Dark Energy From Fifth-Dimensional Brans–dicke Theory

Abstract

Following the approach of the induced-matter theory, we investigate the cosmological implications of a five-dimensional Brans-Dicke theory, and propose to explain the acceleration of the universe. After inducing in a four-dimensional hypersurface, we classify the energy-momentum tensor into two parts in a way that, one part represents all kind of the matter (the baryonic and dark) and the other one contains every extra terms emerging from the scale factor of the fifth dimension and the scalar field, which we consider as the energy-momentum tensor of dark energy. We also separate the energy-momentum conservation equation into two conservation equations, one for matter and the other for dark energy. We perform this procedure for different cases, without interacting term and with two particular (suitable) interacting terms between the two parts. By assuming the parameter of the state equation for dark energy to be constant, the equations of the model admit the power-law solutions. Though, the non-interacting case does not give any accelerated universe, but the interacting cases give both decelerated and accelerated universes. For the interacting cases, we figure out analytically the acceptable ranges of some parameters of the model, and also investigate the data analysis to test the model parameter values consistency with the observational data of the distance modulus of 580 SNe Ia compiled in Union2.1. For one of these interacting cases, the best fitted values suggest that the Brans-Dicke coupling constant (ω) is ≃ −7.75, however, it also gives the state parameter of dark energy (w X ) equal to ≃ −0.67. In addition, the model gives the Hubble and deceleration parameters at the present time to be H • ≃ 69.4 (km/s)/Mpc and q • ≃ −0.38 (within their confidence intervals), where the scale factor of the fifth dimension shrinks with the time.

Cosmological and solar system consequences off(R,T)gravity models

“…To relate the discussion of the dark energy to f (R, T ) modified gravity, we redefine equations (2.13) and (2.14) as 27) and…”

“…Other theories of this type are loop quantum gravity/cosmology [6][7][8], theories based on the Ads/CFT correspondence [9,10] and the holographic gravity/cosmology [11,12]. In addition, there are higher-order gravities including the special case f (R) gravity [13][14][15][16][17][18][19], the induced gravity [20,21], the scalar-tensor theories with the special case of Brans-Dicke theory [22][23][24][25][26][27][28], higher-dimensional theories, e.g., the Kaluza-Klein theories [29] and the braneworld scenarios [30]. Also, there are theories that introduce some modifications in the matter component [31,32] or change the geometrical structure, e.g., the non-commutative theories [33][34][35][36][37][38].…”

Bianchi type-III cosmological model with quadratic EoS in Lyra geometry

“…In the energy budget, it is believed that about 73% of our universe is Dark energy, about 23% is occupied by Dark matter and the usual baryonic matter occupies about 4%. Therefore, the study of the aspect of dark energy has become an interesting topics in the field of fundamental physics [22][23][24][25][26][27][28]. Einstein's cosmological constant Λ is the best match for dark energy and physically, it corresponds to the quantum vacuum energy.…”

Interacting Induced Dark Energy Model

“…The second group includes all the models based on the alternative theories of gravity such as Brans-Dicke (BD) theories [22]- [26], Kaluza-Klein (KK) theories [27]- [29], induced matter (IM) theories [30]- [33], brane world scenarios [34]- [38],Über gravity [39] and some mixture of these alternative theories [40]- [43] in addition to many other ones [44], [45]. Hence, in the recent two decades, explaining the accelerated expansion of the universe through the fundamental theories has been a great challenge.…”