Scalar-tensor theories of gravity: validity of the cosmic no-hair conjecture
This paper deals with the cosmic no-hair conjecture for anisotropic Bianchi models in the scalar-tensor theory of gravity. Herein, we have considered both the Jordan frame and the Einstein frame to describe the scalar-tensor theory of gravity and examine the conjecture. In the Jordan frame, one should restrict both the coupling function of the scalar field and the coupling parameter, in addition to the usual energy conditions for the matter field, to maintain the validity of the cosmic no-hair conjecture, while in the Einstein frame, the restrictions are purely on the energy conditions.