Building Precise Gravitational Wave Models with Black Hole Perturbation Theory

This award will support and extend ongoing research on the dynamics of binary systems in general relativity, and into characterizing the gravitational waves that such binaries produce. The goal of this project is to improve our understanding of how black holes in binary systems interact with one another, and how their interactions affect the gravitational waves they produce. This work will thus provide a foundation for further observational probes of the dynamics of black holes and ultra-strong gravity. This award will also support “sonifications” of gravitational wave signals and visualizations of the sources that produce these waves, using audio to illustrate how gravitational waves encode source information, as well as online tools for studying the behavior of orbits of spinning black holes. The core work supported by this award will use black hole perturbation theory (BHPT), an approach that works well modeling binaries in the small mass ratio limit when a binary can be regarded as a small object orbiting a large black hole. One planned project will continue investigating the endpoint of binary black hole coalescence in this limit. Past work studying this problem for circular orbit geometries significantly clarified how the spectrum of final mode excitation depends on coalescence geometry. The team's current work examines the role eccentricity plays in this process, examining how well a system’s eccentricity as it enters the final merger can be discerned from its late gravitational-wave spectrum. Other projects include continuing investigations of gravitational waves produced by spinning bodies orbiting black holes, the continuation of work to develop surrogate binary black hole models based on the small mass-ratio limit, as well as continuing ongoing development of open-source tools for producing fast waveforms in the small mass-ratio limit. These projects grew from work that constituted major portions of the Ph.D. theses of graduate students supported by a prior NSF award. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.