Aspects of quintessence matter - the driver of the late time acceleration of the universe

TL;DR

This thesis explores scalar field models, including nonminimal couplings and curvature effects, to explain the universe's transition from deceleration to late-time acceleration, addressing fine-tuning issues.

Contribution

It introduces analytic models with scalar fields and interactions that successfully describe the universe's accelerated expansion and resolve fine-tuning problems.

Findings

Scalar field models can drive late-time acceleration.

Interactions between scalar fields and dark matter/energy address fine-tuning.

Curvature effects enable smooth transition from deceleration to acceleration.

Abstract

The present thesis is a collection of papers which deals with analytic models that can drive the present accelerated expansion of the universe, starting from a decelerated expansion in the early matter dominated regime. Both minimally and non minimally coupled scalar fields are employed for the purpose. Interaction between nonminimally coupled scalar field, such as the Brans-Dicke field, with dark matter and dark energy are considered. This interactions are shown to solve some fine tuning problems. Curvature driven acceleration is also considered in this thesis, which shows that a smooth transition from a deceleration to an acceleration is possible in this scenario.