Parameterized and Consistency Tests of Gravity with Gravitational Waves: Current and Future

TL;DR

This paper reviews theory-agnostic methods for testing general relativity with gravitational waves, highlighting current results and future prospects with upgraded detectors and multi-band observations to significantly improve bounds on alternative theories.

Contribution

It introduces and explains parameterized waveform and consistency tests of gravity using gravitational waves, and discusses their potential with future detector upgrades and multi-band observations.

Findings

Current gravitational wave events constrain alternative gravity theories.

Future detectors could improve bounds on gravity theories by many orders of magnitude.

Multi-band observations enhance the testing capabilities of gravitational wave astronomy.

Abstract

Gravitational wave observations offer unique opportunities to probe gravity in the strong and dynamical regime, which was difficult to access previously. We here review two theory-agnostic ways to carry out tests of general relativity with gravitational waves, namely (i) parameterized waveform tests and (ii) consistency tests between the inspiral and merger-ringdown portions. For each method, we explain the formalism, followed by results from existing events, and finally we discuss future prospects with upgraded detectors, including the possibility of using multi-band gravitational-wave observations with ground-based and space-borne interferometers. We show that such future observations have the potential to improve upon current bounds on theories beyond general relativity by many orders of magnitude. We conclude by listing several open questions that remain to be addressed.