On the very high energy (>25GeV) pulsed emission in the Crab pulsar

TL;DR

This paper investigates the origin of very high energy pulsed emission from the Crab pulsar, proposing a synchrotron mechanism near the light cylinder surface as the source, based on observational and theoretical analysis.

Contribution

It introduces a model where synchrotron radiation, driven by cyclotron instability, explains the VHE emission, contrasting with inverse Compton and curvature radiation explanations.

Findings

VHE emission peaks align with optical spectrum phase

Synchrotron mechanism near light cylinder explains the emission

Inverse Compton and curvature radiation are unlikely sources

Abstract

We have examined the recently detected very high energy (VHE) pulsed radiation from the Crab pulsar. According to the observational evidence, the observed emission (>25GeV) peaks at the same phase with the optical spectrum. Considering the cyclotron instability, we show that the pitch angle becomes non-vanishing leading to the efficient synchrotron mechanism near the light cylinder surface. The corresponding spectral index of the emission equals -1/2. By studying the inverse Compton scattering and the curvature radiation, it is argued that the aforementioned mechanisms do not contribute to the VHE radiation detected by MAGIC.