Are ring galaxies the ancestors of giant low surface brightness   galaxies?
  Giant low surface brightness galaxies (GLSBs) have flat discs extending up to ~100 kpc. Their formation is a puzzle for cosmological simulations in the cold dark matter scenario. We suggest that GLSBs might be the final product of the evolution of collisional ring galaxies. In fact, our simulations show that, approximately 0.5-1.5 Gyr after the collision which led to the formation of the ring galaxy, the ring keeps expanding and fades, while the disc becomes very large (~100 kpc) and flat. At this stage, our simulated galaxies match many properties of GLSBs (surface brightness profile, morphology, HI spectrum and rotation curve). 
M. Mapelli (1), B. Moore (1), E. Ripamonti (2), L. Giordano (1), L.   Mayer (1,3), M. Colpi (4), S. Callegari (1) ((1)Univer...