A number of studies have revealed the presence of central supermassive
black holes in several massive disk and elliptical galaxies, and it is
now believed that most (if not all) massive galaxies should have a
central supermassive black hole. These works have also shown that the
mass of these black holes correlate with
and the luminosity or
mass of the elliptical galaxy (in the case of ellipticals) or the bulge
(in the case of disk galaxies; see e.g.
Gültekin et
al. 2009
and references
therein). This suggests a connected growth of black holes
and bulges (and ellipticals). Essentially, black holes would accrete
mass, resulting in AGN activity, until AGN feedback regulates the inflow
of gas, the growth of the black hole, and the formation of stars in the
bulge/elliptical (see e.g.
Younger et
al. 2008).
In this framework, the growth of disk-like bulges would not be connected
with the (bulk of) growth of black holes, and thus the properties of
disk-like bulges would not correlate with the mass of black holes.
This question has been investigated by
Graham (2008),
Hu (2008) and
Gadotti &
Kauffmann (2009),
and these works showed that the correlation between
black hole mass and is
difficult to evaluate in galaxies with
disk-like bulges, as the presence of bars increase
(in ways
difficult to account for) more significantly (in relative terms) than in
galaxies with classical bulges (see
Graham et
al. 2011).
More recently,
Kormendy et
al. (2011)
argued that the luminosities of disk-like bulges do not correlate with
black hole masses, consistent with the picture outlined above.
Nowak et
al. (2010)
and
Erwin (2010)
showed results indicating that, in composite bulges, the black hole mass
correlates better with the luminosity of the classical bulge only, again
showing that the growth of disk-like bulges is to some extent not
coupled with the growth of black holes.