Dark energy can modify the dynamics of dark matter if there exists a direct interaction between them. Thus, a measurement of the structure growth, e.g., redshift-space distortions (RSDs), can provide a powerful tool to constrain the interacting dark energy (IDE) models. For the widely studied Q=3βHρde model, previous works showed that only a very small coupling [β~O(10^-3)] can survive in current RSD data. However, all of these analyses had to assume w>-1 and β>0 due to the existence of the large-scale instability in the IDE scenario. In our recent work [Phys. Rev. D 90, 063005 (2014)], we successfully solved this large-scale instability problem by establishing a parametrized post-Friedmann framework for the IDE scenario. So we, for the first time, have the ability to explore the full parameter space of the IDE models. In this work, we re-examine the observational constraints on the Q=3βHρde model within the parametrized post-Friedmann framework. By using the Planck data, the baryon acoustic oscillation data, the JLA sample of supernovae, and the Hubble constant measurement, we get β=-0.010_-0.033+0.037 (1σ). The fit result becomes β=-0.0148_-0.0089+0.0100 (1σ) once we further incorporate the RSD data in the analysis. The error of β is substantially reduced with the help of the RSD data. Compared with the previous results, our results show that a negative β is favored by current observations, and a relatively larger interaction rate is permitted by current RSD data.
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Li et al. (2014) studied this question.