Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

galaxies were obtained with the Faint Object Spectrograph (FOS). FOS was a single
aperture spectrograph and therefore rather inefficient for mapping velocity fields,
however early results were encouraging and showed that the kinematic signatures of
black holes could indeed be detected in the nuclei of some galaxies (Harms et al.,
1994; Ferrarese et al., 1996; van der Marel & van den Bosch, 1998; Ferrarese & Ford,
1999). The Space Telescope Imaging Spectrograph (STIS, see Brown et al., 2002) was
installed on board HST in 1997 making it possible to obtain long slit spectra of the gas
disks in galactic nuclei, and map out the velocity fields with much greater efficiency,
spatial coverage and resolution. Though the velocity fields may now be mapped much
more precisely, we will see later in this thesis that the observed velocity fields are not
those of uniform, circular disks, but rather pose more of a challenge to interpret.
We show the most reliable black hole determinations to date, as assessed by
Tremaine et al. (2002), in Table 1.2. The means of determination of each M• (by
those methods described briefly above) are also indicated. These data are plotted
in Figure 1.8 against the stellar velocity dispersion in the inner parts of each galaxy
(σc) showing the conspicuous correlation between these two parameters that was first
noted by Ferrarese & Merritt (2000) and Gebhardt et al. (2000a).
The scales on which σc are measured are much larger than the nuclear regions
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