Aspects of quintessence matter - the driver of the late time   acceleration of the universe
  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. 
Sudipta Das