Dark Energy From Fifth Dimensional Brans-Dicke Theory
  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
({\omega}) is -7.75, however, it also gives the state parameter of dark energy
(wX) equal to -0.67. In addition, the model gives the Hubble and deceleration
parameters at the present time to be H0 = 69.4 (km/s)/Mpc and q0 = -0.38
(within their confidence intervals), where the scale factor of the fifth
dimension shrinks with the time.
