Cosmological tests using galaxy-galaxy lensing and clustering amplitudes in KiDS-1000

Wednesday May 6th 2020 @12pm, Zoom Colloquium
Prof. Chris Blake Swinburne University



The physics of gravity on cosmological scales affects both the rate of assembly of galaxy 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 use the latest weak gravitational lensing dataset from the Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy redshift surveys, to perform the most accurate existing amplitude ratio test 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.