Alleviating tension in ΛCDM and the local distance ladder from first principles with no free parameters

Abstract

ABSTRACT At increasing levels of confidence, Λ cold dark matter (ΛCDM) is challenged by tension in the Hubble parameter H0 with respect to the local distance ladder. We introduce a new approach to alleviating H0 tension by accelerated expansion leading up to an unstable de Sitter state (UdS) in the distant future. It shares the same parameters H0 and ΩM, 0 of late-time ΛCDM, wherein dS is assumed to be stable. For the matter density ΩM, 0, we test this by estimates over running inner intervals [0, zmax ] in the Pantheon data of 1048 supernovae supported by simulations over a common distribution of redshift data. We zoom in to the intermediate redshift interval [0.1, 0.4] well covered by data. For UdS, uncertainties in matter density in UdS are about one-half of those in ΛCDM and constancy exceeds that in ΛCDM by a factor greater than 2 as their estimates gradually diverge with z up to a significance of 2.5σ. UdS points to ΩM, 0 ≃ 0.3707 ± 0.015 that may be tested by future high-z observations on H(z).