Scalar tops and perturbed quadrupoles: Probing fundamental physics with spin-precessing binaries

Parity violation in the gravitational interaction has an important impact on fundamental observables and the evolution of the universe. We here investigate for the first time our ability to probe the parity violating nature of the gravitational interaction in modified theories of gravity using gravitational waves from spin-precessing binaries. Focusing on dynamical Chern-Simons gravity, we derive the spin-precession equations, calculate the gravitational waves emitted by spin-precessing, quasi-circular black hole binaries and estimate the level to which the theory could be constrained with future gravitational wave observations.