Obliquely rotating pulsars: screening of the inductive electric field

TL;DR

This paper investigates the role of the inductive electric field in pulsar magnetospheres, showing it cannot be fully screened, which affects pulsar rotation, subpulse drifting, and gamma-ray emission.

Contribution

It introduces the concept that the inductive electric field in pulsars is only partially screened, challenging existing models and explaining phenomena like subpulse drifting and gamma-ray emission.

Findings

Perpendicular inductive field cannot be screened in pulsar magnetospheres.

Screening of the parallel component can be effective but incomplete.

Incomplete screening leads to non-corotation and particle acceleration.

Abstract

Pulsar electrodynamics has been built up by taking ingredients from two models, the vacuum-dipole model, which ignores the magnetosphere but includes the inductive electric field due to the obliquely rotating magnetic dipole, and the corotating-magnetosphere model, which neglects the vacuum inductive electric field and assumes a corotating magnetosphere. We argue that the inductive field can be neglected only if it is screened by a current, ${\bi J}_{\rm sc}$, which we calculate for a rigidly rotating magnetosphere. Screening of the parallel component of the inductive field can be effective, but the perpendicular component cannot be screened in a pulsar magnetosphere. The incompletely screened inductive electric field has not been included in any model for a pulsar magnetosphere, and taking it into account has important implications. One effect is that it implies that the magnetosphere cannot be corotating, and we suggest that drift relative to corotation offers a natural explanation for the drifting of subpulses. A second effect is that this screening of the parallel inductive electric field must break down in the outer magnetosphere, and this offers a natural explanation for the acceleration of the electrons that produce pulsed gamma-ray emission.