Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

in nearby galaxies, and is being used to calibrate other indicators of black hole mass
(such as the use of particular emission line widths), which may be applied more
distantly in the universe. 25% of the ‘good’ black hole determinations available to
date (Tremaine et al., 2002) are based on gas dynamics, so understanding the gas
systems in the nuclei of galaxies is key in ensuring that the M• − σc relation is built
on strong foundations so that it can reliably be applied with the level of assurance
that appears to be becoming common practice.
Progress in explaining the motions that we observe can be made by mapping the
spectra over a larger area of the nuclei, either through the use of multiple spectro-
scopic slit positions, or by using more recently developed integral field spectrographs
which can produce three-dimensional (x,y,λ) maps of large areas simultaneously. The
instruments of choice at the time of writing are STIS on HST for long slit spectra
(Brown et al., 2002), or SAURON on the William Herschell Telescope and OASIS on
the Canada-France-Hawaii Telescope for integral field spectroscopy.
This field is already somewhat saturated with large data sets (particularly from
STIS on HST), of which the analysis has proven somewhat treacherous. Before con-
tinuing to gather increasingly large data sets it is important to address what we could
hope to learn. Many of the existing data were gathered along the same lines as the
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