Revisiting f(R) gravity models that reproduceΛCDMexpansion

Abstract

We reconstruct an f (R) gravity model that gives rise to the particular ΛCDM background evolution of the universe. We find well-defined, real-valued analytical forms for the f (R) model to describe the universe both in the early epoch from the radiation to matter dominated eras and the late time acceleration period. We further examine the viability of the derived f (R) model and find that it is viable to describe the evolution of the universe in the past and there does not exist the future singularity in the Lagrangian. PACS numbers: 98.80.-k,04.50.Kd

Exploring the liminality: properties of haloes and subhaloes in borderlinef(R) gravity

“…First, it is a well-accepted perception that f(R) gravity is flexible and, thanks to its fourth-order field equations, can, in principle, accommodate arbitrary background cosmologies (see for instance, He & Wang 2013, for a concrete example of CDM background cosmology). In spite of the general impression that 'f(R) gravity can accelerate the cosmic expansion', it should be noticed that there is no necessary connection between the 'acceleration' and 'modified gravity' parts of f(R) gravity: the well-studied model of Hu & Sawicki (2007), as an example, can essentially be written as a cosmological constant plus a modification to the GR gravitational law.…”

Revisiting the screening mechanism inf(R)gravity

“…Equation (21) implies that in the perturbed Universe, even at the centers of voids, the local curvature R in fðRÞ gravity has a nonzero lower bound 4Λ. This result does not assume any specific functional form of fðRÞ and just requires that the background expansion is practically indistinguishable from that of the ΛCDM model.…”

“…The first model to be considered is proposed by one of us, which can exactly reproduce the ΛCDM background expansion history [21]. We call this "our model," and it is specified by…”

“…We demonstrate that this relation plays an important role in understanding the screening mechanism in fðRÞ gravity. In order to strengthen our argument, we study two different fðRÞ models: one which exactly reproduces the ΛCDM background expansion [21] and the other being the Hu-Sawicki model (H-S hereafter) [18]. This paper is organized as follows: In Sec.…”

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] …”