Axisymmetric force-free magnetosphere of a pulsar. II. Transition from the self-consistent two-fluid model

TL;DR

This paper presents a self-consistent two-fluid model of a pulsar magnetosphere, revealing realistic particle distributions and velocities that differ from traditional models, with implications for understanding pulsar radiation and instabilities.

Contribution

It introduces a novel two-fluid approach accounting for particle velocity shifts and electric fields, enhancing the physical realism of pulsar magnetosphere models.

Findings

Particles follow slightly curved trajectories with distinct velocities.

Velocity shift suggests the presence of two-stream instability.

Model links pulsar radio and high-energy emission mechanisms.

Abstract

The self-consistent two-fluid model of the pulsar magnetosphere is considered. We concentrate on the case of vanishingly small inertia of the particles. Our approach allows to obtain the realistic particle distributions sustaining the force-free magnetic field configuration of a monopolar structure. The result differs substantially from the customary picture of the radial speed-of-light motion of massless particles. In our case, the electron and positron constituents follow slightly curved trajectories and are characterized by definite number densities and distinct velocities. The velocity shift is determined by the first-order longitudinal electric field, which appears the necessary ingredient of the self-consistent two-fluid model and implies the parallel conductivity of the order of the inverse particle mass. Our model is believed to be a proper context to describe radiation processes in the pulsar magnetosphere, including both the radio and high-energy emissions. The velocity shift is suggestive of the two-stream instability which may underlie the pulsar radio emission mechanism. The differential rotation of the particle flow may cause the diochotron instability expected to be responsible for the radio subpulse phenomenon. The connection between the radio and high-energy emissions of pulsars is predicted as well.