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 pulsar 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 particle kinetic energy output at the equator at the base of the flow and y(0) is the initial Lorentz factor of the flow. The results are applied to the image 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 theory needs to be reexamined in light of these limits.