Roles of dark energy perturbations in the dynamical dark energy models: Can we ignore them?

Chan-Gyung Park, Jai-chan Hwang, Jae-heon Lee, Hyerim Noh

Published 2009-04-26, updated 2009-10-22Version 2

We show the importance of properly including the perturbations of the dark energy component in the dynamical dark energy models based on a scalar field and modified gravity theories in order to meet with present and future observational precisions. Based on a simple scaling scalar field dark energy model, we show that observationally distinguishable substantial differences appear by ignoring the dark energy perturbation. By ignoring it the perturbed system of equations becomes inconsistent and deviations in (gauge-invariant) power spectra depend on the gauge choice.