Origin of spectral bands in the Crab pulsar radio emission

TL;DR

This paper proposes a model where the spectral bands in Crab pulsar radio emission are diffraction fringes caused by the pulsar's plasma-filled magnetosphere, enabling magnetosphere tomography and making testable predictions.

Contribution

It introduces a novel diffraction-based model explaining spectral bands in pulsar emission and allows direct plasma density profiling without prior assumptions.

Findings

Plasma density profile derived from observations.

Spectral bands explained as diffraction fringes.

Model makes testable predictions.

Abstract

The model explaining the spectral "zebra" pattern of the high-frequency interpulse (HFIP) of the Crab pulsar radio emission is proposed. The observed emission bands are diffraction fringes in the spectral domain. The pulsar's own plasma-filled magnetosphere plays a role of a frequency-dependent "diffraction screen". The observed features such as the proportional band spacing, high polarization, constant position angle, and others are explained. The model allows one to perform "tomography" of the pulsar magnetosphere. Indeed, we have obtained the plasma density profile directly from observations, without assuming a particular magnetosphere. Our model is testable and several predictions are made. The two "high-frequency components" observed at the same frequencies as the HFIP are proposed to be related to HFIP.