Kavli Affiliate: George Efstathiou

| First 5 Authors: Pablo Lemos, Elizabeth Lee, George Efstathiou, Steven Gratton,

| Summary:

Recent distance ladder determinations of the Hubble constant $H_0$ disagree

at about the $3.5sigma$ level with the value determined from Planck

measurements of the cosmic microwave background (CMB) assuming a $Lambda$CDM

cosmology. This discrepancy has prompted speculation that new physics might be

required beyond that assumed in the $Lambda$CDM 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 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 Anistropy Probe (WMAP), and demonstrate that these values are

consistent with CMB-independent determinations of $r_d$ derived from

measurements of the primordial deuterium abundance, BAO and supernova data

assuming the $Lambda$CDM 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 $H_0$ and the Planck $Lambda$CDM value and corresponding

tension with the distance ladder estimate.

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