High-Precision Gravitational Wave Physics from a Worldline Quantum Field theory (GraWFTy)

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. With the
presently planed 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 masses, spins and intrinsic parameters of the two compact
objects. Obtaining these waveforms requires solving the extremely difficult field equations of Einstein’s
gravity. Major obstacles are the inclusion of radiative and spin effects at high-precision, as well as
access to the strong gravity regime. 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. My goal is to extend the scope of
worldline quantum field theory to include radiative, higher spin and 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. 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. Our results will set the basis to test Einstein’s theory of gravity in extreme regions, possibly
uncovering deviations from known physics; to understand black-hole formation; and to uncover the nature
of neutron stars.