Transition from a matter-dominated era to a dark energy universe

Abstract

We develop the general program of the unification of matter-dominated era with acceleration epoch for scalar-tensor theory or dark fluid. The general reconstruction of single scalar-tensor theory is fulfilled. The explicit form of scalar potential for which the theory admits matter-dominated era, transition to acceleration and (asymptotically deSitter) acceleration epoch consistent with WMAP data is found. The interrelation of the epochs of deceleration-acceleration transition and matter dominance-dark energy transition for dark fluids with general EOS is investigated. We give several examples of such models with explicit EOS (using redshift parametrization) where matter-dark energy domination transition may precede the deceleration-acceleration transition. As some byproduct, the reconstruction scheme is applied to scalar-tensor theory to define the scalar potentials which may produce the dark matter effect. The obtained modification of Newton potential may explain the rotation curves of galaxies.

Newtonian limit off(R)gravity

“…In fact, since the Taylor expansion of an exponential potential is a power law series, it is not surprising to obtain a power law correction to the Newtonian potential [12] when a less rigorous approach is considered in order to calculate the weak field limit of a generic f (R)-theory. In particular, perturbative calculations will provide effective potentials which can be recovered by means of an appropriate approximation from the general case (40).…”

Cosmological wormholes inf(R)theories of gravity

“…Thus, this choice of f (R) will lead to known forms of a(t) = a 0 (t/t 0 ) n in radiation (n = 1/2) and matter dominated epoch (n = 2/3). Following the results of this reconstruction procedure we take [25][26][27][28][29] …”

Dynamical systems analysis of an interacting dark energy model in the brane scenario

“…On the other hand, the critical point C 3 is completely matter dominated solution (ρ m = 3H 2 ) ( see table II ) and are in accelerating phase for ω m < 2 3 . Phase portrait of the autonomous system (17) are shown in figures 6 and 7 for different choices of the parameters involved. (17) and the values of the relevant physical parameters of those points.…”

“…Phase portrait of the autonomous system (17) are shown in figures 6 and 7 for different choices of the parameters involved. (17) and the values of the relevant physical parameters of those points.…”

“…On the other hand, a group of physicists have explored the second possibility and modified the gravity theory itself, assuming that at large scales, Einstein's theory of general relativity breaks down and a more general action describes the gravitational fields. These theories include f(R)-gravity, Scalar tensor gravity, Einstein-Gauss-Bonnet gravity, Brane world gravity and many others [2,4,[15][16][17][18][19][20][21].…”