Interacting dark energy in the early 2020s: a promising solution to the $H_0$ and cosmic shear tensions

Abstract

We examine interactions between dark matter and dark energy in light of the latest cosmological observations, focusing on a specific model with coupling proportional to the dark energy density. Our data includes Cosmic Microwave Background (CMB) measurements from the Planck 2018 legacy data release, late-time measurements of the expansion history from Baryon Acoustic Oscillations (BAO) and Supernovae Type Ia (SNeIa), galaxy clustering and cosmic shear measurements from the Dark Energy Survey Year 1 results, and the 2019 local distance ladder measurement of the Hubble constant $H_0$ from the Hubble Space Telescope. Considering Planck data both in combination with BAO or SNeIa data reduces the $H_0$ tension to a level which could possibly be compatible with a statistical fluctuation. The very same model also significantly reduces the ${\Omega }_{\mathrm{m}}-{\sigma }_8$ tension between CMB and cosmic shear measurements. Interactions between the dark sectors of our Universe remain therefore a promising joint solution to these persisting cosmological tensions.

Comments: 24 pages, 3 figures. v2: major revision, changed title, mildened conclusions, included late-time datasets and discussion on how these should be treated with slightly more caution when going beyond LCDM, added many references. Version accepted for publication in Physics of the Dark Universe