Novel Dark Matter Constraints from Antiprotons in Light of AMS-02.

Abstract

We evaluate dark matter (DM) limits from cosmic-ray antiproton observations using the recent precise AMS-02 measurements. We properly take into account cosmic-ray propagation uncertainties, fitting DM and propagation parameters at the same time and marginalizing over the latter. We find a significant indication of a DM signal for DM masses near 80GeV, with a hadronic annihilation cross section close to the thermal value, ⟨σv⟩≈3×10^{-26} cm^{3} s^{-1}. Intriguingly, this signal is compatible with the DM interpretation of the Galactic center gamma-ray excess. Confirmation of the signal will require a more accurate study of the systematic uncertainties, i.e., the antiproton production cross section, and the modeling of the effect of solar modulation. Interpreting the AMS-02 data in terms of upper limits on hadronic DM annihilation, we obtain strong constraints excluding a thermal annihilation cross section for DM masses below about 50GeV and in the range between approximately 150 and 500GeV, even for conservative propagation scenarios. Except for the range around ∼80 GeV, our limits are a factor of ∼4 stronger than the limits from gamma-ray observations of dwarf galaxies.