Inverse of the evolution time scale defined according to Eq. (23), as a function of the dimensionless softening length Δ_s/H. It is expressed in units of , where P₀ is the initial orbital period of the perturber. The dashed line is calculated after adopting Eq. (22), with only the contribution with m = 1 included. The solid line is calculated including contributions from all m ≤ 100. The circles indicate the results of numerical simulations.