Dynamics of gravitational clustering
III. The quasi-linear regime for some non-Gaussian initial conditions
Service de Physique Théorique, CEN Saclay, 91191 Gif-sur-Yvette, France
Corresponding author: email@example.com
Accepted: 23 November 2001
Using a non-perturbative method developed in a previous work (Paper II), we derive the probability distribution of the density contrast within spherical cells in the quasi-linear regime for some non-Gaussian initial conditions. We describe three such models. The first one is a straightforward generalization of the Gaussian scenario. It can be seen as a phenomenological description of a density field where the tails of the linear density contrast distribution would be of the form , where α is no longer restricted to 2 (as in the Gaussian case). We derive exact results for in the quasi-linear limit. The second model is a physically motivated isocurvature CDM scenario. Our approach needs to be adapted to this specific case and in order to get convenient analytical results we introduce a simple approximation (which is not related to the gravitational dynamics but to the initial conditions). Then, we find a good agreement with the available results from numerical simulations for the pdf of the linear density contrast for . We can expect a similar accuracy for the non-linear pdf . Finally, the third model corresponds to the small deviations from Gaussianity which arise in standard slow-roll inflation. We obtain exact results for the pdf of the density field in the quasi-linear limit, to first-order over the primordial deviations from Gaussianity.
Key words: cosmology: theory / large-scale structure of Universe
© ESO, 2002