Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

techniques become that strict limits will be able to be placed on black hole masses of
individual galaxies, but we can certainly do a better job of understanding the limita-
tions involved, and understand the dynamics of the nuclear regions far better, which
likely has implications for the connections between central engines and their host
galaxies. It is here that increasing the body of available data (in particular improved
spatial coverage) will have value.
Future comparisons between the stellar and gas kinematics should also produce
interesting results relating to the connections between the various kinematic systems
in an active galaxy. We showed in Chapter 5 that the stellar and gas velocity dis-
persions seem related, and tracing this relationship on larger scales, and combining
models of stars and gas sitting in the same potential, could teach us how these sys-
tems are connected. This is of interest first because it seems reasonable to assume
that the gas provides a good avenue for the stellar kinematics and the central engine
to develop connections (such as the M• − σc relation); and second as a calibration
check between those galaxies where the black hole mass is determined from stellar
dynamics and where the black hole mass is determined through gas dynamics. At the
time of writing, there is not a single example for which the black hole mass has been
reliably determined by both methods.
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