The origin and characteristic scale of galaxies

In this paper, we investigate the influence of the massive neutrino on the early evolution of adiabatic perturbations in the Universe. It is shown that if the neutrino has a non-zero rest mass, the perturbations that are approximately in a critical, stable state (for the Jeans instability) before the recombination of hydrogen will possibly grow into a kind of astronomical object which will have a preferred scale after the recombination. A reasonable estimate of the order of magnitude shows that such objects seem to be corresponding to the observed galaxies.