α_co as a function of the SFR (measured over 5 Myr) in the merger and in simulations of other galaxies. (The system starts in the top left corner, and at first order, moves clockwise). The symbols are the same as in Fig. 1. The dashed lines indicate linear fits (α_co = a_SFR + b) to three regimes: disk galaxies, starbursts, and post-burst phases (see text). The typical dispersions of α_co (estimated by varying the line of sight, see text) is shown in the bottom left corner.