Black Holes
- August 28, 2021
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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Black Holes
Subject – Science and Tech
Context – Indian astrophysicists spot rare merger of three jumbo black holes.
Concept –
- It refers to a point in space where the matter is so compressed as to create a gravity field from which even light cannot escape.
- The concept was theorized by Albert Einstein in 1915and the term ‘black hole’ was coined in the mid-1960s by American physicist John Archibald Wheeler.
- Usually, the black holes belong to two categories:
- One category ranges between a few solar masses and tens of solar masses.These are thought to form when massive stars die.
- The other category is of super massive black holes.These range from hundreds of thousands to billions of times that of the sun from the Solar system to which Earth belongs.
- In April 2019, the scientists at the Event Horizon TelescopeProject released the first-ever image of a Black Hole (more precisely, of its shadow).
The Event Horizon Telescope is a group of 8 radio telescopes (used to detect radio waves from space) located in different parts of the world. - Gravitational waves are created when two black holes orbit each other and merge.
- 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.
About the recent finding –
- A rare merging of three super massive black holes has been spotted by a team of astrophysicists from the Indian Institute of Astrophysics (IIA), working with Professor Francoise Combes from the Paris Observatory.
- This is only the third time such an event has been observed.
- The team were observing the merging of two galaxies — NGC7733 and NGC7734 — in the earth’s celestial neighbourhood when they detected unusual emissions from the centre of the latter and a curious movement of a large bright clump within it, having a different velocity than that of NGC7733. Inferring that this was a separate galaxy, the scientists named it NGC7733N.
- All three merging black holes were part of galaxies in the Toucan constellation.
- They are quite far away given that the earth’s nearest galactic neighbour — the Andromeda galaxy — is 2.5 million light years away.
Final parsec –
- In a press release, the team explains that if two galaxies collide, their black holes will also come closer by transferring the kinetic energy to the surrounding gas.
- The distance between the black holes decreases with time until the separation is around one parsec (3.26 light-years).
- The two black holes, however, are then unable to lose any further kinetic energy to get even closer and merge. This is known as the final parsec problem.
Many Active Galactic Nuclei (AGN), or super massive 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 have been detected before using X-ray observations.