LAUSR

We present a study on the incidence of major mergers and their impact on the triggering of nuclear activity in 47 type I and 236 type II optically-selected AGN from the MaNGA DR15 sample. From an estimate of non-parametric image predictors (Gini, M20, concentration (C), asymmetry (A), clumpiness (S), Sérsic index (n), and shape asymmetry(AS)) using the SDSS images, in combination with a Linear Discriminant Analysis Method, we identified major mergers and merger stages. We reinforced our results by looking for bright tidal features in our post-processed SDSS and DESI legacy images. We find a statistically significant higher incidence of major mergers of 29% ± 3% in our type I+II AGN sample compared to 22% ± 0.8% for a non-AGN sample matched in redshift, stellar mass, color and morphological type, finding also a prevalence of post-coalescence (51% ± 5%) over pre-coalescence (23% ± 6%) merger stages. The levels of AGN activity among our massive major mergers are similar to those reported in other works using [O iii] tracers. However, similar levels are produced by our AGN-galaxies hosting stellar bars, suggesting that major mergers are important promoters of nuclear activity but are not the main nor the only mechanism behind the AGN triggering. The tidal strength parameter Q was considered at various scales looking for environmental differences that could affect our results on the merger incidence, finding non-significant differences. Finally, the H-Hβ diagram could be used as an empirical predictor for the flux coming from an AGN source, useful to correct photometric quantities in large AGN samples emerging from surveys.