Black hole discs in dense stellar systems

The recent discovery of gravitational waves opened new horizons for understanding the Universe. The measurements have unveiled an abundant population of stellar mass black hole mergers. The great challenge is to understand the possible astrophysical mechanisms that may lead to mergers. The existing theoretical models of their astrophysical origin are currently either highly incomplete or in tension with data (Barack+ 2019).

An interesting possibility is that the observed black hole mergers are generated in dense stellar systems such as globular clusters or galactic nuclei harboring a supermassive black hole with or without a gaseous accretion disk. In these systems, stellar mass black holes sink to the center of the cluster and undergo frequent dynamical encounters, forming binaries, which may eventually merge and produce gravitational wave emission.

In this project, the student will work with Prof. Bence Kocsis to build a comprehensive dynamical model of dense stellar systems with a population of stellar mass black holes. The black holes are expected to settle to a flattened disk-like structure which gets twisted and warped due to the fluctuating anisotropy of the otherwise spherical surrounding star cluster. We will use a combination of analytic and numerical methods including statistical mechanics, kinetic theory, and N-body simulations to determine if such subsystems may be long-lived, how it affects the evolution of the cluster, study the formation and evolution of binaries, and examine the implications for electromagnetic and gravitational wave observatories.