Phantom energy-dominated universe as a transient stage in f(R) cosmology

Abstract

The f (R) theories of gravity are the most popular, simple and well succeeded extension of Einstein's General Relativity. They can account for some observational issues of standard cosmology with no need for evoking the dark sector of the universe. In the present article we will investigate LRS Bianchi type-I space-time in f (R) gravity theory within the phantom energy dominated era. We show that in this formalism the phantom energy dominated universe is a transient stage and in the further stage of the universe dynamics, it is dominated, once again, by dark energy. Such an important feature is obtained from the model, rather than imposed to it, and may have a relation to loop quantum cosmology.

An Exponential Shape Function for Wormholes in Modified Gravity*

“…Fig.2 shows that the WH EoS is in the phantom region, that is, ω r < −1. It is well known that a phantom EoS parameter < −1 for the universe will imply in the socalled Big Rip [58] though some alternative to evade such a catastrophic scenario have appeared [59]- [62]. Phantom WHs have also appeared in the literature [54]- [65] though it is important to remark that in these cases the phantom EoS was invoked rather than obtained from the model, as in the present case.…”

Non-exotic wormholes in 4-D Einstein-Gauss-Bonnet gravity

“…−1 < ω < −1/3 but for away the throat where r > r 0 WH EoS is in the phantom region i.e ω < −1. The phantom EoS parameter ω < −1 is well known for Universe will imply in the so-called Big Rip [79] to avoid such a disastrous scenario have appeared [80][81][82][83]. Phantom wormholes have also been reported in the literature [84][85][86] albeit it's worth noting that the phantom EoS was summoned rather than obtained from the model in these situations (as in this instance).…”

Four-dimensional Brane–Chern–Simons Gravity and Cosmology

“…and we have a transient phantom evolution (not ruled out by the current observational data). Theoretical frameworks where this type of evolution is discussed can be seen in [21][22][23].…”