One well known problem of the standard cosmological constant model is the tension between the high level of clustering observed in the CMB and the one obtained from large-scale structures. This may be an indication that the way dark energy affects clustering might differ from a simple cosmological constant. If dark energy actually couples to dark matter, then the way matter clusters will be altered. A model of coupled quintessence, where dark energy is modeled by a scalar field, is a specific example of how this can be achieved. Using redshift distortion data, we can constrain the coupling between dark matter and dark energy, and show that when a coupling is present the tension with CMB is removed. The data also agrees with the weak lensing results from the KIDS-450 survey. Future missions like SKA and Euclid will be able to distinguish between these models and a simple cosmological constant.
Is dark energy really constant?
Tiago Barreiro (IA - Lisbon)