Effect of dark energy sound speed and equation of state on CDM power spectrum

TL;DR

This paper investigates how dark energy's equation of state and sound speed affect the cold dark matter power spectrum, revealing scale-dependent suppression effects compared to the standard Lambda-CDM model.

Contribution

It provides a detailed analysis of the impact of dark energy parameters on the CDM power spectrum across different scales, highlighting the significance of sound speed and equation of state.

Findings

Dark energy parameters suppress the CDM power spectrum compared to Lambda-CDM.

Equation of state influences all scales significantly.

Sound speed effects are prominent only at intermediate scales.

Abstract

We study the influence of equation of state $w$ and effective sound speed $c_e$ of the dark energy perturbations on the cold dark matter(CDM) power spectrum.We consider different cases of the equation of state and the effective sound speed, the cold dark matter power spectrum is found to be generically suppressed in these cases as compared to the $\Lambda$CDM model. The suppression at different length scales depends on the value of $w$ and $c_e$, and the effect of different $w$ is profoundly seen at all length scales. The influence of sound speed is significantly seen only at the intermediate length scales and is negligible at scales very much larger and smaller than the Hubble scale.