Ionized Nebulae in AGN: Cosmic Fluorescent Lamps Powered by Massive Black Holes

The luminous radiation from growing supermassive black holes (known as "active galactic nuclei" or "AGN") is effective at photoionizing the gas clouds in the host galaxy, producing huge ionized nebulae (or "narrow-line regions") glowing like fluorescent lamps that are thousands of light-years across. We are investigating the physical processes that form these nebulae, by measuring their physical sizes using optical spectroscopy from the Southern African Large Telescope (SALT) and MDM Observatory.