Cosmological dynamics of a hybrid chameleon scenario

TL;DR

This paper investigates a hybrid chameleon cosmological model with a non-minimally coupled scalar field, analyzing its stability, phase space, and the universe's evolution, including phantom divide crossing.

Contribution

It introduces a hybrid chameleon model with an effective potential, analyzing its phase space and stability, and demonstrates the universe's evolution features within this framework.

Findings

Hybrid chameleon domination is a stable attractor.

The universe experiences phantom divide crossing.

Effective potential depends on local matter density.

Abstract

We consider a hybrid scalar field which is non-minimally coupled to the matter and models a chameleon cosmology. By introducing an effective potential, we study the dependence of the effective potential's minimum and hybrid chameleon field's masses to the local matter density. In a dynamical system technique, we analyze the phase space of this two-field chameleon model, find its fixed points and study their stability. We show that the hybrid chameleon domination solution is a stable attractor and the universe in this setup experiences a phantom divide crossing.