Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

a galaxy recessional velocity of 6490 km s −1 . The model velocity profiles for these
observations are shown in Figure 4.31. It is not clear that the modeled velocity profiles
match any of the observed kinematics in the nuclear region.
NGC 4261: This E2-3 galaxy has a nuclear dust disk. The STIS slits were aligned
parallel to the galaxy major axis, 5 ◦ from the dust disk axis. Due to a pointing error,
the center of the galaxy was not positioned well during the observations and fell closest
to one of the side slits. We are unable to constrain where the center fell precisely,
however we show the model velocity profiles for the observations in that side slit alone
in Figure 4.32. In the observed velocity profile a central velocity gradient is observed
which seems as if it may correspond to gas rotating in the potential generated by a
∼ 1 × 10 8 M⊙ black hole. We take this to be a lower limit on the mass as the galaxy
nucleus may be beyond the observed slit positions.
NGC 4335: This elliptical galaxy has a nuclear dust disk. The STIS slits were
aligned parallel to the galaxy major axis, 11 ◦ from the dust disk axis. The weighted
mean observation - model residuals are plotted in Figure 4.10 and gives a minimum
at an offset of 50 km s −1 , equivalent to a galaxy recessional velocity of 4723 km s −1 .
The model velocity profiles for these observations are shown in Figure 4.33. The
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