The X-ray jet in the Crab Nebula: radical implications for pulsar theory?

Abstract

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 (γ_0σ_{eq})^{-4/3}, where σ_{eq} is the ratio of Poynting flux to particle kinetic energy output at the equator at the base of the flow and γ_0 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 σ_{eq} \leq 100. It is argued that conventional pulsar theory needs to be reexamined in light of these limits.