The asymptotic behavior of bouncing cosmological models in F(𝒢) gravity theory

Abstract

We reconstruct F (G) gravity theory with an exponential scale factor to realize the bouncing behavior in the early universe and examine the asymptotic behaviour of late-time solutions in this model. We propose an approach to the construction of asymptotic expansions of solutions of the Friedmann equations on the basis of Puiseux series. *

Covariant action for bouncing cosmologies in modified Gauss–Bonnet gravity

“…, where the characteristic scale was set to be l p and the a i are coefficients without units. The expansion could have other different terms, see [14][15][16][17][18][19] for some other terms that can appear. Second, the ǫ parameter is not a priori a small parameter.…”

“…Interesting to note that Lagrangians of the type of our Eq. (29) were found too using different approaches where some reconstruction methods were used by demanding that the scale factor undergoes a bounce at some cosmological time [15][16][17][18][19]. In this way specific R + f (G) gravity bouncing models in the early universe were selected.…”

“…It is certainly of significance to extend Sotiriou's analysis and see whether different higher-order gravities can as well yield bouncing universes. Here we consider a modified Gauss-Bonnet gravity theory with action R + f (G) [14][15][16][17][18][19], where G is the Gauss-Bonnet term, given by G = R 2 − 4R ab R ab + R abcd R abcd , with R abcd , R ab , and R being the Riemann tensor, the Ricci tensor, and the Ricci scalar, respectively, and f (G) means a function of G. Although in four spacetime dimensions G is a topological invariant and does not contribute to the dynamics, f (G) is non trivial even in four dimensions. In this connection, it is impressive that modified Gauss-Bonnet gravity has been proven to be perfectly viable, since it passes solar system tests [20] (see also [14]), naturally leads to late-time cosmic acceleration [20], and is stable under linear cosmological perturbations [21].…”

LRS Bianchi type V perfect fluid cosmological model in f(R, T) theory

“…In literature, many researchers worked on different modified theories of gravity. The theories are f (R) gravity theory [16][17][18][19][20], f (T ) gravity theory, where T is the torsion [21], f (G) gravity theory [22,23] and f (R, T ) gravity theory. In this article, we are interested in f (R, T ) gravity theory because it is the generalization of the f (R) gravity.…”

Loop quantum cosmology scalar field models

“…Indeed, the ultimate goal is to find a consistent way to model this late-time acceleration, which is attributed to the so-called dark energy. Also, the primordial era can also be described by inflationary theories [2][3][4][5][6][7], and by bouncing cosmologies [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27], which both can produced a blue-tilted spectral index of primordial curvature perturbations, which is recently has be verified by the Planck observational data [28]. With regards to the dark matter problem, it is a longstanding problem in theoretical physics, and there are various particle [29] or geometrical [30,31] proposals that may address this problem in a self-consistent way, however no evidence of a particle dark matter exists up to date.…”