Unstable solutions, ω_r/|Ω_e| (left) and γ/|Ω_e| (right), with alternative peaks of FHFI and WHFI derived with DIS-K for a Maxwellian core and different halo-strahl combinations, respectively: Maxwellian–Maxwellian (blue), SKD–Maxwellian (red), Maxwellian–SKD (green), and SKD–SKD (black). The zoomed-in plot in left panel shows the change of sign and polarization corresponding to the low-wave-number peaks in the right panel. The parameters used are indicated in the legend and title.