ASTRONOMY COLLOQUIUM<br>Building the Strongest Gravitational Lenses in the Universe

Galaxy clusters that act as strong gravitational lenses are among the rarest objects in the Universe, so that a small fraction of the total galaxy cluster population dominates the global cluster-scale strong lensing cross section. Simulations point toward a host of astrophysical biases that could cause galaxy clusters selected by the presence of giant arcs to systematical differ from clusters selected on the other bases, such as observable mass proxies. I will present results from several recent and forthcoming papers with empirical evidence for/against several specific astrophysical biases in a strong lensing selected sample of galaxy clusters. Specifically, I will discuss new observational constraints on the roles played by baryonic condensation, line of sight structure, mergers, and orientation bias in strong lensing selected galaxy clusters.

Colloquia are generally preceded by tea and cookies at 3:30 in the Owl room (Dennison 845). For more information, please contact astro.colloquia@umich.edu.