Normalized response function ﹩{\bar{F}}_{{\ell },m,k}﹩ plotted against stellar rotation frequency f _rot for the {ℓ, m, k} = {2, −2, 50} partial tide of the KOI-54 primary model. The real (imaginary) part of the function is shown in the upper (lower) panel, and separate curves are plotted for the DS and MD approaches. Peaks are labeled by the resonant mode's classification within the Eckart–Osaki–Scuflaire scheme. The upper axis scale shows the tidal forcing angular frequency σ _m,k (Equation (7)).