Speaker
Описание
Abstract.
The origin of ultra-high-energy cosmic rays (UHECRs) with energies above $10^{20}$ eV is still unknown, since standard stellar mechanisms are insufficient to account for their production. We propose an alternative framework, exploring the possibility that these extremely high-energy particles originate from superheavy dark matter (SHDM). By investigating cosmological evolution in $R^2$-modified gravity (the Starobinsky model), we demonstrate that post-inflationary dynamics and the reheating of the universe significantly differ from standard General Relativity. The suggested cosmological model naturally accommodates the formation and survival of SHDM relics with masses reaching $\sim 10^{13}$ GeV.
We subsequently examine two primary channels through which these massive relics can produce UHECRs. The first is resonance-enhanced annihilation inside high-density environments, such as the Galactic Center. The second mechanism involves the decay of quasi-stable SHDM particles via virtual black holes in the context of multidimensional gravity theories. Both proposed channels provide a robust theoretical explanation for the UHECR particle fluxes detected by the Pierre Auger Observatory and the Telescope Array.