Combining full-shape and BAO analyses of galaxy power spectra: a 1.6% CMB-independent constraint on H0

We present cosmological constraints from a joint analysis of the pre- and post-reconstruction galaxy power spectrum multipoles from the final data release of the Baryon Oscillation Spectroscopic Survey (BOSS). Geometric constraints are obtained from the positions of BAO peaks in reconstructed spectra, which are analyzed in combination with the unreconstructed spectra in a full-shape (FS) likelihood using a joint covariance matrix, giving stronger parameter constraints than FS-only or BAO-only analyses. We introduce a new method for obtaining constraints from reconstructed spectra based on a correlated theoretical error, which is shown to be simple, robust, and applicable to any flavor of density-field reconstruction. Assuming ΛCDM with massive neutrinos, we analyze clustering data from two redshift bins z_eff=0.38,0.61 and obtain 1.6% constraints on the Hubble constant H₀, using only a single prior on the current baryon density ω_b from Big Bang Nucleosynthesis (BBN) and no knowledge of the power spectrum slope n_s. This gives H₀ = 68.6±1.1 km s^-1Mpc^-1, with the inclusion of BAO data sharpening the measurement by 40%, representing one of the strongest current constraints on H₀ independent of cosmic microwave background data, comparable with recent constraints using BAO data in combination with other data-sets. Restricting to the best-fit slope n_s from Planck (but without additional priors on the spectral shape), we obtain a 1% H₀ measurement of 67.8± 0.7 km s^-1Mpc^-1. Finally, we find strong constraints on the cosmological parameters from a joint analysis of the FS, BAO, and Planck data. This sets new bounds on the sum of neutrino masses ∑ m_ν < 0.14 eV (at 95% confidence) and the effective number of relativistic degrees of freedom N_eff = 2.90^+0.15_-0.16, though contours are not appreciably narrowed by the inclusion of BAO data.