Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

gas disks were computed by making a circular thin disk assumption and deriving
the inclination angle from the observed axis ratio of the dust. For the galaxies with
dust lanes, inclinations were set at 80 ◦ (we do not observe disks below about 70 ◦ ,
which we interpret of the lower limit of the range of inclinations in systems where we
see lanes). The measured axis ratios and derived inclinations are given in Table 4.1,
along with dust masses.
4.2.2 Flux distributions
To model the observed gas kinematics we first need a description of the intrinsic
emission line flux distribution, for which we make use of the flux profiles obtained
from the Gaussian fits to our STIS spectroscopic results that we presented in Chapter
3, Tables 3.5 to 3.25. We model the face on flux profile as a double exponential,
151
F(R) = F1e −R/R1 + F2e −R/R2 , (4.1)
deriving the parameters assuming an infinitesimally thin disk, inclined at the angle
given in Table 4.1. We iterate a fit of the double exponential to the flux data, taking
into account the flux errors and convolution with the STIS PSF, aperture size and
pixel size.
The STIS PSF was represented by a combination of five Gaussians which represent