Cosmic turbulence revisited

Inflation is found to naturally provide mechanisms for the direct generation of cosmic turbulence on the same scales as those on which density perturbations are formed. Since the observational constraints on turbulence could translate into constraints on inflation itself, these results call for a reexamination of the issue of cosmic turbulence. It is found that by the end of inflation, the amplitude of the generated turbulent velocity has been suppressed by a factor approximately greater than 10 exp 100. Inflation therefore assures the absence of turbulence on scales of galaxies and clusters of galaxies. In addition, it is shown that the density fluctuations generated by inflation can excite longitudinal turbulence after they reenter the Hubble radius at later cosmic epochs.