COSMOLOGICAL IMPLICATIONS OF A RELIC NEUTRINO ASYMMETRY
J. LESGOURGUES (1), S. PASTOR (1), S. PRUNET (2)
(1) SISSA--ISAS and INFN, Sezione di Trieste, Via Beirut 2-4, I-34013 Trieste, Italy
(2) CITA, 60 St George Street, Toronto, Ontario M5S 3H8, Canada


Abstract:
We consider some consequences of a cosmological lepton asymmetry in the form of neutrinos. A relic neutrino degeneracy enhances the contribution of massive neutrinos to the present energy density of the Universe, and modifies the power spectrum of radiation and matter. Comparing with current observations of cosmic microwave background anisotropies and large scale structure, we derive some constraints on the relic neutrino degeneracy and on the spectral index in the case of a flat Universe with a cosmological constant. Finally, we calculate the precision with which the small neutrino mass suggested by Super--Kamiokande ($m_{SK}\sim0.07$ eV) could be constrained by the future Planck satellite and Sloan Digital Sky Survey. Assuming a large relic neutrino asymmetry still allowed by current experimental data, we find that such a mass can be detected