Galaxy And Mass Assembly (GAMA): the effect of galaxy group environment on active galactic nuclei

© 2017 The Author(s). In galaxy clusters, efficiently accreting active galactic nuclei (AGNs) are preferentially located in the infall regions of the cluster projected phase-space, and are rarely found in the cluster core. This has been attributed to both an increase in triggering opportunities for infalling galaxies, and a reduction of those mechanisms in the hot, virialized, cluster core. Exploiting the depth and completeness (98 per cent at r 9.9 in 695 groups with 11.53 ≤ log 10 (M 200 /M ⊙ ) ≤ 14.56 at 13.5,AGNs are preferentially found in the infalling galaxy populationwith 3.6s confidence. At lower halo masses, we observe no difference in AGN fraction between core and infalling galaxies. These observations support a model where a reduced number of low-speed interactions, ram pressure stripping and intra-group/cluster medium temperature, the dominance of which increase with halo mass, work to inhibit AGN in the cores of groups and clusters with log 10 (M 200 /M ⊙ ) > 13.5, but do not significantly affect nuclear activity in cores of less massive structures