Can interacting dark energy solve the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>H</mml:mi><mml:mn>0</mml:mn></mml:msub></mml:math> tension?

Abstract

The answer is yes. We indeed find that interacting dark energy can alleviate the current tension on the value of the Hubble constant ${H}_{0}$ between the cosmic microwave background anisotropies constraints obtained from the Planck satellite and the recent direct measurements reported by Riess et al. 2016. The combination of these two data sets points toward a nonzero dark matter-dark energy coupling $\ensuremath{\xi}$ at more than two standard deviations, with $\ensuremath{\xi}=\ensuremath{-}0.2{6}_{\ensuremath{-}0.12}^{+0.16}$ at 95% C.L., i.e. with a moderate evidence for interacting dark energy with an odds ratio of $6\ensuremath{\mathbin:}1$ respect to a non interacting cosmological constant. However the ${H}_{0}$ tension is better solved when the equation of state of the interacting dark energy component is allowed to freely vary, with a phantomlike equation of state $w=\ensuremath{-}1.185\ifmmode\pm\else\textpm\fi{}0.064$ (at 68% C.L.), ruling out the pure cosmological constant case, $w=\ensuremath{-}1$, again at more than two standard deviations. When Planck data are combined with external datasets, as BAO, JLA Supernovae Ia luminosity distances, cosmic shear or lensing data, we find perfect consistency with the cosmological constant scenario and no compelling evidence for a dark matter-dark energy coupling.