Cosmological phase space of R^n gravity

Abstract

We present some exact solutions and a phase space analysis of metric $f(R)$-gravity models of the type $R^n$. We divide our discussion in $n\ne 2$ and $n=2$ models. The later model is a good approximation, at late times to the $f(R)=\frac{2}{\pi }R{\tan }^{-1}(R/{\beta }^2)$ gravity model, being this an example of a non--singular case. For $n\ne 2$ models we have found power law solutions for the scale factor that are attractors and that comply with WMAP 5-years data if $n<-2.55$ or $1.67<n<2$. On the other hand, the quadratic model has the de Sitter solution as an attractor, that also complies with WMAP 5-years data.

8 pages, 3 figures

References in corpus (1)

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Data Processing, Sky Maps, and Basic Results