Brane-induced cosmological acceleration and crossing of w_eff = -1

Abstract

The cosmological observation indicates that the effective equation of state parameter w ef f varies with z: It changes from w ef f > −1 to w ef f < −1 at z ∼ 0.2. We investigate under which condition it exhibits such behaviors based on the fivedimensional braneworld scenario. It is possible in the model with or without an energy exchange between the four dimensional universe and the fifth dimension. However the curves of w ef f are quite different between the two cases.