Formalizing Anisotropic Inflation in Modified Gravity

TL;DR

This paper explores anisotropic cosmological evolution during pre-inflationary and inflationary periods within various modified gravity theories, analyzing specific solutions and the effects of anisotropies on universe dynamics.

Contribution

It formalizes anisotropic inflationary models in modified gravity frameworks including $F(R)$ and Gauss-Bonnet gravity, with analysis of specific solutions and singularities.

Findings

Anisotropies influence the evolution of the universe near inflation.

Various exact solutions, including de Sitter, are obtained in anisotropic contexts.

Exotic solutions with finite-time singularities are discussed.

Abstract

Motivated by the fact that the pre-inflationary era may evolve in an exotic way, in this work we formalize anisotropic evolution in the context of modified gravity, focusing on pre-inflationary and near the vicinity of the inflationary epochs. We specialize on specific metrics like Bianchi and Taub and we formalize the inflationary theory in vacuum $F(R)$ gravity, in $F(R)$ gravity with an extra scalar field and in Gauss-Bonnet gravity. We discuss the qualitative effects of the anisotropies on the evolution of the Universe and also we consider several specific solutions, like the de Sitter solution, in both the isotropic and anisotropic contexts. Furthermore, several exotic modified gravity cosmological solutions, like the ones which contain finite time singularities, are also discussed in brief.