The stability of the Einstein static state in f(T) gravity

The stability of the Einstein static universe against the homogeneous scalar perturbations in f(T) gravity is analyzed. Both the spatial closed and open universes are considered. We find that the stable Einstein static solutions exist in both cases. Considering a concrete f(T) model and assuming that the cosmic energy has a constant equation of state w, we obtain that, in the closed case, w<1/3 is required. Thus, f(T) theory gives a larger region of w than that in general relativity (−1