Can F(R)-gravity be a viable model: the universal unification scenario for inflation, dark energy and dark matter
Abstract
We review on the viability of F(R)-gravity. We show that recent cosmic acceleration, radiation/matter-dominated epoch and inflation could be realized in the framework of F(R)-gravity in the unified way. For some classes of F(R)-gravity, the correction to the Newton law is extremely small and there is no so-called matter instability (the very heavy positive mass for additional scalar degree of freedom is generated). The reconstruction program in modified gravity is also reviewed and it is demonstrated that any time-evolution of the universe expansion could be realized in F(R)-gravity. Special attention is paid to modified gravity which unifies inflation with cosmic acceleration and passes local tests. It turns out that such a theory may describe also dark matter.