A beaming model for the OJ287 periodic optical outbursts

An analytical model for the description of the quasi-periodic optical outbursts observed in the blazar OJ 287 is presented. The astrophysical scenario that can account for the observed double-peaked structure of the cyclic outbursts consists of a pair of supermassive black holes (BHs) in a binary system, both of them creating a jet. The two jets are bent by the interaction of their magnetized plasma with the ambient medium. The combination of this bending with a long-term precession of the jet axes gives rise to a time-dependent orientation of the emitting outflows. The quasi-periodic optical outbursts that we observe arise from the relativistic beaming effect when part of the bent jets is directed toward us. The theoretical result is a light curve that, for a given choice of the model parameters, describes very well the observational data taken over more than a century, and predicts the future behaviour. This successful agreement between model and observations may be further evidence for the presence of binary BH systems in the cores of active galactic nuclei (AGNs).