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arXiv · 1006.5214

Cosmological Density Perturbations with a Scale-Dependent Newton's G

Herbert W. Hamber·Reiko Toriumi
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Abstract

We explore possible cosmological consequences of a running Newton's constant $ G ( \Box ) $, as suggested by the non-trivial ultraviolet fixed point scenario in the quantum field-theoretic treatment of Einstein gravity with a cosmological constant term. In particular we focus here on what possible effects the scale-dependent coupling might have on large scale cosmological density perturbations. Starting from a set of manifestly covariant effective field equations derived earlier, we systematically develop the linear theory of density perturbations for a non-relativistic, pressure-less fluid. The result is a modified equation for the matter density contrast, which can be solved and thus provides an estimate for the growth index parameter $γ$ in the presence of a running $G$. We complete our analysis by comparing the fully relativistic treatment with the corresponding results for the non-relativistic (Newtonian) case, the latter also with a weakly scale dependent $G$.

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Herbert W. Hamber, Reiko Toriumi. 2010-06-27. Cosmological Density Perturbations with a Scale-Dependent Newton's G. https://doi.org/10.1103/physrevd.82.043518

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