We measure the expansion rate of the recent Universe and the calibration scale of the baryon acoustic oscillation (BAO) from low-redshift data. BAO relies on the calibration scale, i.e., the sound horizon at the end of drag epoch rd, which often imposes a prior of the cosmic microwave background (CMB) measurement from the Planck satellite. In order to make really independent measurements of H0, we leave rd completely free and use the BAO data sets combined with the 31 observational H(z) data, GW170817 and Pantheon sample of Type Ia supernovae. In ΛCDM model, we get H0=68.63−1.77+1.75 km s−1 Mpc−1, rd=146.85−3.77+3.29 Mpc. For the two model-independent reconstructions of H(z), we obtain H0=68.02±1.82 km s−1 Mpc−1, rd=148.18−3.78+3.36 Mpc in the cubic expansion, and H0=68.58±1.76 km s−1 Mpc−1, rd=148.02−3.60+3.63 Mpc in the polynomial expansion. The values of Hubble constant H0 and sound horizon rd are consistent with the estimate derived from the Planck CMB data assuming a flat ΛCDM model, but H0 is in 2.4∼2.6σ tension with SH0ES 2019, respectively.
@article{arxiv.2006.16692,
title = {Hubble constant and sound horizon from the late-time Universe},
author = {Xue Zhang and Qing-Guo Huang},
journal= {arXiv preprint arXiv:2006.16692},
year = {2021}
}