Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

show the relationship between the two parameters for each galaxy. It is clear that
the non-rotators lie at the bottom of the ∆100pc distribution, so it is conceivable that
irregular motions conceal any remaining signs of rotation in these cases. We note that
we detect rotation in all cases where the disk is ∼ > 25 ◦ from face on, other than those
cases where the dust morphology is highly irregular. The only exception is NGC 5490
where the signal to noise was particularly poor.
In Figure 3.24 we show the values of ∆100pc plotted as a function of dust disk axis
ratio, or dust lane width to length ratio; if the dust were all in circular disks this
would be an indicator of disk inclination. We included lines showing an indication
of the projection of several values of ∆100pc at different disk inclinations through the
relation
�
�
�
�
∆obs ≈ ∆int.sini ≈ ∆int × 1 −
81
� �2 b
, (3.6)
a
Where ∆obs is the observed ∆100pc parameter at a given inclination, ∆int is the
presumed intrinsic rotation of the disk and b/a is the axis (or width:length) ratio.
This is not a rigorously valid means of projecting these values, but it serves our
purposes of illustration here.