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M.S.E. Roberts (Eureka Scientific / McGill University / MIT), M. Lyutikov (McGill University / CITA), V.M. Kaspi, C.R. Tam (McGill University)
The supernova remnant G11.2-0.3 seems to be a textbook example of a composite supernova remnant with remarkably symmetric properties. It has a very circular X-ray and radio shell with a centrally located pulsar and wind nebula (PWN) observed in both radio and X-rays. The energy output of the pulsar has been nearly constant since its birth, probably in the historical event of 386 A.D., and hasn't moved significantly from its birth location. Despite the system's apparent simplicity, the X-ray PWN is quite different from the ``typical" bright torus of the Crab and Vela PWN. Instead, it is very narrow (jet-like) with no obvious toroidal component. We present a series of Chandra X-ray images of the nebula showing the emission is dominated by hot spots which move, brighten, and dim on timescales of a few weeks. This is reminiscent of the behavior of the faint Vela outer jet or the faint jets of the Crab nebula, but why there is no corresponding disk-type outflow is mysterious. If the observed variations are just due to modulated outflow from the pulsar, then the motion is highly superluminal. On the other hand, there appears to be evidence of preferred radii for the spots, suggesting local enhancements of the magnetic field. These are possibly related to the ion cyclotron radius or some form of standing wave within a radio emitting sheath. This may shed light on similar patterns seen in jets coming from black holes.
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The author(s) of this abstract have provided an email address for comments about the abstract: roberts@physics.mcgill.ca
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.