Observations from the CSIRO’s Australia Telescope Compact Array have confirmed the existence of the first known “middleweight” black hole, three years after it was first discovered.


Dubbed HLX-1 (“hyper-luminous X-ray source 1”), the middle weight black hole lies in a galaxy known as EST 243-49, about 300 million light-years away.  It was discovered in 2009 by chance, when scientists found it stood out as a very bright X-ray source.


Prior to the discovery of HLX-1, scientists had only ever confirmed the existence of supermassive black holes, ones a million to a billion times the mass of the Sun, and stellar mass black holes, ones three to thirty times the mass of the Sun.


Research conducted so far indicates the black hole is likely to be between 20,000 to 90,000 times the mass of our Sun.


"We don't know for sure how supermassive black holes form, but they might come from medium-size ones merging. So finding evidence of these intermediate-mass black holes is exciting,” CSIRO’s Dr Ron Ekers said.


The middleweight black hole expels extreme temperatures and shines X-rays after to consumes a gas from a star or gas cloud.


"A number of other bright X-ray sources have been put forward as possibly being middleweight black holes. But all of those sources could be explained as resulting  from lower mass black holes," Dr Farrell said. "Only this one can't. It is ten times brighter than any of those other candidates. We are sure this is an intermediate-mass black hole — the very first,” Dr Ekers said.


A team of CSIRO scientists have been studying the black hole since 2010.


"From studying other black holes we know that sucking in the gas creates X-rays, but there's then a sort of reflux, with the region around the black hole shooting out jets of high-energy particles that hit gas around the black hole and generate radio waves," Dr Sean Farrell, an ARC Postdoctoral Fellow at the University of Sydney said.