Large Angle Bending of the Light-Month Jet in Centaurus A

Abstract

An intercontinental VLBI observation of Cen A is presented. We found that the jet exhibits bending with an angle of 60° at 2 light-months from the core. Because of the large viewing angle of the jet in Cen A, this bending should be a real bend of this magnitude, rather than a projection effect. Two possible interpretations of the bending jet — jet collision with ambient matter, and a changing angle of jet ejection — have been considered and rejected. The possibility is discussed that the observed bending of Cen A is an apparent bend resulting from observing a limb-brightened jet with insufficient resolution, and compared with a numerical simulation of a jet. Another implication of the bending jet is discussed based on a similarity with two other AGNs, 3C 273 and Vir A, in which similar features have been reported on the light-months scale. The relationship between the mass and the structure scale in Vir A and Cen A is very similar. This feature in Cen A suggests that such mis-alignments on the light-month scale are common and are related to the formation mechanism of AGN jets.