The Mass Of Black Holes in the Nuclei Of Spirals
  We use rotation curve kinematics of 1000 spiral galaxies to investigate if these galaxies could host BH (Black Hole) remnants that once powered the QSO phenomenon. The rotation curves of both early and late-type spirals are used to place upper limits on the BH mass. We find that the central objects in spirals are 10-100 times less massive than those detected in ellipticals, suggesting that the contribution to the QSO phenomenon by the BH remnants hosted in these objects is negligible. The upper limits on the mass of the BHs resident in late type spirals are stringent: $M_{BH}\leq 10^{6}-10^{7} M_{\odot}$, indicating that only low luminosity activity possibly occurred in these objects. 
Paolo Salucci (1), Charu Ratnam (2), Pierluigi Monaco (3) and Luigi   Danese(1) ((1)SISSA (2)Indian Institute Of Astrophysic...