Supporting Cluster Cosmology from Dark Energy Survey and the Large Synoptic Survey Telescope

Significant international investment over the last decade has resulted in new cluster surveys that can deliver precise measurements of key cosmological parameters. However, are those measurements accurate? Recent results from clusters detected by the Dark Energy Survey (DES) are in significant tension with those from other cosmological probes. This tension is most likely due to hitherto uncorrected systematic effects in the analysis. In this thesis project, we will address the question of whether clusters can be trusted as credible probes of the late time acceleration of the Universe. The project will focus on the analysis of X-ray observations from the XMM-Newton and eROSITA space telescopes and optical/near-IR observations from the Dark Energy Survey and the Large Synoptic Survey Telescope. Specific goals include the quantification of the evolution in the intrinsic scatter between galaxy-richness and halo-mass.