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

Abstract The possibility of crossing a phantom divide line in the extension of symmetric teleparallel gravity or the gravity, where Q is the non‐metricity, is investigated. The cosmic evolution of the effective equation of state parameter for dark energy is studied considering exponential, logarithmic, and combined theories. Moreover, the exponential model behaves like the ΛCDM at high redshifts before deviating to or , respectively, depending on the value of model parameter. It also approaches a desitter phase asymptotically. However, the crossing of the phantom divide line, that is, , is realized in the combined theory. Furthermore, statefinder diagnostics are studied in order to differentiate between several dark energy models. To ensure the three model's stability, the stability analysis is employed using linear perturbations. It is demonstrated how to reassemble 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 gravity models.