Kinematics and flux evolution of superluminal components in QSO B1308+326

Abstract

Search for Doppler-boosting effect in flux evolution of superluminal components in blazars has been an important subject, which can help clarify their kinematic and emission properties. The kinematics and flux evolution observed at 15GHz for the three superluminal components (knot-c, -i and -k) in QSO B1308+326 (z=0.997) were investigated in detail. It is shown that the precessing jet nozzle model previously proposed by Qian et al. (1991, 2014, 2017, 2022a, 2022b) can be used to fully simulate their kinematics on pc-scales with a nozzle precession period of 16.9 yr. With the acceleration/deceleration in their motion found in the model-simulation of their kinematics we can derive their bulk Lorentz factor and Doppler factor as function of time and predict their Doppler-boosting effect. Interestingly, the flux evolution of the three superluminal components can be well interpreted in terms of their Doppler-boosting effect. The full explanation of both their kinematic behavior and flux evolution validates our precessing nozzle model and confirms that superluminal components are physical entities moving relativistically toward us at small viewing angles.