摘要：The modified Chaplygin gas could be considered to abide by the unified dark fluid model because the model might describe the past decelerating matter dominated era and at present time it provides an accelerating expansion of the Universe. In this paper, we have employed thePlanck2015 cosmic microwave background anisotropy, type-Ia supernovae, observed Hubble parameter data sets to measure the full parameter space of the modified Chaplygin gas as a unified dark matter and dark energy model. The model parametersBs,α, andBdetermine the evolutional history of this unified dark fluid model by influencing the energy densityρMCG = ρMCG0[Bs + (1 − Bs)a−3(1 + B)(1 + α)]1/(1 + α). We assumed the pure adiabatic perturbation of unified modified Chaplygin gas in the linear perturbation theory. In the light of Markov chain Monte Carlo method, we find thatBs= 0.727+0.040+0.075−0.039−0.079,α= −0.0156+0.0982+0.2346−0.1380−0.2180,B= 0.0009+0.0018+0.0030−0.0017−0.0030at 2σlevel. The model parametersαandBare very close to zero and the nature of unified dark energy and dark matter model is very similar to cosmological standard model ΛCDM.
