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Merger of three jumbo black holes spotted

GS Paper 3

Topics Covered: Awareness in space.



A rare merging of three supermassive black holes has been spotted by a team of astrophysicists in India.


Key facts:

  • All three merging black holes were part of galaxies in the Toucan constellation.
  • The discovery was made using data from the Ultraviolet Imaging Telescope (UVIT) onboard the first Indian space observatory ASTROSAT, the European integral field optical telescope called MUSE mounted on the Very Large Telescope (VLT) in Chile and infrared images from the optical telescope (IRSF) in South Africa.


Important learning from this discovery:

  • Presence of third black hole solves the final parsec problem:

What is it?

If two galaxies collide, their black hole will also come closer by transferring the kinetic energy to the surrounding gas. The distance between the blackholes decreases with time until the separation is around a parsec (3.26 light-years). The two black holes are then unable to lose any further kinetic energy to get even closer and merge. This is known as the final parsec problem.


How presence of third black hole solves this problem?

The presence of a third black hole can solve this problem. The two can come closer when another black hole or a star passes by and takes away some of their combined angular momentum. Thus, the dual merging blackholes merge with each other in the presence of a third.


Significance of the discovery:

Many Active Galactic Nuclei (AGN, supermassive black hole at the centre of a galaxy) pairs have been detected in the past, but triple AGN are extremely rare, and only a handful has been detected before using X-ray observations.


What is a black hole?

  • A black hole is an object in space that is so dense and has such strong gravity that no matter or light can escape its pull. Because no light can escape, it is black and invisible.
  • There’s a boundary at the edge of a black hole called the event horizon, which is the point of no return — any light or matter that crosses that boundary is sucked into the black hole. It would need to travel faster than the speed of light to escape, which is impossible.
  • Anything that crosses the event horizon is destined to fall to the very centre of the black hole and be squished into a single point with infinite density, called the singularity.


Insta Curious:

There are supermassive blackholes, which are several million solar masses in size, at the centres of galaxies, and these are known as Active Galactic Nuclei. Learn more about them here.



Prelims Link:

  1. About the General Theory of Relativity.
  2. When was the first gravitational wave detected?
  3. LIGO- mission objectives, observatories and funding.
  4. What are event horizon and singularity in the context of a black hole?
  5. LIGO India- proposed site, partners and objectives.
  6. Where is Virgo locator located?

Mains Link:

Discuss the applications and significance of findings of the Laser Interferometer Gravitational-Wave Observatory (LIGO) detector.

Sources: the Hindu.