Astronomers Find Smallest Known Galaxy With a Supermassive Black Hole

Posted on September 17, 2014

Supermassive black hole at the center of M60-UCD1

Scientists have discovered the smallest known galaxy to have a supermassive black hole at its center. The black hole was found using data from NASA's Hubble Space Telescope and the Gemini North telescope on Hawaii's Mauna Kea. The black hole is located in the M60-UCD1 dwarf galaxy. An artist's interpretation of the black hole and galaxy is pictured above.

The black hole at the center of M60-UCD1 has five times the mass of the black hole at the center of the Milky Way. It has the mass of 21 million suns and makes up 15% of the mass of M60-UCD1. The Milky Way's central black hole has the mass of 4 million suns and makes up less than .01% of the Milky Way's total mass.

The M60-UCD1 galaxy has an amazing amount of stars. NASA says if you lived inside M60-UCD1 you could see at least 1 million stars with the naked eye. On Earth you can see only about 4,000 stars with the naked eye.

The astronomers believe the discovery of the supermassive black hole at the center of a tiny galaxy means that dwarf galaxies could be stripped remnants of galaxies that were once much larger.

University of Utah astronomer Anil Seth, lead author of the M60-UCD1 study published in Nature, says, "We don't know of any other way you could make a black hole so big in an object this small. There are a lot of similar ultracompact dwarf galaxies, and together they may contain as many supermassive black holes as there are at the centers of normal galaxies."

This video shows a simulation of how M60-UCD1 was formed from a much larger galaxy when it stripped stars from the orbiting galaxy during a process that took about 500 million years. Seth says astronomers don't know when this lengthy event took place but it could have been billions of years ago. Take a look:

The research paper on the black hole found in the ultra-compact dwarf galaxy is located here in the journal Nature.

Image: NASA, ESA, STScI-RCC14-41a