Study of Cosmic Expansion through Several Equation of States

Abstract

In this thesis, we discuss the cosmic acceleration of expanding universe through various cosmic parameters in the framework of f (Q) gravity. This gravity is also termed as modi¯ed symmetric teleparallel gravity, where Q stands for "non-metricity". The FRW space-time with perfect °uid are taken as geometry and matter of the universe. We consider two models for cosmic scale factor a(t) as power law form and Dabrowski and Marosek form. In the presence of holographic dark energy density, we study the dif- ferent parameterizations of its model parameter c(z) where z represents the redshift function. These parameterizations help to study the cosmic expan- sion through the cosmological parameters. We plot the equation of state parameter for each model in order to illustrate the cosmic analysis associ- ated with this theory. We examine the squared speed of sound parameter for these models to assess their stability. With regard to the particular values of the model parameters, we achieve some positive outcomes. In addition, we look into how energy conditions can be used to distinguish between the various models and to analyze how matter and energy behave in f (Q) gravity models. For example, by employing energy conditions to test this, one can produce the observed accelerated expansion of the cosmos which is thought to be driven by dark energy.