Revisiting predictions for cosmic-ray antinucleon fluxes from Galactic Dark Matter

TL;DR

This paper predicts cosmic-ray antinucleon fluxes from both secondary processes and dark matter, using advanced models to set limits on dark matter properties and evaluate future detection prospects with experiments like GAPS.

Contribution

It provides updated predictions for antiproton, antideuteron, and antihelium fluxes, and assesses the impact of future GAPS data on dark matter constraints using state-of-the-art models.

Findings

GAPS could improve dark matter annihilation cross-section limits by up to tenfold for light DM.

Current AMS-02 data constrains dark matter annihilation cross-section in various propagation scenarios.

Detection prospects for antinuclei depend on experimental setup, propagation models, and hadronization tuning.

Abstract

The data on cosmic antiprotons have reached an outstanding precision on energies spanning from GeV to hundreds of TeV, thanks to the space-based AMS-02 experiment. The balloon-borne GAPS experiment, which just completed its first Antarctic flight, will address antiproton and antideuteron fluxes well below GeV energies. Antinuclei in cosmic rays, as well as being produced by spallation reactions between cosmic-ray nuclei and the atoms of the interstellar medium, may hide contributions from exotic sources, such as particle dark matter annihilation in the Galaxy. In this paper, we present predictions for cosmic antiproton, antideuteron and antihelium fluxes both from secondary and dark matter origin. We use state-of-the-art production spectra, nuclear coalescence for antinuclei, and Galactic propagation models to derive upper limits on the dark matter annihilation cross-section from AMS-02 antiproton data in different propagation scenarios (BIG and QUAINT). We quantify the impact of future GAPS data, showing that its sensitivity to sub-GV antiprotons could improve the $\langle\sigma v\rangle$ constraints by up to an order of magnitude for light DM ($m_{\chi} \lesssim 50$ GeV). For heavier antinuclei, the detection perspective with existing and upcoming experiments are derived for those scenarios consistent with AMS-02 antiproton flux. The detectability of such signals strongly depends on the experiment, the propagation model, and the hadronization tuning. Our analysis underscores the complementarity of antinuclei channels for indirect DM searches and the critical role of low-energy windows in constraining light DM candidates.