2015/06/10 by Lixin Xu, Xu, Lixin · 1 citation
Physics and Astronomy · #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #astro-ph.CO
paper · pdf · doi:10.48550/arxiv.1506.03232
8 pages, 7 figures
arxiv created 2015/06/10 · arxiv updated 2015/06/11
An f(R) gravity model is proposed to realize a late time accelerated expansion of our Universe. To test the viability of an f(R) gravity model through cosmic observations, the background evolution and the Einstein-Boltzmann equation should be solved for studying the effects on the cosmic microwave background power spectrum and on the matter power spectrum. In the market, we already have the modified versions of \bf CAMB code, for instance \bf EFTCAMB and \bf MGCAMB. However, in these publicly available Einstein-Boltzmann codes, a specific background cosmology, for example the ΛCDM or wCDM, is assumed. This assumption would be non-proper for a specific f(R) model where the background evolution may be different from a ΛCDM cosmology. Therefore the main task for this paper is to present a code to calculate the anisotropies in the microwave background for any f(R) gravity model based on \bf CAMB code, i.e. \bf FRCAMB, where the background and perturbation evolutions are included consistently. As results, one can treat \bf FRCAMB as a blackbox to output the CMB power spectrum and matter power spectrum, once an f(R) function, its first two derivative with respect to R, i.e. fR≡ df/dR, fRR≡ d2f/dR2 and the reasonable values of the model parameters are inputted properly. As by-products, one can also output the effective equation of state of f(R) model, the evolution of the dimensionless energy densities and other interesting cosmological quantities.