7-11 September 2015
Warsaw, Poland
Europe/Zurich timezone

General relativistic corrections in N-body simulations -- The N-body gauge

9 Sep 2015, 11:10
Rm 207 ()

Rm 207


Christian Fidler (CP3 , Belgium)


We discuss different gauge choices and their advantages in the context of N-body simulations. The initial conditions for N-body simulations are usually generated by employing the Zel'dovich approximation. We show that the initial displacements generated in this way generally receive a first-order relativistic correction. We identify a novel gauge, called N-body gauge in the following, in which this relativistic correction is absent. Therefore the Zel'dovich approximation provides accurate initial conditions in the N-body gauge. Furthermore we show that a conventional Newtonian N-body simulation includes all first-order relativistic contributions in the absence of pressure perturbations and anisotropic stresses if we identify the coordinates in Newtonian simulations with those in the N-body gauge. We therefore conclude that the N-body gauge is uniquely suited for N-body simulations. When setting the initial conditions using the Zel'dovich approximation and running a conventional Newtonian N-body simulation the results include all linear relativistic effects if the output is understood in terms of the N-body gauge. In addition we analyse the limitations of the N-body gauge due to pressure perturbations and anisotropic stresses from residual radiation or a non standart cosmology.

Presentation Materials

Your browser is out of date!

If you are using Internet Explorer, please use Firefox, Chrome or Edge instead.

Otherwise, please update your browser to the latest version to use Indico without problems.