Physical cosmology includes the scientific study of the origin, evolution and dynamics of the

universe. Due to impressive progress both on the theoretical and observational side, scientists

are able to resolve many of the puzzles of the universe. Nevertheless, many questions are not

answered completely. For instance, "What are the constituents of the universe?" and "How

does the dynamics of the universe evolve?" The curiosity to get convincing answers to these

questions, motivates one to work in this field.

According to the hot Big Bang model, the universe started from a bang and its properties change with

time. The discovery of the Cosmic Microwave Background Radiation (CMBR) by Penzias

and Wilson in 1965 was important in making the Big Bang model the accepted model of

the universe 5]. A landmark discovery in 1998 by two groups working independently on

Supernovae Ia was instrumental in changing the way we understand our universe. They

found that the expansion of the universe is accelerating 6, 7].

To explain the accelerated expansion of the universe, various models have been proposed. The

most widely accepted one is the Lambda Cold Dark Matter (ΛCDM) model 8]. According

to this model, the universe is flat and is expanding at an accelerated rate. It is composed of

baryonic matter, dark matter and dark energy. Dark energy is the name given to the cause

of the cosmic acceleration.