Quintessential and phantom power-law solutions in scalar tensor model of dark energy

TL;DR

This paper investigates a scalar-tensor dark energy model with kinetic and Gauss-Bonnet couplings, exploring conditions for power-law expansion, stability, and mechanisms to avoid Big Rip singularities.

Contribution

It introduces conditions for quintessential and phantom power-law solutions in a scalar-tensor dark energy model, including stability analysis and singularity avoidance mechanisms.

Findings

Kinetic and Gauss-Bonnet couplings can prevent Big Rip singularity.

Conditions for power-law solutions are derived and analyzed.

Stability of solutions is examined using autonomous system and center manifold analysis.

Abstract

We consider a scalar-tensor model of dark energy with kinetic and Gauss Bonnet couplings. We study the conditions for the existence of quintessential and phantom power-law expansion, and also analyze these conditions in absence of potential (closely related to string theory). A mechanism to avoid the Big Rip singularity in various asymptotic limits of the model has been studied. It was found that the kinetic and Gauss-Bonnet couplings might prevent the Big Rip singularity in a phantom scenario. The autonomous system for the model has been used to study the stability properties of the power-law solution, and the centre manifold analysis was used to treat zero eigenvalues.