What term describes the observational signature of vigorous accretion onto a supermassive black hole at a galactic center?

Answer

An Active Galactic Nucleus (AGN)

The presence of an Active Galactic Nucleus (AGN) is cited as the direct observational evidence resulting from the intense feeding and energy generation caused by accretion onto a central supermassive black hole.

What term describes the observational signature of vigorous accretion onto a supermassive black hole at a galactic center?
Geologyprocessplanetmassaccretion