Determination of the intrinsic scatter in the M-sigma and M-L relations
  We report on recently derived improved versions of the relations between
supermassive black hole mass (M_BH) and host-galaxy bulge velocity dispersion
(sigma) and luminosity (L) (the M-sigma and M-L relations), based on ~50 M_BH
measurements and ~20 upper limits. Particular attention is paid to recovery of
the intrinsic scatter (epsilon_0) in both relations. The scatter was found to
be significantly larger than estimated in most previous studies. The large
scatter requires revision of the local black hole mass function, and it implies
that there may be substantial selection bias in studies of the evolution of the
M-sigma and M-L relations. When only considering ellipticals, the scatter
appears to decrease. These results appear to be insensitive to a wide range of
assumptions about the measurement errors and the distribution of intrinsic
scatter. We also report on the effects on the fits of culling the sample
according to the resolution of the black hole's sphere of influence.
