Constraint on coupled dark energy models from observations

The coupled dark energy models, in which the quintessence scalar field nontrivially couples to the cold dark matter, have been proposed to explain the coincidence problem. In this paper we study the perturbations of coupled dark energy models and the effects of this interaction on the current observations. Here, we pay particular attention to its imprint on the late-time integrated Sachs-Wolfe effect. We perform a global analysis of the constraints on this interaction from the current observational data. Considering the typical exponential form as the interaction form, we obtain that the strength of interaction between dark sectors is constrained as beta < 0.085 at 95% confidence level. Furthermore, we find that future measurements with smaller error bars could improve the constraint on the strength of coupling by a factor of 2, when compared to the present constraints.