Sunyaev-Zeldovich effect (SZE) surveys are now producing galaxy cluster samples of hundreds of objects that are approximately mass-limited to high redshift. I will discuss the cluster sample from ACT, focusing on the use of the sample for constraining cosmological parameters. Such constraints are ultimately limited by systematic uncertainties in the relationship between SZE signal and mass. To overcome this uncertainty we use dynamical mass measurements from cluster member galaxy velocity dispersion.
Received Mar 5, 2013