Relative orientation of the spin vectors of neighboring halos. Only close halo pairs (i.e., CHs separated from their NN1 by 1 < R_isol/r_vir < 4) are considered for this figure. Upper panel: cosine of the mean angle (cos ⟨θ⟩) between the spin vectors of CHs and their NN1 in bins of R_isol2/r_vir. Lower panel: frequency distribution of cos θ for close halo pairs where the CHs are separated from their NN2 by 1 < R_isol2/r_vir < 4 (red) and 20 < R_isol2/r_vir < 63 (blue).