Top panel: 2QZ0028-28 K-band spectrum extracted from the central arcsec, along with the various components used for the fit (blue are for Hα components, magenta are for [NII] lines of component B). Vertical dotted lines show the rest-frame wavelength for Hα and [NII]λ6584, by using the same reference as in Fig. 1. Middle panel: residuals of the fit. Bottom panel: result of the subtraction between the spectrum extracted from the region with narrow Hα emission NW of the nucleus (Fig. 4) and the spectrum extracted from the region without narrow Hα emission, SE of the nucleus, after scaling the two spectra to match the intensity of the broad line. A clear narrow Hα component is detected, illustrating that the detection of this component and its distribution are not artifacts of the spectral fit.