Radio pulsar activity and the crustal Hall drift

Abstract

Models of pulsar radio emission that are based on an inner accelerating region require the existence of very strong and small-scale surface magnetic field structures at or near the canonical polar cap. The aim of this paper is to identify a mechanism that creates such field structures and maintains them over a pulsar's lifetime. The likely physical process that can create the required `magnetic spots' is the Hall drift occurring in the crust of a neutron star. It is demonstrated that the Hall drift can produce small-scale strong surface magnetic field anomalies (spots) on time-scales of 104 yr by means of non-linear interaction between poloidal and toroidal components of the subsurface magnetic field. These anomalies are characterized by strengths of about 1014 G and curvature radii of field lines of about 106 cm, both of which are fundamental for generation of observable radio emission.