Search

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., Comment: 5 pages, 2 figures, 1 table, matches published version

A new analysis of cosmic ray (CR) data collected by the SOKOL experiment in space found that the deuteron-to-helium ratio at energies between 500 and 2000 GeV/nucleon takes the value d/He ~ 1.5. As we will show, this result cannot be explained by standard models of secondary CR production in the interstellar medium and points to the existence of a high-energy source of CR deuterons. To account for the deuteron excess in CRs, we argue that the only viable solution is hadronic interaction processes of accelerated particles inside old supernova remnants (SNRs). From this mechanism, however, the B/C ratio is also expected to increase at energy above ~50 of GeV/nucleon, in conflict with new precision data just released by the AMS-02 experiment. Hence, if this phenomenon is a real physical effect, hadronic production of CR deuterons must occur in SNRs characterized by low metal abundance. In such a scenario, the sources accelerating C-N-O nuclei are not the same as those accelerating helium or protons, so that the connection between d/He ratio and B/C ratio is broken, and the latter cannot be used to place constraints on the production of light isotopes or antiparticles., Comment: 5 pages, 3 figures, matches published version