2012/08/31 by Ryuichi Takahashi, Masanori Sato, Takahiro Nishimichi +2 · 1 citation
Physics and Astronomy · #astro-ph.CO #gr-qc
paper · pdf · doi:10.1088/0004-637x/761/2/152
11 pages, 7 figures, minor changes, references added, accepted for publication in ApJ
arxiv created 2012/11/05 · arxiv updated 2015/06/11
Based on a suite of state-of-the-art high-resolution N-body simulations, we revisit the so-called halofit model (Smith et al. 2003) as an accurate fitting formula for the nonlinear matter power spectrum. While the halofit model has been frequently used as a standard cosmological tool to predict the nonlinear matter power spectrum in a universe dominated by cold dark matter, its precision has been limited by the low-resolution of N-body simulations used to determine the fitting parameters, suggesting the necessity of improved fitting formula at small scales for future cosmological studies. We run high-resolution N-body simulations for 16 cosmological models around the Wilkinson Microwave Anisotropy Probe (WMAP) best-fit cosmological parameters (1, 3, 5, and 7 year results), including dark energy models with a constant equation of state. The simulation results are used to re-calibrate the fitting parameters of the halofit model so as to reproduce small-scale power spectra of the N-body simulations, while keeping the precision at large scales. The revised fitting formula provides an accurate prediction of the nonlinear matter power spectrum in a wide range of wavenumber (k ≤ 30h Mpc-1) at redshifts 0 ≤ z ≤ 10, with 5% precision for k≤1 h Mpc-1 at 0 ≤ z ≤ 10 and 10% for 1 ≤ k≤ 10 h Mpc-1 at 0 ≤ z ≤ 3. We discuss the impact of the improved halofit model on weak lensing power spectra and correlation functions, and show that the improved model better reproduces ray-tracing simulation results.