Prospects for Cosmology with Cluster Mass Profiles

We test the precision with which weak lensing data can provide characteristic cluster mass profiles within Cold Dark Matter scenarios. Using a parallel treecode to simulate volumes as large as 500h-1 Mpc with good resolution, we generate samples of large clusters within a standard CDM model and an open CDM model with Omega_o=0.3. We mock high-quality lensing data by including realistic errors, selecting cluster samples based on velocity dispersion, and fitting profiles within a realistic range in radius. We find that a sample of ten clusters can determine logarithmic profile slopes with 1 sigma errors of about 7%. Increasing the sample size to twenty brings this error down to less than 5%, but this is still insufficient to distinguish the two models. However, measures of cluster profiles obtained with weak lensing do place strong constraints for general CDM--like models of structure formation, and we discuss the optimal strategy for obtaining data samples to use for this purpose.