High-Precision Gravitational Wave Physics from a Worldline Quantum Field Theory

Introduction

This project will determine the gravitational waves emitted in the encounter of two black holes or neutron stars in our universe at highest precision. The gravitational waves emerging from such violent mergers are now routinely detected at the LIGO-Virgo-KAGRA observatories since their discovery in 2016.

Future Developments

With the presently planned third generation of observatories, the experimental accuracy will dramatically increase. Theoretical predictions for the emitted waveforms at highest precision are therefore needed in order to determine the source parameters, such as:

1. Masses
2. Spins
3. Intrinsic parameters of the two compact objects

Obtaining these waveforms requires solving the extremely difficult field equations of Einstein’s gravity.

Challenges

Major obstacles include:

• The inclusion of radiative and spin effects at high precision
• Access to the strong gravity regime

Methodology

Together with my research group, I have recently devised a novel quantum formalism to attack this classical physics scenario – worldline quantum field theory – that is methodologically rooted in elementary particle physics.

It is the leading formalism to compute observables in the gravitational scattering of spinning black holes and neutron stars.

Goals

My goal is to extend the scope of worldline quantum field theory to include:

• Radiative effects
• Higher spin effects
• Tidal effects that discriminate between black holes and neutron stars

Moreover, I will uncover a hidden supersymmetry in the scattering of two spinning black holes.

Theoretical Tools

Finally, by matching to curved space-times, I will develop theoretical tools that apply to strong gravitational fields as they arise close to the merger. These are presently unreachable by analytical methods.

Expected Outcomes

Our results will set the basis to:

• Test Einstein’s theory of gravity in extreme regions, possibly uncovering deviations from known physics
• Understand black hole formation
• Uncover the nature of neutron stars