Interacting generalized Chaplygin gas

A model with the interaction between generalized Chaplygin gas ( GCG) and dark matter is studied. We show that the stationary attractor exists and the universe will enter a de Sitter phase in which the energy densities of both the GCG and dark matter are constant. Because of the interaction between the GCG and the dark matter, the equation of state parameter, w, of the GCG can cross the phantom divide and remains less than- 1 once crossed. The larger the GCG model parameter alpha, the earlier the w crosses the divide and the universe enters the accelerating era, and the larger the present value of w and the present acceleration. By investigating the deceleration parameter, we find that a small alpha is favored by observations.