Cosmic Acceleration and Modified Gravitational Models

TL;DR

This paper reviews how modified gravity models, especially those with low-curvature corrections, can explain the universe's late-time acceleration by providing stable de Sitter solutions.

Contribution

It analyzes specific low-curvature modifications to Einstein-Hilbert action that can produce stable accelerating solutions, addressing cosmic acceleration without dark energy.

Findings

Many models contain unstable de Sitter solutions

Certain parameter choices lead to stable late-time acceleration

Modified gravity can mimic dark energy effects

Abstract

There is now overwhelming observational evidence that our Universe is accelerating in its expansion. I discuss how modified gravitational models can provide an explanation for this observed late-time cosmic acceleration. We consider specific low-curvature corrections to the Einstein-Hilbert action. Many of these models generically contain unstable de Sitter solutions and, depending on the parameters of the theory, late-time accelerating attractor solutions.