Magnetohydrodynamic waves in the pulsar magnetosphere

TL;DR

This paper investigates the properties of MHD waves in pulsar magnetospheres, deriving their dispersion relations and suggesting they could explain plasma fluctuations and emission variability.

Contribution

It provides a linear analysis of force-free MHD equations to identify and characterize specific wave modes in pulsar magnetospheres, extending standard MHD concepts.

Findings

Waves can exist in the pulsar magnetosphere under force-free conditions.

Derived dispersion relations for magnetospheric waves.

Wave periods estimated to be between 10^{-2} and 10^{-4} seconds.

Abstract

MHD waves can be responsible for plasma fluctuations and short-term variations of the pulsar emission. We consider the properties of plane and cylindrical waves that can exist in the force-free magnetosphere. Waves are considered by means of a linear analysis of the force-free MHD equations. We argue that these particular types of waves can exist in the magnetosphere of pulsars. These waves are closely related to the Alfven waves of the standard magnetohydrodynamics but are modified by the force-free condition and non-zero charge density. We derive the dispersion relation for magnetospheric waves and show that the wave periods are likely within the range $\sim 10^{-2}-10^(-4}$ s depending on the magnetospheric parameters.