Studies of Structure Formation and Cosmology with the South Pole Telescope

The South Pole Telescope collaboration (SPT) has carried out a deep, multi-frequency survey of the cosmic microwave background (CMB) as seen from the south geographic pole. Galaxy clusters, the most massive collapsed structures in the Universe, with masses that are ~1x10^15 solar masses, can be detected through signatures that they leave in these CMB maps. This signature, the so-called Sunyaev- Zel‘dovich Effect, allows us to use the deep CMB survey from SPT to find all galaxy clusters of a given mass, regardless of their distance (or equivalently, their redshift). We have used the SPT survey together with extensive ground based follow-up observations to identify and measure distances to the largest sample of SZE selected galaxy clusters to date. The clusters allow us to test the cosmological structure formation model, and they provide a powerful new probe of the accelerating expansion of the cosmos. Our results to date affirm the hierarchical structure formation model and, consistent with other cosmo- logical probes, point to a Universe dominated by a cosmological constant.