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Indexed by:期刊论文

Date of Publication:2014-03-24

Journal:PHYSICAL REVIEW D

Included Journals:SCIE、Scopus

Volume:89

Issue:6

ISSN No.:2470-0010

Abstract:Varying gravitational constant G(t) (VG) cosmology is studied in this paper, where the modified Friedmann equation and the modified energy conservation equation are given with respect to the constant G theory. Considering the extended Chaplygin gas (ECG) as background fluid (or thinking that ECG fluid is induced by the variation of G), the unified model of dark matter and dark energy is obtained in VG theory. The parameter spaces are investigated in the VG-ECG model by using the recent cosmic data. Constraint results show beta = - G/HG = -0.003(-0.020-0.055)(+0.021+0.034) for the VG-GCG unified model and beta = -0.027(-0.032-0.066)(+0.032+0.059) for the VG-MCG unified model. Equivalently, they correspond to the limits on the current variation of Newton's gravitational constant at 95.4% confidence level vertical bar(G) over dot/G vertical bar(today) less than or similar to 4.1 x 10(-12) yr(-1) and vertical bar(G) over dot/G vertical bar(today) less than or similar to 6.6 x 10(-12) yr(-1). And for z <= 3.5, bounds on the variaton of vertical bar(G) over dot/G vertical bar in the VG-ECG unified model are in accordance with the experiment explorations of varying G. In addition, in VG theory the used observational data point still cannot distinguish the VG-GCG and VG-MCG unified model from the most popular.CDM cosmology. Furthermore, to see the effects of varying G and physical properties for VG-ECG fluid, we discuss the evolutionary behaviors of cosmological quantities in VG theory, such as vertical bar(G) over dot/G vertical bar, vertical bar(G) over dot/G vertical bar and equation of state w, etc. For beta < 0 a quintom scenario crossing over w = -1 can be realized in the VG-GCG model.