Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

models. Pronounced differences can be produced by differences in the angle of the
slits compared to the kinematic major axis of the gas. This may pose problems in
morphologically complex systems where we have no way of a priori determining the
kinematic axes.
4.3 Descriptions of individual galaxies
For each galaxy we compare the three models we obtained for 0, 1 × 10 8 M⊙ and
9 × 10 8 M⊙ black holes to the observed velocities in all three slits. We do not model
UGC 7115 (where we only have one spectroscopic slit, and relatively low signal to
noise), nor NGC 3801 (where we are clearly not on the nucleus and not aligned with
the kinematic axis). We present the results in Figures 4.23 to 4.41 and describe each
galaxy in turn below.
NGC 193: This S0 galaxy has a complex dust morphology with two distinct dust
systems clearly visible. The STIS slits were aligned parallel to the galaxy major axis,
which is also almost perpendicular to the radio jets. The weighted mean observation
- model residuals are plotted in Figure 4.1 and gives a minimum at an offset of
47 km s −1 , equivalent to a galaxy recessional velocity of 4390 km s −1 . The model
velocity profiles for these observations are shown in Figure 4.23, two plots are shown,
161