An ultracompact dwarf galaxy proved to be the smallest-known to contain a light-sucking supermassive black hole.
The recent finding suggests huge black holes may be more common in the universe than researchers previously believed, the University of Utah reported.
"It is the smallest and lightest object that we know of that has a supermassive black hole," Anil Seth, lead author of an international study of the dwarf galaxy published in Thursday's issue of the journal Nature said. "It's also one of the most black hole-dominated galaxies known."
To make their findings the researchers used the Gemini North 8-meter optical-and-infrared telescope and photos taken by NASA's Hubble telescope to discover the tiny galaxy M60-UCD1 contained a supermassive black hole. The researchers believe the finding indicates other super-compact dwarf galaxies may also contain black holes, and these galaxies may actually be pieces of larger ones that were torn apart during galactic collisions.
"We don't know of any other way you could make a black hole so big in an object this small," Seth said. "There are a lot of similar ultracompact dwarf galaxies, and together they may contain as many super-massive black holes as there are at the centers of normal galaxies."
Black holes are believed to be collapsed stars, or collections of them. Those with the mass of at least a million sun-like stars are believed to be supermassive. The black hole at the center of our galaxy is believed to be equivalent to about four million suns; the super-massive black hole at the center of M60-UCD1 is equal to about 21 million suns and takes up 15 percent of the galaxy's total mass.
"We believe this once was a very big galaxy with maybe 10 billion stars in it, but then it passed very close to the center of an even larger galaxy, M60, and in that process all the stars and dark matter in the outer part of the galaxy got torn away and became part of M60," Seth said. "That was maybe as much as 10 billion years ago. We don't know."
The researcher believes the galaxy may be in trouble.
"Eventually, this thing may merge with the center of M60, which has a monster black hole in it, with 4.5 billion solar masses - more than 1,000 times bigger than the supermassive black hole in our galaxy. When that happens, the black hole we found in M60-UCD1 will merge with that monster black hole," Seth said.
