The BOSS-WiggleZ overlap region II: dependence of cosmic growth on galaxy type

TL;DR

This study measures the growth rate of cosmic structures using galaxy clustering data from WiggleZ and BOSS-CMASS surveys, analyzing galaxy type dependence and testing RSD models to improve cosmological constraints.

Contribution

It provides new measurements of the growth rate from overlapping galaxy surveys, assessing galaxy type effects and model systematics with mock catalogues.

Findings

Measured $f\sigma_8$ at z=0.54 for WiggleZ and CMASS galaxies.

Combined analysis yields $f\sigma_8$ consistent with LCDM-GR.

Investigated galaxy type dependence and RSD model limitations.

Abstract

The anisotropic galaxy 2-point correlation function (2PCF) allows measurement of the growth of large-scale structures from the effect of peculiar velocities on the clustering pattern. We present new measurements of the auto- and cross- correlation function multipoles of 69,180 WiggleZ and 46,380 BOSS-CMASS galaxies sharing an overlapping volume of ~0.2 (Gpc/h)^3. Analysing the redshift-space distortions (RSD) of galaxy 2-point statistics for these two galaxy tracers, we test for systematic errors in the modelling depending on galaxy type and investigate potential improvements in cosmological constraints. We build a large number of mock galaxy catalogues to examine the limits of different RSD models in terms of fitting scales and galaxy type, and to study the covariance of the measurements when performing joint fits. For the galaxy data, fitting the monopole and quadrupole of the WiggleZ 2PCF on scales 24<s<80 Mpc/h produces a measurement of the normalised growth rate $f\sigma_8$(z=0.54)=0.409$\pm$0.059, whereas for the CMASS galaxies we found a consistent constraint of $f\sigma_8$(z=0.54)=0.466$\pm$0.074. When combining the measurements, accounting for the correlation between the two surveys, we obtain $f\sigma_8$(z=0.54)=0.413$\pm$0.054, in agreement with the LCDM-GR model of structure growth and with other survey measurements.