Effects of dark sectors' mutual interaction on the growth of structures

Abstract

We present a general formalism to study the growth of dark matterperturbations when dark energy perturbations and interactionsbetween dark sectors are present. We show that the dynamicalstability on the growth of structure depends on the form of couplingbetween dark sectors. By taking the appropriate coupling whichenables the stable growth of structure, we find that the effect ofthe interaction between dark sectors overwhelms that of dark energyperturbation on the growth of dark matter perturbation. Due to theinfluence of the interaction, the growth index can differ from thevalue without interaction by an amount up to the observationalsensibility, which provides an opportunity to probe the interactionbetween dark sectors through future observations on the growth ofstructure.