Testing gravity using galaxy-galaxy lensing and clustering amplitudes in KiDS-1000, BOSS and 2dFLenS

TL;DR

This study tests general relativity on cosmological scales by comparing galaxy-galaxy lensing and clustering amplitudes using KiDS-1000, BOSS, and 2dFLenS data, finding results consistent with Einstein's theory.

Contribution

It provides the most precise amplitude-ratio test of gravity to date, using combined weak lensing and spectroscopic data across multiple redshift bins.

Findings

Results are consistent with general relativity predictions.

Measured E_G statistic with 15-20% errors across redshift bins.

Robustness confirmed against various analysis choices.

Abstract

The physics of gravity on cosmological scales affects both the rate of assembly of large-scale structure, and the gravitational lensing of background light through this cosmic web. By comparing the amplitude of these different observational signatures, we can construct tests that can distinguish general relativity from its potential modifications. We used the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys BOSS and 2dFLenS, to perform the most precise existing amplitude-ratio test. We measured the associated E_G statistic with 15-20% errors, in five dz = 0.1 tomographic redshift bins in the range 0.2 < z < 0.7, on projected scales up to 100 Mpc/h. The scale-independence and redshift-dependence of these measurements are consistent with the theoretical expectation of general relativity in a Universe with matter density Omega_m = 0.27 +/- 0.04. We demonstrate that our results are robust against different analysis choices, including schemes for correcting the effects of source photometric redshift errors, and compare the performance of angular and projected galaxy-galaxy lensing statistics.