  Using media with extremely low group velocities one can create an optical
analog of a curved space-time. Leonhardt and Piwnicki have proposed that a
vortex flow will act as an optical black hole. We show that although the
Leonhardt - Piwnicki flow has an orbit of no return and an infinite red-shift
surface, it is not a true black hole since it lacks a null hypersurface.
However a radial flow will produce a true optical black hole that has a Hawking
temperature and obeys the first law of black hole mechanics. By combining the
Leonhardt - Piwnicki flow with a radial flow we obtain the analog of the Kerr
black hole.
