This award supports the development of methods of constructing initial data for black-hole/black-hole and neutron-star/black-hole binary systems that are increasingly astrophysically realistic. Effort will focus on the problem of binary systems that are in quasiequilibrium and in quasi-circular orbits. Current methods will be extensively tested for constructing equal-mass binary black hole initial data sets prior to extending these techniques to the construction of unequal-mass initial data sets. The ability to construct neutron stars will be incorporated into the initial data codes and consistent quasiequilibrium binary models containing both a neutron star and a black hole will be constructed. One goal will be to extend current initial-data techniques to allow them to compute a quasiequilibrium "conformal three-geometry".
The collision of a pair of orbiting black holes or neutron stars is a dramatic event that may soon be detected by gravitational wave observatories such as LIGO and LISA. Simulations, starting from compact binary initial data, like that constructed under this award, will provide the theoretical foundation for interpreting much of the data obtained by LIGO. The detection of black holes events with LIGO will offer the most direct evidence possible for their existence, and the observation of gravitational waves in general will open up an exciting new window for exploring the universe. This award will allow improvement of the techniques and numerical tools for constructing black-hole and neutron-star initial data and explore the space of interesting solutions. The development of these techniques and numerical codes will provide an excellent training ground for students and researchers at the undergraduate and graduate levels. The codes developed under this award will be optimized for the latest generation of supercomputers, and made available within the scientific community.