Density distribution of the cosmological matter field

DOI: 
10.1093/mnras/sty2613
Publication date: 
01/09/2018
Main author: 
Klypin, Anatoly
IAA authors: 
Prada, Francisco
Authors: 
Klypin, Anatoly;Prada, Francisco;Betancort-Rijo, Juan;Albareti, Franco D.
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Pages: 
2499
Abstract: 
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 catalogs, 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<SUP>-2</SUP>, 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 &lt; 5h<SUP>-1</SUP>Mpc with rms density fluctuations σ &gt; 1. In combination with the spherical infall model that works well for small fluctuations σ &lt; 1, the PDF is now approximated with just few percent errors over the range of twelve orders of magnitude - a remarkable example of precision cosmology. We find that at ̃5 - 10% level the PDF explicitly depends on redshift (at fixed σ) and on cosmological density parameter Ω<SUB>m</SUB>. We test different existing analytical approximations and find that the often used log-normal approximation is always 3-5 times less accurate than either the double-exponential approximation or the spherical infall model.
Database: 
ADS
URL: 
https://ui.adsabs.harvard.edu/#abs/2018MNRAS.481.4588K/abstract
ADS Bibcode: 
2018MNRAS.481.4588K
Keywords: 
cosmology: Large scale structure;dark matter;galaxies: halos;methods: numerical;Astrophysics - Cosmology and Nongalactic Astrophysics