Thermodynamical Aspects of Some Cosmological Models

TL;DR

This thesis investigates the thermodynamic properties of various cosmological models, including dark energy and scalar-tensor theories, to assess their stability and compatibility with thermodynamic laws in explaining cosmic acceleration.

Contribution

It provides a comprehensive thermodynamic analysis of multiple cosmological models, including quintessence, Brans-Dicke, and reconstructed dark energy models, highlighting their stability and physical viability.

Findings

Certain dark energy models satisfy the Generalized Second Law

Brans-Dicke models show thermodynamic consistency under specific conditions

The $ ext{Λ}$CDM-like model demonstrates thermodynamic stability

Abstract

The research work in the thesis is focused on the thermodynamic analysis of cosmological models, especially the models that explain late-time cosmic acceleration. According to the cosmological principle, the universe is spatially homogeneous and isotropic. FRW metric is considered to describe it. In the initial chapter, an overview of cosmology is presented. Chapter 2 delves into thermodynamics applied to cosmology, emphasizing the Generalized Second Law. It thoroughly covers Hayward-Kodama temperature and discusses the apparent horizon and the conditions for thermodynamic stability. Chapter 3 presents a thermodynamic comparison of quintessence models, focusing on thawing and freezing scenarios. Chapter 4 examines Brans-Dicke cosmological models in a spatially isotropic and homogeneous universe, assessing their compatibility with the Generalized Second Law of Thermodynamics. Chapter 5 explores the thermodynamic viability of various dark energy models reconstructed using the cosmological jerk parameter. Chapter 6 examines a model in a spatially flat FRW spacetime that mimics the characteristics of the $\Lambda$CDM model, assessing its thermodynamic stability. Chapter 7 serves as the epilogue of this thesis, offering not only the final conclusions but also a brief discussion on the presented work and potential future prospects.