Cosmological constraints in covariant f(Q) gravity with different connections

Abstract

Recently it has been shown that the cosmological dynamics of covariant f(Q) gravity depend on different affine connections. In this paper, two specific f(Q) models are investigated with SNe+CC+BAO+QSO observational data, and the spatial curvature of the universe is studied in covariant f(Q) gravity. It is found that the parameters $${\mathcal {X}}_0$$ X 0 and $${\mathcal {X}}'_0$$ X 0 ′ characterizing affine connections significantly affect the behavior of the effective equation of state $$w_Q$$ w Q and may drive it across the phantom divide line. These results imply some inertial effects of the universe change the cosmic dynamics. However based on the Bayesian evidence, the zero inertial effect is more favored in the flat universe. Moreover, a closed universe is favored not only in the $$\Lambda $$ Λ CDM model but also in covariant f(Q) gravity. The f(Q) models have less support evidence than the $$\Lambda $$ Λ CDM model in the non-flat universe.

Non-metricity with boundary terms: 𝖿(𝖰,𝖢) gravity and cosmology

“…A symmetric teleparallel affine connection is a torsion-free, curvature-free affine connection, with both spherical and translational symmetries, implying that the Lie derivatives of the connection coefficients with respect to the generating vector fields of spatial rotations and translation vanish. There are three types of affine connections with such symmetries [56]. In order to proceed to specific cosmological applications we need to consider each of these symmetric teleparallel connections and this is performed in the following subsections.…”

“…Finally, we consider a non-vanishing, torsion-free and curvature-free affine connection Γ whose non-trivial coefficients are given by (i = 1, 2, 3) [56] Γ t tt = −H(t), Γ t ii = γ(t) , (4.23) which lead to…”

“…Alternatively, one can start from the torsional formulation of gravity and obtain f (T) gravity [11,12], f (T, T G ) gravity [13,14], etc. Finally, there is an alternative way to build classes of modified gravities, namely to use non-metricity [15,16] resulting to f (Q) gravity [51][52][53][54][55][56].…”