Brans-Dicke cosmology with a $\Lambda$- term: a possible solution to $\Lambda$CDM tensions

Understand

We present a full-fledged analysis of Brans-Dicke cosmology with a cosmological constant and cold dark matter (BD-$\Lambda$CDM for short).

• We extend the scenarios where the current cosmological value of the BD-field is restricted by the local astrophysical domain to scenarios where that value is fixed only by the cosmological observations, which should be more natural in view of the possible existence of local screening mechanims.
• Our analysis includes both the background and perturbations equations in different gauges.
• We find that the BD-$\Lambda$CDM is favored by the overall cosmological data as compared to the concordance GR-$\Lambda$CDM model, namely data on distant supernovae, cosmic chronometers, local measurements of the Hubble parameter, baryonic acoustic oscillations, Large-Scale Structure formation and the cosmic microwave background under full Planck 2018 CMB likelihood.