The WiggleZ Dark Energy Survey: constraining galaxy bias and cosmic growth with 3-point correlation functions

TL;DR

This paper measures the three-point correlation function of galaxies in the WiggleZ survey across different epochs to constrain galaxy bias and the growth of cosmic structure, providing new tests of the LCDM model.

Contribution

It presents the first measurements of the 3PCF at multiple redshifts in the WiggleZ survey and uses these to constrain galaxy bias and sigma_8(z), testing cosmological models.

Findings

3PCF measured at three redshifts (z=0.35, 0.55, 0.68)

Constraints on sigma_8(z) with 10-20% accuracy

Results consistent with LCDM predictions

Abstract

Higher-order statistics are a useful and complementary tool for measuring the clustering of galaxies, containing information on the non-gaussian evolution and morphology of large-scale structure in the Universe. In this work we present measurements of the three-point correlation function (3PCF) for 187,000 galaxies in the WiggleZ spectroscopic galaxy survey. We explore the WiggleZ 3PCF scale and shape dependence at three different epochs z=0.35, 0.55 and 0.68, the highest redshifts where these measurements have been made to date. Using N-body simulations to predict the clustering of dark matter, we constrain the linear and non-linear bias parameters of WiggleZ galaxies with respect to dark matter, and marginalise over them to obtain constraints on sigma_8(z), the variance of perturbations on a scale of 8 Mpc/h and its evolution with redshift. These measurements of sigma_8(z), which have 10-20% accuracies, are consistent with the predictions of the LCDM concordance cosmology and test this model in a new way.