Determining the Hubble constant without the sound horizon: Measurements from galaxy surveys
Oliver H. E. Philcox, Blake D. Sherwin, Gerrit S. Farren, Eric J. Baxter
Abstract
Two sources of geometric information are encoded in the galaxy power spectrum: the sound horizon at recombination and the horizon at matter-radiation equality. Analyzing the BOSS 12th data release galaxy power spectra using perturbation theory with ${\mathrm{\ensuremath{\Omega}}}_{m}$ priors from Pantheon supernovae but no priors on ${\mathrm{\ensuremath{\Omega}}}_{b}$, we obtain constraints on ${H}_{0}$ from the second scale, finding ${H}_{0}={65.1}_{\ensuremath{-}5.4}^{+3.0}\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$; this differs from the best fit of SH0ES at 95% confidence. Similar results are obtained if ${\mathrm{\ensuremath{\Omega}}}_{m}$ is constrained from uncalibrated baryon acoustic oscillations: ${H}_{0}={65.6}_{\ensuremath{-}5.5}^{+3.4}\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. Adding the analogous lensing results from Baxter and Sherwin from 2020, the posterior shifts to ${70.6}_{\ensuremath{-}5.0}^{+3.7}\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$. Using mock data, Fisher analyses, and scale cuts, we demonstrate that our constraints do not receive significant information from the sound horizon scale. Since many models resolve the ${H}_{0}$ controversy by adding new physics to alter the sound horizon, our measurements are a consistency test for standard cosmology before recombination. A simple forecast indicates that such constraints could reach ${\ensuremath{\sigma}}_{{H}_{0}}\ensuremath{\simeq}1.6\text{ }\text{ }\mathrm{km}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{Mpc}}^{\ensuremath{-}1}$ in the era of Euclid.