The cosmic gravity-velocity relation

We present a numerical study of the relation between the cosmic peculiar velocity field and the gravitational acceleration field. We show that on mildly non-linear scales (3-10 Mpc Gaussian smoothing), the distribution of the Cartesian coordinates of each of these fields is very well approximated by a Gaussian. In particular, their negentropies are small compared to those of the velocity divergence and density fields. We find that at these scales the relation between the velocity and acceleration fields follows linear theory to high accuracy. The non-linear correction of Kudlicki et al. (2000a) works still better: its reconstruction errors are several times smaller than those of the linear theory approximation.