What is an Active Galactic Nucleus (AGN)?

28-09-2024

10:07 AM

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What is an Active Galactic Nucleus (AGN)? Blog Image

Overview:

Researchers from the Indian Institute of Astrophysics (IIA) recently found evidence of an interaction between a radio jet emitted from a special kind of galaxy called Active Galactic Nuclei (AGN) and the surrounding interstellar medium.

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