Stability of the curvature perturbation in dark sectors` mutual interacting models

We consider perturbations in a cosmological model with a small coupling between dark energy and dark matter. We prove that the stability of the curvature perturbation depends on the type of coupling between dark sectors. When the dark energy is of quintessence type, if the coupling is proportional to the dark matter energy density, it will drive the instability in the curvature perturbations: however if the coupling is proportional to the energy density of dark energy, there is room for the stability in the curvature perturbations. When the dark energy is of phantom type, the perturbations are always stable, no matter whether the coupling is proportional to the one or the other energy density. (C) 2008 Elsevier B.V. All rights reserved.

NNSF Natural Science Foundation of China

Natural Science Foundation of China (NSFC)

Shanghai Science and Technology Commission

Shanghai Science and Technology Commission

Shanghai Education Commission

Shanghai Education Commission

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

FAPESP

CNPQ Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)