Abstract
Transonic (withMach numberMs 1) motion of a pulsar relative to the external medium can
help its compact pulsar wind nebula develop a double-torus X-ray morphology. The double-torus structure
can reverberate as a whole under the dynamic pressure of the external flow. For a flow aligned with the
symmetry axis of the nebula, the response of the double-torus is uniform in azimuth. For a misaligned
flow, the leeward sides of the tori respond with some delay relative to their windward sides. The delay can
cause a curious swaying in the short midsection of the leeward jet of the compact X-ray nebula. Within the
framework of the relativisticmagnetohydrodynamical model of a pulsar wind nebula we study the dynamics
of the nebular outflows contributing to the swaying of the jet. When applied to the Vela X-ray nebula, the
model allows us to naturally relate two distinct phenomena, the swaying of the bright midsection of the Vela
lee jet and the reverberation of its double-torus.