The morphology of galaxies reflects their assembly history and ongoing dynamical perturbations from the environment. Analyzing stacked i-band images from the Pan-STARRS1 3{pi} Steradian Survey, we study the optical morphological asymmetry of the host galaxies of a large, well-defined sample of nearby active galactic nuclei (AGNs) to investigate the role of mergers and interactions in triggering nuclear activity. The AGNs, comprising 245 type 1 and 4514 type 2 objects, are compared with 4537 star-forming galaxies (SFGs) matched in redshift (0.04~0.4 effectively trace systems that are candidate ongoing mergers. Contrary to theoretical expectations, galaxy interactions and mergers are not the main drivers of nuclear activity, at least not in our sample of low- redshift, relatively low luminosity AGNs, whose host galaxies are actually significantly less asymmetric than the control sample of SFGs. Moreover, type 2 AGNs are morphologically indistinguishable from their type 1 counterparts. The level of AGN activity does not correlate with asymmetry, not even among the major merger candidates. As a by-product, we find, consistent with previous studies, that the average asymmetry of SFGs increases above the main sequence, although not all major mergers exhibit enhanced star formation.

Cone search capability for table J/ApJ/925/70/table1 (and measurements)