Top row: CO-line peak channel of the three detected sources. The observed CO transition and the velocity corresponding to the center of the channel (defined as the velocity shift with respect to the systemic redshift) are reported in the up-left and bottom-right corner of the images, respectively. The blue ellipses are the regions from which the spectra in Fig. 2 were extracted. In the XID 666 CO-line peak image (right panel) we show the contours of the blue-shifted peak channel centered at −206.5 km s⁻¹ (2, 3, 4σ, black solid lines) over the red-shifted peak channel (see Sect. 4 for details). Bottom row: dust-continuum image of the three detected sources. In all the images the black ellipse in the left-bottom corner represents the clean beam.