Abstract

Cosmological n-body simulation are usually based on a Newtonian treatment of gravity. The forthcoming large scale structure surveys will allow to reach sub-percent precision and therefore relativistic effect could become relevant. This motivated the development of the first relativistic n-body code, gevolution. However, if the gevolution code is based on a metric formulation of gravity, it still work in a perturbative approach, the weak field expansion. Therefore one could argue (and some do) that gevolution cannot capture purely non-linear effects. This motivates the development of cosmological codes based on numerical relativity (NR). In this talk, the first NR n-body code able to evolve a pure dark matter universe from redshift 1000 to 0 will be presented. The difficulties of generating good initial condition will be discussed, with a special attention on the momentum constraint.