Crossing Phantom Divide in f(Q)$f(Q)$ Gravity

Abstract

We investigate the possibility of crossing a phantom divide line in the extension of symmetric teleparallel gravity or the f (Q) gravity, where Q is the non-metricity. We study the cosmic evolution of the effective equation of state parameter for dark energy considering exponential, logarithmic, and combined f (Q) theories. Moreover, the exponential model behaves like the ΛCDM at high redshifts before deviating to ω e f f < −1 or ω e f f > −1, respectively, depending on the value of model parameter. It also approaches a de-sitter phase asymptotically. However, the crossing of the phantom divide line, i.e., ω = −1, is realized in the combined f (Q) theory. Furthermore, statefinder diagnostics are studied in order to differentiate between several dark energy models. To ensure the three model's stability, we employ the stability analysis using linear perturbations. We demonstrate how to reassemble f (Q) via a numerical inversion approach based on existing observational constraints on cosmographic parameters and the potential of bridging the phantom divide in the resulting model. It explicitly demonstrates that future crossings of the phantom dividing line are a generic feature of feasible f (Q) gravity models.

A model-independent method with phantom divide line crossing in Weyl-type f(Q,T) gravity

“…These values clearly show that the present cosmos is an accelerating phase and lies in the phantom phase. Thus, these results are consistent with several cosmological models that have been proposed in the literature [60][61][62].…”

How Different Connections in Flat FLRW Geometry Impact Energy Conditions in f(Q)$f(Q)$ Theory?

“…\end{equation}$$Several important publications came up very recently on this modified $$f(Q)$$‐gravity theory and its cosmological implications, see refs. [29–57] and the references therein. However, all these studies were conducted in the coincident gauge choice, line element in Cartesian coordinates.…”

Singularity Free Star Model Characterized by Quintessence Field in Quadratic f(Q)$f(Q)$ Gravity

“…In ref. [31] it is examined if it is possible to cross a phantom divide line in the extension of symmetric teleparallel gravity or the $$f(Q)$$ gravity, where Q is the non‐metricity. Exponential, logarithmic, and combined $$f(Q)$$ theories are taken into consideration in order to study the cosmic evolution of the effective EoS parameter for dark energy.…”