H0 and S8 tensions necessitate early and late time changes to ?CDM

An only early or only late time alteration to ACDM has been inadequate at resolving both the H0 and S8 tensions simultaneously; however, a combination of early and late time alterations to ACDM can provide a solution to both tensions. As an illustration, we examine a combined early dark energy, decaying dark matter model. While early dark energy has the ability to resolve the H0 tension, it leads to a discrepancy in S8 measurements. We show that the addition of decaying dark matter helps resolve the S8 discrepancy that would otherwise be enhanced in an early dark energy model, while the latter is able to relieve the H0 disagreement to within the 95th percentile interval. Our results show a preference for the combined model over ACDM with AAIC = -6.72, hinting that both early and late Universe modifications may be necessary to address the cosmological tensions.