Density waves in the inner parts of disk galaxies
  Density waves in the central kpc of galaxies, taking the form of spirals, bars and/or lopsided density distributions, are potential actors of the redistribution of angular momentum. They may thus play an important role in the overall evolution of the central structures, not mentioning the possible link with the active/non-active central mass concentration. I present here some evidence for the presence of such structures, and discuss their importance in the context of dynamical evolution. 
Eric Emsellem (1) (Centre de Recherche Astronomique de Lyon)