Distinguishing modified gravity from dark energy

被引:268
作者
Bertschinger, Edmund [1 ]
Zukin, Phillip [1 ]
机构
[1] MIT, Dept Phys, Cambridge, MA 02139 USA
来源
PHYSICAL REVIEW D | 2008年 / 78卷 / 02期
关键词
D O I
10.1103/PhysRevD.78.024015
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The acceleration of the Universe can be explained either through dark energy or through the modification of gravity on large scales. In this paper we investigate modified gravity models and compare their observable predictions with dark energy models. Modifications of general relativity are expected to be scale independent on superhorizon scales and scale dependent on subhorizon scales. For scale-independent modifications, utilizing the conservation of the curvature scalar and a parametrized post-Newtonian formulation of cosmological perturbations, we derive results for large-scale structure growth, weak gravitational lensing, and cosmic microwave background anisotropy. For scale-dependent modifications, inspired by recent f(R) theories we introduce a parametrization for the gravitational coupling G and the post-Newtonian parameter gamma. These parametrizations provide a convenient formalism for testing general relativity. However, we find that if dark energy is generalized to include both entropy and shear stress perturbations, and the dynamics of dark energy is unknown a priori, then modified gravity cannot in general be distinguished from dark energy using cosmological linear perturbations.
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页数:13
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