Stable clustering, the halo model and nonlinear cosmological power spectra
Abstract
We present the results of a large library of cosmological Nbody simulations, using powerlaw initial spectra. The nonlinear evolution of the matter power spectra is compared with the predictions of existing analytic scaling formulae based on the work of Hamilton et al. The scaling approach has assumed that highly nonlinear structures obey `stable clustering' and are frozen in proper coordinates. Our results show that, when transformed under the selfsimilarity scaling, the scalefree spectra define a nonlinear locus that is clearly shallower than would be required under stable clustering. Furthermore, the smallscale nonlinear power increases as both the power spectrum index n and the density parameter Ω decrease, and this evolution is not well accounted for by the previous scaling formulae. This breakdown of stable clustering can be understood as resulting from the modification of dark matter haloes by continuing mergers. These effects are naturally included in the analytic `halo model' for nonlinear structure; we use this approach to fit both our scalefree results and also our previous cold dark matter data. This method is more accurate than the commonly used PeacockDodds formula and should be applicable to more general power spectra. Code to evaluate nonlinear power spectra using this method is available from <externallink type="url">http://as1.chem.nottingham.ac.uk/~res/software.html</A>. Following publication, we will make the powerlaw simulation data publically available through the Virgo website <externallink type="url">http://www.mpagarching.mpg.de/Virgo/</A>.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 June 2003
 DOI:
 10.1046/j.13658711.2003.06503.x
 arXiv:
 arXiv:astroph/0207664
 Bibcode:
 2003MNRAS.341.1311S
 Keywords:

 methods: Nbody simulations;
 cosmology: theory;
 largescale structure of Universe;
 Astrophysics
 EPrint:
 V2: 23 Latex Pages. Replaced with a version consistent with refereed journal article. Section 3.4 reduced, Fig added to section 6, references added