Selection bias in dynamically-measured super-massive black hole samples:
  dynamical masses and dependence on S\'ersic index
  We extend the comparison between the set of local galaxies having dynamically
measured black holes with galaxies in the Sloan Digital Sky Survey (SDSS). We
first show that the most up-to-date local black hole samples of early-type
galaxies with measurements of effective radii, luminosities, and S\'ersic
indices of the bulges of their host galaxies, have dynamical mass and S\'ersic
index distributions consistent with those of SDSS early-type galaxies of
similar bulge stellar mass. The host galaxies of local black hole samples thus
do not appear structurally different from SDSS galaxies, sharing similar
dynamical masses, light profiles and light distributions. Analysis of the
residuals reveals that velocity dispersion is more fundamental than S\'ersic
index n in the scaling relations between black holes and galaxies. Indeed,
residuals with S\'ersic index could be ascribed to the (weak) correlation with
bulge mass or even velocity dispersion. Finally, targetted Monte Carlo
simulations that include the effects of the sphere of influence of the black
hole, and tuned to reproduce the observed residuals and scaling relations in
terms of velocity dispersion and stellar mass, show that, at least for galaxies
with Mbulge > 1e10 Msun and n>5, the observed mean black hole mass at fixed
S\'ersic index is biased significantly higher than the intrinsic value.
