Density distribution of the cosmological matter field

Klypin, A.; Prada, F.; Betancort-Rijo, J.; Albareti, F. D.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society, Volume 481, Issue 4, p.4588-4601

Advertised on:
12
2018
Number of authors
4
IAC number of authors
1
Citations
34
Refereed citations
30
Description
The one-point probability distribution function (PDF) of the matter density field in the universe is a fundamental property that plays an essential role in cosmology for estimates such as gravitational weak lensing, non-linear clustering, massive production of mock galaxy catalogues, and testing predictions of cosmological models. Here we make a comprehensive analysis of the dark matter PDF, using a suite of ˜7000 N-body simulations that covers a wide range of numerical and cosmological parameters. We find that the PDF has a simple shape: it declines with density as a power-law P ∝ ρ-2, which is exponentially suppressed on both small and large densities. The proposed double-exponential approximation provides an accurate fit to all our N-body results for small filtering scales R < 5 h-1 Mpc with rms density fluctuations σ > 1. In combination with the spherical infall model that works well for small fluctuations σ < 1, the PDF is now approximated with just few per cent errors over the range of 12 orders of magnitude - a remarkable example of precision cosmology. We find that at {˜ } 5{-}10{{ per cent}} level the PDF explicitly depends on redshift (at fixed σ) and on cosmological density parameter Ωm. We test different existing analytical approximations and find that the often-used lognormal approximation is always 3-5 times less accurate than either the double-exponential approximation or the spherical infall model.
Related projects
 The Invisible Scaffolding of Space
Cosmology with Large Scale Structure Probes
The Cosmic Microwave Background (CMB) contains the statistical information about the early seeds of the structure formation in our Universe. Its natural counterpart in the local universe is the distribution of galaxies that arises as a result of gravitational growth of those primordial and small density fluctuations. The characterization of the
FRANCISCO SHU
KITAURA JOYANES