Speaker
Description
We introduce a new method for measuring the Hubble parameter from low-redshift large-scale observations that is independent of the comoving sound horizon. The method uses the baryon-to-photon ratio determined by the primordial deuterium abundance, together with Big Bang Nucleosynthesis (BBN) calculations and the present-day CMB temperature to determine the physical baryon density $\Omega_b h^2$. The baryon fraction $\Omega_b/\Omega_m$ is measured using the relative amplitude of the baryonic signature in galaxy clustering, scaling the physical baryon density to the physical matter density. The physical density $\Omega_mh^2$ is then compared with the geometrical density $\Omega_m$ from Alcock-Paczynski measurements from Baryon Acoustic Oscillations (BAO) and voids, to give $H_0$. Current data is only weakly constraining and therefore consistent with both the distance-ladder and CMB $H_0$ determinations, but near-future large-scale structure surveys (such as the full DESI and Euclid surveys) will obtain 3--4$\times$ tighter constraints. Including type Ia supernovae and uncalibrated BAO, and using the baryon signature in BOSS galaxy clustering, we measure $H_0 = 67.1^{+6.3}_{-5.3}$ km s$^{-1}$ Mpc$^{-1}$. We find similar results when varying analysis choices, such as measuring the baryon signature from the reconstructed correlation function, or excluding supernovae or voids.
