Britannica
Sources used in this answer
How long does a typical episode of quasar activity last?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Quasar
Six quasar host galaxies, as observed by the Hubble Space Telescope.
Shown are apparently normal, solitary galaxies (left), colliding galaxies (centre), and merging galaxies (right).
Current scientific estimates indicate that quasar activity is episodic in nature. A typical individual episode of quasar activity is estimated to last approximately one million years, while the total lifetime of a quasar is estimated to be around 10 million years.1
This activity occurs as a central black hole accretes gas at a high rate, a process that may be triggered by a galactic merger. Eventually, this activity ceases, leaving behind a dormant massive black hole within the host galaxy.1