1999/10/18 by P. Fosalba, Fosalba, P., E. Gaztanaga +4
Economics, Econometrics and Finance · Physics and Astronomy · #Astrophysics (astro-ph) #Cosmology and Gravitation Theories #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Stochastic processes and financial applications #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9910308
2 pages, Latex using newpasp.sty, 2 figures. To appear in the proceedings of the IGRAP meeting on "Clustering at high redshift" (Marseille, June 1999)
arxiv created 1999/10/18 · openalex publication_date 1999/10/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The gravitational evolution of the cosmic one-point Probability Distribution Function (PDF) can be estimated using an analytic approximation that combines gravitational Perturbation Theory (PT) with the Edgeworth expansion around a Gaussian PDF. We present an alternative to the Edgeworth series based on an expansion around the Gamma PDF, which is more appropriate to describe a realistic PDF. The Gamma expansion converges when the PDF exhibits exponential tails, which are predicted by PT and N-body simulations in the weakly non-linear regime (i.e, when the variance, σ2, is small). We compare both expansions to N-body simulations and find that the Gamma expansion yields a better overall match to the numerical results.