Merger of three supermassive black holes discovered by Indian astrophysicists: All you need to know
Indian astrophysicists have discovered three supermassive black holes merging together to form a triple-active galactic nucleus. The three black holes have been discovered at the centre of a recently discovered galaxy.
In a major breakthrough, Indian astrophysicists have discovered three supermassive black holes merging together to form a triple active galactic nucleus. The three black holes have been discovered at the centre of a recently discovered galaxy that increases the possibility of further spotting such rare occurrences.
The study which was published as a letter in the Journal Astronomy and Astrophysics was primarily intended to investigate the nature of the nuclear emission from the galaxies in the interacting pair NGC 7733NGC 7734.
The researchers in the paper said that they have confirmed the existence of the third galaxy, NGC 7733N, in the NGC 773334 group. They added that it appears to overlap with the northern arm of NGC 7733.
Indian researchers discover three supermassive black holes from three galaxies merging together to form a triple active galactic nucleus in our nearby universe— PIB India (@PIB_India) August 27, 2021
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What is a Supermassive black hole?
A black hole is formed from the death of a star with such as a gravitational field that the matter gets sucked into the small space under it, trapping the light of the dead star.
Supermassive black holes are difficult to detect as they do not emit any light, however, they can reveal their presence by interacting with their surroundings.
When the dust and gas from the surroundings fall onto a supermassive black hole, some of the mass is swallowed by the black hole, however, some of it is converted into energy and is emitted as electromagnetic radiation that makes the black hole appear luminous.
They are called the Active Galactic Nuclei (AGN) and release a huge amount of energy and ionized particles into the galaxy and its environment.
Triple merging galaxy:
A team of researchers from the Indian Institute of Astrophysics (IIA) came upon the rare occurrence while studying a known interacting galaxy pair, NGC7733, and NGC7734.
They detected the unusual emissions from the center of NGC7734, as well as a large, bright clump along the northern arm of NGC7733. As the researchers dug deeper, they found that the clump has been moving with a different velocity in comparison to the galaxy NGC7733 itself, indicating that it was not part of the galaxy instead it was a small separate galaxy behind arm.
Researchers led by a team comprising Mousami Das, Jyoti Yadav, and Sudhanshu Barway from the Indian Institute of Astrophysics, used data from the Ultra-Violet Imaging Telescope (UVIT) onboard the first Indian Space Observatory ASTROSAT, infrared images from the optical telescope in South Africa, and the European Integral field optical telescope called MUSE mounted on Very Large Telescope (VLT) in Chile.
The researchers said in a statement that the UV and H-alpha images also supported the presence of the third galaxy by revealing the star formation along with the tidal tails, which could have formed from the merger of NGC7733N with the larger galaxy.
Interaction and merger of the galaxies: What do we know?
The interaction and the merger of the galaxies are the main drivers of galaxy evolution which leads to the growth of supermassive blackhole bulges and massive galaxies.
Interaction of the galaxies starts when they come close and exert tremendous gravitational forces on each other, during which, the supermassive black holes can get further close and the dual black holes start consuming gas from their surroundings and become dual AGN (Active Galactic Nuclear).
The paper mentioned that the galaxy interactions can also lead to triple merger systems, and if the SMBHs of the individual galaxies are accreting, a triple AGN system will form.
What happens during a collision between two galaxies?
The team from IIA explained that if two galaxies collide, their black hole 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 between them is around parsec (3.26 light-years).
The two black holes are then unable to lose any further kinetic energy in order to get even closer and merge, it is known as the final parsec problem.
However, the presence of the third black hole can solve this problem as the dual merging black holes can transfer their energy to the third black hole and merge with each other.