Modified gravity bridges the cosmological tensions

arXiv (Cornell University)

Abstract

The standard model of cosmology, $Λ$CDM, is plagued by various tensions with recent observations. The most pressing one is the Hubble tension, where the observed expansion rate of our Universe is $5σ$ larger than that predicted by $Λ$CDM. Recently, the result from DESI also reveals a new inconsistency between the baryon acoustic oscillation and cosmic microwave background (CMB) observations in $Λ$CDM. It is found that these major cosmological tensions can be traced back to a common physical origin - the non-minimal coupling between gravity and matter, different from the expectation of general relativity (GR). Bayesian model comparison reveals strong evidence of non-minimally coupled gravity over GR and $Λ$CDM, with a Bayes factor $\ln B=+12.1$. The non-minimal coupling model predicts that gravity in the early Universe should be $\sim5\%$ stronger on cosmological scales than it is today, which is consistent with current observation and will be tested by upcoming CMB and big bang nucleosynthesis experiments.

Authors 1

1. G. R. Ye corresponding Aachen Institute Lorentz

   Leiden University

   Affiliation as printed

   Institute Lorentz , Leiden University , PO Box 9506 , Leiden 2300 RA , The Netherlands