In this paper, we interpret the dark energy phenomenon as an averaged effect caused by small scale inhomogeneities of the universe with the use of the spatial averaged approach of Buchert. Two models are considered he...In this paper, we interpret the dark energy phenomenon as an averaged effect caused by small scale inhomogeneities of the universe with the use of the spatial averaged approach of Buchert. Two models are considered here,one of which assumes that the backreaction term QD and the averaged spatial Ricci scalar (R)D obey the scaling laws of the volume scale factor a D at adequately late times, and the other one adopts the ansatz that the backreaction term QD is a constant in the recent universe. Thanks to the effective geometry introduced by Larena et al. in their previous work,we confront these two backreaction models with latest type Ia supernova and Hubble parameter observations, coming out with the results that the constant backreaction model is slightly favoured over the other model and the best fitting backreaction term in the scaling backreaction model behaves almost like a constant. Also, the numerical results show that the constant backreaction model predicts a smaller expansion rate and decelerated expansion rate than the other model does at redshifts higher than about 1, and both backreaction terms begin to accelerate the universe at a redshift around 0.5.展开更多
We study the Stiickelberg holographic superconductors away from the probe limit. We find that the backreaction of the spacetime can bring richer physics in the phase transition. Moreover we observe that the ratio ω9 ...We study the Stiickelberg holographic superconductors away from the probe limit. We find that the backreaction of the spacetime can bring richer physics in the phase transition. Moreover we observe that the ratio ω9 /Tc changes with the strength of the backreaction and is not a universal constant.展开更多
文摘In this paper, we interpret the dark energy phenomenon as an averaged effect caused by small scale inhomogeneities of the universe with the use of the spatial averaged approach of Buchert. Two models are considered here,one of which assumes that the backreaction term QD and the averaged spatial Ricci scalar (R)D obey the scaling laws of the volume scale factor a D at adequately late times, and the other one adopts the ansatz that the backreaction term QD is a constant in the recent universe. Thanks to the effective geometry introduced by Larena et al. in their previous work,we confront these two backreaction models with latest type Ia supernova and Hubble parameter observations, coming out with the results that the constant backreaction model is slightly favoured over the other model and the best fitting backreaction term in the scaling backreaction model behaves almost like a constant. Also, the numerical results show that the constant backreaction model predicts a smaller expansion rate and decelerated expansion rate than the other model does at redshifts higher than about 1, and both backreaction terms begin to accelerate the universe at a redshift around 0.5.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 11275066 and 10905020Program of Changjiang Scholars and Innovative Research Team in University under Grant No. IRT0964Hunan Provincial Natural Science Foundation of China under Grant Nos. 12JJ4007 and 11JJ7001
文摘We study the Stiickelberg holographic superconductors away from the probe limit. We find that the backreaction of the spacetime can bring richer physics in the phase transition. Moreover we observe that the ratio ω9 /Tc changes with the strength of the backreaction and is not a universal constant.
