Model fitting of the kinematics of ten superluminal components in blazar 3C 279

• Published in: Research in astronomy and astrophysics 2013-07, Vol.13 (7), p.783-802
• Main Author: Qian, Shan-Jie
• Format: Article
• Language: English
• Subjects: Astronomy; Blazars; Blazar天体; Fittings; Helical; Kinematics; Magnetic fields; Precession; Trajectories; VLBI观测; 模型拟合; 组件; 耀变体; 超光速; 运动学
• ISSN: 1674-4527; 2397-6209
• DOI: 10.1088/1674-4527/13/7/003

The kinematics of ten superluminal components （C11-C16, C18, C20, C21 and C24） of blazar 3C 279 are studied from VLBI observations. It is shown that their initial trajectory, distance from the core and apparent speed can be well fitted by the precession model proposed by Qian. Combined with the results of the model fit for the six superluminal components （C3, C4, C7a, C8, C9 and C10） already pub-lished, the kinematics of sixteen superluminal components can now be consistently interpreted in the precession scenario with their ejectiontimes spanning more than 25 yr （or more than one precession period）. The results from model fitting show the possible existence of a common precessing trajectory for these knots within a pro- jected core distance of ～0.2-0.4 mas. In the framework of the jet-precession scenario, we can, for the first time, identify three classes of trajectories which are character-ized by their collimation parameters. These different trajectories could be related to the helical structure of magnetic fields in the jet. Through fitting the model, the bulk Lorentz factor, Doppler factor and viewing angle of these knots are derived. It is found that there is no evidence for any correlation between the bulk Lorentz factor of the components and their precession phase （or ejection time）. In a companion paper, the kinematics of another seven components （C5a, C6, C7, C17, C19, C22 and C23） have been derived from model fitting, and a binary black-hole/jet scenario was envisaged. The precession model proposed by Qian would be useful for understanding the kine- matics of superluminal components in blazar 3C 279 derived from VLBI observations, by disentangling different mechanisms and ingredients. More generally, it might also be helpful for studying the mechanism of jet swing （wobbling） in other blazars.