Growing electrostatic modes in the isothermal pair plasma of the pulsar magnetosphere

2017

J Astrophys Astron

The magnetospheres around neutron stars should be very particular because of their strong magnetic field and rapid rotation. A study of the pulsar magnetospheres is of crucial importance since it is the key issue to understand how energy outflow to the exterior is produced. In this paper, we discuss magnetohydrodynamic processes in the pulsar magnetosphere. We consider in detail the properties of magnetohydrodynamic waves that can exist in the magnetosphere and their instabilities. These instabilities lead to formation of magnetic structures and can be responsible for a short-term variability of the pulsar emission.

“…(17)- (22) to Eqs. (26) and (30) were made by taking into account terms of the two lowest orders in λ/L. The third term on the r.h.s.…”

Section: Equations For Mhd Waves In Pulsar Plasmamentioning

confidence: 99%

Magnetorotational and Tayler Instabilities in the Pulsar Magnetosphere

2017

J Astrophys Astron

“…The role of a diocotron instability in causing drifting sub-pulses in radio pulsar emission has been considered by Fung et al (2006). Note that the diocotron modes should be substantially suppressed in a neighbourhood of the light cylinder where relativistic effects become important (Petri 2007). The non-axisymmetric diocotron instability has been observed in 3D numerical modelling of the pulsar magnetosphere by Spitkovski & Arons (2002).…”

Section: Introductionmentioning

confidence: 99%

“…In all these cases, the plasma was assumed to be one-dimensional which is justified for plasma in a strong magnetic field. The electrostatic oscillations with a low frequency have been studied recently by Mofiz et al (2011), who found that the thermal and magnetic pressures can generate oscillations that propagate in the azimuthal direction near the equator.…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic waves in the pulsar magnetosphere

2011

A&A

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.

“…They also may affect the radiation but, perhaps, idealised quasi-static magnetospheric models cannot be valid in the presence of physical instabilities. For example, the electrostatic oscillations with a low frequency have been considered recently by Mofiz et al (2011), who found that the thermal and magnetic pressures can generate oscillations that propagate near the equator. These low-frequency electromagnetic waves are of central importance for understanding the underlying processes in the formation of the radio spectrum (see, e.g., Melrose 1996 and reference therein).…”

Section: Introductionmentioning

confidence: 99%

Force-free pulsar magnetosphere: instability and generation of magnetohydrodynamic waves

2012

A&A

Context. Magnetohydrodynamic (MHD) instabilities can play an important role in the structure and dynamics of the pulsar magnetosphere. Aims. We consider the instability caused by differential rotation that is suggested by many theoretical models. Methods. Stability is considered by means of a linear analysis within the frame of the force-free MHD. Results. We argue that differentially rotating magnetospheres are unstable for any particular geometry of the magnetic field and rotation law. The characteristic growth time of instability is of the order of the rotation period. The instability can lead to fluctuations of the emission and enhancement of diffusion in the magnetosphere.