Neutrinos as a diagnostic of cosmic ray galactic-extragalactic transition

Motivated by a recent change in viewing the onset of the extragalactic component in the cosmic ray spectrum, we have fitted the observed data down to 10(8.6) GeV and have obtained the corresponding power emissivity. This transition energy is well below the threshold for resonant p gamma absorption on the cosmic microwave background, and thus source evolution is an essential ingredient in the fitting procedure. Two-parameter fits in the spectral and redshift evolution indices show that a standard Fermi E-i(-2) source spectrum is excluded at larger than 95% confidence level (CL). Armed with the primordial emissivity, we follow Waxman and Bahcall to derive the associated neutrino flux on the basis of optically thin sources. For pp interactions as the generating mechanism, the neutrino flux exceeds the AMANDA-B10 90% CL upper limits. In the case of p gamma dominance, the flux is consistent with AMANDA-B10 data. In the new scenario the source neutrino flux is considerably enhanced, especially below 10(9) GeV. Should data from AMANDA-II prove consistent with the model, we show that IceCube can measure the characteristic power law of the neutrino spectrum, and thus provide a window on the source dynamics.