Abstract: Blazars are among the most powerful objects in the Universe. These active galactic nuclei launch a relativistic jet that is viewed under a small inclination angle from Earth. They are characterized by a high time variability along the whole electromagnetic spectrum, reaching from scales of minutes to years. Is the time period between such blazar flares declining, then they can be caused by jet precession in an inspiraling supermassive binary black hole at the blazar center.
 
In this talk, I show how spin-orbit coupling in a supermassive binary black hole system tens to hundreds of years before its merger causes a change of jet direction and a connected jet precession motion, if at least one black hole launches a jet. If the jet of such system points at Earth, it will be seen as a blazar with decreasing flaring periodicity on scales of years. 
This jet precession model is applied to two examples: The multi-wavelength light curves of J1048+7143 and the possible neutrino cadence of TXS 0506+056. It is shown how the flaring episodes are consistent with a jet precession scenario and how predictions for future flares are made. Using this model, the time of the merger of the binary is predicted as well. This way, I model the expected gravitational wave signal of both sources and make an estimation of e.g. LISA’s detection potential for them.