Effect of rotation and self-gravity on the propagation of MHD waves

Magnetohydrodynamics waves and instabilities in rotating, self-gravitating, anisotropic and
collision-less plasma were investigated. The general dispersion relation was obtained using standard mode
analysis by constructing the linearized set of equations. The wave mode solutions and stability properties of
the dispersion relations are discussed in the propagations transverse and parallel to the magnetic field. These
special cases are discussed considering the axis of rotation to be in transverse and along the magnetic field. In
the case of propagation transverse to the magnetic field with axis of rotation parallel to the magnetic field, we
derived the dispersion relation modified by rotation and self-gravitation. In the case of propagation parallel to
the magnetic field with axis of rotation perpendicular to the magnetic field, we obtained two separate modes
affected by rotation and self-gravitation. This indicates that the Slow mode and fire hose instability are not
affected by rotation. Numerical analysis was performed for oblique propagation to show the effect of rotation
and self-gravitation. It is found that rotation has an effect of reducing the value of the phase speeds on the fast
and Alfven wave modes, but self-gravitation affect only on the Slow modes, thereby reducing the phase speed
compare to the ideal magneto hydrodynamic (MHD) case.
Keywords. Rotation—self-gravity—MHD—instability.