  This poster discusses a possible explanation for the relationship between the
mass of the central supermassive black hole and the velocity dispersion in the
bulge of the host galaxy. We suppose that the black hole and the dark matter
halo are forming simultaneously as matter falls in, and a self-similar system
then exists in which the mass and the velocities of the system evolve as
power-law functions of time. This leads naturally to a relationship between the
black hole mass and the velocities in the halo which, with a reasonable choice
of cosmological parameters, is in good agreement with the observed
relationship. We also confirm this relationship with more robust numerical
results.
