Supermassive binary black hole mergers

Understand

When galaxies collide, dynamical friction drives their central supermassive black holes close enought to each other such that gravitational radiation becomes the leading dissipative effect.

• Gravitational radiation takes away energy, momentum and angular momentum from the compact binary, such that the black holes finally merge.
• In the process, the spin of the dominant black hole is reoriented.
• On observational level, the spins are directly related to the jets, which can be seen at radio frequencies.