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

Abstract

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 emission‐line 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 3.2σ. 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 Λ 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 ≈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.

Searching for modified gravity: scale and redshift dependent constraints from galaxy peculiar velocities

“…Following the analysis of the WiggleZ baryon acoustic oscillations (Blake et al 2011b), we estimated the = 0, 2, 4 multipole power spectra in the (9, 11, 15, 22, 1, 3)-hr survey regions in the overlapping redshift ranges 0.2 < z < 0.6, 0.4 < z < 0.8 and 0.6 < z < 1.0. We measured the spectra in 14 wavenumber bins of width ∆k = 0.02 h Mpc −1 in the range 0.02 < k < 0.3 h Mpc −1 .…”

Homogeneity and isotropy in the Two Micron All Sky Survey Photometric Redshift catalogue

“…A historically popular alternative method is to generate lognormal realizations of the galaxy density field and Poisson-sample them with galaxies (Beutler et al 2011;Blake et al 2011). The lognormal distribution has been advocated as a possible model to describe the distribution of the non-linear matter density in the Universe (Coles & Jones 1991), and, since it is based on locally transforming a Gaussian random field, it can be used to generate large numbers of fast independent realizations.…”

21 cm observation of large-scale structures atz ~ 1

“…This scale can be considered as a standard ruler with a comoving length of ∼150 Mpc, and these features have been first observed in the CMB anisotropies and are usually referred to as acoustic peaks (Mauskopf et al 2000;Larson et al 2011). The BAO modulation has been subsequently observed in the distribution of galaxies at low redshift (z < 1) in the galaxygalaxy correlation function by the SDSS (Eisenstein et al 2005;Percival et al 2007;Percival et al 2010), 2dGFRS (Cole et al 2005), as well as WiggleZ (Blake et al 2011) optical galaxy surveys.…”