Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

is not a good indicator of the gas distribution for these galaxies.
In Figure 5.2 we show the weighted mean velocity dispersion (σ100) as a function
of the axis ratio. Here it is clear that there is no relationship between this parameter
and the inclination. We interpret this to mean that the velocity dispersion is fairly
evenly distributed three-dimensionally, so is not just a consequence of observing the
organized motions from different angles, but is an intrinsic property of the gas within
the disks. The slight rise seen from the lowest to highest dust ratios is likely a
consequence of the σ100 parameter picking up more of the organized motion, but this
is a small effect. As mentioned in §4.2.4, gas at T ∼ 10 4 K would have a thermal
velocity dispersion of σth ∼ 10 km s −1 , which is well below the minimum observed
dispersion in any of the galaxies, indicating that non-thermal random motions are
present (and important) in all of the gas disks.
We again highlight the galaxy NGC 383, which also sits high in the velocity
dispersion distribution. The fact that this galaxy is high in both parameters may
indicate that the gas is in a state far from being satisfactorily represented by a settled
thin disk.
We show the point-to-point variations in the gas velocity profile, as parameterized
by ɛ100 in Figure 5.3. Here we observe that, for the most part, ɛ100 is not a function of
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