Galactical explosion 10 times brighter than any previously observed

By Al Mayadeen English
Source: News websites
12 May 15:52

Observations revealed that the cosmic explosions that were captured are the largest ever witnessed by astronomers.

This image provided by NASA shows the star Wolf-Rayet 124, center, captured by the James Webb Space Telescope in June 2022. (AP)

Scientists could have captured the largest cosmic explosion to have ever been witnessed, whose flare-up could be traced to 8 billion years away.

Initially, astronomers captured what they believed was an unremarkable flicker in the sky, however, deeper observations led them to believe that the event was the largest explosion they ever witnessed, which was likely to have been the result of a supermassive black hole swallowing up a gigantic cloud of gas.

The recorded flare-up proved 10 times brighter than any previously known supernova and has lasted more than three years, making this the "most energetic explosion on record" as reported by The Guardian.

Dr. Philip Wiseman, an astronomer at Southampton University who led the observations, said the explosion “went unnoticed for a year as it gradually got brighter,” noting that only subsequent observations allowed scientists to fully comprehend the event's almost unfathomable size.

“We’ve estimated it’s a fireball 100 times the size of the solar system, with a brightness about 2tn times the sun’s,” Wiseman explained adding that “in three years, this event has released about 100 times as much energy as the sun will in its 10bn-year lifetime.”

Moreover, scientists highlighted that the explosion, which became known as AT2021lwx, has not been the brightest phenomenon that has been witnessed historically. While GRB 221009A, a gamma-ray burst that was spotted earlier last year, was brighter, even though it only lasted for minutes. The energy release of the newly discovered explosion lasted for years and remains ongoing.

In that regard, the event did not grasp astronomers' attention, but the calculations that happened during the observation of the event revealed the extent of the importance of the incredibly rare event which shocked scientists.

Wiseman exclaimed, “When I told our team the numbers they were all just so shocked."

"Once we understood how extremely bright it was, we had to come up with a way to explain it.”

It was outside the plausible range for a supernova (exploding star) and so astronomers turned to the other common scenario that cause bright flashes in the night sky – a so-called tidal disruption event. These events typically involve a star straying too close to a black hole and being shredded, with the part being swallowed and the rest being stretched out in a swirling disc.

"Simulations, however, indicated that a star with up to 15 times the mass of the sun would have been needed to explain AT2021lwx. We believe a far larger cloud of gas is more plausible since it is quite uncommon to see such a massive star," according to Wiseman.

Supermassive black holes are normally surrounded by a wide halo of gas and dust, and as such, scientists suggested that part of this material may have been disrupted, resulting in a collision of galaxies that could have in turn been propelled inwards. The material would have produced enormous amounts of heat and light as it spiraled towards the event horizon, the black hole's circular outer border, lighting a section of the ring and heating it to 12–13,000°C.