Middleweight black hole found

In recent decades, astronomers have found good evidence for supermassive black holes – such as the one believed to reside in the center of our Milky Way galaxy, and many other galaxies. Supermassive black holes have a million to a billion times the mass of our sun. What’s more, astronomers have evidence for stellar mass black holes, three to 30 times our sun’s mass. But now outbursts of super-hot gas observed by a telescope in Australia have provided evidence for a middleweight black hole, according to a paper published today (July 6, 2012) in Science Express.

The object has been labeled HLX-1 (“hyper-luminous X-ray source 1”) by astronomers. It lies in a galaxy called ESO 243-49, about 300 million light-years away. The arrow in the image below points to it.

This report comes from CSIRO, the Commonwealth Scientific and Industrial Research Organisation, is Australia’s national science agency. Dr Sean Farrell, an ARC Postdoctoral Fellow at the University of Sydney and a member of the research team, which included astronomers from France, Australia, the U.K. and the U.S., said:

This is the first object that we’re really sure is an intermediate-mass black hole.

The evidence comes from bright X-ray and radio flares from this object, which are created as mass from a companion object – probably an ordinary star – which is ripped away and fed into the black hole. These emisions have allowed the astronomers to put an upper limit on the mass of the black hole of 90,000 times the mass of our sun. However, Dr Farrell says that this is a conservative estimate, and for a variety of reasons a lower figure of around 20,000 solar masses is more likely.

Read more about this story from CSIRO

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