Interacting scalar tensor cosmology in light of SNeIa, CMB, BAO and OHD
  observational data sets
  During this work, an interacting chameleon like scalar field scenario, by
considering SNeIa, CMB, BAO and OHD data sets is investigated. In fact, the
investigation is realized by introducing an ansatz for the effective dark
energy equation of state, which mimics the behaviour of chameleon like models.
Based on this assumption, some cosmological parameters including Hubble,
deceleration and coincidence parameters in such mechanism are analysed. It is
realized that, to estimate the free parameters of a theoretical model, by
regarding the systematic errors it better the whole of the above observational
data sets to be considered. In fact, if one considers SNeIa, CMB and BAO but
disregards OHD it maybe leads to different results. Also to get a better
overlap between the counters with the constraint $\chi _{\rm{m}}^2\leq 1$, the
$\chi _{\rm{T}}^2$ function could be re-weighted. The relative probability
functions are plotted for marginalized likelihood $\mathcal{L}
(\Omega_{\rm{m0}} ,\omega_1, \beta)$ according to two dimensional confidence
levels $68.3\%$, $90\%$ and $95.4\%$. Meanwhile, the value of free parameters
which maximize the marginalized likelihoods using above confidence levels are
obtained. In addition, based on these calculations the minimum value of
$\chi^2$ based on free parameters of an ansatz for the effective dark energy
equation of state are achieved.
