Imprints of Dark Energy on Cosmic Structure Formation I) Realistic Quintessence Models and the Non-Linear Matter Power Spectrum

TL;DR

This study investigates how realistic quintessence dark energy models influence large-scale structure formation, revealing significant deviations from LambdaCDM predictions in the non-linear matter power spectrum, which are crucial for interpreting cosmological data.

Contribution

It performs a likelihood analysis to identify viable quintessence models and uses high-resolution simulations to quantify their impact on structure formation beyond previous assumptions.

Findings

Quintessence models cause up to 40% differences in the non-linear power spectrum.

Structure formation is about 20% more efficient at small scales compared to LambdaCDM.

Imprints of dark energy on structure formation cannot be captured by standard fitting functions.

Abstract

Dark energy as a quintessence component causes a typical modification of the background cosmic expansion, which in addition to its clustering properties, can leave a potentially distinctive signature on large scale structures. Many previous studies have investigated this topic, particularly in relation to the non-linear regime of structure formation. However, no careful pre-selection of viable quintessence models with high precision cosmological data was performed. Here we show that this has led to a misinterpretation (and underestimation) of the imprint of quintessence on the distribution of large scale structures. To this purpose we perform a likelihood analysis of the combined Supernova Ia UNION dataset and WMAP5-years data to identify realistic quintessence models. Differences from the vanilla LambdaCDM are especially manifest in the predicted amplitude and shape of the linear matter power spectrum, though these remain within the uncertainties of the SDSS data. We use these models as benchmark for studying the clustering properties of dark matter halos by performing a series of high resolution N-body simulations. We find that realistic quintessence models allow for relevant differences of the dark matter distribution with the respect to the LambdaCDM scenario well into the non-linear regime, with deviations up to 40% in the non-linear power spectrum. Such differences are shown to depend on the nature of DE, as well as the scale and epoch considered. At small scales (k~1-5 h Mpc^{-1}, depending on the redshift) the structure formation process is about 20% more efficient than in LambdaCDM. We show that these imprints are a specific record of the cosmic structure formation history in DE cosmologies and therefore cannot be accounted in standard fitting functions of the non-linear matter power spectrum.