Hello Robert,
Thanks so much for that very interesting information. It adds another aspect to our visual observations. Galaxy evolution and structure is really fascinating and I welcome posts that explain clearly the nature of the galaxies we are observing, especially if it saves us from having to wade through the SIMBAD interface!
The Wikipedia article below on NGC 5139, postulating the possibility of a black hole at its centre, and certain evidence that it may be the core of a cannabalised dwarf galaxy is just one example of a very familiar object with a truly remarkable history.
I'm sure I'm not the only visual observer thinking "more posts like that please!!!"
http://en.wikipedia.org/wiki/Omega_Centauri