Last Year Likely Witnessed the Brightest Cosmic Explosion ‘Since Human Civilization Began’

Scientists have confirmed that a rare gamma-ray burst (GRB) detected last year was likely the brightest cosmic explosion that has occurred “since human civilization began”.

The explosion in question was officially named GRB 221009A, and quickly nicknamed the BOAT, or brightest of all time, following its discovery on October 9 2022.

“GRB 221009A was likely the brightest burst at X-ray and gamma-ray energies to occur since human civilization began,” said Louisiana State University assistant professor of physics and astronomy Eric Burns in a NASA press release.

Explosions as luminous and powerful as the BOAT are likely to occur just once every 10,000 years, according to the results of a new study led by Burns that estimated the frequency of the events. The gamma blast was initially detected by instruments aboard orbital spacecraft, which, blinded by the power of the GRB, immediately sent alerts to Earth-bound scientists warning of the event.

Powerful telescopes were then brought to bear on GRB 221009A to study the less energetic aftermath of the cosmic outburst. The explosion was estimated to take place roughly two billion light-years from Earth, which placed it well beyond the borders of our Milky Way, but still made it one of the closest GRBs found to date. 

The data also revealed that the BOAT was roughly 70 times brighter than any previously discovered GRB, allowing it to easily outshine its host galaxy. The spectacular event likely signalled the death of a star, and the birth of a new black hole.

“Gamma-ray bursts are always energetic, but this one was absolutely astonishing,” says Daniele Bjørn Malesani of the Radboud University in the Netherlands in a press release from the Niels Bohr Institute. “During the 290 seconds that it lasted, GRB 221009A released roughly 1,000 times as much energy as our Sun has emitted during all of its lifetime of 4.5 billion years.”

GRB’s are often accompanied by supernova explosions that are seen to brighten in the weeks following the event. However, observations made by NASA’s James Webb Space Telescope and Hubble have so far failed to find evidence of this in the aftermath. This could be because the location of the GRB – a few degrees above the galactic plane – is cloaked by choking clouds of cosmic dust and gas. 

Astronomers are hoping that further observations from the powerful telescopes in the coming months will help answer the question of whether the supernova renmant is there, and extremely faint, or whether it never happened at all.

“We cannot say conclusively that there is a supernova, which is surprising given the burst’s brightness,” commented astrophysics professor Andrew Levanat, also from Radboud University. “If it’s there, it’s very faint. We plan to keep looking,but it’s possible the entire star collapsed straight into the black hole instead of exploding”.

How Are Gamma-Ray Bursts Created?

Gamma Ray Bursts (GRBs) are the brightest and most powerful class of explosion known to take place in the observable universe in the wake of the Big Bang that created it. Most GRBs occur when a star many times the mass of our Sun runs out of the fuel needed to power the nuclear reaction at its heart. 

The subsequent collapse spawns a new black hole, which upon its creation drives a narrow stream of particles away from it at a velocity close to the speed of light, triggering a super-luminous burst of gamma-rays.

Astronomers also believe that these rare radiation explosions are triggered when two hyper-dense neutron stars collide, or in the rare instances wherein such a star violently merges with a nearby black hole.

GRBs are extremely difficult to catch. This is because they are exceedingly short lived – with the initial burst lasting between a tenth of a second to over two hours – and appear seemingly at random. Gamma-rays are also easily absorbed by Earth’s atmosphere, and so scientists must rely on orbital spacecraft to detect the initial outpouring of radiation, and to figure out where to target observations by larger telescopes.

The energetic events are also thought to be responsible for the creation of complex heavy elements such as gold, and platinum. A collection of papers describing the discovery has been published in The Astrophysical Journal Letters. Stick with IGN to stay up to date with the biggest and brightest news from the world of science.

Anthony is a freelance contributor covering science and video gaming news for IGN. He has over eight years experience of covering breaking developments in multiple scientific fields and absolutely no time for your shenanigans. Follow him on Twitter @BeardConGamer

Image credit: NASA/Swift/A. Beardmore (University of Leicester)