Streaming instabilities in relativistic magnetoplasmas

Stability of superluminous and subluminous waves propagating transverse to the direction of the external uniform magnetic field is investigated in streaming relativistic homogeneous plasmas. In the relativistic regime for ΩΩ≫ck, the superlum inous waves are dynamically unstable for all streaming velocities U, which are smaller than U_c, or for magnetic fields Ω, which are greater than Ω_c, but for the waves with frequencies ω≪Ω ($\Omega \gg ck$), there exists a minimum streaming velocity above which the system is unstable. In the nonrelativistic regime the system is unstable if streaming is much larger than the thermal velocity but otherwise stable. The unstable region is bounded by Ω_min and Ω_max; Ω_min being $k{v}_t$ ($v_t$ being the electron thermal velocity) and Ω_max being kU.