Time Evolution of Density Parameters for Matter and Dark Energy and their Interaction Term in Brans-Dicke Gravity

Roy, Sudipto and Nandi, Dipika and Ghosh, Sumana and Das, Apashanka (2018) Time Evolution of Density Parameters for Matter and Dark Energy and their Interaction Term in Brans-Dicke Gravity. [Preprint]

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Abstract

In the framework of Brans-Dicke (BD) theory, the present study determines the time dependence of BD parameter, energy density and equation of state (EoS) parameter of the cosmic fluid in a universe expanding with acceleration, preceded by a phase of deceleration. For this purpose, a scale factor has been so chosen for the present model that the deceleration parameter, obtained from it, shows a signature flip with time. Considering the dark energy to be responsible for the entire pressure, the time evolution of energy parameters for matter and dark energy and the EoS parameter for dark energy have been determined. A term, representing interaction between matter and dark energy, has been calculated. Its negative value at the present time indicates conversion of matter into dark energy. It is evident from the present study that the nature of dependence of the scalar field upon the scale factor plays a very important role in governing the time evolution of the cosmological quantities studied here. This model has an inherent simplicity in the sense that it allows one to determine the time evolution of dark energy for a homogeneous and isotropic universe, without involving any self-interaction potential or cosmological constant in the formulation.

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Creators	Email	ORCID
Roy, Sudipto	roy.sudipto1@gmail.com	0000-0002-8811-2511
Nandi, Dipika	dipika.nandi949@gmail.com
Ghosh, Sumana	sumanaghosh284@gmail.com
Das, Apashanka	saanjaay131@gmail.com