RCSLenS: Testing gravitational physics through the cross-correlation of weak lensing and large-scale structure

TL;DR

This paper tests gravitational physics by comparing galaxy motions and light deflection using combined large-scale survey data, confirming consistency with General Relativity at multiple redshifts.

Contribution

It introduces a new consistency check for gravitational physics using combined redshift-space distortion and galaxy-galaxy lensing data from multiple surveys.

Findings

Measured E_G at z=0.32 and z=0.57, consistent with GR predictions.

First high-redshift measurement of the gravitational slip statistic.

Demonstrates the potential of combined survey data for cosmological tests.

Abstract

The unknown nature of dark energy motivates continued cosmological tests of large-scale gravitational physics. We present a new consistency check based on the relative amplitude of non-relativistic galaxy peculiar motions, measured via redshift-space distortion, and the relativistic deflection of light by those same galaxies traced by galaxy-galaxy lensing. We take advantage of the latest generation of deep, overlapping imaging and spectroscopic datasets, combining the Red Cluster Sequence Lensing Survey (RCSLenS), the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), the WiggleZ Dark Energy Survey and the Baryon Oscillation Spectroscopic Survey (BOSS). We quantify the results using the "gravitational slip" statistic E_G, which we estimate as 0.48 +/- 0.10 at z=0.32 and 0.30 +/- 0.07 at z=0.57, the latter constituting the highest redshift at which this quantity has been determined. These measurements are consistent with the predictions of General Relativity, for a perturbed Friedmann-Robertson-Walker metric in a Universe dominated by a cosmological constant, which are E_G = 0.41 and 0.36 at these respective redshifts. The combination of redshift-space distortion and gravitational lensing data from current and future galaxy surveys will offer increasingly stringent tests of fundamental cosmology.