Direct measurement of upward-going ultrahigh energy dark matter at the Pierre Auger Observatory

Abstract

Abstract It is assumed that two types of dark matter particles exist: superheavy dark matter particles (SHDM), the mass of which ∼ inflaton mass, and light fermion dark matter (DM) particles, which are the ultrahigh energy (UHE) products of the decay of SHDM. The Earth will be taken as a detector to search for the UHE DM particles directly. These upward-going particles, which pass through the Earth and air and interact with nuclei, can be detected by the fluorescence detectors (FD) of the Pierre Auger Observatory (Auger), via fluorescent photons due to the development of an extensive air shower. The numbers and fluxes of expected UHE DM particles are evaluated in the incoming energy range between 1 EeV and 1 ZeV with the different lifetimes of decay of SHDM and mass of Z′. According to the Auger data from 2008 to 2019, the upper limit for UHE DM fluxes is also estimated at 90% confidence limit with the FD of Auger. Finally, it is reasonable to make a conclusion that UHE DM particles could be directly detected in the energy range between O(1 EeV) and O(10 EeV) with the FD of Auger. This might prove whether SHDM particles exist in the Universe.