How does the Event Horizon Telescope capture the image of the black hole if no light can escape near the event horizon?

Question

The Event Horizon Telescope claimed they capture the first image of blackhole, at the center of galaxy M87. In the image we can see lightrays are bent near the blackhole, but how do we receive the light rays if the definition of the event horizon is the boundary where light cannot escape? Does the picture just show a place that is further outside of the blackhole? What's the significance of this?

Answer 1

the black hole is in the process of gobbling up matter in its vicinity. As that matter spirals its way in towards the event horizon, it is frictionally heated to tremendous temperatures- hot enough to strongly radiate light- before it gets close enough to the EH for it to fade into darkness. It is that light, emitted by the infalling matter at some distance away from the EH, that our telescopes detect.