GAMA; Activity of emission-line systems in G23

After applying several cuts to the initial catalog of ~41000 galaxies, we extract a sample of 9809 galaxies. We then compare the spectral diagnostic Baldwin, Philips & Terlevich (BPT) classification of 1154 emission-line galaxies (38% resolved in W1) to their location in the WISE color-color diagram, leading to the creation of a new zone for mid-infrared "warm" galaxies located 2{sigma} above the star-forming sequence, below the standard WISE active galactic nucleus (AGN) region.

We find that the BPT and WISE diagrams agree on the classification for 85% and 8% of the galaxies as non-AGN (star-forming=SF) and AGN, respectively, and disagree on ~7% of the entire classified sample. Thirty-nine percent of the AGNs (all types) are broad-line systems for which the [NII] and [H{alpha}] fluxes can barely be disentangled, giving in most cases spurious [NII]/[H{alpha}] flux ratios. However, several optical AGNs appear to be completely consistent with SF in WISE.