Magnetohydrodynamic wave modes in relativistic anisotropic quantum plasma

Abstract

This paper presents an overview of waves and instabilities in relativistic degenerate plasma using magnetohydrodynamic double polytropic laws. The model equations are closed by the double polytropic laws. The general dispersion relation has been derived using the normal mode analysis, which consists of two interesting modes, i.e., shear Alfvén mode and modified magnetosonic modes (both slow and fast). The shear Alfvén mode is significantly modified by anisotropic pressure and relativistic effects and remains unaffected from quantum effects. The shear Alfvén mode develops the firehose instability, which is free from the relativistic factor. The obtained slow and fast magnetosonic modes are further discussed in parallel, perpendicular, and oblique modes of propagation. The Alfvén and sound waves propagate in parallel mode, while only the magnetosonic mode propagates in perpendicular mode. The sound wave and magnetosonic wave modes are found to be modified by relativistic and quantum effects. The oblique wave propagation provides fast and slow modes, which propagate with the combined force of anisotropic pressure, Bohm force, magnetic field, and exchange potential. The applicability of the results obtained from the dispersion relation in the relativistic degenerate anisotropic magnetohydrodynamic model can be to the pulsar magnetosphere environment.