What glowing disk of orbiting gas can surround a feeding black hole?

The glowing disk of orbiting gas that can surround a feeding black hole is an accretion disk.

An accretion disk forms when gas, dust or stellar debris falls toward a massive object but cannot plunge straight in because it carries angular momentum. Instead, the material settles into a rapidly rotating disk and gradually spirals inward as turbulence, magnetic effects and friction transfer angular momentum outward.

The disk glows because gravitational potential energy is converted into heat. Near a stellar-mass black hole, the inner gas can reach millions of degrees and emit strongly in X-rays. Around supermassive black holes, the disk may radiate across optical, ultraviolet and X-ray wavelengths, helping make quasars some of the brightest objects in the universe.

The disk is not the black hole itself, and it is not the event horizon. The event horizon is the one-way boundary surrounding the black hole; the accretion disk remains outside it, although its innermost material can approach the black hole closely. Accretion disks also occur around young stars, white dwarfs and neutron stars.