Research on Gravitational Waves and Black Hole Binaries

University Of North Carolina At Chapel Hill, Chapel Hill NC

Investigators

Abstract

Astronomical observations have shown that virtually all massive galaxies can be expected to have a supermassive black hole residing at their center. Surrounded by dense star clusters, these black holes will frequently capture stars into highly eccentric orbits. A fraction of these stars will be compact objects: stellar mass black holes or neutron stars. As these compact stars orbit, they radiate gravitational waves, causing the orbit to decay and the star to eventually be swallowed by the supermassive black hole. The emitted radiation is potentially observable in future space-based gravitational wave detectors. The theoretical work funded by this award will provide better understanding of the expected signals from highly-eccentric compact merging binaries. Detection of gravitational waves from such extreme-mass-ratio binaries will provide a unique strong-field test of gravity and a probe of the nature of black holes. This award contributes to scientific workforce development through the involvement of graduate students and the training they receive in physical modeling, mathematical analysis, and numerical and computational methods. In greater detail, the primary research efforts associated with this award are: (1) refined development of two accurate mathematical and numerical gravitational self-force methods, and the associated computer codes, that are useful for computing gravitational waves from merging compact binaries with small mass ratios and highly eccentric orbits; (2) using one such method to make highly accurate comparisons of calculated gravitational waves with the distinct and complementary post-Newtonian approach; and (3) using the second numerical self-force method to calculate the orbital decay, gravitational wave emission, and merger of eccentric binaries in the late stages of their orbital decay.