Supposedly nothing can escape from a black hole, yet astronomers are locating black hole candidates by the X-rays they emit. How can X-rays be coming from a black hole?
A) The X-rays come from a highly compressed region in an accretion disk outside the event horizon of the black hole.
B) X-rays are not light or matter and can therefore escape from inside the black hole.
C) If the black hole is rotating, it modifies spacetime around it so much that particles and X-rays are created in the vacuum just outside the event horizon.
D) The X-rays are produced by vibrations of the black hole itself and therefore do not come from inside the black hole.

Question

Quizplus · Accepted Answer

The X-rays detected by astronomers originate from the material in the accretion disk around the black hole, not from within the black hole itself. This material heats up as it spirals inwards, before crossing the event horizon, emitting X-rays in the process.

Supposedly Nothing Can Escape from a Black Hole, Yet Astronomers