Possible evidence for a supermassive binary black hole in 3C454.3

Context. The kinematic behaviors of thirteen superluminal components observed at 43 GHz in blazar 3C454.3 are investigated and model-fitted in terms of the precessing jet-nozzle scenario previously proposed.Aims. In order to search for the possible precession of jet-nozzle and periodic ejection of superluminal components in 3C454.3, the thirteen components are divided into the following two groups: group-A and group-B. Group-A consists of six components (B4, B5, K2, K3, K09, and K14) and group-B consists of seven components (B1, B2, B3, B6, K1, K10, and K16).Methods. For each component of group-A and group-B, the observed kinematic features (trajectory, core separation, coordinates, and apparent velocity versus time) were model-fitted in terms of our precessing jet-nozzle scenario, and its kinematic parameters (bulk Lorentz factor, viewing angle, apparent velocity, and Doppler factor versus time) were derived and compared with the observations.Results. It is found that the superluminal components of group-A and group-B may be regarded to be produced by a double-jet system, consisting of jet-A and jet-B which ejects the components of group-A and group-B, respectively. Both jets are likely precessing with the same period of ∼10.5 yr (5.6 yr in the source frame) with modeled time coverages of ∼2 and ∼1.5 periods, respectively. The motion of these components in the inner-jet regions (core separation ≲0.3–0.5 mas) is explained to follow a precessing common trajectory respective for jet-A and jet-B. The recurrence of the curved trajectory for the pair of knots B6 and K10 exhibits a significant clue as to periodicity.Conclusions. The analysis and explanation of the entire kinematics of the thirteen superluminal components observed in 3C454.3 in terms of our precessing jet-nozzle scenario might possibly imply that blazar 3C454.3 hosts a supermassive binary black hole, which creates two precessing relativistic jets pointing closely toward us with small angles.