Probing the interaction between dark energy and dark matter with the parametrized post-Friedmann approach

Understand

There possibly exists some direct, non-gravitational coupling between dark energy and dark matter.

• This possibility should be seriously tested by using observations, which requires us to understand such a scenario from the aspects of both expansion history and growth of structure.
• It is found that once calculating the perturbations in the interacting dark energy (IDE) scenario, for most cases the curvature perturbation on superhorizon scales is divergent, which is a catastrophe for the IDE cosmology.
• We found a solution to this issue, which is to establish an effective theory to treat the dark energy perturbations totally based on the basic facts of dark energy.