Cosmic acceleration and ekpyrotic bounce with Chameleon field

TL;DR

This paper presents a Chameleon cosmology model that unifies an ekpyrotic bounce with late-time dark energy, using numerical methods to analyze the evolution and observational constraints of the universe.

Contribution

It introduces a non-singular bouncing cosmological scenario with a non-minimally coupled scalar field that connects early ekpyrotic contraction to late-time acceleration.

Findings

The model successfully describes a universe transitioning from ekpyrotic contraction to dark energy domination.

Numerical solutions show the scalar field evolution aligns with observational data.

The scenario provides a unified framework for early universe bounce and late-time acceleration.

Abstract

In this article, we explore the homogeneous and isotropic flat Friedmann-Robertson-Walker (FRW) model in Chameleon cosmology. By considering a non-minimal coupling between the scalar field and matter, we present a non-singular bouncing cosmological scenario of the universe. The universe initially exhibits the ekpyrotic phase during the contracting era, undergoes a non-singular bounce, and then in expanding era, it smoothly transits to the decelerating era having matter and radiation dominated phases. Further, this decelerating era is smoothly connected to the late-time dark energy-dominated era of the present epoch. We use numerical solution techniques to solve non-minimally coupled gravity equations for understanding the evolution of scalar field along with other quantities like effective potential in the model. The model thus unifies an ekpyrotic, non-singular, asymmetric bounce with the dark energy era of the present epoch. We study the evolution of bouncing model and confront the model with observational results on the equation of state parameter by constraining the model parameters.