What we recently learnt about Crab: structure of the wind, the shock, flares and reconnection

Abstract

We can probe observationally and reproduce theoretically intricate properties of the Crab Nebula nearest to the pulsar - The Inner Knot. The tiny knot is indeed a bright spot on the surface of a quasi-stationary magnetic relativistic shock that accelerates particles. It is required that the part of the wind that produces the Inner Knot has low magnetization; thus, it is not a site of gamma-ray flares. We develop a model of particle acceleration during explosive reconnection events in relativistic highly magnetized plasma and apply the model to explain the Crab gamma-ray flares. Particles are efficiently accelerated by charge-starved DC-type electric fields during initial stages of magnetic flux merges. By implication, the magnetic reconnection is an important, and possibly dominant process of particle acceleration in high energy astrophysical sources.