Title: All Mergers Great and Small

Abstract: Of the many particle properties of dark matter that remain unknown, the self-collisional cross section is one that may be possible to measure using astronomical observations, and only astronomical observations.  In this talk, I will show that the hierarchical growth of structure in the Universe can be thought of as a series of massive dark matter collider experiments.  I will show what kinds of signatures collisional dark matter leaves in these merger events, and what scale of cross section each type of system may be sensitive to.