The Globular Cluster/Central Black Hole Connection in Galaxies
  We explore the relation between the total globular cluster population in a
galaxy (N_GC) and the the mass of its central black hole (M_BH). Using a sample
of 33 galaxies, twice as large as the original sample discussed by Burkert &
Tremaine (2010), we find that N_GC for elliptical and spiral galaxies increases
in almost precisely direct proportion to M_BH. The S0-type galaxies by contrast
do not follow a clear trend, showing large scatter in M_BH at a given N_GC.
After accounting for observational measurement uncertainty, we find that the
mean relation defined by the E and S galaxies must also have an intrinsic or
"cosmic" scatter of +-0.2 in either logN_GC or logM_BH. The residuals from this
correlation show no trend with globular cluster specific frequency. We suggest
that these two types of galaxy subsystems (central black hole and globular
cluster system) may be closely correlated because they both originated at high
redshift during the main epoch of hierarchical merging, and both require
extremely high-density conditions for formation. Lastly, we note that roughly
10% of the galaxies in our sample (one E, one S, and two S0) deviate strongly
from the main trend, all in the sense that their M_BH is at least 10x smaller
than would be predicted by the mean relation.
