Unveiling multiple AGN activity in galaxy mergers
  In this paper we present an overview of the MAGNA (Multiple AGN Activity) project aiming at a comprehensive study of multiple supemassive black hole systems. With the main goal to characterize the sources in merging systems at different stages of evolution, we selected a sample of objects optically classified as multiple systems on the basis of emission line diagnostics and started a massive multiband observational campaign. Here we report on the discovery of the exceptionally high AGN density compact group SDSS~J0959+1259. A multiband study suggests that strong interactions are taking place among its galaxies through tidal forces, therefore this system represents a case study for physical mechanisms that trigger nuclear activity and star formation. We also present a preliminary analysis of the multiple AGN system SDSS~J1038+3921.} 
A. De Rosa, S. Bianchi, T. Bogdanovic, R. Decarli, J. Heidt, R.   Herrero-Illana, B. Husemann, S. Komossa, E. Kun, N. Loisea...
astro-ph.GA astro-ph.HE