Using N-body numerical simulations, we investigate the stability of a nuclear disk of a few pc characteristic radius, around a supermassive black hole (SBH), and embedded in a galactic bulge. We find that with an SBH of a suitable range of mass, placed at its center, the nuclear disk is subject to one-armed (m=1) natural instabilities. We propose a feedback cycle for this mode, based on waves between corotation and OLR, and where the “indirect term”, and the massive bulge play a fundamental role. Nuclear disks formed from accreted gas could be the precursors of this type of structure and may be common in central regions of galaxies. Density waves could be an efficient mechanism of fueling the gas in the central few tens of parsecs in galaxies.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html