Dynamical friction from linear perturbation theory using the finite-time approach (solid lines) and the steady-state approach (dotted lines) as a function of V. As time passes, the finite-time result, Eq. (69), approaches the steady-state result, Eq. (58). In the zero-temperature limit, we have T = 0, while in the normal fluid case we have ρ_s = 0. (a) t = 0.1R_max/V. (b) t = R_max/V. (c) t = 10R_max/V.