Speaker
Joe Mohr
Description
The South Pole Telescope (SPT) is currently being used to survey the cosmic microwave background in search of galaxy clusters, the most massive collapsed structures in the Universe. A small fraction of the cosmic microwave photons that pass through these clusters scatter with the reservoir of high energy electrons produced during the cluster formation. These interactions lead to a distortion of the microwave background spectrum and leave a barely observable signature called the Sunyaev-Zel'dovich effect (SZE). With deep, high angular resolution maps from SPT, it is now possible for the first time to use the SZE to assemble large, well-defined cluster samples extending to high redshift.
SPT selection of clusters using their SZE signatures is the first, most critical step toward scientific discovery, but other important steps follow. Studies of cosmology and structure formation using these clusters require additional observations in the optical and near-infrared to define the cluster galaxy population and its redshift, in the X-ray to define the intracluster medium and estimate cluster mass and with wide field space based optical cameras to constrain the cluster masses using weak lensing.
Initial results from the first optical and X-ray followup studies are leading to an emerging understanding of the SPT cluster sample. These are very massive clusters that exhibit regularity through so-called scaling relations in their X-ray and SZE properties. Characterization of the SPT cluster population at z>1 awaits impending near-infrared observations scheduled for this fall and followup using high throughput X-ray observatories like XMM. Longer timeline studies of the SPT clusters in combination with the Dark Energy Survey multiband optical/near-infrared and the e-ROSITA X-ray survey promise exciting scientific discoveries in the years to come.