Building relativistic second-order initial conditions for simulations of large-scale structure.

Abstract: One of the main challenges of cosmology is to understand the physics of the early universe. One way to probe this early period is the study of primordial non-Gaussianity (PNG) through the bispectrum of the matter distribution. The future large-scale structure (LSS) surveys are expected to provide a precise measurement of the distribution of matter in the late universe and therefore add more constraints on PNG. For this purpose, one needs to understand the full evolution of the perturbations beyond the linear theory since the LSS formation is a non-linear process. Among all the non-linearities generated, the relativistic effects are a well known contaminant of the PNG. In this talk, I will explain how we can simulate the large-scale structure of the universe with the N-body simulation “gevolution” by accounting for all the relevant second-order relativistic non-linearities generated from the primordial epoch to the initial redshift of the simulation. This is a crucial step for the estimation of the systematic effects affecting the PNG.