Empirical Constraints on the Coevolution of Supermassive Black Holes and
  their Host Spheroids
  We investigate the evolution of the MBH-{\sigma} relation by examining the
relationship between the intrinsic scatter in the MBH-{\sigma} relation and
galaxy bolometric nuclear luminosity, the latter being a probe of the accretion
rate of the black hole (BH). Our sample is composed of galaxies with classical
bulges when possible, of which 38 have dynamically measured BHs masses, and 17
have BHs masses measured by reverberation mapping. In order to obtain the
bolometric nuclear luminosity for galaxies with low nuclear luminosity, we
convert the X-ray nuclear luminosity measured by Chandra to bolometric
luminosity. We find that the scatter in the MBH-{\sigma} relation is
uncorrelated with nuclear luminosity over seven orders of magnitude in
luminosity, with the high luminosity end approaching the Eddington luminosity.
This suggests that at the present epoch galaxies evolve along the MBH-{\sigma}
relation. This conclusion is consistent with the standard paradigm that BHs
grow contemporaneously with their host stellar spheroids.
