Neutrinos as a signature of ultrahigh energy photons at high redshift - art. no. 023001

Sources of ultrahigh energy photons operating at high redshift produce a di ffuse background of neutrinos. At high redshift, when the cosmic microwave background radiation has a higher temperature, an electromagnetic cascade o riginated by an energetic photon can generate neutrinos via muon and pion p roduction and decay. We calculate numerically the neutrino spectrum of the cascade neutrinos produced by various photon sources (which need not necess arily generate a large flux of primary neutrinos). A distinctive feature of this flux is a "bump" in the neutrino spectrum at energies E similar to 10 (17) eV. The detection of such neutrinos can help us understand the origin of ultrahigh-energy cosmic rays.