Model independent constraints on transition redshift

This paper aims to put constraints on the transition redshift z(t), which determines the onset of cosmic acceleration, in cosmological-model independent frameworks. In order to perform our analyses, we consider a flat universe and assume a parametrization for the comoving distance D-c(z) up to third degree on z, a second degree parametrization for the Hubble parameter H(z) and a linear parametrization for the deceleration parameter q(z). For each case, we show that type Ia supernovae and H(z) data complement each other on the parameter space and tighter constrains for the transition redshift are obtained. By combining the type Ia supernovae observations and Hubble parameter measurements it is possible to constrain the values of zt, for each approach, as 0.806 +/- 0.094, 0.870 +/- 0.063 and 0.973 +/- 0.058 at l sigma c.l., respectively. Then, such approaches provide cosmological -model independent estimates for this parameter.