Session Y02: Black Holes and Gravitational Waves via Effective Field Theory Methods

Black Holes as Probes of an Effective Field Theory Extension to General Relativity

Direct observation of gravitational waves (GW) from merging black holes has opened up the possibility of exploring the theory of gravity in the strong regime at an unprecedented level. It is therefore interesting to explore which extensions to General Relativity (GR) could be detected. An Effective Field Theory (EFT) satisfying the following requirements has been recently proposed. It is testable with GW observations, it is consistent with other experiments, including short distance tests of GR, it agrees with widely accepted principles of physics, such as locality, causality and unitarity, and it does not involve new light degrees of freedom. The most general theory satisfying these requirements corresponds to adding to the GR Lagrangian operators constructed out of powers of the Riemann tensor, suppressed by a scale comparable to the curvature of the observed merging binaries. The presence of these operators modifies the metric corresponding to black hole solutions, the gravitational potential between compact objects, as well as their effective mass and current quadrupoles, ultimately correcting the waveform of the emitted GW. I will report on the status of the development of this theory and on the current constraints on its parameters as obtained from GW observations.   

Quantum Field Theory Tools for Gravitational Wave Science

Future gravitational wave detectors will map out and characterize every binary merger in the history of the universe. The possibilities for new and unexpected scientific discoveries from this wealth of data is staggering, but hinges crucially on complementary advances in our theoretical understanding of the nature of gravitational wave sources. However, the path from Einstein's equation to precision binary dynamics is notoriously difficult, and conventional methods may not scale to the demands of future detectors. I will describe our recent efforts in solving the relativistic two-body problem using modern tools from quantum field theory.