The WiggleZ Dark Energy Survey: testing the cosmological model with baryon acoustic oscillations at z=0.6

We measure the imprint of baryon acoustic oscillations (BAOs) in the galaxy clustering pattern at the highest redshift achieved to date, z = 0.6, using the distribution of N = 132 509 emissionline galaxies in the WiggleZ Dark Energy Survey. We quantify BAOs using three statistics: the galaxy correlation function, power spectrum and the band-filtered estimator introduced by Xu et al. The results are mutually consistent, corresponding to a 4.0 per cent measurement of the cosmic distance-redshift relation at z = 0.6 [in terms of the acoustic parameter 'A(z)' introduced by Eisenstein et al., we find A(z = 0.6) = 0.452 +/- 0.018]. Both BAOs and power spectrum shape information contribute towards these constraints. The statistical significance of the detection of the acoustic peak in the correlation function, relative to a wiggle-free model, is 3.2 sigma. The ratios of our distance measurements to those obtained using BAOs in the distribution of luminous red galaxies at redshifts z = 0.2 and 0.35 are consistent with a flat Lambda cold dark matter model that also provides a good fit to the pattern of observed fluctuations in the cosmic microwave background radiation. The addition of the current WiggleZ data results in a approximate to 30 per cent improvement in the measurement accuracy of a constant equation of state, w, using BAO data alone. Based solely on geometric BAO distance ratios, accelerating expansion (w < -1/3) is required with a probability of 99.8 per cent, providing a consistency check of conclusions based on supernovae observations. Further improvements in cosmological constraints will result when the WiggleZ survey data set is complete.