Astronomers from the University of Michigan have found a new super-massive black hole in the center of a galaxy. This discovery is special because this is the smallest black hole ever observed up to date.
The black hole is surrounded by a disk of hot gas, and a large torus of cooler dust and gas and dust. The fluorescence of iron atoms excited by X-rays coming from the hot gas disk creates a light blue ring on the back of the torus.
The new discovery was named RGG 118. This supermassive black hole is actually a dwarf, disc galaxy at a distance of 340 million light years from our solar system. The discovery of astronomers from the University of Michigan (U-M) is the smallest black hole ever observed. It has just 50,000 times the mass of the sun, which makes it more than two times smaller than any black hole known today. Compared with the largest black holes known to astronomers, RGG 118 is a full 100,000 times less massive.
According to the assistant professor of astronomy in U-M College of Literature, Science and Arts Elena Gallo, this is "a teeny supermassive black hole". But despite its small size it's consuming material at a rate similar to the most active black holes.
According to astronomers, black holes can be of two types. The "supermassive" type has a mass typically at least 100,000 time the mass of our sun and the "stellar mass" type has just the mass of several suns. Black holes form when large stars collapse.
Scientists believe that our Milky Way, as well as every large galaxy, has a supermassive black hole at its core. The recently discovered black hole is the first one to be identified in a dwarf galaxy. This discovery comes to give astronomers a window to a younger universe, according to the first author of the paper, the U-M doctoral student Vivienne Baldassare. The study was published in the Astrophysical Journal Letters.
The black hole at the center of the young and small galaxy RGG 118 is an active one, unlike the black holes present in most present-day galaxies, like our Milky Way. The small black hole RGG 118 is swallowing gas, dust and stars.
The team of astronomers used for their observations the 6.5 meter Clay Telescope in Chile and NASA's Chandra X-ray Observatory. The new black hole was found through the Sloan Digital Sky Survey.
Astronomers have yet to figure out how supermassive black holes form. Some scientists hypothesize that they form from giant clouds of gas, while others think they descend from large stars about 100 times the mass of our sun.
