Astrophysical implications of the neutrino rest mass. II - The density-perturbation spectrum and small-scale fluctuations in the microwave background. III - Nonlinear growth of perturbations and the missing mass

It is noted that if the neutrino has a rest mass, a scale comparable to the distance between clusters of galaxies would have been singled out in the universe. On smaller scales, the amplitude of neutrino density perturbations should diminish in proportion to a high power of the perturbation wavelength. Consideration is given to the evolution of adiabatic and entropic (isothermal) density perturbations, and it is shown that the existence of a neutrino rest mass would imply smaller fine-scale fluctuations in the microwave background radiation than models in which m_v is equal to zero. Also included is a discussion of the influence that a finite rest mass for the neutrino would have on the phenomenon of missing mass in galaxies and clusters of galaxies, on the nonlinear stage in the evolution of primordial irregularities, and on the problem of observing neutral hydrogen in the spectrum of distant quasars.