The ‘biggest explosion since the Big Bang’ has been detected by astronomers and it comes from a supermassive black hole in a galaxy 390 million light years away.
Astronomers from Curtin University in Australia used the new Murchison Widefield Array radio telescope to study the blast in the distance galactic core.
The extremely powerful eruption occurred hundreds of millions of years ago in the Ophiuchus galaxy cluster, and was five times as powerful as the previous ‘largest explosion’ record holder.
The Curtin team say there are a lot of questions to be answered about the ‘fossil’ remains of the explosion, adding ‘we don’t know why it’s so big’ or what caused it.
This image combines data from the Chandra X-Ray space telescope and the Murchison radio telescope array to show the explosion in different wavelengths. The pink circle is the blast radius and the outer blue area shows further remnants of the massive outburst
It was so powerful it punched a cavity in the cluster plasma – super-hot gas surrounding the black hole – big enough to fit 15 Milky Way Galaxies inside it.
Explosions from supermassive black holes are common and part of their normal cycle, according to the research team.
Most of the time the giant black holes are quiet and invisible but when material is falling into them they ‘blaze with radiation’.
It goes through a period of feeding where it gobbles up plasma from the cluster – this is then followed by periods of explosive outbursts where it shoots out jets of plasma when it is full.
Professor Melanie Johnston-Hollitt, lead author on the paper and an expert in galaxy clusters said it was ‘extraordinarily energetic’.
‘We’ve seen outbursts in the centres of galaxies before but this one is really, really massive,’ she said.
‘We don’t know why it’s so big but it happened very slowly like an explosion in slow motion that took place over hundreds of millions of years.’
She likened spotting the ancient remnants of such a massive explosion to discovering the first dinosaur bones.
‘It’s a bit like archaeology,’ she said.
‘We’ve been given the tools to dig deeper with low-frequency radio telescopes so we should be able to find more outbursts like this now.’
The team say it is a ‘very aged fossil’ of the most powerful outburst seen in any galaxy cluster studied by humans so far.
‘It may have aged out of the observable radio band because of the cluster asymmetry,’ the authors speculated in the paper.
They add that it is a very weak radio source but, given the size of the blast radius in the plasma, it should have been much more powerful in the past.
The age of the outburst is between 240 and 400 million years, as radio properties suggest it must have happened at least 240 million years ago and optical data indicates the upper limit to the age is 400 million years, Johnston-Hollitt said.
The giant cavity had been spotted by astronomers before – a team using X-Ray telescopes originally discovered the cluster plasma in 2008.
Johnston-Hollitt said they ‘dismissed the idea it could have been caused by an energetic outburst, because it would have been too big.’
Turns out they were wrong, the expert said: ‘It turns out it really is that. The Universe is a weird place’.
It wasn’t until they examined the same part of space using a radio telescope rather than an x-ray telescope that they realised it was a massive explosion.
‘The radio data fit inside the X-rays like a hand in a glove,’ said co-author Dr Maxim Markevitch, from NASA’s Goddard Space Flight Center.
‘This is the clincher that tells us an eruption of unprecedented size occurred here.’
The Murchison Widefield Array (MWA) is a low frequency radio telescope and is the first of four Square Kilometre Array (SKA) precursors to be completed. It allowed the team to dive deeper into the distance galaxy to uncover the secret
The finding underscores the importance of studying the Universe at different wavelengths, Johnston-Hollitt said.
‘Going back and doing a multi-wavelength study has really made the difference here,’ she said.
WHAT IS THE MURCHISON WIDEFIELD ARRAY?
The Murchison Widefield Array (MWA) is a low-frequency radio telescope.
It is the first of four telescopes that will make up the Square Kilometre Array (SKA) when it is completed.
A consortium of partner institutions from seven countries (Australia, USA, India, New Zealand, Canada, Japan, and China) financed the development.
It has been designed to look for ‘neutral atomic hydrogen emissions’ from the earliest days of the universe.
It will also study the Sun’s heliosphere, the Earth’s ionosphere and map the extragalactic radio sky.
Professor Johnston-Hollitt said the finding is likely to be the first of many.
‘We made this discovery with Phase 1 of the MWA, when the telescope had 2,048 antennas pointed towards the sky,’ she said.
‘We’re soon going to be gathering observations with 4,096 antennas, which should be ten times more sensitive.’
‘I think that’s pretty exciting.’
Lead author of the study Dr Simona Giacintucci, from the Naval Research Laboratory in the United States, said there was some similarity to a volcano on Earth.
She said the blast was similar to the 1980 eruption of Mount St. Helens, which ripped the top off the mountain.
‘The difference is that you could fit 15 Milky Way galaxies in a row into the crater this eruption punched into the cluster’s hot gas,’ she said.
The discovery was made using four telescopes around the world including two orbiting the planet.
They were NASA’s Chandra X-ray Observatory, ESA’s XMM-Newton, the Murchison Widefield Array in Australia and the Giant Metrewave Radio Telescope in India.
WHAT IS THE CHANDRA X-RAY OBSERVATORY?
NASA’s Chandra X-ray Observatory is a telescope specially designed to detect X-ray emission from very hot regions of the Universe such as exploded stars, clusters of galaxies, and matter around black holes.
Because X-rays are absorbed by Earth’s atmosphere, Chandra must orbit above it, up to an altitude of 86,500 miles (139,000 km) in space.
It launched on on July 23, 1999 and is sensitive to X-ray sources 100 times fainter than any previous X-ray telescope, enabled by the high angular resolution of its mirrors.
There are no concrete plans from Nasa to replace Chandra and further study the X-ray wavelength of light.
The Chandra X-ray telescope is now in its 20th year of operation and has surpassed its projected operational lifespan by nearly 15 years.
Chandra automatically went into so-called safe mode in October because of a gyroscope problem.