Symmetry analysis and exact solutions of modified Brans-Dicke cosmological equations

TL;DR

This paper conducts a symmetry analysis of modified Brans-Dicke cosmological equations, deriving exact solutions that describe different expansion regimes of the universe, potentially aiding in cosmological model development.

Contribution

It introduces exact solutions to modified Brans-Dicke equations using symmetry analysis, highlighting their implications for early and late universe expansion behaviors.

Findings

Early universe expansion is linear with a variable equation of state.

Late universe expansion is exponential with a constant Hubble parameter.

Solutions provide insights into cosmological modeling with modified gravity theories.

Abstract

We perform a symmetry analysis of modified Brans-Dicke cosmological equations and present exact solutions. We discuss how the solutions may help to build models of cosmology where, for the early universe, the expansion is linear and the equation of state just changes the expansion velocity but not the linearity. For the late universe the expansion is exponential and the effect of the equation of state on the rate of expansion is just to change the constant Hubble parameter.