A supermassive black hole with a mass of 40 billion times that of the Sun, which is considered the largest black hole ever identified so far, has been discovered within the Holm15A galaxy which is itself located in the Abell 85 cluster about 700 million light years away from us.
The researchers of the Observatory of the University of Munich (USM) and the Max Planck Institute for Extraterrestrial Physics (MPE) made the discovery by analyzing the photometric data collected by the Wendelstein Observatory and those of new high-resolution observations made by the Very Large Telescope (VLT).
The supermassive black hole is located right in the centre of the central galaxy of the cluster, since in this area the researchers noticed an area with a diffused light as large as the Large Magellanic Cloud, one of the satellite galaxies of the Milky Way. This very area made astronomers suspicious and made them think that it was a black hole with a very high mass.
The Abell 85 cluster is a group of more than 500 galaxies relatively far away so that astronomer Jens Thomas stresses the importance of this study because there are very few direct measurements of the supermassive black hole mass at such a distance. The determination of mass was made based on the movements of the stars circulating around the core of the Holm15A galaxy.
Astronomers came to the conclusion that it is a huge supermassive black hole of 40 billion solar masses, “many times larger than expected from indirect measurements, such as stellar mass or galaxy velocity dispersion,” as Roberto Saglia, another of the authors of the study, explains.
According to the astronomers, this enormous nucleus was formed through the fusion between two galaxies and the fusion of the two central supermassive black holes.