An Interacting Model of Dark Energy in Brans-Dicke Theory

Abstract

In this paper it is shown that in nonminimally coupled Brans-Dicke theory containing a self-interacting potential, a suitable conformal transformation can automatically give rise to an interaction between the normal matter and the Brans-Dicke scalar field. Considering the scalar field in the Einstein frame as the quintessence matter, it has been shown that such a non-minimal coupling between the matter and the scalar field can give rise to a late time accelerated expansion for the universe preceded by a decelerated expansion for very high values of the Brans-Dicke parameter ω. We have also studied the observational constraints on the model parameters considering the Hubble and Supernova data.

A Theoretical Study of the Cosmic Expansion in the Framework of Brans-Dicke Theory

“…This scale factor has been so chosen that the deceleration parameter (≡ − 2 ) calculated from it shows a signature flip as a function of time. This is in accordance with the well known observation that the universe has changed its phase of expansion from deceleration to acceleration [18,19,24]. This empirical scale factor is expressed as,…”

“…Approximately seventy percent of the total matter-energy content of the universe is dark energy at the present time [18]. For a proper choice of and another parameter (to be defined later), we must have × = approximately.…”

“…Several studies reveal that 0 has a negative value close to (−1) [18]. To have 0 < 0, the condition to be satisfied by is given by, < For the whole of the lower range of values and for a part of its upper range, the above condition is satisfied.…”

“…Several studies based on BD theory show that, the dimensionless parameter is required to have a very low value, of the order of unity, for an accelerated expansion of the universe [18]. Once it was shown that, assuming the BD scalar field to be interacting with the dark matter, a generalized form of the BD theory can account for an accelerated expansion even with a high value of [19].…”

A Study of Transition of the Expansion of the Universe from a Phase of Deceleration to Acceleration through a Conversion of Matter into Dark Energy in the Framework of Brans-Dicke Theory

“…According to some studies, the matter content of the universe may not remain proportional to 0 0 3 [31,36]. There may be an interconversion between dark energy and matter (both baryonic and dark matter) [34,36]. In the present model, a factor ( ) has been introduced to account for the conversion of matter into dark energy or its reverse process.…”