The age of quasars
Supermassive black holes feed at their most furious, lighting the universe's brightest beacons.
- When
- Known to
- ± 500 million years
- Era
- Galaxy Assembly, Stelliferous
Around redshift 2 to 3, quasar activity peaks: black holes are being fed by abundant cold gas and galaxy mergers are frequent. The energy released blows gas out of host galaxies and throttles their own star formation, a feedback loop now thought to explain why the largest galaxies stopped growing. Quasar numbers decline steeply afterwards as the fuel runs out.