Interpretation of cosmic ray spectrum above the knee measured by the Tunka-133 array

Abstract

A probable interpretation of the fine structure of all particle energy spectrum between the knee and the ankle (the sharp first knee at 3–4 PeV, the spectrum hardening at 20–30 PeV, the second knee at 200–300 PeV) as well as a $<\ln A>$ (E) dependence measured recently by the Tunka-133 experiment, is presented. We show that these features are compatible with the combined model where cosmic rays around the knee are produced by the group of dedicated sources and the extragalactic light component appears in the energy region of 10¹⁶–${10}^{17}\text{eV}$ and reaches about 50% of all particles around (2–3)$\times {10}^{17}\text{eV}$.