KiDS+2dFLenS+GAMA: Testing the cosmological model with the $E_{\rm G}$ statistic

TL;DR

This paper measures the $E_{G}$ statistic combining lensing, galaxy clustering, and redshift distortions to test General Relativity, revealing a preference for a lower matter density than CMB estimates.

Contribution

It provides new $E_{G}$ measurements using combined data sets and discusses the impact of matter density tension on GR tests.

Findings

$E_{G}$ measurements favor a lower matter density than CMB.

The study finds consistency with a flat $ m{ extLambda CDM}$ universe assuming GR.

Public release of the 2dFLenS dataset for community use.

Abstract

We present a new measurement of $E_{\rm G}$, which combines measurements of weak gravitational lensing, real-space galaxy clustering and redshift space distortions. This statistic was proposed as a consistency test of General Relativity (GR) that is insensitive to linear, deterministic galaxy bias and the matter clustering amplitude. We combine deep imaging data from KiDS with overlapping spectroscopy from 2dFLenS, BOSS DR12 and GAMA and find $E_{\rm G}(\overline{z}=0.267)=0.43 \pm 0.13$ (GAMA), $E_{\rm G}(\overline{z}=0.305)=0.27 \pm 0.08$ (LOWZ+2dFLOZ) and $E_{\rm G}(\overline{z}=0.554)=0.26 \pm 0.07$ (CMASS+2dFHIZ). We demonstrate that the existing tension in the value of the matter density parameter hinders the robustness of this statistic as solely a test of GR. We find that our $E_{\rm G}$ measurements, as well as existing ones in the literature, favour a lower matter density cosmology than the Cosmic Microwave Background. For a flat $\Lambda$CDM Universe and assuming GR, we find $\Omega_{\rm m}(z=0)=0.25\pm0.03$. With this paper we publicly release the 2dFLenS dataset at: \url{http://2dflens.swin.edu.au}.