Three-color emission line images of Arp 220. The emission line maps are obtained integrating the continuum-subtracted data-cube around [Fe II] 1.257 μm (left), Paα (center), and H₂ 1–0 S(1) 2.122 μm (right) in the velocity ranges −400 km s⁻¹ < v < −200 km s⁻¹ (blue), −200 km s⁻¹ < v < 200 km s⁻¹ (green) and 200 km s⁻¹ < v < 400 km s⁻¹ (red), with respect to the median value between z_E^* and z_W^*, z_m = 0.0181. The red crosses mark the position of the two nuclei.