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arXiv · 1008.2751

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

Kari Enqvist·Gerasimos Rigopoulos
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Abstract

Cosmic structures at small non-linear scales $k>L\sim 0.2 h $ 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 $\phi$ - $\psi \neq 0$. 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.

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Kari Enqvist, Gerasimos Rigopoulos. 2010-08-16. Non-linear mode coupling and the growth of perturbations in LCDM. https://doi.org/10.1088/1475-7516%2F2011%2F03%2F005

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