Winds,B‐Fields, and Magnetotails of Pulsars

Abstract

We investigate the emission of rotating magnetized neutron stars due to the acceleration and radiation of particles in the relativistic wind and in the magnetotail of the star. We consider that the charged particles are accelerated by driven collisionless reconnection. Outside the light cylinder, the star's rotation acts to wind up the magnetic field to form a predominantly azimuthal, slowly decreasing with distance, magnetic field of opposite polarity on either side of the equatorial plane normal to the star's rotation axis. The magnetic field annihilates across the equatorial plane, with the magnetic energy going to accelerate the charged particles to relativistic energies. For a typical supersonically moving pulsar, the star's wind extends outward to the standoff distance with the interstellar medium. At larger distances, the power output of the pulsar's wind Ėw of the electromagnetic field and relativistic particles is redirected and collimated into the magnetotail of the star. In the magnetotail it is proposed that equipartition is reached between the magnetic energy and the relativistic particle energy. For such conditions, synchrotron radiation from the magnetotails may be a significant fraction of Ėw for high-velocity pulsars. An equation is derived for the radius of the magnetotail rm(z') as a function of distance z' from the star. For large distances z', on the order of the distance traveled by the star, we argue that the magnetotail has a "trumpet" shape because of the slowing down of the magnetotail flow. We compare results with the Guitar Nebula and Mouse Nebula and conclude that the tail of the Mouse Nebula may be connected with the long magnetotail behind the pulsar. We argue that the shock waves and elongated structures may also be observed in misdirected or shutoff pulsars and may be used as a tool for finding these objects.