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Astronomers discover first-ever “middleweight” black hole

HLX-1 was discovered by chance in 2009 when astronomers stumbled upon bright amount of X-Rays emitting from it.

A team of international astronomers have unearthed the first "middleweight" black hole currently known to exist in the universe.

Dubbed Hyper-Luminous X-ray Source 1 (or HLX-1 for short), the black hole was spotted with Australia’s CSIRO radio telescope in ESO 243-29, a galaxy just a mere 300 million light-years from Earth.

HLX-1 was discovered by chance in 2009 when astronomers stumbled upon bright amount of X-Rays emitting from it.

"This is the first object that we're really sure is an intermediate-mass black hole," said Dr Sean Farrell, an ARC Postdoctoral Fellow at the University of Sydney and a member of the research team.

He added, "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."

“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."

Dubbed Hyper-Luminous X-ray Source 1 (or HLX-1 for short), the black hole was spotted with Australia’s CSIRO radio telescope in ESO 243-29, a galaxy just a mere 300 million light-years from Earth.

The new middleweight black hole
Prior to this discovery, black holes were thought to exist in “small stellar varieties” that are three to thirty times heavier than our sun, and “supermassive black holes” that are equal to millions of solar masses.

The extra large black holes that are found in most galaxies can rip apart and stars. The new middleweight black hole is between these two types.

Going by the brightness of the X-ray and radio flares, the team placed an upper limit of the black hole to be up to 90,000 solar masses. However, experts believe for a number of reasons, a lower figure, equal to the matter of around 20,000 suns is more likely.

Farrell stated, "From the radio emissions released by our intermediate mass black hole HLX-1, we can also calculate its approximate size. So we've been able to refine our estimate of how big HLX-1 is to between around 9 x 103 times the size of our sun and 9 x 104 times the size of our sun.

"It's further proof that HLX-1 is indeed sized as an intermediate mass black hole."

May explain giant black holes
It is thought that the rare find could help scientists understand how supermassive black hole formed and what determines their size.

CSIRO’s Dr. Ron Ekers said, “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.”

Astronomers are also looking for signs of disturbance around the site that would provide evidence that HLX-1 may have been the central black hole of a low-mass "dwarf" galaxy that has since been engulfed by ESO 243-49.

Study leader, Natalie Webb, of the Centre d'Etude Spatiale des Rayonnements in France says, "I am very excited that we have finally found the observational evidence to substantiate these theoretically proposed objects.”