When it comes to natural explosions on Earth, nothing tops a volcano and, in modern times, few top the Mt. St. Helens blast. In space, the biggest blasts beyond the original Big Bang belong to the supernovas – stellar explosions that usually collapse into a black hole. Now, imagine the Mt. St. Helens of supernovas. Having trouble picturing it? You don’t have to – astronomers have discovered what they believe to be the largest non-Big Bang explosion ever. How big is (or was) it?
“In some ways, this blast is similar to how the eruption of Mt. St. Helens in 1980 ripped off the top of the mountain. 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.”
In a paper published in the Astrophysical Journal and summarized in a NASA press release and at Phys.org, Simona Giacintucci of the Naval Research Laboratory in Washington, DC, and lead author of the study described the discovery of the blast in the Ophiuchus galaxy cluster about 390 million light-years from Earth. A supermassive black hole in that cluster was first detected in 2016 astronomers using NASA's Chandra X-Ray Observatory, but at the time they couldn’t believe the even-more-massive cosmic hole in the gas surrounding the black hole was the result of an explosion. More recently, astronomers paired the Chandra X-ray data with that of the ESA's XMM-Newton, the Murchison Widefield Array (MWA) in Western Australia and the Giant Metrewave Radio Telescope (GMRT) in India and confirmed that it was indeed a big blast.
"The radio data fit inside the X-rays like a hand in a glove. This is the clincher that tells us an eruption of unprecedented size occurred here."
Co-author Dr. Maxim Markevitch from NASA's Goddard Space Flight Center rightly called the explosion “unprecedented” – it’s at least five times larger than the previous largest explosion. The supermassive cosmic hole was caused by explosive jets shooting away from the erupting supermassive black hole and through a cloud of gas. The radio emissions detected by the telescopes came from electrons traveling at almost the speed of light filling the hole.
While the blast took hundreds of millions of years to carve a void that 15 Milky Ways could fit into, it’s all over now. Professor Melanie Johnston-Hollitt, the director of the MWA, an expert in galaxy clusters and a co-author of the study, compares the discovery to finding dinosaur bones and then recreating the living beast. Knowing what to look for, she expects to find more massive explosions – possibly breaking the record. Putting the discovery in terms non-astronomers can understand:
“The Universe is a weird place."
Indeed it is.