/sci/ - Science & Math

In this picture, why is there yellow/orange stuff around the black hole (X and Y coordinates), but not in front of it (Z coordinate)?

If the black hole pulls matter equally from all directions, then that yellow/orange stuff would form a sphere around the black hole. In that case the black hole would not be visible in the picture, because it would be inside the sphere. Instead, here it seems as if the yellow/orange stuff formed a torus around the black hole (seen as a ring in the 2D picture). How come?