Testing approximate predictions of displacements of cosmological dark matter halos

Understand

We present a test to quantify how well some approximate methods, designed to reproduce the mildly non-linear evolution of perturbations, are able to reproduce the clustering of DM halos once the grouping of particles into halos is defined and kept fixed.

• The following methods have been considered: Lagrangian Perturbation Theory (LPT) up to third order, Truncated LPT, Augmented LPT, MUSCLE and COLA.
• The test runs as follows: halos are defined by applying a friends-of-friends (FoF) halo finder to the output of an N-body simulation.
• The approximate methods are then applied to the same initial conditions of the simulation, producing for all particles displacements from their starting position and velocities.