This is not just some special effect; this is what a black hole would like up close based on the actual math of physics of Relativity. The black hole is surrounded by a disk of gas, and the intense gravity near the black hole distorts the view. The disk behind the hole actually has its light bent around so we can see it; the top side of the disk is seen as the big arch above the hole, and the bottom of the disk is the smaller more circular one below it. Light *just* above the event horizon can circle the black hole several times before coming out again, and that makes the thin a ring around it. Also, the gas on the left is coming at you, and looks brighter due to relativistic beaming, the gravity of the hole collecting the light and focusing it like a mirror.
