1203.2796 (Gerasimos Rigopoulos et al.)

A non-linear approximation for perturbations in ΛCDM    [PDF]

Gerasimos Rigopoulos, Wessel Valkenburg

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.

View original: http://arxiv.org/abs/1203.2796