CO(2−1) spectrum (left), integrated line map (center left panel), line flux versus W_CO (center right panel) and signal over noise (S/N) versus W_CO (right) of our 7 PdBI targets with secure (PEPJ123712+621753, PEPJ123759+621732, PEPJ123646+621141 and PEPJ123750+621600) and tentative line detection (PEPJ123709+621507, PEPJ123721+621346 and PEPJ123633+621005). In each spectrum, the yellow area displays the part of the spectrum over which the line fluxes are integrated. Dashed lines in the right two panels outline this value of W_CO. To create the center right and right panels, we fixed the central frequency when increasing W_CO to the central frequency of the yellow area displayed in the left panel. Dotted-dashed lines and triple-dotted-dashed lines represent the line flux and error of each object, respectively. Beam sizes are displayed in the lower left corner of each integrated line map.