Recently a super massive black hole has discovered by the scientists of the event horizon telescope . The name of the back hole is Messier 87. A black hole usually absorbs the light so we can't see it. But it has an event horizon which we can see.
It's theory is given by Stephen Hawkings.
We can see a black hole and it's event horizon by "Hawkings radiation".
More about "Hawkings radiation" go to https://www.google.com/url?sa=t&source=web&rct=j&url=https://en.m.wikipedia.org/wiki/Hawking_radiation&ved=2ahUKEwj0j--d9tvhAhWaXSsKHQwbDXsQFjAOegQICRAu&usg=AOvVaw1JubLngqjOiptxbOgCJTJ-
