Tight $H_0$ constraint from galaxy redshfit surveys: combining baryon acoustic osillation measurements and Alcock-Paczynski test

TL;DR

This paper combines galaxy redshift survey data with BAO and Alcock-Paczynski methods to tightly constrain the Hubble constant, achieving results consistent with CMB measurements but in tension with local measurements.

Contribution

The study demonstrates that combining BAO and AP methods significantly improves the precision of H0 constraints from galaxy surveys, highlighting the AP method's effectiveness.

Findings

H0 constrained to 67.78^{+1.21}_{-1.86} km/s/Mpc with 2.26% precision

BAO+AP reduces error bars by 32% compared to BAO alone

Results are consistent with Planck CMB measurements but in tension with local measurements

Abstract

We report a tight Hubble constant constraint $67.78^{+1.21}_{-1.86}$ km s$^{-1}$ Mpc$^{-1}$ (2.26\% precision) derived from galaxy redshift surveys. We combine the BAO measurements from 6dFGS, the SDSS DR7 main galaxies, the BOSS DR12 galaxies, and eBOSS DR14 quasars, and also apply the tomographic Alcock-Paczynski (AP) method to the BOSS DR12 galaxies, to place constraints on $H_0$ in the spatially flat $\Lambda$CDM framework. Our result is fully consistent with the CMB constraints from Planck, but in $2.58\sigma$ tension with local measurements of Riess et al. 2016. Compared with the BAO alone constraint, the BAO+AP combined result reduces the error bar by 32%. This shows the strong power of the tomographic AP method in extracting cosmological information from galaxy redshift surveys.