CFHTLenS: Testing the Laws of Gravity with Tomographic Weak Lensing and Redshift Space Distortions

TL;DR

This paper combines weak lensing and galaxy velocity data to test Einstein's gravity, finding no significant deviations from General Relativity within current measurement uncertainties.

Contribution

It provides the strongest joint constraints on metric potentials by combining cosmic shear tomography with galaxy growth measurements from multiple surveys.

Findings

No significant deviation from General Relativity detected.

Constraints on metric potential deviations are consistent with Einsteinian gravity.

Method demonstrates the power of combining lensing and redshift space distortion data.

Abstract

Dark energy may be the first sign of new fundamental physics in the Universe, taking either a physical form or revealing a correction to Einsteinian gravity. Weak gravitational lensing and galaxy peculiar velocities provide complementary probes of General Relativity, and in combination allow us to test modified theories of gravity in a unique way. We perform such an analysis by combining measurements of cosmic shear tomography from the Canada-France Hawaii Telescope Lensing Survey (CFHTLenS) with the growth of structure from the WiggleZ Dark Energy Survey and the Six-degree-Field Galaxy Survey (6dFGS), producing the strongest existing joint constraints on the metric potentials that describe general theories of gravity. For scale-independent modifications to the metric potentials which evolve linearly with the effective dark energy density, we find present-day cosmological deviations in the Newtonian potential and curvature potential from the prediction of General Relativity to be (Delta Psi)/Psi = 0.05 \pm 0.25 and (Delta Phi)/Phi = -0.05 \pm 0.3 respectively (68 per cent CL).