%0 Journal Article
%T A non-linear approximation for perturbations in ¦«CDM
%A Gerasimos Rigopoulos
%A Wessel Valkenburg
%J Physics
%D 2012
%I arXiv
%R 10.1103/PhysRevD.86.043523
%X We describe inhomogeneities in a {\Lambda}CDM universe with a gradient series expansion and show that it describes the gravitational evolution far into the non-linear regime and beyond the capacity of standard perturbation theory at any order. We compare the gradient expansion with exact inhomogeneous {\Lambda}LTB solutions (Lema\^itre-Tolman-Bondi metric with the inclusion of a cosmological constant) describing growing structure in a {\Lambda}CDM universe and find that the expansion approximates the exact solution well, following the collapse of an over-density all the way into a singularity.
%U http://arxiv.org/abs/1203.2796v2