On generation of Crab giant pulses

TL;DR

This paper proposes a model where Crab giant pulses are generated near the light cylinder through anomalous cyclotron resonance, producing narrow emission bands at low frequencies, requiring high plasma densities and energetic particles from magnetic reconnection.

Contribution

It introduces a novel mechanism for Crab giant pulse generation involving anomalous cyclotron resonance on closed magnetic field lines near the light cylinder, matching observed spectral structures.

Findings

Emission bands fit observed spectral structures.

High plasma density needed, about 3×10^5 times the Goldreich-Julian density.

Energetic particles with Lorentz factors around 7×10^7 are involved.

Abstract

We propose that Crab giant pulses are generated on closed magnetic field lines near the light cylinder via anomalous cyclotron resonance on the ordinary mode. Waves are generated in a set of fine, unequally spaced, narrow emission bands at frequencies much lower than a local cyclotron frequency. Location of emission bands is fitted to spectral structures seen by Eilek et al. (2006). To reproduce the data, the required density of plasma in the giant pulses emission region is much higher, by a factor $\sim 3 \times 10^5$, than the minimal Goldreich-Julian density. Emission is generated by a population of highly energetic particles with radiation-limited Lorentz factors $\gamma \sim 7 \times 10^7$, produced during occasional reconnection close to the Y point, where the last closed field lines approach the light cylinder.