Problems in Gravitation

The main emphasis of the Center for Relativity is on astrophysical applications of general relativity, using computers to simulate binary black holes and other relativistic objects. Professor Matzner's research concerns simulation of the interactions of astrophysical black holes. He and his group model the behavior of the gravitational field in such encounters. They have very good evidence that black hole interactions would generate very strong gravitational radiation, and that these events would be the strongest signals observable by the current generation of gravitational wave detectors.

The work involves very large domain computation, so they have developed mesh-refined, and continuously distorted grid coordinates; both of these allow more distant regions of the domain to be modeled more economically. Singularities at the centers of black holes are excised from the computational domain. The excision surface is roughly spherical, and they overlap the spherical domains close to the black holes with Cartesian coordinates further away. They have produced long-term simulations of moving black holes as they cross a (moderate-sized) computational grid. The next steps, definitely nontrivial, will evolve binary black holes and will attempt to extract predictions of the gravitational radiation produced in the interaction.

The group hopes to produce realistic dynamics of black hole interactions and realistic determinations of the expected gravitational radiation. This is expected to have dramatic influence on both the design and data reduction from gravitational radiation detectors. Current ground-based detectors include the NSF-funded LIGO (located at two sites: Livingstone, Louisiana, and Hanford, Washington, GEO 600 (Hanover Germany), Virgo (Pisa, Italy), and TAMA (near Tokyo). A space-based detector called LISA is scheduled for launch in 2012.