Inductive spikes in the Crab Nebula - a theory of gamma-ray flares

TL;DR

This paper proposes a theory that rapid gamma-ray flares in the Crab Nebula result from sudden drops in pulsar wind mass-loading, causing high-energy particles to produce beamed gamma-ray bursts.

Contribution

It introduces a novel mechanism linking pulsar wind variability to gamma-ray flares, explaining rapid emission changes and polarization in the Crab Nebula.

Findings

Flares are caused by high Lorentz factor particles from wind drops.

Emission is synchrotron radiation in the Nebula's magnetic field.

Mechanism may apply to other pulsars like J0537-6910 and B0540-69.

Abstract

We show that the mysterious, rapidly variable emission at ~400 MeV observed from the Crab Nebula by the AGILE and Fermi experiments could be the result of a sudden drop in the mass-loading of the pulsar wind. The current required to maintain wave activity in the wind is then carried by very few particles of high Lorentz factor. On impacting the Nebula, these particles produce a tightly beamed, high luminosity burst of hard gamma-rays, similar to those observed. This implies (i) the emission is synchrotron radiation in the toroidal field of the Nebula, and, therefore, linearly polarized and (ii) this mechanism potentially contributes to the gamma-ray emission from other powerful pulsars, such as the Magellanic Cloud objects J0537-6910 and B0540-69.