Using the Sunyaev-Zel ’ dovich Effect to Probe the Gas in Clusters

The thermal Sunyaev-Zel’dovich effect is an important prob e f clusters of galaxies, and has the attractive property of being proportional to the the rmal energy content of the intracluster medium. With the assistance of X-ray data, the ef f ct can be used to measure the number of hot electrons in clusters, and thus measure clu ster baryon contents. Cluster absolute distances and other structural parameters can als o be measured by combining thermal Sunyaev-Zel’dovich, X-ray, and other data. This review presents an introduction to the effect, shows some representative results, and sketches im minent developments.