Using galaxy clusters as a dark energy probe (Chris Lidman, ESO-Chile)

Galaxy clusters are the most massive virialised structures in the Universe. Their number density depends on both the geometry of the Universe and the rate at which structure grows. Galaxy clusters are also rich in relatively dust-free, early-type galaxies, which are known to host only Type Ia supernovae.  So there is the potential to use clusters to provide relatively large numbers of very distant Type Ia supernova that do not require extinction corrections, which is one of the largest sources of systematic error in supernova cosmology. In this talk I will describe how clusters can be used as a dark energy probe, both through the number density of clusters and the through the Type Ia supernovae that can be found in them..