We investigate the wave properties for isothermal plasma state around to the de Sitter black hole’s horizon using 3+1 split of spacetime. The corresponding Fourier analyzed perturbed perfect GRMHD equations are used to obtain the complex dispersion relations. We obtain the real values of the wave number k, from these relations, which are used to evaluate the quantities like phase and group velocities etc. These have been analyzed graphically in the neighborhood of the horizon.

• M. Khayrul Hasan(Department of Mathematics, Shahjalal University of Science and Technology) Corresponding Author
• M. Hossain Ali(Department of Applied Mathematics, University of Rajshahi)