0 the centre of a galaxy (= group of stars) that is very far away, producing large amounts of energy
There were also serious concerns regarding the idea of cosmologically distant quasars.
Quasars show the locations where massive black holes are growing rapidly (via accretion).
This would mean that a quasar varying on a time scale of a few weeks can not be larger than a few light-weeks across.
Gravitational lensing was first observed in 1979, in the form of a quasar lensed by a foreground galaxy.
This pair provide evidence for the theory that quasars are switched on by galactic collisions.
This early burst of star formation is thought to have made a protogalaxy's luminosity comparable to a present day starburst galaxy or a quasar.
Such information as there is about the host galaxies of radio-loud quasars and blazars suggests that they are also hosted by elliptical galaxies.
It has been called the naked quasar and the quasar without a home because it appears to lack a host galaxy.