Transition of equation of state of effective dark energy in the Dvali-Gabadadze-Porrati model with bulk contents

We investigate the effect of the bulk contents in the Dvali-Gabadadze-Porrati (DGP) braneworld on the evolution of the universe. We find that, although the pure DGP model cannot accommodate the transition of the effective equation of state of dark energy, once the bulk matter T₅⁵ is considered, the modified model can realize the weff crossing -1. However, this transition of the equation of state cannot be realized by just considering bulk-brane energy exchange or the Gauss-Bonnet effect while the bulk matter contribution is not included. T₅⁵ plays the major role in the modified DGP model to have the weff crossing -1 behavior. We show that our model can describe the superacceleration of our universe with the equation of state of the effective dark energy and the Hubble parameter in agreement with observations.