Understanding the Kiloparsec-Scale Structure of M87

Abstract

Motivated by the determination of proper motions in the M87 jet by Biretta, Zhou, & Owen, we have investigated the relationship between the dynamics of the jet in M87 and the kiloparsec-scale radio and optical structure. Our results show that relativistic effects play an important role in the appearance of shocks in relativistic jets. We argue that knot A in the M87 jet, which appears to be almost transverse to the flow, is in fact a highly oblique shock, and that the direction of its normal with respect to the flow is within about 10^deg^ of the Mach angle (the angle beyond which no shock is possible). A modest pressure jump