Institute for Advanced Study Informal Astrophysics Seminar

In this talk, I will discuss several analytic methods for chaotic gravitational dynamics, applied to dense stellar systems. I begin with a statistical mechanics approach to the chaotic four-body problem, which yields distribution functions for the velocities and orbital parameters of the products of these interactions, including the properties of dynamically-formed triple star systems. Until recently, observational constraints for the properties of binary, and particularly triple, star systems in Galactic GCs were lacking; their high densities make them notoriously difficult to access observationally. Here, we report the discovery of populations of photometric triple star candidates in 19 clusters, demonstrating that triples are ubiquitous in Galactic GCs. Triples are sensitive probes of stellar-mass black holes (BHs), which act to destroy higher-order multiples during dynamical interactions; the presence of large numbers of triple stars presented here predicts that no black holes should exist in the densest GCs. Finally, we illustrate that empirical measurements of the binary and triple fractions in star clusters are alone sufficient to constrain the initial cluster conditions.