  By etching a hole in the mirrors or by placing a scatterer in the center of a
cavity, we can create a sink for light. In a Bose-Einstein condensate of
photons this sink results in the creation of a so-called radial vortex, which
is a two-dimensional analogue of a Schwarzschild black hole. We theoretically
investigate the Hawking radiation and the associated greybody factor of this
Schwarzschild black hole. In particular, we determine the density-density and
velocity-velocity correlation functions of the Hawking radiation, which can be
measured by observing the spatial correlations in the fluctuations in the light
emitted by the cavity.
