The X-ray jet in the Crab nebula: Radical implications for pulsar theory?

The recent Chandra image of the Crab nebula shows a striking, axisymmetric polar jet. It is shown that jets are formed in axisymmetric, magnetized pul sar winds and that the jet luminosity scales relative to the total as (y(0) sigma (eq))(-4/3), where sigma (eq) is the ratio of Poynting flux to parti cle kinetic energy output at the equator at the base of the flow and y(0) i s the initial Lorentz factor of the flow. The results are applied to the im age of the Crab nebula, and the limit is set for the Crab pulsar of sigma ( eq) less than or equal to 10(2). It is argued that conventional pulsar theo ry needs to be reexamined in light of these limits.