  The angular momentum of galaxies is routinely ascribed to a process of tidal
torques acting during the early stages of gravitational collapse, and is
predicted from the initial mass distribution using second-order perturbation
theory and the Zel'dovich approximation. We have tested this theory for a flat
hierarchical cosmogony using a large N-body simulation with sufficient dynamic
range to include tidal fields, allow resolution of individual galaxies, and
thereby expand on previous studies. We find relatively good correlation between
the predictions of linear theory and actual galaxy evolution. While structure
formation from early times is a complex history of hierarchical merging,
salient features are well described by the simple spherical-collapse model.
Most notably, we test several methods for determining the turnaround epoch, and
find that turnaround is succesfully described by the spherical collapse model.
The angular momentum of collapsing structures grows linearly until turnaround,
as predicted, and continues quasi-linearly until shell crossing. The predicted
angular momentum for well-resolved galaxies at turnaround overestimates the
true turnaround and final values by a factor of ~3 with a scatter of ~70
percent, and only marginally yields the correct direction of the angular
momentum vector. We recover the prediction that final angular momentum scales
as mass to the 5/3 power. We find that mass and angular momentum also vary
proportionally with peak height.
