Pulsar Electrodynamics: an unsolved problem

TL;DR

This paper reviews pulsar electrodynamics, focusing on the role of inductive electric fields, plasma responses, and gap formation, and discusses implications for pulsar radio emission mechanisms.

Contribution

It introduces a comprehensive self-consistent model of pulsar electrodynamics, emphasizing the importance of inductive fields, plasma response, and new gap types, advancing understanding of pulsar emission processes.

Findings

Identification of the role of inductive electric fields in pulsar magnetospheres

Proposal of a new class of gaps due to current starvation

Discussion of plasma waves and their role in radio emission

Abstract

Pulsar electrodynamics is reviewed emphasizing the role of the inductive electric field in an oblique rotator and the incomplete screening of its parallel component by charges, leaving `gaps' with $E_\parallel\ne0$. The response of the plasma leads to a self-consistent electric field that complements the inductive electric field with a potential field leading to an electric drift and a polarization current associated with the total field. The electrodynamic models determine the charge density, $\rho$, and the current density, ${\bf J}$, charge starvation refers to situations where the plasma cannot supply $\rho$, resulting in a gap and associated particle acceleration and pair creation. It is pointed out that a form of current starvation also occurs implying a new class of gaps. The properties of gaps are discussed, emphasizing that static models are unstable, the role of large-amplitude longitudinal waves, and the azimuthal dependence that arises across a gap in an oblique rotator. Wave dispersion in a pulsar plasma is reviewed briefly, emphasizing its role in radio emission. Pulsar radio emission mechanisms are reviewed, and it is suggested that the most plausible is a form of plasma emission.