LINEAR HYDROMAGNETIC-WAVES IN AN ULTRARELATIVISTIC, COLLISIONLESS PLASMA WITH A PRESSURE ANISOTROPY

Magnetohydrodynamic (MHD) waves in a strongly magnetized collisionless plasma are considered. Consideration is carried on for the plasma wit h an anisotropic pressure tenser. We have derived a closed set of MHD equations describing linear hydromagnetic waves, and found the corresp onding dispersion relation. We found the general solution of the dispe rsion equation, and considered various special cases corresponding to various standard types of MHD waves and the firehouse instability. Alt ernative solutions are found by means of the equations of state derive d earlier for a medium with such properties and an ultrarelativistic t emperature in Tsikarishvili et al. [Phys. Rev. A 46, 1078 (1992)].