Cosmic microwave background anisotropy in the decaying neutrino cosmology

It is attractive to suppose for several astrophysical reasons that the Universe has close to the critical density in light (similar to 30 eV) neutrinos which decay radiatively with a lifetime of similar to 10(23) s. In such a cosmology the Universe is re-ionized early and the last scattering surface of the cosmic microwave background significantly broadened. We calculate the resulting angular power spectrum of temperature fluctuations in the cosmic microwave background. As expected, the acoustic peaks are significantly damped relative to the standard case. This would allow a definitive test of the decaying neutrino cosmology with the forthcoming MAP and Planck surveyor missions.