The Evolution, Destruction, and Gravitational-wave Production of Star Clusters in a Milky-Way-mass Galaxy

Even before the first detection of gravitational waves, the dynamical processes that form binary black holes in dense star clusters were well understood. But after several years, we have reached the point that—given a set of initial conditions and stellar evolution prescriptions—the production of binary black holes in globular clusters is largely a solved problem. But what can this theoretical framework tell us about the formation of globular clusters? And what do their gravitational waves tell us about clusters as tracers of galaxy formation across cosmic time? In this talk, I will describe a new project to create star-by-star N-body models of the entire star cluster system for a Milky Way-mass galaxy. Taking our initial conditions and environmental effects directly from an MHD simulation of an L* galaxy, we can largely reproduce the masses and structural parameters of the massive clusters in the Milky Way. In this galaxy, only a handful of clusters are responsible for the majority of binary black hole production. These clusters produce large numbers of hierarchical and eccentric black hole mergers, as well as runaway stellar mergers (the potential progenitors of intermediate mass black holes), providing a direct link between the study of cluster formation, galaxy assembly, and gravitational-wave astronomy.