Model independent H(z) reconstruction using the cosmic inverse distance ladder

Abstract

Recent distance ladder determinations of the Hubble constant H₀ disagree at about the 3.5σ level with the value determined from Planck measurements of the cosmic microwave background (CMB) assuming a ΛCDM^† cosmology. This discrepancy has prompted speculation that new physics might be required beyond that assumed in the ΛCDM model. In this paper, we apply the inverse distance ladder to fit a parametric form of H(z) to baryon acoustic oscillation (BAO) and Type Ia supernova (SNe) data together with priors on the sound horizon at the end of the radiation drag epoch, r_d. We apply priors on r_d, based on inferences from either Planck or the Wilkinson Microwave Anisotropy Probe (WMAP), and demonstrate that these values are consistent with CMB-independent determination of r_d derived from measurements of the primordial deuterium abundance, BAO and supernova data assuming the ΛCDM cosmology. The H(z) constraints that we derive are independent of detailed physics within the dark sector at low redshifts, relying only on the validity of the Friedmann-Robertson-Walker (FRW) metric of General Relativity. For each assumed prior on r_d, we find consistency with the inferred value of H₀ and the Planck ΛCDM value and corresponding tension with the distance ladder estimate.