Final answer:
The accretion rate characterizes how fast a black hole accumulates matter, forming an accretion disk from which material spirals inwards due to gravitational attraction, heating up and emitting high-energy radiation before crossing the event horizon.
Step-by-step explanation:
The rate at which a black hole 'eats' or accumulates matter is known as the accretion rate. This process is characterized by the formation of an accretion disk around the black hole, where matter from a nearby star or other cosmic material spirals inward due to the black hole's intense gravitational pull.
As material falls towards the event horizon of the black hole, it heats up and emits high-energy radiation, such as X-rays, before ultimately crossing into the black hole where it cannot escape. It's important to note that while Hawking radiation is associated with black holes, it involves the theoretical emission of particles due to quantum effects near the event horizon, not the process of the black hole accreting matter.