The H0 Olympics: A fair ranking of proposed models
Vivian Poulin, Guillermo Franco Abellán, Nils Schöneberg
Abstract
Despite the remarkable success of the Λ Cold Dark Matter (ΛCDM) cosmological model, a growing discrepancy has emerged (currently measured at the level of ∼4−6σ) between the value of the Hubble constant H_0 measured using the local distance ladder and the value inferred using the cosmic microwave background and galaxy surveys. While a vast array of ΛCDM extensions have been proposed to explain these discordant observations, understanding the (relative) success of these models in resolving the tension has proven difficult — this is a direct consequence of the fact that each model has been subjected to differing, and typically incomplete, compilations of cosmological data. In this talk, based on the eponymous review paper published in Physics Report, we present the result of a comparison of seventeen different models which have been proposed to resolve the H_0 tension (spanning both early- and late-Universe solutions), and quantify the relative success of each using a series of metrics and a vast array of data combinations. We refer to this contest as the “H_0 Olympics”; the goal being to identify which of the proposed solutions, and more broadly which underlying mechanisms, are most likely to be responsible for explaining the observed discrepancy (should unaccounted for systematics not be the culprit). This work also establishes a foundation of tests which will allow the success of novel proposals to be meaningfully “benchmarked”.