Upper Limits to Fluxes of Neutrinos and Gamma-Rays from Starburst Galaxies

Loeb and Waxman have argued that high energy neutrinos from the decay of pions produced in interactions of cosmic rays with interstellar gas in starburst galaxies would be produced with a large enough flux to be observable. Here we obtain an upper limit to the diffuse neutrino flux from starburst galaxies which is a factor of ∼5 lower than the flux which they predict. Compared with predicted fluxes from other extragalactic high energy neutrino sources, starburst neutrinos with ∼ PeV energies would have a flux considerably below that predicted for AGN models. We also estimate an upper limit for the diffuse GeV γ-ray flux from starbust galaxies to be O(10) of the observed γ-ray background, much less than the component from unresolved blazars.