Speaker
Description
Ultra-high-energy cosmic rays (UHECRs) are atomic nuclei that reach Earth with energies of up to several hundred exaelectronvolts. Identifying their sources is a key challenge in high-energy astrophysics. Motivated by the fact that candidate astrophysical accelerators exhibit high diversity in terms of their relevant properties, such as luminosity and Lorentz factor, we study the compatibility of a population of sources with non-identical maximum cosmic-ray energy with the observed energy spectrum and composition of UHECRs at Earth. We find that the allowed source-to-source variance of the maximum energy must be low to describe the data. This suggests that the UHECR flux at Earth is dominated by a single source or that a mechanism exists that naturally aligns the maximum energy of all contributing sources.
