An unified model for superluminal motion and state transition on microquasars and quasars

Superluminal motion has been interpreted as relativistically moving out flow. The increasing observations of such sources provide chance to investigate their mechanism in detail. This paper proposes that superluminal motion may be jet precession induced blob motion. This model can interpret a number of observational phenomena which are not well understood under the scenario of bulk motion, such as the absence of the receding blob after the outburst and the receding blob becomes brighter than the approaching one in XTE J1550-564 . Moreover the compton scattering of photos from a warped accretion disk may form a structured jet. And the precession of the structured jet may lead to the complicated state transitions observed in microquasars like GRS 1915+105. Applying to AGNs, the model may explain the scales of length and time of the phenomena proportioning to the mass of the black hole. The new model can be tested easily on microquasars, i.e., XTE J1550-564, on which the previous receding blob should move towards the core instead of away from it after 2002, and the previous approaching blob shall disappear. %For GRS 1915+105 the vibration of the two blobs should be observed in both %the time scales of year and days.