Cosmology of the selfaccelerating third order Galileon

TL;DR

This paper investigates a specific subset of third order Galileon models that exhibit self-acceleration and stable spherical solutions, analyzing their cosmological evolution and potential instabilities.

Contribution

It identifies a previously unexplored constrained subset of third order Galileon Lagrangians that produce self-accelerating solutions with stability considerations.

Findings

Confirmed self-acceleration in the model

Discovered potential instabilities in galileon perturbations

Explored cosmological evolution consistent with self-acceleration

Abstract

In this paper we start from the original formulation of the galileon model with the original choice for couplings to gravity. Within this framework we find that there is still a subset of possible Lagrangians that give selfaccelerating solutions with stable spherically symmetric solutions. This is a certain constrained subset of the third order galileon which has not been explored before. We develop and explore the background cosmological evolution of this model drawing intuition from other even more restricted galileon models. The numerical results confirm the presence of selfacceleration, but also reveals a possible instability with respect to galileon perturbations.