Dispersion diagrams for electron–proton plasma (left column) and electron–positron plasma (right column) for frequency ratio ω_p/ω_c = 5 and density ratio between the hot and background plasma n_th/n_tb = 1/2 (a–b), 1/10 (c–d). The rows show the dispersion in the E_x (longitudinal waves) and E_y (transverse waves). The Bernstein (overlaid red curves), X, Z, X₂, and XZ modes are denoted together with plasma frequency ω_p (black dotted line). Analytical curves of X₂ and XZ modes are overlaid in maroon for electron–positron plasma.