COLD QUASARS

Quasars are the energetic centers of young galaxies, powered by a supermassive black hole that is surrounded by a disc of hot material swirling inward. These turbulent whirlpools energetically fling matter and radiation outward--allowing us to observe them--which can be bad news for the host galaxy. To form stars, a galaxy needs cold gas that can clump together, not gas that's heated up and swept away by a raging black hole. So quasars are thought to signal a downturn in a galaxy's ability to form stars. A set of galaxies that contain both violent quasars and cold pools of gas were found, meaning theses galaxies might still be capable of a making new stars. Bright blue, luminous quasars with cold signatures were also discovered. That implies the quasars have blown away the material immediately around them but haven't swept the gas and dust entirely out of the galaxy yet. It is theorized that cold quasars are yet another, shorter intermediate phase lasting 10 million to 100 mmillion years. This cosmically brief period could explain why quasars seem novel: They're simply not around long enough to show up in big numbers.