Acquisition of angular momentum by tidal torques in expanding, spherical-symmetric density perturbations - an analysis of different approximations. II

This paper analyzes different approximations of the evolution of expanding spherical-symmetric density perturbations which gain angular momentum by tidal torques. The evolution of expanding spherical-symmetric density perturbations is improved and extended, with regard to both initial configuration and evolution, mainly in the context of an Einstein-de Sitter universe. Qualitative estimates are made of the angular momentum and of the spin parameter for different masses and peak heights. It is shown that, to obtain close agreement with a median value of spin parameter of about 0.05 found by several authors, an underestimate by a factor of at least 4 of the rate of acquisition of angular momentum has to be assumed.