Andrew works on producing mock data for the Roman telescope's galaxy redshift survey. He has previously worked on astrophysical tests of the nature of dark matter, running cosmological simulations with different dark matter models and then comparing them with the observed Universe. The ability to map out dark matter is an important part of these comparisons, so Andrew works on gravitational lensing, where the distribution of dark matter can be inferred from the way that in which it distorts the images of background galaxies. Andrew is also interested in galaxy clustering, redshift-space distortions, galaxy clusters and strongly lensed gravitational waves.