The sign-changeable interaction between variable generalized Chaplygin gas and dark matter

In this paper, we study a cosmological model with the sign-changeable interaction between variable generalized Chaplygin gas (VGCG) and dark matter. The dynamical analysis indicates that there exists a stable scaling attractor, which can help to alleviate the coincidence problem. Furthermore, when the parameters of the model take some fixed values, the attractor corresponds to the phase w = -0.939 and the equation of state of VGCG approaches it from either w > -1 or w < -1 depending on the choice of its initial cosmic density parameter and the ratio of pressure to critical energy density. So, the phantom divide can be crossed. We find the interaction term Q can change its sign from Q < 0 to Q > 0 as the universe expands, which is different from the usual interaction. Also, we place constraints on the parameters from the point of view of dynamics.