Kinematical models of latetime cosmology and the statefinder diagnostic
  The present work deals with kinematical models of latetime cosmology. It is
based on purely phenomenological assumption about the deceleration parameter.
The models are confronted to observational data sets of type Ia supernovae
distance modulus measurements and measurements of Hubble parameter at different
redshift. Constraints on the cosmological parameters are obtained by Markov
Chanin Monte Charlo (MCMC) analysis using the observation data sets. The values
of present Hubble parameter, deceleration parameter and the redshift of
transition from decelerated to accelerated phase of expansion are estimated for
the present kinematical models. Further the properties of dark energy for the
present models are explored with general relativistic assumptions. The dark
energy diagnostics, namely the Om diagnostic and the statefinder are adopted
for a comparison of the present models. A phase space constructed of two
different statefinder parameters breaks the degeneracy of the models. It is
observed that the kinematical models attain the corresponding {\Lambda}CDM
value on the phase space in the course of evolution. The evolution of matter
density contrast at linear level has also been studied for the present
kinematical models.
