Numerical studies of compact object binaries

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Gravitational waves are ripples in space and time which carry information to us about the most violent events in the universe: Collisions of black holes or neutron stars, supernovae and the big bang itself. During the last decade gravitational wave detectors have been built, most notably the U.S. Advanced Laser Interferometer Gravitational Wave Observatory (LIGO). As early as 2015 these detectors plan to begin searches for gravitational waves. The first GW discovery will be a watershed event, similar to the recent discovery of the Higgs boson. Less dramatic, but arguably even more important will be the subsequent stream of further GW observations, which will yield far-reaching insights into our Universe: Are the observed compact object mergers consistent with general relativity? How do massive stars die, and what compact objects do they leave behind? How does matter behave at supernuclear densities? How do black holes and Neutron stars interact near the centres of galaxies and in globular clusters? This revolution requires precise knowledge of the expected gravitational waves, which can only be obtained from supercomputer calculations. Knowing the shape of the expected waves allows to find weaker waves, increasing the number of gravitational waves that will be observed. Knowledge of the waveform is also required to determine the precise information about the origin of the wave: for instance, the masses and rotation rates of black holes and neutron stars, their location in the universe. Prof. Pfeiffer and his research group at CITA are world-leaders in computer simulations of colliding black holes and neutron stars, and in applying their results to gravitational wave astrophysics. With collaborators in the U.S. they have developed an outstanding computer code to simulate colliding compact objects, and have performed the most exhaustive study of colliding black holes. Prof. Pfeiffer’s group also participates in the LIGO Scientific Collaboration where it leads the development of low-latency search pipelines that can decide within minutes whether gravitational waves have passed through the telescopes. This proposal seeks funding to continue this research group to ensure LIGO will discover gravitational waves as quickly as possible, will be as sensitive as possible, and will be able to determine, with minimal bias, the properties of the objects emitting the gravitational waves. This research program spans a gamut of interwoven themes. We propose to continue what we do well: Perform binary black hole calculations and construct waveform templates based on these simulations. Given the accomplishments of Pfeiffer’s present Discovery Grant, the complete solution for quasi-circular black hole binaries appears feasible, and is our objective. We propose to expand into a survey of eccentric binary black holes. Such systems -if they exist- must form in profoundly different ways than quasi-circular binaries, and exhibit properties that are absent in quasi-circular binaries. Unfortunately, eccentric binaries are much more difficult to detect. Our simulations will aid in detecting them and –at the least– allow to quantify how sensitive LIGO actually is to such sources. We propose to intensify direct participation in LIGO’s search efforts. Finally, we propose to develop a novel, next generation relativistic astrophysics code which removes limiting restrictions of the current code. It will be the foundation for future world-class science from this research group. The variety of objectives balances immediate needs of LIGO for the first breakthrough discovery with strategic development of long-term scientific leadership. We request funding for about 60% of this research program, with the remainder anticipated from other sources.