The authors consider nonlinear evolution of the inflationary scale-free spectrum of adiabatic density perturbations in (1) a neutrino-dominated universe (sharp short-wavelength cutoff), and (2) an axion-, gravitino-, or photino-dominated universe (some small-scale power). In (2) galaxy formation begins long before the present (as defined by covariance function), resolving a possible problem in (1). Both models are found to be acceptable upon cluster analysis. The authors believe that a new picture, based on (2), merits consideration.

• Received 23 May 1983

DOI:https://doi.org/10.1103/PhysRevLett.51.935