Integrated CO 2–1 emission in each source. The black contours show the NOEMA 1.3 mm continuum emission, the same as in Fig. 2. The red and blue contours show the redshifted and blueshifted CO emission in outflows, respectively. The contour levels start from 3σ and increase in steps of 3σ, where σ is the rms of the integrated CO emission. The red and blue arrows mark the identified outflow axes.