A correlation between central supermassive black holes and the globular
  cluster systems of early-type galaxies
  Elliptical, lenticular, and early-type spiral galaxies show a remarkably
tight power-law correlation between the mass M_BH of their central supermassive
black hole (SMBH) and the number N_GC of globular clusters:
M_BH=m*N_GC^(1.08+/-0.04) with m=1.7*10^5 solar masses. Thus, to a good
approximation the SMBH mass is the same as the total mass of the globular
clusters. Based on a limited sample of 13 galaxies, this relation appears to be
a better predictor of SMBH mass (rms scatter 0.2 dex) than the M_BH-sigma
relation between SMBH mass and velocity dispersion sigma. The small scatter
reflects the fact that galaxies with high globular cluster specific frequency
S_N tend to harbor SMBHs that are more massive than expected from the
M_BH-sigma relation.
