Bianchi I cosmology in the presence of a causally regularized viscous fluid

Understand

We analyze the dynamics of a Bianchi I cosmology in the presence of a viscous fluid, causally regularized according to the Lichnerowicz approach.

• We show how the effect induced by shear viscosity is still able to produce a matter creation phenomenon, meaning that also in the regularized theory we address, the Universe is emerging from a singularity with a vanishing energy density value.
• We discuss the structure of the singularity in the isotropic limit, when bulk viscosity is the only retained contribution.
• We see that, as far as viscosity is not a dominant effect, the dynamics of the isotropic Universe possesses the usual inviscid power-law behavior but in correspondence of aneffective equation of state, depending on the bulk viscosity coefficient.