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 pi(+/-) mesons, whereas the tau neutrinos mainly come from the production and the decay of the D-S(+/-) mesons. We estimate the three intrinsic neutrino flavor ratios for 1 GeV < E < 10(12) GeV in the pp interactions and found them to be 1 : 2 : 3 x 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.