Cosmological constraints from baryon acoustic oscillations and clustering of large-scale structure

Abstract

We constrain cosmological parameters using combined measurements of the baryon acoustic oscillation (BAO) feature in the correlation function of galaxies and Lyα absorbers that together cover 0.1 < z < 2.4. The BAO position measurements alone - without fixing the absolute sound horizon `standard ruler' length with cosmic microwave background (CMB) data - constrain Ω_m = 0.303 ± 0.040 (68 per cent confidence) for a flat Λ cold dark matter (ΛCDM) model, and w=-1.06^{+0.33}_{-0.32}, Ω _m=0.292^{+0.045}_{-0.040} for a flat wCDM model. Adding other large-scale structure (LSS) clustering constraints - correlation function shape, the Alcock-Paczynski test and growth rate information - to the BAO considerably tightens constraints (Ω_m = 0.290 ± 0.019, H₀ = 67.5 ± 2.8 km s^-1 Mpc^-1, σ₈ = 0.80 ± 0.05 for ΛCDM, and w = -1.14 ± 0.19 for wCDM). The LSS data mildly prefer a lower value of H₀, and a higher value of Ω_m, than local distance ladder and Type IA supernovae (SNe) measurements, respectively. While tension in the combined CMB, SNe and distance ladder data appear to be relieved by allowing w < -1, this freedom introduces tension with the LSS σ₈ constraint from the growth rate of matter fluctuations. The combined constraint on w from CMB, BAO and LSS clustering for a flat wCDM model is w = -1.03 ± 0.06.