Astronomers now think supermassive black holes at the heart of what are called "active galaxies" may explain many of the most violent phenomena seen anywhere in the universe-such as "quasars", or "quasi-stellar" objects.
If the black hole is in a very rich material environment, lots of stars, or gas or whatever else might be around, then that's fuel that can fall onto the black hole and through the process of heating result in high emission. If the black hole has either already vacuumed up-giant vacuum cleaner-all that extra material or is in an environment where there isn't a lot of extra material then there is no fuel to be sucked into the black hole, no matter that can be sucked down and heated up, and so it does not emit so much. So in that sense the ecology of the environment affects the way the black hole works.
Assoc. Dir., High Energy Astrophysics Div.
Harvard-Smithsonian Center for Astrophysics