  We investigate the hypothesis that the cores of elliptical galaxies and
bulges are created from the binding energy liberated by the coalescence of
supermassive binary black holes during galaxy mergers. Assuming that the
central density profiles of galaxies were initially steep power laws, we define
the ``mass deficit'' as the mass in stars that had to be removed from the
nucleus in order to produce the observed core. We use nonparametric
deprojection to compute the mass deficit in a sample of 35 early-type galaxies
with high-resolution imaging data. We find that the mass deficit correlates
well with the mass of the nuclear black hole, consistent with the predictions
of merger models. We argue that core sizes in halos of non-interacting dark
matter particles should be comparable to those observed in the stars.
