Primeval adiabatic perturbations - Effect of massive neutrinos

Under the assumptions that the universe is presently dominated by neutrinos whose mass is some tens of eV, and that primeval density fluctuations are adiabatic and linear, the mass distribution autocorrelation function prior to galaxy formation is computed. The computation, which includes massive neutrinos, zero-mass weakly interacting particles, ordinary matter and radiation, solves for the distribution of massive neutrinos as a function of momentum magnitude and direction. Matter and radiation are considered as a single, ideal fluid. The mass distribution coherence length prior to galaxy formation, which may be compared to the present clustering length of galaxies, is too large in the conventional scenario unless the universe is as dense as 100 h km/sec per Mpc, and the initial density fluctuation spectrum is steep.