Tau Neutrinos from Astrophysical and Cosmological Sources

Previous work on the neutrino spectra from high energy sources has not included the tau neutrinos directly produced by the decays in the source. Here we consider the tau neutrino component and discuss how its inclusion modifies the expected neutrino spectra. We discuss implications for interpreting any observed tau neutrino component in TeV - UHE events as evidence of nu_mu --> nu_tau oscillations.