First Radio Waves Detected From Middleweight Black Hole HLX-1
By Juliana Chan | Featured Research
July 11, 2012
Scientists have detected the first radio emissions from a ‘middleweight’ black hole, also the first of its kind to be discovered.
AsianScientist (Jul. 11, 2012) – Scientists have detected the first radio emissions from a ‘middleweight’ black hole, also the first of its kind to be discovered.
Called HLX-1 (hyper-luminous X-ray source 1), the black hole lies in a galaxy called ESO 243-49 about 300 million light-years away. HLX-1 was discovered by chance in 2009 because it stood out as a very bright X-ray source.
Before it was found, astronomers had good evidence for only supermassive black holes — ones a million to a billion times the mass of the Sun — and “stellar mass” ones, three to thirty times the mass of the Sun.
The size of HLX-1 lies in between these two sizes at around 20,000 times the mass of our sun which classifies it an intermediate mass black hole.
“Black holes are areas where the matter is so densely squeezed into a small space, that it makes gravity pull strongly enough to stop light from escaping,” explained Dr. Sean Farrell, an ARC Postdoctoral Fellow at the University of Sydney.
As gas from a star or gas cloud is being sucked into a black hole, it is heated to extreme temperatures and shines in X-rays; This is then followed by a subsequent reflux in the region around the black hole, shooting out jets of high-energy particles and generating radio waves.
By studying the source’s X-ray emission, the researchers predicted two occasions when it should also be brightening in radio waves — and they were right both times.
“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,” 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.”
So why have the team found only this one confirmed intermediate-mass black hole? It may be linked to how ‘hungry’ these black holes are, the researchers explain.
“There maybe lots of others out there that are not currently feeding, and so are not detectable, or are feeding at a very low rate, so they don’t stand out as intermediate-mass black holes,” said CSIRO’s Dr Ron Ekers.
The research team is now looking for other signs of disturbance around the site of the black hole, such as gas streams, which would give evidence of star formation about HLX-1.
The article can be found at: Webb N et al. (2012) Radio Detections During Two State Transitions of the Intermediate Mass Black Hole HLX-1.