The Influence of Dark Matter Halos on Dynamical Estimates of Black Hole
  Mass: Ten New Measurements for High-sigma Early-Type Galaxies
  Adaptive-Optics assisted SINFONI observations of the central regions of ten
early-type galaxies are presented. Based primarily on the SINFONI kinematics,
ten black hole masses occupying the high-mass regime of the M_BH-sigma relation
are derived using three-integral Schwarzschild models. The effect of dark
matter inclusion on the black hole mass is explored. The omission of a dark
matter halo in the model results in a higher stellar mass-to-light ratio,
especially when extensive kinematic data are used in the model. However, when
the diameter of the sphere of influence -- computed using the black hole mass
derived without a dark halo -- is at least 10 times the PSF FWHM during the
observations, it is safe to exclude a dark matter component in the dynamical
modeling, i.e. the change in black hole mass is negligible. When the spatial
resolution is marginal, restricting the mass-to-light ratio to the right value
returns the correct M_BH although dark halo is not present in the model.
Compared to the M_BH-sigma and M_BH-L relations of McConnell et al. (2011), the
ten black holes are all more massive than expected from the luminosities and
seven black hole masses are higher than expected from the stellar velocity
dispersions of the host bulges. Using new fitted relations which include the
ten galaxies, we find that the space density of the most massive black holes
(M_BH >~ 10^9 Msun) estimated from the M_BH-L relation is higher than the
estimate based on the M_BH-sigma relation and the latter is higher than model
predictions based on quasar counts, each by about an order of magnitude.
