Smallest Supermassive Black Hole Discovered by the Astronomers

Astronomers from the University of Michigan discovered a ‘tiny’ supermassive black hole in the center of RGG118, a dwarf galaxy that is about 340 million light-years away.

The results of this discovery were published in the Astrophysical Journal Letters by Vivienne Baldassare, the first author of the scientific paper. The team at the University of Michigan employed the services of 6.5m Clay Telescope in Chile and Chandra’s X-ray Observatory in NASA to observe RGG118. This galaxy was first identified while conducting the Sloan Digital Sky Survey.

Supermassive Blackhole

The newly discovered black hole is termed ‘tiny’ because it is only 50,000 times the size of the sun and over two times smaller than a similar known object. Additionally, it is 100, 000 times smaller than the biggest black hole found to date! Despite its ‘tiny’ size, this black hole is using up material at a rate comparable to that of the much larger ones.

It is believed that at the core of every big galaxy, our own Milky Way included, there is a supermassive black hole. Astronomers hold two opinions on the formation of these black holes. One hypothesis states that gigantic gas clouds ‘seed’ the black holes while another one states they have evolved from super-colossal stars believed to be 100 times as big as the sun.

The newly discovered black hole is the first one found at the center of a dwarf galaxy. This RGG18 dwarf galaxy is so small that it is most unlikely that it has merged with any other galaxy, and this aspect makes the discovery significant. It gives a new window of opportunity for astronomers to learn more about a ‘younger’ universe. Astronomers believe that larger galaxies have been formed through mergers. Hence, these small galaxies could be analogous to galaxies of an earlier universe and might help the astronomers learn which of the two hypotheses is correct.


By investigating and studying the small galaxies and the interactions with their black holes, astronomers hope to gain more insight into the working of an earlier universe. The black holes of the present day galaxies, including our Milky Way, are dormant. The smaller galaxies such as the RGG118 are known to have active black holes that are still consuming gas, dust and stars. The active central black hole is in the process of shaping the history and helping in the evolution of the small galaxy by regulating the movement of gases and dust and temperature perhaps to form potential stars. Hence, this extremely significant discovery seems to be an ideal subject for investigation and enquiry to take a step forward in understanding as to how our universe came to be.