Astronomy

Giant explosion in a black hole

Print edition : March 27, 2020

Evidence for the biggest explosion seen in the universe comes from a combination of X-ray data from Chandra and XMM-Newton, and the Murchison Widefield Array and Giant Metrewave Telescope, as shown here. The eruption is generated by a black hole located in the cluster's central galaxy, which has blasted out jets and carved a large cavity in the surrounding hot gas.

AN international team of astronomers from the United States, Australia and New Zealand has detected the biggest explosion seen in the universe from a black hole in a distant galaxy cluster hundreds of millions of light years away. Data from the Indian Giant Metrewave Radio Telescope (GMRT) of the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research also played a role in this discovery.

“In some ways, this blast is similar to how the eruption of Mt St. Helens in 1980 ripped off the top of the mountain,” said Simona Giacintucci of the Naval Research Laboratory in Washington, D.C., and lead author of the study. “A key difference is that you could fit fifteen Milky Way galaxies in a row into the crater this eruption punched into the cluster's hot gas.”

Besides radio data from the GMRT, the study used X-ray data from the National Aeronautics and Space Administration’s (NASA) Chandra X-ray Observatory and the European Space Agency’s XMM-Newton, and radio data from the Murchison Widefield Array (MWA) in Australia. The outburst occurred in the Ophiuchus galaxy cluster, which is about 390 million light years from the earth.

Galaxy clusters are the largest structures in the universe held together by gravity, containing thousands of individual galaxies, dark matter and hot gas.

In the centre of the Ophiuchus cluster, there is a large galaxy that contains a supermassive black hole. According to the scientists, this black hole is probably the source of this gigantic eruption.

Although black holes are famous for pulling material towards them, they often expel prodigious amounts of material and energy. This happens when matter falling towards the black hole is redirected into jets, or beams, that blast outward into space and slam into any surrounding material.

Chandra observations reported in 2016 first revealed hints of the giant explosion in the Ophiuchus galaxy cluster in the form of an unusual curved edge in the cluster image. They considered whether this represented part of the wall of a cavity in the hot gas created by jets from the supermassive black hole. However, they discounted this possibility, in part because a huge amount of energy would have been required for the black hole to create a cavity this large.

The latest study by Simona Giacintucci and her colleagues shows that an enormous explosion did, in fact, occur. First, they showed that the curved edge was also detected by XMM-Newton, thus confirming the Chandra observation. Their crucial advance was the use of new radio data from the MWA and archived GMRT data from the Ophiuchus cluster to show the curved edge is indeed part of the wall of a cavity because it borders a region filled with radio emission. This emission is from electrons accelerated to nearly the speed of light. The acceleration likely originated from the supermassive black hole.

”The radio data fit inside the X-rays like a hand in a glove,” said co-author Maxim Markevitch of NASA. “This is the clincher that tells us an eruption of unprecedented size occurred here.”

The amount of energy required to create the cavity in Ophiuchus is about five times greater than the previous record holder, MS 0735+74 and hundreds and thousands of times greater than typical clusters. The results of the study were recently published in “The Astrophysical Journal”.

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