  Recently, we proposed an enhancement of the Regge-Wheeler-Zerilli formalism
for first-order perturbations about a Schwarzschild background that includes
first-order corrections due to the background black-hole spin. Using this
formalism, we investigate gravitational wave recoil effects from a spinning
black-hole binary system analytically. This allows us to better understand the
origin of the large recoils observed in full numerical simulation of spinning
black hole binaries.

General Relativity and Quantum Cosmology