Science & Technology
Number of Giant Radio Galaxies
- 12 Sep 2020
- 2 min read
Why in News
Indian Researchers working on giant radio galaxies (GRG) at Inter-University Centre for Astronomy and Astrophysics (IUCAA) Pune, India and Leiden University, Netherlands, have found nearly 400 new GRGs.
- GRGs are large single structures in the universe.
Key Points
- Radio Galaxies: The universe has billions of galaxies and almost all have supermassive black holes at the centre.
- Some of these black holes are active and produce jets travelling almost at the speed of light.
- A black hole is a place 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.
- These jets are visible in radio light or at radio wavelengths of the electromagnetic spectrum.
- Such galaxies, which have active black holes shooting high-speed jets, are called radio galaxies.
- A radio galaxy is a strong source of electromagnetic radiation or radio waves.
- They are extremely weak in radio luminosity making it difficult for even a sensitive radio telescope to detect them.
- Some of these black holes are active and produce jets travelling almost at the speed of light.
- Giant Radio Galaxies: When some of these radio galaxies grow to enormous sizes, bigger than 33 lakh light years across, they are called giant radio galaxies (GRGs).
- GRGs were discovered in 1974 and until 2016, only about 300 GRGs were known. The latest findings indicate that they are over 800.
- It is not clearly understood how some objects grow to such large scales and what is the fuel of their respective black holes.
- The length of jets indicates how powerful and active a black hole is as well as about the environment density of black holes.
- Significance: The study of GRGs gives important clues to unveiling how these massive black holes accrete mass and the efficiency with which they produce the magnificent jets.
