Cutoff frequency across the background condition. The white contours refer to the magnetic field lines. The vertical white dashed–dotted line refers to the slit we considered to achieve the results in Figure 6. The solid black line across the domain is the equipartition layer (c_s = v_A). The dashed and dotted lines refer to the cutoff layers where v_ac = 4 mHz and 3 mHz, respectively. We have clipped the regions within the yellow dashed rectangular box to achieve the plot on right for better visualization purposes.