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 (ISW) 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
two, when compared to the present constraints.
