The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the large-scale two-point correlation function

We obtain constraints on cosmological parameters from the spherically averaged redshift-space correlation function of the CMASS Data Release 9 (DR9) sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). We combine this information with additional data from recent cosmic microwave background (CMB), supernova and baryon acoustic oscillation measurements. Our results show no significant evidence of deviations from the standard flat Λ cold dark matter model, whose basic parameters can be specified by Ω_m = 0.285 ± 0.009, 100 Ω_b = 4.59 ± 0.09, n_s = 0.961 ± 0.009, H₀ = 69.4 ± 0.8 km s⁻1 Mpc⁻¹ and σ₈ = 0.80 ± 0.02. The CMB+CMASS combination sets tight constraints on the curvature of the Universe, with Ω_k = −0.0043 ± 0.0049, and the tensor-to-scalar amplitude ratio, for which we find r < 0.16 at the 95 per cent confidence level (CL). These data show a clear signature of a deviation from scale invariance also in the presence of tensor modes, with n_s < 1 at the 99.7 per cent CL. We derive constraints on the fraction of massive neutrinos of f_ν < 0.049 (95 per cent CL), implying a limit of ∑m_ν < 0.51 eV. We find no signature of a deviation from a cosmological constant from the combination of all data sets, with a constraint of w_DE = −1.033 ± 0.073 when this parameter is assumed time-independent, and no evidence of a departure from this value when it is allowed to evolve as w_DE(a) = w₀ + w_a(1 − a). The achieved accuracy on our cosmological constraints is a clear demonstration of the constraining power of current cosmological observations.