Ab-initio pulsar magnetosphere: the role of general relativity

TL;DR

This study demonstrates that general relativistic effects, especially frame-dragging, are crucial for pair production and pulsar emission mechanisms in low-obliquity pulsar magnetospheres, contrasting flat spacetime results.

Contribution

It introduces the first general-relativistic particle-in-cell simulations showing pair cascades in aligned pulsars, highlighting the importance of spacetime curvature effects.

Findings

Frame-dragging increases local current density beyond Goldreich-Julian value.

Unscreened electric fields trigger pair cascades in relativistic simulations.

Field oscillations observed may relate to pulsar radio emission.

Abstract

It has recently been demonstrated that self-consistent particle-in-cell simulations of low-obliquity pulsar magnetospheres in flat spacetime show weak particle acceleration and no pair production near the poles. We investigate the validity of this conclusion in a more realistic spacetime geometry via general-relativistic particle-in-cell simulations of the aligned pulsar magnetospheres with pair formation. We find that the addition of frame-dragging effect makes local current density along the magnetic field larger than the Goldreich-Julian value, which leads to unscreened parallel electric fields and the ignition of a pair cascade. When pair production is active, we observe field oscillations in the open field bundle which could be related to pulsar radio emission. We conclude that general relativistic effects are essential for the existence of pulsar mechanism in low obliquity rotators.