Bulk viscous FWR with time varying constants revisited

Abstract

We study a full causal bulk viscous cosmological model with flat FRW symmetries and where the ``constants'' $G,c$ and $Λ$ vary. We take into account the possible effects of a $c-$variable into the curvature tensor in order to outline the field equations. Using the Lie method we find the possible forms of the ``constants'' $G$ and $c$ that make integrable the field equations as well as the equation of state for the viscous parameter. It is found that $G,c$ and $Λ$ follow a power law solution verifying the relationship $G/c^{2}=κ.$ Once these possible forms have been obtained we calculate the thermodynamical quantities of the model in order to determine the possible values of the parameters that govern the quantities, finding that only a growing $G$ and $c$ are possible while $% Λ$ behaves as a negative decreasing function.