Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

et al., 2000; Tomita et al., 2000; Tran et al., 2001; Laine et al., 2003). This dust and
gas presumably provides a bulk of the fuel for the central engine.
The kinematics of the disk are not well understood, and important questions
remain regarding the importance of non-circular motions (such as turbulence, inflow,
outflow, winds, etc...). It is also of interest whether these disks are short lived or
long lived, and whether they are providing fuel to the central engine or playing a
role in the collimation of the jets. Disks have been identified that are non-uniform in
continuum light and are surrounded by arcs, filaments, and diffuse absorbing clumps,
suggesting that the dust (and by association the gas) in the cores of these galaxies is
not dynamically settled (for example, Martel et al., 2000, ; Figure 1.4).
Assuming that this gas and dust indeed provides the primary fuel source of the
central engine, a long standing problem is the ‘fueling problem’ – that is how to
remove the large angular momentum of the gas in a disk and get it into the central
engine. This problem is described in a well known cartoon by Phinney (1994) of a
baby being fed by a huge (angular momentum) spoon into its tiny mouth (Figure 1.6).
Also, typical findings are that 60% of quiescent early-type galaxies have detections
of emission line gas (e.g. Philips et al., 1986; Goudfrooij et al., 1994) and about 40%
have nuclear dust (e.g. van Dokkum & Franx, 1995; Tran et al., 2001). Despite the
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