Non-minimally coupled quintessence DE model with a cubic galileon term --A Dynamical System Analysis

TL;DR

This paper investigates a non-minimally coupled scalar field with a cubic Galileon term as a dark energy model, analyzing its fixed points, stability, and evolution, showing it predicts a perpetually accelerating universe with specific stability constraints.

Contribution

It introduces a novel fixed point due to the Galileon term and explores stability conditions in a non-minimally coupled dark energy model, extending previous cubic Galileon studies.

Findings

Stable fixed points identified with perturbative analysis

Model predicts an eternally accelerating universe

Stability imposes restrictions on coupling and self-interaction choices

Abstract

We consider a scalar field which is generallly non-minimally coupled to gravity and has a characteristic cubic Galilean-like term in the kinetic part of the action, in presence of a generic self-interaction as a candidate Dark Energy model. The system is dynamically analyzed and novel fixed points with perturbative stability are demonstrated. Evolution of the system is numerically studied near a novel fixed point which owes its existance to the Galileon character of the model. It turns out that demanding the stability of this novel fixed points puts strong restriction on the allowed non-minimal coupling and the choice of the self-interaction. The evolutions of the system is charted out on a $r-s$ diagram. The evolution of the equation of state parameter is studied which shows that our model predicts accelerated universe throughout and the phantom limit is only approached closely but never crossed. Our result thus extends the findings of of \cite{Cubic_Galileon_NMC} for more general NMC than linear and quadratic couplings.