Non-linear mode coupling and the growth of perturbations in LCDM

Abstract

Cosmic structures at small non-linear scales $k>L\sim 0.2h$ Mpc${}^{-1}$ have an impact on the longer (quasi-)linear wavelengths with $k<L$ via non-linear UV-IR mode coupling. We evaluate this effect for a $\Lambda$CDM universe applying the effective fluid method of Baumann, Nicolis, Senatore and Zaldarriaga. For $k<L$ the $\Lambda$CDM growth function for the density contrast is found to receive a scale dependent correction and an effective anisotropic stress sources a shift between the two gravitational potentials, setting $\varphi$ - $\psi \ne 0$. Since such a situation is generically considered as a signature of modified gravity and/or dark energy, these effects should be taken into account before any conclusions on the dark sector are drawn from the interpretation of future observations.

11 pages, 1 figure

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Cited by in corpus (7)

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• A parametrization of the growth index of matter perturbations in various Dark Energy models and observational prospects using a Euclid-like survey
• Zel'dovich approximation and General Relativity
• Evolution of dark matter velocity dispersion
• The adhesion model as a field theory for cosmological clustering
• Relativistic perturbations in $\Lambda$CDM: Eulerian & Lagrangian approaches
• The Effective Fluid Approach to Cosmological Nonlinearities: Applications to Preheating