1998/11/17 by B. Novosyadlyj, Novosyadlyj, B., Ruth Durrer +4 · 2 citations
Physics and Astronomy · #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #Scientific Research and Discoveries #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9811262
13 pages, 20 figures, LaTeX (l-aa) (accepted by A&A)
arxiv created 1999/03/06 · arxiv updated 2009/12/01
An accurate analytic approximation of the transfer function for the power spectra of primordial density perturbations in mixed dark matter models is presented. The fitting formula in a matter-dominated Universe (Ω0=ΩM=1) is a function of wavenumber k, redshift z and four cosmological parameters: the density of massive neutrinos, Ων, the number of massive neutrino species, Nν, the baryon density, Ωb and the dimensionless Hubble constant, h. Our formula is accurate in a broad range of parameters: k≤ 100 h/Mpc, z≤ 30, Ων≤ 0.5, Nν≤ 3, Ωb≤ 0.3, 0.3≤ h≤ 0.7. The deviation of the variance of density fluctuations calculated with our formula from numerical results obtained with CMBfast is less than 6% for the entire range of parameters. It increases with Ωbh2 and is less than ≤ 3% for Ωbh2≤ 0.05. The performance of the analytic approximation of MDM power spectra proposed here is compared with other approximations found in the literature. Our approximation turns out to be closest to numerical results in the parameter space considered here.