Viscous Dark Cosmology with Account of Quantum Effects

The analytic properties of the energy density ρ(t) of the cosmic fluid, and the Hubble parameter H(t), are investigated near to the future singularity t = ts assuming different forms for the equation of state. First, it is shown that the inclusion of quantum effects coming from the conformal anomaly modifies the singularity. Thereafter, we consider the effect coming from a bulk viscosity in the fluid. The viscosity tends to reduce the magnitude of ts, but does not alter the singularity itself (the exponent). Main emphasis is laid on the simple case when the equation of state is p = wρ, with w a constant.