A minimal model for extragalactic cosmic rays and neutrinos

Understand

We aim to explain in a unified way the experimental data on ultrahigh energy cosmic rays (UHECR) and neutrinos, using a single source class and obeying limits on the extragalactic diffuse gamma-ray background (EGRB).

• If UHECRs only interact hadronically with gas around their sources, the resulting diffuse CR flux can be matched well to the observed one, providing at the same time large neutrino fluxes.
• However, air showers in the Earth's atmosphere induced by UHECRs with energies $E>3\times 10^{18}$ eV would reach in such a case their maxima too high.
• Therefore additional photo-hadronic interactions of UEHCRs close to the accelerator have to be present, in order to modify the nuclear composition of CRs in a relatively narrow energy interval.