Dynamical age of the universe as a constraint on the parametrization of   dark energy equation of state
  The dynamical age of the universe depends upon the rate of the expansion of the universe, which explicitly involves the dark energy equation of state parameter $w(z)$. Consequently, the evolution of $w(z)$ has a direct imprint on the age of the universe. We have shown that the dynamical age of the universe as derived from CMB data can be used as an authentic criterion, being independent of the priors like the present value of the Hubble constant $H_{0}$ and the cosmological density parameter $\Omega_{M}^{0}$, to constrain the range of admissible values of $w$ for quiessence models and to test the physically viable parametrizations of the equation of state $w(z) $ in kinessence models. An upper bound on variation of dark energy density is derived and a relation between cosmological density parameters and the transition redshift is established. 
Vinod B. Johri and P. K. Rath