Inflationary universe with a viscous fluid avoiding self‐reproduction

Abstract

We consider a universe with a bulk viscous cosmic fluid, in a flat Friedmann-Lemaitre-Robertson-Walker geometry. We derive the conditions for the existence of inflation, and those which at the same time prevent the occurrence of self-reproduction. Our theoretical model gives results which are in perfect agreement with the most recent data from the PLANCK surveyor.

Viscous cosmology for early- and late-time universe

“…In other related works [73,127], viscous coupled-fluid models were investigated when the equation of state was assumed to be inhomogeneous. Furthermore, in [128] the authors studied the important self-reproduction problem of the universe, namely the graceful exit from inflation, where it was shown how inflation without self-reproduction can actually be obtained by imposing restrictions on the value of the thermodynamic parameter in the equation of state. Finally, we mention the very different approach which consists in applying particle physics theory and the relativistic Boltzmann equation in order to derive expressions for the bulk and the shear viscosities, and the corresponding entropy production, in the specific lepton-photon era, where the temperature dropped from 10 12 K to 10 10 K. Calculations of this kind were recently given in Ref.…”

Viscous fluid holographic bounce

“…Assuming that the bounce has a holographic origin we will represent the energy conservation laws in terms of the cutoff radius which, as mentioned above, is identified with the particle horizon. The motivation for describing the holographic bounce by a viscous fluid, is that the inclusion of viscosity allows one to achieve better agreement between theoretical models and astronomical observations [42][43][44].…”

Inflation in terms of a viscous van der Waals coupled fluid

“…It is of interest to study the influence of the interaction between energy and matter on the inflation, in the presence of a bulk viscosity. Despite the fact that the viscosity is very small in the inflationary universe, the inclusion of viscosity allows one to get a better agreement with the Planck astronomical observations in several cases [16][17][18]. For a recent review on the the early viscous universe, see Ref.…”