So far, BHs have been discovered in every galaxy that contains a bulge and that has been observed with enough resolution to find a BH consistent with the correlations in Figure 2. The canonical BH is about 0.13% of the mass of the bulge; the scatter is more than a factor of 10. Table 2 lists the strongest BH mass limits. We fail to find BHs in pure disk and related galaxies. These are discussed in the next section.
|Galaxy||Type||MB,nucleus||M upper limit||D||Reference|
|M 33||Scd||-10.21||1.0 e3||24||0.8||Gebhardt + 2001|
|NGC 205||Sph||-10||9.0 e4||15||0.72||Jones + 1996|
|NGC 4395||Sm||8.0 e4||30||2.6||Filippenko + 2001|
|IC 342||Scd||-14||5.0 e5||33||1.8||Böker + 1999|
Note - These galaxies do not contain bulges; the absolute magnitude MB,nucleus and velocity dispersion refer to the nuclear star cluster. NGC 205 is a spheroidal galaxy; it does not fit into the traditional Hubble Sequence, but it is physically related to late-type galaxies (Kormendy 1985, 1987).