Letter to the Editor

Magnetohydrodynamic waves in the pulsar magnetosphere

¹ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
e-mail: vadim.urpin@uv.es
² A.F. Ioffe Institute of Physics and Technology and Isaac Newton Institute of Chile, Branch in St. Petersburg, 194021 St. Petersburg, Russia

Received: 8 September 2011
Accepted: 7 October 2011

Abstract

Context. MHD waves can be responsible for plasma fluctuations and short-term variations of the pulsar emission.

Aims. We consider the properties of plane and cylindrical MHD waves that can exist in the force-free magnetosphere.

Methods. Waves are considered by means of a linear analysis of the force-free MHD equations.

Results. We argue that these particular types of MHD waves can exist in the magnetosphere of pulsars. These waves are closely related to the Alfvén waves of the standard magnetohydrodynamics modified by the force-free condition and non-zero charge density. We derive the dispersion equation fror magnetospheric waves and show that the wave periods are likely within the range  ~10^-2−10^-6 s depending on the magnetospheric parameters.