I What Causes High Energy Radiation Emissions from Black Holes?

[richard lareva]

My understanding is that once light or anything else crosses the event horizon, it will not re-emerge. However, we detect high energy beams of radiation coming from opposite sides of some of the celestial bodies that I have been told are types of black holes. Obviously I'm missing something here.

 

[phyzguy]

The radiation we see coming from black holes is emitted from outside the event horizon. As gas falls into the black hole, it gains gravitational potential energy and gets hot, causing it to radiate. The radiation is emitted before the gas crosses the event horizon.