Velocity peaks and caustic rings.

The late infall of cold dark matter onto an isolated galaxy produces hows w ith definite velocity vectors at any physical point in the galactic halo. I t also produces caustic rings, which are places in space where the dark mat ter density is very large. The self-similar model of galactic halo formatio n predicts that the caustic ring radii a, follow the approximate law a(n) s imilar or equal to 1/n. Bumps in the rotation curves of NGC 3198 and of our own galaxy are interpreted as due to caustic rings of dark matter.