2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/108214I review some of the basic information on the Cosmic Neutrino Background momentum distribution. In particular, I discuss how present data from several cosmological observables such as Big Bang Nucleosynthesis, Cosmic Microwave Background and Large Scale Structure power spectrum constrain possible deviations from a standard Fermi-Dirac thermal distribution.Talk given at "Neutrino Oscillations in Venice" Conference, Venice, February 7-10 2006Astrophysicstext