The role of interactions
  Interactions between galaxies are suggested to be a mechanism responsible for feeding Active Galactic Nuclei (AGN). Theoretical models show that interactions are an efficient way to drive gas from the galaxy to the nucleus, however, the observational evidence on this subject is controversial. Here we review results in this field, discuss possible limitations of previous studies and the importance of dealing with selection effects. We also show that there is no significant difference in the percentage of low luminosity AGN and normal galaxies with companions, and discuss possible interpretations of this result. 
H. R. Schmitt (NRAO)