The merging/AGN connection - II. Ionization of the circumnuclear regions S. F. Sánchez, T. Becker, B. Garcia-Lorenzo, C. R. Benn, L. Christensen, A. Kelz, K. Jahnke and M. M. Roth A&A, 429 2 (2005) L21-L24 Published online: 17 December 2004 DOI: 10.1051/0004-6361:200400107