INTRINSIC AND OSCILLATED ASTROPHYSICAL NEUTRINO FLAVOR RATIOS REVISITED

The pp interactions taking place in the cosmos around us are a source of the astrophysical neutrinos of all the three flavors. In these interactions, the electron and the muon neutrinos mainly come from the production and the decay of the π± mesons, whereas the tau neutrinos mainly come from the production and the decay of the mesons. We estimate the three intrinsic neutrino flavor ratios for 1 GeV ≤E≤1012 GeV in the pp interactions and found them to be 1:2:3×10-5. We study the effects of neutrino oscillations on these intrinsic ratios. We point out that the three ratios become 1:1:1 if L(pc)/E(GeV)≥10-10 in the presence of neutrino oscillations, where L is the distance to the astrophysical neutrino source in units of parsecs.