Researchers have discovered three supermassive black holes from so many galaxies that merge to form a triple active galactic nucleus, a compact region at the center of a newly discovered galaxy that has a much higher luminosity than normal, the Department of Science and Technology he said on Friday.

This rare occurrence in the nearby universe indicates that the small merged clusters are ideal laboratories for detecting multiple accumulating supermassive black holes and increases the chance of detecting such rare occurrences.

“Supermassive black holes are difficult to detect because they do not emit light. But they can reveal their presence by interacting with their environment, ”said the DST.

When surrounding dust and gas falls on a supermassive black hole, some of the mass is swallowed up by the black hole, but some of it is converted into energy and emitted as electromagnetic radiation that makes the black hole appear very luminous. . “They are called active galactic nuclei (AGN) and they release huge amounts of ionized particles and energy into the galaxy and its surroundings. Both ultimately contribute to the growth of the environment around the galaxy and ultimately to the evolution of the galaxy itself, ”he said.

A team of researchers from the Indian Institute of Astrophysics consisting of Jyoti Yadav, Mousumi Das, and Sudhanshu Barway along with Francoise Combes from the College de France, Chaire Galaxies et Cosmologie, Paris, while studying a pair of known interacting galaxies, NGC7733 and NGC7734, detected Unusual emissions from the center of NGC7734 and a large, bright cluster along the northern arm of NGC7733. Their investigations showed that the group moves with a different speed compared to the galaxy NGC7733 itself.

“The scientists meant that this group was not part of NGC7733; rather, it was a separate little galaxy behind the arm. They named this galaxy NGC7733N, ”said the DST.

This study, published as a letter in the journal Astronomy and Astrophysics, used data from the Ultraviolet Imaging Telescope (UVIT) aboard India’s first ASTROSAT space observatory, 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.

The UV and H-alpha images also supported the presence of the third galaxy by revealing star formation along with tidal tails that could have formed from the merger of NGC7733N with the larger galaxy. Each of the galaxies harbors an active supermassive black hole at its core and thus forms a very rare triple AGN system.

According to the researchers, a major factor that impacts galaxy evolution is the interactions of galaxies that occur when galaxies move close to each other and exert tremendous gravitational forces on each other. During such galaxy interactions, the respective supermassive black holes can move closer to each other. Dual black holes begin to consume gas from their surroundings and become dual AGN.

The IIA team explains that if two galaxies collide, their black holes will also move closer, transferring kinetic energy to the surrounding gas. The distance between the black holes decreases over time until the separation is about one parsec (3.26 light years). The two black holes cannot lose any more kinetic energy to get even closer and merge. This is known as the trailing parsec problem.

The presence of a third black hole can solve this problem. The two merging black holes can transfer their energy to the third black hole and merge with each other, the DST said. Many AGN pairs have been detected in the past, but triple AGNs are extremely rare and only a few have been detected before using X-ray observations. However, the IIA team hopes that these triple AGN systems will be more common. in small groups of galaxies that merge. Although this study focuses on only one system, the results suggest that the small merged clusters are ideal laboratories for detecting multiple supermassive black holes, he added.