A Case for Radio Galaxies as the Sources of IceCube's Astrophysical
  Neutrino Flux
  We present an argument that radio galaxies (active galaxies with mis-aligned
jets) are likely to be the primary sources of the high-energy astrophysical
neutrinos observed by IceCube. In particular, if the gamma-ray emission
observed from radio galaxies is generated through the interactions of
cosmic-ray protons with gas, these interactions can also produce a population
of neutrinos with a flux and spectral shape similar to that measured by
IceCube. We present a simple physical model in which high-energy cosmic rays
are confined within the volumes of radio galaxies, where they interact with gas
to generate the observed diffuse fluxes of neutrinos and gamma rays. In
addition to simultaneously accounting for the observations of Fermi and
IceCube, radio galaxies in this model also represent an attractive class of
sources for the highest energy cosmic rays.
