Second largest black hole detected in Milky Way

Astronomers have detected signs of an invisible black hole with a mass 100 thousand times that of the Sun around the centre of the Milky Way.

The team assumes that this possible “intermediate mass” black hole is a key to understanding the birth of the supermassive black holes located in the centres of galaxies.

A team of astronomers led by Tomoharu Oka, a professor at Keio University in Japan, found an enigmatic gas cloud, called CO-0.40-0.22, only 200 light years away from the centre of the Milky Way.

The CO-0.40-0.22 unusual has a surprisingly wide velocity dispersion — the cloud contains gas with a very wide range of speeds.

The team found this mysterious feature with two radio telescopes, the Nobeyama 45m Radio Telescope in Japan and the ASTE Telescope in Chile, both operated by the National Astronomical Observatory of Japan.

The team observed CO-0.40-0.22 to obtain 21 emission lines from 18 molecules. The results show that the cloud has an elliptical shape and consists of two components — a compact but low density component with a very wide velocity dispersion of 100 km per second, and a dense component extending 10 light years with a narrow velocity dispersion.

There are no holes inside of the cloud. Also, X-ray and infrared observations did not find any compact objects. These features indicate that the velocity dispersion is not caused by a local energy input, such as supernova explosions.