Early evolution of a young AGN jet in NGC 1275: Kinematics and jet–ambient medium interactions on (sub-)parsec scales

NGC 1275, the central galaxy of the Perseus cluster, hosts a radio jet whose most recent activity began only about 20 years ago, providing a rare opportunity to investigate how an AGN jet propagates and interacts with the ambient medium on (sub-)parsec scales at an exceptionally early stage. We present a kinematic study of this young jet from its emergence in 2003 through its first two decades, based on the Very Long Baseline Array (VLBA) data at 43 GHz. We find that the C3 component, a bright feature located at the jet termination region, has maintained a nearly constant apparent velocity of 0.26c throughout the observing period. In addition, we detect the emergence of several new subcomponents from C3, each exhibiting apparent speeds higher than that of C3. Our analysis suggests that these features arise from interactions between the jet and the ambient medium, in which portions of the jet termination region fragment into subcomponents and propagate outward. These results provide direct observational evidence of jet-ambient medium interactions at a very early evolutionalry stage on (sub-)parsec scales.