A team of astronomers at the International Research Centre for Radio Astronomy have detected an explosion in a galaxy 390 million light-years from Earth that was so powerful that it tore a massive cavity in the plasma of a supermassive black hole as if a supervolcano "ate" an entire mountainside. The explosion, which came from the centre of the Ophiuchus cluster of galaxies, was so violent that it pierced the plasma surrounding the black hole. The explosion was five times more powerful than any previously detected event.
"We've seen explosions in the centres of galaxies before, but this one is really huge," explained Melanie Johnston-Hollitt, co-author of the study. "And we don't know why it's so big, but it happened very slowly, like a slow-motion explosion that took place over hundreds of millions of years".
The study's lead researcher, Simona Giacintucci of the Naval Research Laboratory in the United States, said the explosion was similar to the 1980 eruption of Mount St. Helena, which ripped the top off the mountain; one of the most catastrophic volcanic eruptions of the 20th century.
It can't be that big (can it?)
At first, scientists dismissed the idea that what they had captured could have been caused by an energy burst, because it was too big. "They were sceptical because of the size of the burst. But in reality, it was...The universe is a strange place," says Johnston-Hollitt.
They didn't take the big bang for granted until they observed the Ophiuchus cluster of galaxies with radio telescopes. "The radio data fits inside the X-rays like a hand in a glove," says Maxim Markevitch of NASA's Goddard Space Flight Center. "This is the deciding factor that tells us that an eruption of unprecedented size took place here." What caused it remains a mystery. For the moment.
Compared to the discovery of the first dinosaur fossils
"It's a bit like archaeology," explained Johnston-Hollitt, "We've been given the tools to dig deeper with low-frequency radio telescopes, so now we should be able to find more explosions like this.
"We made this discovery with MWA Phase 1, when the telescope had 2048 antennas pointed up to the sky," he said. "We will soon be collecting observations with 4096 antennas, which should be ten times more sensitive". "I think it's very exciting", she concluded.
This colossal discovery highlights the importance of scanning the sky at different wavelengths, because what is visible at one wavelength may be invisible at another, and our universe has many layers to delve into that we cannot yet understand.
The discovery was made with four telescopes: NASA's Chandra X-ray Observatory, ESA's XMM-Newton, the Murchison Widefield Array (MWA) in Western Australia and the giant Metrewave Radio Telescope (GMRT) in India.
Reference: Discovery of a giant radio fossil in the Ophiuchus Galaxy Cluster. The Astrophysical Journal . February 27th, 2020. arxiv.org/abs/2002.01291