An accelerated universe from Brans-Dicke theory in the Einstein frame

Abstract

The current acceleration of the universe is not consistent with the theory of general relativity (GR). The substitutes of GR have been studied widely. One of them is the Brans-Dicke (BD) theory. Thereinto, most studies of BD theory are in the frame of Jordan representation. In this paper we investigate the accelerating cosmology from BD theory in the other frame, i.e. in the Einstein frame, where it indicates the interaction between the matter and the BD scalar field. We apply the Markov Chain Monte Carlo method to study the cosmic constraints on BD theory according to the current experiment data from the kinematical observations: the Union2 dataset of type supernovae Ia (SNIa) and the observational Hubble data (OHD), and the dynamical observations: the baryon acoustic oscillation (BAO), the cosmic microwave background (CMB) data, and the cluster X-ray gas mass fraction. It is shown that an expanded universe from deceleration to acceleration is given in this theory. And the constraint results on BD model parameters are β = −0.0067(±0.2268) −0.2372−0.4407 +0.2395+0.4168 , γ = 0.0237(±0.0342) −0.0329−0.0647 +0.0326+0.0715 , e = −0.0063(±0.0073) −0.0073−0.0130 +0.0072+0.0158 ; and the constraints values of some correlative cosmological parameters are the dimensionless matter density Ω 0m = 0.2853(±0.0132) −0.0133−0.0247 +0.0132+0.0262 , the cosmic age = 13.5699(±0.2398) −0.2374−0.4568 +0.2371+0.4806 Gyr, and the current Hubble parameter H 0 = 70.2623(±1.2695) −1.2675−2.5150 +1.2749+2.4532 .