Supermassive black holes, which likely reside at the centers of virtually all galaxies, are unimaginably dense, compact regions of space from which nothing—not even light—can escape. As such a black hole, weighing in at millions or billions of times the mass of the Sun, devours material, it is surrounded by a swirling disk of gas. When gas from this disk falls towards the black hole, it releases a tremendous amount of energy. This energy creates a brilliant and powerful galactic core called a quasar, whose light can greatly outshine its host galaxy.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/nasaswebbtos.jpg)
Source:
https://phys.org/news/2020-08-space-telescope-quasars-host-galaxies.html