What is an Active Galactic Nucleus (AGN)?

About Active Galactic Nucleus (AGN):

• An AGN is an extremely bright central region of a galaxy that is dominated by the light emitted by dust and gas as it falls into a black hole.
• The extremely luminous central region is emitting so much radiation that it can outshine the rest of the galaxy altogether.
• AGNs emit radiation across the entire electromagnetic spectrum, from radio waves to gamma rays.
• This radiation is produced by the action of a central supermassive black hole that is devouring material that gets too close to it.
• A galaxy hosting an AGN is called an ‘active galaxy’.
• AGNs are the most luminous, persistent sources of electromagnetic radiation in the Universe. This means they can be used to discover distant objects. 
• Astronomers have also classified different types of AGN based on their observed characteristics.
  • The most powerful AGNs are known as quasars, which give rise to extremely luminous galactic centres.
  • A blazar is an AGN with a jet of light and energy that is pointed toward the Earth.

Q1: What is a black hole?

A black hole is a region in space where gravity pulls so much that even light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying. Because no light can get out, it is difficult to detect a black hole. The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together. Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity.

Source: IIA finds proof of interaction between radio jet, interstellar gas