Black holes are the cosmic gluttons, consuming anything that approaches too closely, even light.
Now, a team of worldwide researchers has identified a
supermassive black hole that devours the mass of one Earth every second.
By observing other light objects billions of years old, the
scientists determined that the newly found behemoth was the brightest and
fastest-growing supermassive black hole of the previous nine billion years
(that we know of).
This dazzling cosmic beast, located in the constellation
Centaurus, is more than 500 times bigger than the supermassive black hole at
the centre of our own galaxy.
The results, which are presently being reviewed, were
published in a physics academic journal last week.
"People have been looking for these kinds of objects
since the 1960s," said lead author Christopher Onken, an astronomer at the
Australian National University.
"And somehow, this one seemed to have escaped all our
previous efforts to find it."
While searching the Milky Way for nearby pairs of binary
stars — stars that circle the same centre of mass — the team came onto the
strange object.
They were using the SkyMapper telescope at Siding Spring
Observatory near Coonabarabran, between the New South Wales areas of Central
West and North West Slopes.
Adrian Lucy, a PhD candidate at Columbia University in New
York, discovered over 200 possibilities for binary stars, but according to Dr.
Onken, there was something peculiar about them.
One of them turned out to be unlike a binary system in every
way.
To get a closer look at the peculiar object, the crew travelled
to Cape Town's South African Astronomical Observatory's 1,9-meter telescope.
Here, they were able to examine the different wavelengths of
light emitted by SMSS J114447.77-430859.3, or J1144 for short.
"You really see the detailed fingerprints of what's
making up these objects," Dr Onken said.
And it did not resemble a giant star in any way.
Instead, the object featured brilliant lines showing that
gas was flowing very quickly, indicating that it was propelled by a
supermassive black hole.
Several of the brightest objects in the sky, quasars, are
powered by supermassive black holes, which have a mass of millions or billions
of Suns.
From Earth, these brilliant objects resemble stars, but
their light originates from the accretion disc, a ring of gas, dust, and stars
that swirls around the black hole.
As this material is pulled into the black hole's gaping
mouth by its enormous gravitational attraction, it becomes very hot and
produces blinding light.
"The gas is kind of funnelling down into a pancake
shape, and that material then heats up through friction," Dr Onken said.
Like a ball rolling down a hill, the material accelerates as
it approaches the event horizon of a black hole — the point from which not even
light can escape — releasing its potential energy.
"Eventually all that stuff falls into the black hole
past the event horizon, adding to the mass of the black hole as it does
so."
This bright, fast-moving cloud of gas enabled Dr. Onken and
his colleagues to estimate the supermassive black hole's mass at three billion
Suns.
In comparison, Sagittarius A*, the supermassive black hole
at the centre of our galaxy, has a mass of around 4 million Suns.
And although J1144 was fainter than previous quasars
discovered in the last 60 years, it was still far more distant and brighter than
other objects of the same age.
"That was very exciting because these are pretty
unusual finds," Dr Onken said.
In addition, the scientists analysed J1144's brightness over
the last 45 years by analysing its appearance in earlier data sets.
They discovered that the brightness of the enormous quasar
remained constant throughout time, suggesting that its black hole was
continually consuming gas and everything else that came its way.
Michael Cowley, an astronomer at the Queensland University
of Technology, said that the supermassive black hole's size indicated that it
was most likely related with a huge galaxy.
"Usually you'll find that the more massive the black
hole, the more massive the galaxy is as well," said Dr Cowley, who was not
involved in the study.
Keep an eye out for J114 just north-west of the Southern
Cross.(Supplied: Christian Wolf/ANU/IAU) |
This quasar's brightness is about 7,000 times brighter than
all of the light in the Milky Way, making it visible from your backyard with
the right telescope.
Dr. Onken recommended a telescope with a diameter of 30 to
40 centimetres and a camera capable of lengthy exposures.
J1144 is situated in the sky approximately north-west of the
Southern Cross, emanating from the constellation Centaurus.
"It's just right overhead at sunset at this time of
year," Dr Onken said.
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