Testing lambert [formula omitted] equation of state with observational hubble parameter data

Abstract

In this paper, we investigate the possibility that the Universe is driven by a single dark fluid described by a Lambert W equation of state parameter, weff, which is essentially dependent on two parameters ϑ1 and ϑ2 which need to be fixed from observations. We obtain the constraints on these parameters using the latest 51 data points of H(z) measurements, spanning the redshift range 0.07≤z≤2.36. The present study shows that the Universe is indeed undergoing an accelerated expansion phase following the decelerated one at the transition redshift, zt=0.77±0.03 (1σ) and is well consistent with the recent observations. We also find that at low redshifts, weff evolves only in the quintessence regime (−1<weff<−13) within 1σ confidence level. Its present value is found to be −0.96±0.02 (1σ). The fact that the present value of weff is very close to the Cosmological Constant Λ implies that our proposed equation of state parameter might serve as a unification of dark matter and dark energy. Furthermore, we compare the evolution of H(z) for the model under consideration with that of the ΛCDM model. Finally, we observe that for the best-fit case, the differences between the two models are negligible at z∼0.67.