Non-linear dark energy clustering

TL;DR

This paper investigates how dark energy clustering, influenced by its sound speed, affects matter distribution at non-linear scales, using advanced perturbative methods to quantify these effects.

Contribution

It introduces a comprehensive analysis of dark energy clustering effects on non-linear matter power spectra using the time renormalization group method.

Findings

Dark energy sound speed modifies linear power spectrum on observable scales.

Non-linear corrections due to dark energy clustering are below 1%.

Non-linear effects on the matter growth index can reach 10-15% on small scales.

Abstract

We consider a dark energy fluid with arbitrary sound speed and equation of state and discuss the effect of its clustering on the cold dark matter distribution at the non-linear level. We write the continuity, Euler and Poisson equations for the system in the Newtonian approximation. Then, using the time renormalization group method to resum perturbative corrections at all orders, we compute the total clustering power spectrum and matter power spectrum. At the linear level, a sound speed of dark energy different from that of light modifies the power spectrum on observationally interesting scales, such as those relevant for baryonic acoustic oscillations. We show that the effect of varying the sound speed of dark energy on the non-linear corrections to the matter power spectrum is below the per cent level, and therefore these corrections can be well modelled by their counterpart in cosmological scenarios with smooth dark energy. We also show that the non-linear effects on the matter growth index can be as large as 10-15 per cent for small scales.