Theoretical reevaluations of the black hole mass - bulge mass relation -
  I. Effect of the seed black hole mass
  We explore the effect of varying the mass of the seed black hole on the
resulting black hole mass - bulge mass relation at z ~ 0, using a semi-analytic
model of galaxy formation combined with large cosmological N-body simulations.
We constrain our model by requiring the observed properties of galaxies at z ~
0 are reproduced. In keeping with previous semi-analytic models, we place a
seed black hole immediately after a galaxy forms. When the mass of the seed is
set at 10^5 M_sun, we find that the model results become inconsistent with
recent observational results of the black hole mass - bulge mass relation for
dwarf galaxies. In particular, the model predicts that bulges with ~ 10^9 M_sun
harbour larger black holes than observed. On the other hand, when we employ
seed black holes with 10^3 M_sun, or randomly select their mass within a
10^(3-5) M_sun range, the resulting relation is consistent with observation
estimates, including the observed dispersion. We find that to obtain stronger
constraints on the mass of seed black holes, observations of less massive
bulges at z ~ 0 are a more powerful comparison than the relations at higher
redshifts.
