Heavy decaying dark matter and large-scale anisotropy of high-energy cosmic rays

Abstract

We examine the role of the large-scale anisotropy of the high-energy cosmic ray distribution in a search for the heavy decaying dark matter (DM) signal. Using recent anisotropy measurements from the extensive air shower (EAS) observatories, we constrain the lifetime of the DM particles with masses 10⁷ ≤ M_X ≤ 10¹⁶ GeV. These constraints appear to be weaker than that obtained with the high-energy gamma-ray limits. We also estimate the desired precision level for the anisotropy measurements to discern the decaying DM signal marginally allowed by the gamma-ray limits and discuss the prospects of the DM search with the modern EAS facilities.