Fig. 5. Perpendicular velocity-space signatures of ion cyclotron damping.

From the MMS measurements, the perpendicular velocity-space signatures (a) $C_{E_{\perp 1}}\left(v_{\perp 1},v_{\perp 2};\tau \right)$ and (b) $C_{E_{\perp 2}}\left(v_{\perp 1},v_{\perp 2};\tau \right)$ over correlation interval τ = 77 s. Analytical model prediction using the eigenfunction solutions of the Vlasov–Maxwell dispersion relation of the perpendicular velocity-space signatures of ion cyclotron damping, (c) $C_{E_{\perp 1}}\left(v_{\perp 1},v_{\perp 2}\right)$ and (d) $C_{E_{\perp 2}}\left(v_{\perp 1},v_{\perp 2}\right)$ averaged over one wave period, showing a qualitatively similar pattern as the MMS measurements. Source data are provided as a Source Data file.