The development of computational methods for solving Einstein's equations is motivated by the current deployment of gravitational wave detectors such as the ground-based LIGO and the future space-based LISA. To fully understand and analyze the signals and waveforms measured with such facilities it is essential that accurate, robust, and efficient computational tools be available for solving Einstein's equations over very long time scales. The research supported by this award will continue the development of the Spectral Einstein Code by the Caltech-Cornell numerical relativity collaboration. The high accuracy and efficiency of spectral methods could allow simulations over longer timescales than existing finite difference codes and could provide the additional accuracy needed for aspects of LIGO and LISA data analysis using currently available computer hardware.
This research will have a broad impact on our understanding of fundamental physics, in particular testing General Relativity for strong field situations like black holes. In addition, it will have a significant impact on the broader area of computational science. The computational techniques involved can be used to solve problems in many other areas, including fluid dynamics, meteorology, seismology, and astrophysics. Young researchers trained in these techniques are in great demand.
The primary goal of the project is the numerical solution of Einstein's equations by supercomputer simulations. In particular, the aim is to track the coalescence and merger of binary systems containing black holes and neutron stars and to calculate the gravitational waves emitted. These systems are prime targets for the NSF LIGO gravitational wave detector that is poised to directly detect gravitational waves for the first time. The research will have a broad impact on our understanding of fundamental physics. There are currently no real tests of general relativity in the strong field regime of black holes. For experiments like LIGO to confront theory with observation, one must be able to calculate what the theory predicts. For example, do the black holes that LIGO may observe have the properties predicted by Einstein’s theory? The research will also help LIGO actually detect these astrophysical events by providing theoretical signals that can be searched for in the data. Effectively, one is increasing the sensitivity of the experiment by knowing what to look for. During the grant period, the researchers made significant strides in accomplishing these goals. For example, they produced a catalog of 171 high-precision theoretical waveforms of merging binary black holes. This catalog will be used by them and other researchers to learn about such systems and to provide theoertical models that can be used in LIGO searches. They also carried out simulations of systems containing neutron stars with a much more realistic treatment of the properties of neutron stars than had been attempted before. The postdocs, graduate students and undergraduates working on this project receive cross-disciplinary training in computational modeling and various fields of physics and astronomy. These scientists will become leaders in the field or highly-skilled members of the industrial STEM work force.
