Formation of filament-like structures in the pulsar magnetosphere and the short-term variability of pulsar emission

Abstract

Magnetohydrodynamic (MHD) instabilities can play an important role in the dynamics of the pulsar magnetosphere and can be responsible for the formation of various structures. We consider the instability caused by a gradient of the magnetic pressure which can occur in a non-neutral magnetospheric plasma. We arguethat the pulsar magnetospheres are always unstable. The unstable disturbances have a form of filaments directed along the magnetic field lines with plasma motions being almost parallel (or anti-parallel) to the magnetic field. The growth rate of instability is high and can reach a fraction of $ck$, where $k$ is the wavevector of unstable disturbances. The instability can be responsible for fluctuations of plasma and the short-term variability of pulsar emission.