Dark Energy From a Positive Jerk Parameter

In this paper, we demonstrate that the variation of acceleration, namely the jerk parameter j, could give hints for determining the dark energy equation of state (EoS). In particular, it is possible to show that a viable cosmological model is compatible with a constant jerk, here conventionally rewritten as j = 1+ϵ, with ϵ > 0 representing a departure from the ΛCDM model. This suggests that the cosmological constant could be seen as a limiting case of a more general dark energy model. We use the most recent union 2.1 compilation of supernovae Ia, showing at 1σ confidence level, that j is compatible with the condition j ≥ 1. In doing so, we infer a corresponding cosmological model, viable with a negative acceleration parameter, in the observed range -1 < q 0 < 0.