Dynamics of dark matter inside and near galaxy clusters.

I will be visiting Geneva for the next 6 months, and I am happy to start new projects here. During this short talk I will tell about a few of my main interests at the moment. 1. Zeldovich pancakes. Cosmological structures collapse first along the one direction. That makes a flat pancake. We found a way to observed such pancakes. As a spin-off it seems that we can measure the “turn-around radius”, which is a radius where the infall into a cluster exactly cancels the Hubble expansion. This is a property typically at scales about 10 Mpc. Maybe this can be used to measure cosmological parameters, maybe to test alternative gravity models. 2. The velocity anisotropy of dark matter. The mass profile of structures is quite well known, however, what about dynamics of the DM? The first thing we can expect to measure is possibly the velocity anisotropy. I will briefly discuss how to do that.