Results from our 3D stacking analysis, for w = 1. From left to right: [C II] line extracted from the stacked cube within a 2″ radius from the centre, a zoom-in view of the broad line component once the narrow component has been removed, combined image of the [C II] line wings from ±420–840 km s⁻¹ (see vertical dotted lines in the spectrum), for the full sample (1st row), the max sub-sample (2nd row), and min sub-sample (3rd row). We also show the one (red curve) and two-component fits (blue solid and dashed curves) to the stacked line. The extent of the narrow component emission is shown with the black contours in the combined images, and the white circle corresponds to the area within a 2″ radius from the centre.