2006/10/31 by Yong-Seon Song, Wayne Hu, Ignacy Sawicki · 1 citation
Physics and Astronomy · #astro-ph #gr-qc #hep-th
paper · pdf · doi:10.1103/physrevd.75.044004
published as Phys.Rev.D75:044004,2007 · 10 pages, 6 figures, minor typo fixes reflects version accepted by PRD
arxiv created 2007/01/15 · arxiv updated 2009/12/01
We study the evolution of linear cosmological perturbations in f(R) models of accelerated expansion in the physical frame where the gravitational dynamics are fourth order and the matter is minimally coupled. These models predict a rich and testable set of linear phenomena. For each expansion history, fixed empirically by cosmological distance measures, there exists two branches of f(R) solutions that are parameterized by B propto d2 f/dR2. For B<0, which include most of the models previously considered, there is a short-timescale instability at high curvature that spoils agreement with high redshift cosmological observables. For the stable B>0 branch, f(R) models can reduce the large-angle CMB anisotropy, alter the shape of the linear matter power spectrum, and qualitatively change the correlations between the CMB and galaxy surveys. All of these phenomena are accessible with current and future data and provide stringent tests of general relativity on cosmological scales.