Precision determination of corotation radii in galaxy disks:
  Tremaine-Weinberg v. Font-Beckman for NGC 3433
  Density waves in galaxy disks have been proposed over the years, in a variety
of specific models, to explain spiral arm structure and its relation to the
mass distribution, notably in barred galaxies. An important parameter in
dynamical density wave theories is the corotation radius, the galactocentric
distance at which the stars and gas rotate at the same speed as the
quasi-static propagating density wave. Determining corotation, and the pattern
speed of a bar have become relevant to tests of cosmologically based theories
of galaxy evolution involving the dynamical braking of bars by interaction with
dark matter haloes. Here comparing two methods, one of which measures the
pattern speed and the other the radius of corotation, using two instruments (an
integral field spectrometer and a Fabry-Perot interferometer) and using both
the stellar and interstellar velocity fields, we have determined the bar
corotation radius, and three further radii of corotation for the SAB(s)b galaxy
NGC3433. The results of both methods, with both instruments, and with both disk
components give excellent agreement. This strengthens our confidence in the
value of the two methods, and offers good perspectives for quantitative tests
of different theoretical models.
