Skewness as a test of dark energy perturbations

We investigate the role played by dark energy perturbations in the skewness $S_3$ of large-scale matter distribution. We consider a two-fluid universe composed by matter and dark energy, with perturbations in both components, and we estimate numerically the skewness of the matter density field as a function of the dark energy parameters. We characterize today's $S_3$ value for quintessence and phantom dark energy cosmologies as well as its dependence on the matter density parameter $\Omega_{m0}$ and the dark energy sound speed $c^2_s$ with accurate numerical fitting. These fits can be used to test cosmology against future high quality data on large scale structure.