two ratios are found to be inconsistent with each other, as the / data require enhanced secondary production. Thus, we derive conservative (i.e., B/C-driven) and speculative ( / -driven) upper limits to the SNR flux contributions for the and 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−1, but it is always sub-dominant below a few GeV n−1, 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 and is tightly constrained by the data. Thus, the presence of interaction processes in SNRs does not critically affect the total background for DM searches.