X-rays from Black Holes

Huh? Well, yes, black holes are "black" because their gravity is so strong that any light emitted from inside them can't escape. However, light can be emitted from outside black holes, and in fact it often is - it believed that many of the most luminous objects in the universe (quasars) are powered by material falling into a black hole. A recent study by RXTE suggests that the X-ray emitted by these objects is not from material falling into the black hole, but material flowing away from the black hole very rapidly in a narrow cone, called jets (go here for details). Very interesting indeed. To learn more about RXTE, listen to this interview I broadcast a while back.