We consider modified $f(R)$ gravity which may unify $R^m$ early-time inflation with late-time $\Lambda \mathrm{CDM}$ epoch. It is shown that such a model passes the local tests (Newton law, stability of Earth-like gravitational solution, very heavy mass for additional scalar degree of freedom) and suggests the realistic alternative for general relativity. Various scenarios for the future evolution of $f(R)$ $\Lambda \mathrm{CDM}$ era are discussed.

• Received 9 October 2007

DOI:https://doi.org/10.1103/PhysRevD.77.026007