The Termination Shock in a Striped Pulsar Wind

Abstract

Toroidal stripes of opposite magnetic polarity are formed in the equatorial belt of the wind emanating from an obliquely rotating pulsar magnetosphere. Such a striped wind transfers most of its spindown energy because the angular distribution of the energy flux in the pulsar wind is maximum at the equator. The alternating field annihilates either in the pulsar wind or at the termination shock so that the flow in the equatorial belt downstream of the termination shock is weakly magnetized. At high latitudes, the magnetization of the flow is higher than in the equatorial belt whereas the total energy flux is smaller. At such a distribution of the energy flux and magnetization, the downstream flow separates into an equatorial disk and a magnetically collimated polar jet. Particle acceleration at the termination shock in a striped wind is discussed. It is argued that the radio emitting electrons are accelerated by driven reconnection of the alternating field at the shock whereas the Fermi acceleration of electrons preaccelerated in the reconnection process results in a high energy tail responsible for the X- and γ-ray emission.