4. WHICH GALAXIES CONTAIN BHS? WHICH DO NOT?
M UPPER LIMITS

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.

Table 2. Limits on Supermassive Black Holes (2001 March)

Galaxy	Type	MB,nucleus	M upper limit		D	Reference
			(M)	(km/s)	(Mpc)
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).