An astronomer at The University of Alabama is part of an international team of researchers who found a mid-sized black hole, a cosmic oddity in observations of the universe.
The finding, which demonstrate an effective method to detect this class of black holes, was announced today in the journal Nature Astronomy.
Two types of black holes are well-known. Massive stars create stellar-mass black holes when they die, while galaxies host supermassive black holes at their centers, with masses equivalent to millions or billions of Suns.
Between these extremes are intermediate-mass black holes. They could grow into supermassive black holes as they take in more mass from stars and cosmic particles that pass too close, but few robust candidates have been found.
“It’s a class of black of hole that we don’t have a lot of data evidence they exist,” said Dr. Jimmy Irwin, UA associate professor of astronomy and physics. “If we understand how intermediate-mass black holes form, we can understand how large black holes form.”
Irwin, who has a background in these types of black holes, was an adviser for a team of researchers using data from the European Space Agency’s XMM-Newton X-ray space observatory, as well as NASA’s Chandra X-Ray Observatory and Swift X-Ray Telescope, to find a rare telltale sign of activity. They detected an enormous flare of radiation in the outskirts of a distant galaxy, thrown off as a star passed too close to a black hole and was subsequently devoured.
The data showed the star likely began falling into the black hole in October 2003 in observations from Earth, producing a burst of recordable and visible energy that tapered off over the next decade, Irwin said.
Such star-triggered outbursts are rare for this type of black hole, so the discovery suggests many more might lurk in a dormant state in galaxy peripheries across the local universe.