BPT diagnostic diagram showing the [O III] λ5007/Hβ flux ratio measured for the companion galaxy (Region 2), and the lower limits for the host galaxy (Region 1) and Region 3, as listed in Table 1. For reference, we show the Kauffmann et al. (2003) (black dotted) and Kewley et al. (2001) (black dashed) curves which attempt to differentiate between galaxies primarily ionised by star formation (lower left) and AGN (upper right) at low-z. We also show local sources from the SDSS (Abazajian et al. 2009, 2D histogram) for comparison.