There is a massive black hole at the center of the Milky Way, now named Sagittarius A* (pronounced “a-star”). We can't actually see it, but we are getting enough data to know what's happening over there. From that data, astronomers from the European Space Observatory have constructed an animated simulation of the stuff swirling around the black hole.
Astronomers collected the data for the visualization using an instrument on the European Southern Observatory’s Very Large Telescope, located in the deserts of northern Chile. The instrument, appropriately named GRAVITY, detected flares of infrared radiation coming from the disk surrounding Sagittarius A*. The researchers believe the bursts originated very close to the black hole, in an incredibly tumultuous region known as the innermost stable orbit. Here, cosmic material is slung around violently, but it remains far away enough that it can circle the black hole safely without getting sucked into the darkness.
Don't worry, the Earth is far enough away from Sagittarius A* so that we won't be sucked into it anytime soon. Read more about Sagittarius A* at the Atlantic.
That said, the black circle gets referred to as the black hole's shadow and is somewhat larger than the actual event horizon. I've seen references that it is about 2.5x bigger, although I haven't kept up to date on it (a quick reference here that I have only had time to skim). The bending of the light seems to spread it out more, so you end up with a larger dark disk where it is much less likely for light to come toward you from.
I also haven't seen a reference to other literature, but if the light source is an accretion disk, there is expected to be a bit of gap between the inner edge of the accretion disk and event horizon. There is a distance from the black hole known as the innermost stable circular orbit. Stuff piling up any further than that can stay in orbit a long time by itself, and depends on friction, plasma effects, or radiated energy to decay in fall in closer. But once past the ISCO, orbits are no longer stable and decay without further interactions with other stuff, so you would end up with kind of a relatively empty area where stuff starts falling faster. This new work seems to be discussing how much light would come out of that gap.
There is a lot of work and graphics around for what a black hole does to near by light sources because the of Event Horizon Telescope that is attempting to image this with radio telescopes. The spin of the black hole would affect which way it is easier for bent light to go, so there are also predictions on how to measure the spin from said image.