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 Ly-\alpha 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 \Omega_m = 0.303 +/- 0.040 (68 per cent confidence) for a flat \Lambda CDM model, and w = -1.06^{+0.33}_{-0.32}, \Omega_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 (\Omega_m = 0.290 +/- 0.019, H_0 = 67.5 +/- 2.8 km s^{-1} Mpc^{-1}, \sigma_8 = 0.80 +/- 0.05 for \Lambda CDM, and w = -1.14 +/- 0.19 for wCDM). The LSS data mildly prefer a lower value of H_0, and a higher value of \Omega_m, than local distance ladder and type IA supernovae (SNe) measurements, respectively. While tension in the combined CMB, SNe and distance ladder data appears to be relieved by allowing w < -1, this freedom introduces tension with the LSS \sigma_8 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.