The WiggleZ Dark Energy Survey: Joint measurements of the expansion and growth history at z < 1

TL;DR

This study combines galaxy clustering measurements from the WiggleZ survey with other data to precisely map the universe's expansion rate and distance-redshift relation up to redshift 0.73, supporting the cosmological-constant dark energy model.

Contribution

It provides the first joint measurements of the distance-redshift relation and expansion rate at multiple redshifts using galaxy clustering data, improving constraints on cosmic expansion history.

Findings

Measured D_A(z) and H(z) at three redshifts with ~7% precision.

Results are consistent with a cosmological-constant dark energy model.

Expansion rate accelerates at redshift z < 0.7.

Abstract

We perform a joint determination of the distance-redshift relation and cosmic expansion rate at redshifts z = 0.44, 0.6 and 0.73 by combining measurements of the baryon acoustic peak and Alcock-Paczynski distortion from galaxy clustering in the WiggleZ Dark Energy Survey, using a large ensemble of mock catalogues to calculate the covariance between the measurements. We find that D_A(z) = (1205 +/- 114, 1380 +/- 95, 1534 +/- 107) Mpc and H(z) = (82.6 +/- 7.8, 87.9 +/- 6.1, 97.3 +/- 7.0) km/s/Mpc at these three redshifts. Further combining our results with other baryon acoustic oscillation and distant supernovae datasets, we use a Monte Carlo Markov Chain technique to determine the evolution of the Hubble parameter H(z) as a stepwise function in 9 redshift bins of width dz = 0.1, also marginalizing over the spatial curvature. Our measurements of H(z), which have precision better than 7% in most redshift bins, are consistent with the expansion history predicted by a cosmological-constant dark-energy model, in which the expansion rate accelerates at redshift z < 0.7.