Dense Star Clusters as LIGO Source Factories

Fred Rasio (Northwestern University) // September 26, 2016


Abstract: Theoretical predictions for compact binary mergers from field populations of binary stars are extremely sensitive to the assumptions of stellar evolution, leading, for example, to predicted merger rates for binary black holes that span several orders of magnitude. But in dense stellar environments such as globular clusters, binary black holes form by well-understood gravitational interactions. In this talk I will present an overview of recent theoretical work on the dynamical formation of black hole binaries based on realistic N-body simulations of globular clusters. By calibrating theoretical models against observed Milky Way and extragalactic globular clusters, we find that the mergers of dynamically formed binaries could eventually be detected by Advanced LIGO at a rate of ~ 100 per year, potentially dominating the overall detection rate of gravitational wave sources. Dynamical processes in globular clusters can also form very naturally the more massive black hole binaries like the one that produced GW150914, the first merger signal detected by LIGO a year ago.

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