Quasars
- Quasars, or quasi-stellar objects, are
Extremely luminous star-like sources of radiation with very high redshifts
- Quasars were first discovered in the 1960s due to their strong radio emissions but were also notable for their
- High luminosities
- Extremely large redshifts
- Small size
Formation of Quasars
- After the discovery of supermassive black holes at the centres of galaxies, astronomers were able to determine that quasars are a type of active galactic nucleus, meaning
- They are supermassive black holes surrounded by an accretion disc of matter
- They are found at the centre of extremely distant galaxies
- When they become active, i.e. when matter falls into it, they become quasars
Structure of a Quasar
The quasar features a black hole surrounded by an accretion disk and emits jets of radiation
- As matter falls into the black hole, jets of radiation are emitted from the poles
- The equivalent of 100 solar masses of matter can fall into a quasar each year
- The gravitational potential energy of infalling matter is transferred to electromagnetic radiation
- Now it is known that quasars are strong emitters of all wavelengths, not just radio waves
Redshift of Quasars
- Quasars are thought to be some of the most distant measurable objects in the known universe
- This is evidenced by the extremely large redshifts they show
- This allows astronomers to see very far back to an early Universe as it was not long after the Big Bang
