Astronomers find clues to a large black hole at the center of the Milky Way

Japanese astronomers have found evidence of a large black hole near the center of the Milky Way with a radio telescope. This black hole is believed to have a mass 100,000 times that of our Sun.

The scientists pointed the powerful telescope at an elliptical gas cloud near the center of the Milky Way galaxy. The various gases, including the toxic hydrogen cyanide and carbon monoxide, move at very different speeds; this differs from the velocities normally observed in other gas clouds.

Observations from the telescope show that the gas molecules are attracted and propelled by an enormous gravitational pull. The most likely source of this, according to computer models, is a black hole with a diameter of up to 1.4 trillion kilometers. The black hole may be part of an ancient dwarf galaxy, which was swallowed up when the Milky Way galaxy was formed billions of years ago.

This makes this possible black hole the second largest discovered black hole in the Milky Way Galaxy. At its center is a gigantic black hole with a mass 4 million times that of our sun, called the Sagittarius A star. The gas cloud containing the newly discovered black hole is located 200 light-years from the center of the Milky Way and is 150 trillion kilometers wide.

This is the first time such a medium-sized black hole has been discovered. Scientists say there are over 100 million smaller black holes in the Milky Way galaxy, 60 of which have been discovered so far. These arise, among other things, when certain stars explode at the end of their lifespan. It is still unknown how many larger black holes, such as the Sagittarius A star and the newly discovered black hole, exist, and how they form. One theory is that the larger black holes are formed by several smaller ones and that they grow in part due to the attraction of matter near the black hole, via the enormous gravity.

The observations were made with the Atacama Submillimeter Telescope Experiment, a radio telescope located in the Chilean Atacama Desert, at an altitude of 4800 meters. The research is published under the title Millimeter-wave emission from an intermediate-mass black hole candidate in the Milky Way in the journal Nature Astronomy. The research team was led by Tomoharu Oka of Japan’s Keio University.