Quantum gravity and gravitational-wave astronomy

TL;DR

This paper reviews how quantum gravity theories might influence gravitational-wave observations, discussing potential observable effects like stochastic backgrounds and modified GW propagation, and assesses the feasibility of testing quantum gravity through future GW data.

Contribution

It provides a comprehensive overview of quantum gravity phenomenology related to gravitational waves, highlighting both model-dependent and model-independent approaches and potential observable signatures.

Findings

Certain quantum gravity models predict detectable stochastic GW backgrounds.

Modified luminosity distances could be observed with future GW interferometers.

Testing quantum gravity with GW observations remains challenging but feasible.

Abstract

We review the present status of quantum-gravity phenomenology in relation to gravitational waves (GWs). The topic can be approached from two direction, a model-dependent one and a model-independent one. In the first case, we introduce some among the most prominent cosmological models embedded in theories of quantum gravity, while in the second case we point out certain common features one finds in quantum gravity. Three cosmological GW observables can be affected by perturbative as well as non-perturbative quantum-gravity effects: the stochastic GW background, the propagation speed of GWs and the luminosity distance of GW sources. While many quantum-gravity models do not give rise to any observable signal, some predict a blue-tilted stochastic background or a modified luminosity distance, both detectable by future GW interferometers. We conclude that it is difficult, but still possible, to test quantum gravity with GW observations.