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论文类型：期刊论文

发表时间：2013-07-02

发表刊物：PHYSICAL REVIEW D

收录刊物：SCIE、Scopus

卷号：88

期号：2

ISSN号：2470-0010

摘要：In this paper, we investigate a unified dark fluid model with a fast transition and entropic perturbations. An effective sound speed is designated as an additional free model parameter when the entropic perturbations are included, and, if the entropic perturbations are zero, the effective sound speed will decrease to the adiabatic sound speed. In order to analyze the viability of the unified model, we calculate the squared Jeans wave number with the entropic perturbations. Furthermore, by using the Markov Chain Monte Carlo method, we perform a global fitting for the unified dark fluid model from the type Ia supernova Union 2.1, baryon acoustic oscillation, and the full information of the cosmic microwave background measurement given by the WMAP 7 yr data points. The constrained results favor a small effective sound speed. Compared to the cosmological constant and cold dark matter, it is found that the cosmic observations do not favor the phenomenon of a fast transition for the unified dark fluid model.