Top row: size of the gap after 2.5 Gyr of evolution as a function of the impact parameters (subhalo mass, angle θ, and amplitude of the relative velocity w). Bottom row: density contrast as a function of the same parameters. The two panels on the left show the discrete variation of the curves, varying the velocity amplitude w or collision angle θ. The two panels on the right show two sets of lines, solid for a subhalo of mass 10⁷ M_⊙ and dashed for 10⁸ M_⊙.