A recollimation shock 80 mas from the core in the jet of the radio galaxy 3C120: Observational evidence and modeling

摘要: We present Very Long Baseline Array observations of the radio galaxy 3C120 at 5, 8, 12, and 15 GHz designed to study a peculiar stationary jet feature (hereafter C80) located ~80 mas from core, which was previously shown display brightness temperature ~600 times lager than expected such distances. The high sensitivity images -- obtained between December 2009 June 2010 has revealed that C80 corresponds eastern flux density peak an arc emission A80), downstream extends large (~20 in size) bubble-like structure resembles inverted bow shock. linearly polarized closely follows total intensity A80, with electric vector position angle distributed nearly perpendicular arc-shaped structure. Despite nature C80/A80, superluminal components speeds up ~3 c have been detected its position, resembling behavior observed HST-1 complex M87. C80/A80 structure, lack motion, excess are best reproduced by model based on synchrotron conical shock cone opening \eta=10 degrees, viewing \theta=16 completely tangled upstream magnetic field, Lorentz factor \gamma=8.4. good agreement our numerical modeling leads us conclude associated recollimation de-projected distance ~190 pc nucleus.