Upper four panels: PACS spectrum towards the central spaxel. Only lines that are detected with a signal-to-noise ratio greater than 3 somewhere in the mapped region (not necessarily the central spaxel) are marked as a detected line. Only upper and lower state energy levels are indicated for clarity. Lower panel: same as the other panels but for the SPIRE spectrum towards the central region. The [O i] lines are marked in green, the H₂O lines in blue and the CO lines in red. In this figure, there are different units for the PACS and SPIRE observations and no continuum subtraction has been made.