Cosmological Singularities in Conformal Weyl Gravity

TL;DR

This paper explores how conformal Weyl gravity can potentially avoid both initial and future cosmological singularities by analyzing stability conditions of emergent universe scenarios and types of finite-time singularities.

Contribution

It demonstrates that conformal Weyl gravity allows for stable emergent universe states and can prevent finite-time singularities, offering a singularity-free cosmological model.

Findings

Stable emergent universe states are possible with certain parameters.

Conformal Weyl gravity can avoid initial singularities.

Finite-time future singularities can be prevented in this theory.

Abstract

In this work, we study the issue of the past and future cosmological singularities in the context of the fourth-order conformal Weyl gravity. In particular, we investigate the emergent universe scenario proposed by Ellis {\it et al}, and find the stability conditions of the corresponding Einstein static state using the fixed point approach. We show that depending on the values of the parameters of the conformal Weyl gravity theory, there are possibilities for having initially stable emergent states for an FRW universe with both the positive and negative spatial curvatures. This represents that the conformal Weyl gravity can be free of the initial singularity problem. Then, following Barrow {\it et al}, we address the possible types of the finite-time future cosmological singularities. We discuss how these singularities also can be avoided in the context of this theory.