Dark energy–dark matter interactions as a solution to the S8 tension

Abstract

In this work we consider a scenario where the dark energy is a dynamical fluid whose energy density can be transferred to the dark matter via a coupling function proportional to the energy density of the dark energy. In particular, we investigate this model’s ability to address the S8 tension and find that against data from Planck, BAO and Pantheon the model (1) can significantly reduce the significance of the tension, (2) does so without exacerbating nor introducing any other tension (such as the H0 tension) and (3) without worsening the fit to the considered data sets with respect to the ΛCDM model. We also test the model against data from weak lensing surveys such as KiDS and DES, and find that the model’s ability to address the S8 tension further improves, without a significant impact on any other parameter nor statistical measure.