A definitive merger-AGN connection at z~0 with CFIS: mergers have an
  excess of AGN and AGN hosts are more frequently disturbed
  The question of whether galaxy mergers are linked to the triggering of active
galactic nuclei (AGN) continues to be a topic of considerable debate. The issue
can be broken down into two distinct questions: 1) Can galaxy mergers trigger
AGN? 2) Are galaxy mergers the dominant AGN triggering mechanism? A complete
picture of the AGN-merger connection requires that both of these questions are
addressed with the same dataset. In previous work, we have shown that galaxy
mergers selected from the Sloan Digital Sky Survey (SDSS) show an excess of
both optically-selected, and mid-IR colour-selected AGN, demonstrating that the
answer to the first of the above questions is affirmative. Here, we use the
same optical and mid-IR AGN selection to address the second question, by
quantifying the frequency of morphological disturbances in low surface
brightness r-band images from the Canada France Imaging Survey (CFIS). Only ~30
per cent of optical AGN host galaxies are morphologically disturbed, indicating
that recent interactions are not the dominant trigger. However, almost 60 per
cent of mid-IR AGN hosts show signs of visual disturbance, indicating that
interactions play a more significant role in nuclear feeding. Both mid-IR and
optically selected AGN have interacting fractions that are a factor of two
greater than a mass and redshift matched non-AGN control sample, an excess that
increases with both AGN luminosity and host galaxy stellar mass.
