Viscous Generalized Chaplygin Gas

Viscous GCG(generalized Chaplygin gas) cosmology is discussed, assuming that there is bulk viscosity in the linear barotropic fluid and GCG. The dynamical analysis indicates that the phase wg = −1 + √ 3γκτg/(γ − √ 3κτγ) is a dynamical attractor and the equation of state of GCG approaches it from either wg > −1 or wg < −1 depending on the choice of its initial cosmic density parameter and the ratio of pressure to critical energy density. Obviously, the equation of state wg can cross the boundary wg = −1. Also, from the point of view of dynamics, the parameters of viscous GCG should be in the range of γ > √ 3κτγ/(1 − √ 3κτg) and 0 < α < 1 + √ 3κγτg/(γ − √ 3κτγ − √ 3κγτg).