What is an active galactic nucleus?
Q: What is an active galactic nucleus?
A: An active galactic nucleus (AGN) is a compact region at the centre of a galaxy that radiates huge luminosity over the electromagnetic spectrum cause by mass dragged in by the gravitational pull of a supermassive black hole.
Q: In what wavebands is the electromagnetic radiation from an AGN observed?
A: The radiation from an AGN is observed in the radio, microwaves, infrared, optical, ultra-violet, X-ray and gamma ray wavebands.
Q: What is a galaxy hosting an AGN called?
A: A galaxy hosting an AGN is called an active galaxy.
Q: What can AGN be used for?
A: AGN can be used to discover distant objects.
Q: Why do all theories about the cosmos have to account for AGNs?
A: All theories about the cosmos have to account for AGNs because they are one of the basic facts about the universe and the most luminous and persistent sources of electromagnetic radiation.
Q: What are relativistic jets?
A: Relativistic jets are extremely powerful jets of plasma which come from some AGNs, notably radio galaxies and quasars.
Q: What is the length that the relativistic jets can reach in some AGNs?
A: The lengths of relativistic jets can reach several thousand or even hundreds of thousands of light years in some AGNs.
