Towards a possible solution for the coincidence problem: f(G) gravity as background

TL;DR

This paper investigates the cosmic coincidence problem within f(G) gravity by exploring interaction models between dark energy and dark matter, proposing new models that successfully address the problem and align with observational data.

Contribution

It introduces a set-up to identify f(G) gravity models that solve the coincidence problem, proposing two new models that succeed where popular models fail.

Findings

Popular f(G) models do not solve the coincidence problem.

Two new f(G) models successfully address the coincidence problem.

The b-interaction term aligns best with observational data.

Abstract

In this article we address the well-known cosmic coincidence problem in the framework of the f(G) gravity. In order to achieve this, an interaction between dark energy and dark matter is considered. A set-up is designed and a constraint equation is obtained which generates the f(G) models that do not suffer from the coincidence problem. Due to the absence of a universally accepted interaction term introduced by a fundamental theory, the study is conducted over three different forms of logically chosen interaction terms. To illustrate the set-up three widely known models of f(G) gravity are taken into consideration and the problem is studied under the designed set-up. The study reveals that the popular f(G) gravity models does not approve of a satisfactory solution of the long standing coincidence problem, thus proving to be a major setback for them as successful models of universe. Finally, two non-conventional models of f(G) gravity have been proposed and studied in the framework of the designed set-up. It is seen that a complete solution of the coincidence problem is achieved for these models. The study also reveals that the b-interaction term is much more preferable compared to the other interactions, due to its greater compliance with the recent observational data.