GS Paper - 3 (Science and Technology)

Indian researchers have discovered three supermassive black holes from three galaxies merging together to form a triple active galactic nucleus (AGN), that has a much-higher-than-normal luminosity. The rare occurrence in the nearby universe indicates that small merging groups are ideal laboratories to detect multiple accreting supermassive black holes and increases the possibility of detecting such occurrences.


  1. Supermassive black holes are difficult to detect because they do not emit any light, but can reveal their presence by interacting with their surroundings.
  2. When the dust and gas from the surroundings fall onto a supermassive black hole, some of the mass is swallowed 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.
  3. A team of researchers from the Indian Institute of Astrophysics studying a known interacting galaxy pair, NGC7733, and NGC7734, detected unusual emissions from the centre of NGC7734 and a large, bright clump along the northern arm of NGC7733.
  4. The study used 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.
  5. According to the researchers, a major factor impacting galaxy evolution is galaxy interactions, which happen when galaxies move close to each other and exert tremendous gravitational forces on each other.