Why do astronomers believe black holes are the source of an AGN's energy?

Question

1. It's expected since black holes have been found at the center of most galaxies.

2. Radio jets are seen in many AGN and those only come from black holes.

3. black holes have been observed directly there.

4. only black holes can produce so much energy in such a small place.

Answer 1

ok i'm not even sure anymore.. here's an article you figure it out lol....

http://www.space.com/scienceastronomy/07...

first i thought it was 1, then i found this article and thought it was 2, now reading more i think ti's 3....

Answer 2

4. is the best answer