Constraining cosmic deceleration-acceleration transition with type Ia supernova, BAO/CMB and H(z) data

Understand

We revisit the kink-like parametrization of the deceleration parameter q(z), which considers a transition, at $z_t$, from cosmic deceleration to acceleration.

• In this parametrization the initial, at $z \gg z_t$, value of the q-parameter is $q_i$, its final, z=-1, value is $q_f$ and the duration of the transition is parametrized by $\tau$.
• By assuming a flat space geometry we obtain constraints on the free parameters of the model using recent data from type Ia supernovae, BAO, CMB and the Hubble parameter H(z).
• The use of H(z) data introduces an explicit dependence of the combined likelihood on the present value of the Hubble parameter $H_0$, allowing us to explore the influence of different priors when marginalizing over this parameter.