Stochastic Langevin coefficient L_t → h(L_t,I_t) associated with the stochastic diffusion of a retrograde massive perturber of mass μ_t = 100μ_⋆ along the grey dashed line, I_t = const., identified in Fig. 10. The coefficient g associated with the stochastic of this massive perturber is the same as in Fig. 12. Following Eq. (72), one can note that for a massive enough perturber (or for light enough bath wires), one has h(J_t) → −(μ_t/μ_⋆)A(J_t) and g(J_t) → 0. This non-vanishing contribution is the friction force by polarisation, which drives dynamical friction.