Relativistic binary systems, in which two compact stars orbit each other in a very tight orbit, are among the most important sources of gravitational radiation for current laser interferometer detectors such as LIGO. The theoretical study of gravitational wave sources is crucial for the interpretation of data to be collected by the interferometers, and for the planning of future, more advanced detectors. This project consists of two closely related studies: (1) Numerical calculations of the final mergers of compact binary systems containing a black hole and a neutron star. These are to be performed using a sophisticated 3-D relativistic hydrodynamic code and as part of a new collaboratione between Northwestern and Penn State University. The new hydrodynamic calculations represent a significant improvement over previous, more approximate treatments based on Newtonian gravity. (2) Stellar dynamical simulations of black holes in dense star clusters. Frequent dynamical interactions in these systems can lead to the formation of large numbers of coalescing black hole binaries and may represent a dominant source of detectable stellar black hole mergers for gravitational wave detectors. The study of coalescing compact binaries is important in many other areas of astrophysics, such as gamma-ray bursts, and the production of heavy elements in galaxies. The stellar dynamics and relativistic hydrodynamics computer codes to be developed are general tools, which are useful for studying many other problems involving relativistic stars and fluids. This research involves the training of several undergraduate students, including students from under-represented minorities, and one graduate student. Outreach activities will take advantage of the resources of the nearby Adler Planetarium and Astronomy Museum in Chicago, allowing the results and methodology to be presented to a large and diverse public.
