Non-linear Matter Spectra in Coupled Quintessence

TL;DR

This paper investigates how a dark-energy scalar field interacting with cold dark matter affects matter power spectra, using advanced non-linear methods and simulations to reveal scale-dependent biases and enhancements.

Contribution

It extends the time-renormalization-group method to multi-component matter sectors and analyzes the impact of dark sector interactions on non-linear matter spectra.

Findings

Scale-dependent bias arises from initial conditions of baryons and dark matter.

Extra coupling enhances bias effects to 2-3% at BAO scales.

Results agree well with N-body simulations.

Abstract

We consider cosmologies in which a dark-energy scalar field interacts with cold dark matter. The growth of perturbations is followed beyond the linear level by means of the time-renormalization-group method, which is extended to describe a multi-component matter sector. Even in the absence of the extra interaction, a scale-dependent bias is generated as a consequence of the different initial conditions for baryons and dark matter after decoupling. The effect is enhanced significantly by the extra coupling and can be at the 2-3 percent level in the range of scales of baryonic acoustic oscillations. We compare our results with N-body simulations, finding very good agreement.