Revising the Halofit Model for the Nonlinear Matter Power Spectrum
Abstract
Based on a suite of state-of-the-art high-resolution N-body simulations, we revisit the so-called halofit model as an accurate fitting formula for the nonlinear matter power spectrum. While the halofit model has frequently been 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 an 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 best-fit cosmological parameters (one-, three-, five-, and seven-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 wavenumbers (k <= 30 h 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.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- December 2012
- DOI:
- 10.1088/0004-637X/761/2/152
- arXiv:
- arXiv:1208.2701
- Bibcode:
- 2012ApJ...761..152T
- Keywords:
-
- cosmology: theory;
- large-scale structure of universe;
- methods: numerical;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- General Relativity and Quantum Cosmology
- E-Print:
- 11 pages, 7 figures, minor changes, references added, accepted for publication in ApJ