Question

What are the different death scenarios for a black hole? I know they can evaporate through Hawking radiation - but is there any other way? What if you just kept shoveling more and more mass and energy into the black hole?

Answer 1

Hawking radiation is a very slow process of the black hole losing energy and shrinking. If you counter this by supplying a little bit of matter or energy falling into the black hole you can easily overcome it and sustain the black hole.

Other than Hawking radiation I don't think there is any known process for black holes to shrink. The area theorem in classical general relativity states that the area of black hole horizon always increases in any physical process. So at least classically there is no way for black holes to die, or even shrink a little. Hawking radiation evades that because it is a quantum process (which is also why it is a slow process).

As for the final stage of the evaporation, I think the honest answer is nobody knows. The logical possibilities are either the black hole shrinks to nothing and disappears, or it leaves behind some long-lived "remnant". Either one of this possibilities has its strong and weak points, but ultimately you'd need to know more about a quantum theory of gravity to know for sure.