  A natural consequence of the galaxy formation paradigm is the existence of
supermassive black hole (SMBH) binaries. Gravitational perturbations from a
far-away SMBH companion can induce high orbital eccentricities on dark matter
particles orbiting the primary SMBH via the eccentric Kozai-Lidov mechanism.
This process yields an influx of dark matter particles into the primary SMBH
ergosphere, where test particles linger for long timescales. This influx
results in high self-gravitating densities, forming a dark matter clump that is
extremely close to the SMBH. In such a situation, the gravitational wave
emission between the dark matter clump and the SMBH is potentially detectable
by LISA. If dark matter self-annihilates, the high densities of the clump will
result in a unique co-detection of gravitational wave emission and high energy
electromagnetic signatures.
