Astronomers detect the largest cosmic explosion ever seen

() — Astronomers have discovered the largest cosmic explosion ever seen, and it is 10 times brighter than any known exploding star or supernova.

The glow from the explosion, called AT2021lwx, has lasted for three years, while most supernovae only glow for a few months.

The phenomenon, which is still detected by telescopes, occurred nearly 8 billion light-years away from Earth when the universe was about 6 billion years old. The luminosity of the explosion is also three times brighter compared to other events such as when stars fall into supermassive black holes.

But what triggered such a huge, long-lasting cosmic explosion? The astronomers said they believe a supermassive black hole disrupted a large cloud of gas or dust, potentially thousands of times larger than our sun. It is possible that the cloud deviated from the course of its orbit and flew towards the black hole, according to the researchers.

As the black hole swallowed pieces of the hydrogen cloud, shock waves likely reverberated through the cloud’s remnants and into the swirling mass of material orbiting the black hole.

The AT2021lwx event dethrones the gamma-ray burst GRB 221009A as the brightest cosmic explosion on record, which was reported in 2022. The gamma-ray burst was actually brighter, but it only lasted a fraction of AT2021lwx, which is releasing more energy overall.

The findings were published Thursday in Monthly Notices of the Royal Astronomical Society.

Astronomers first detected the explosion in November 2020 with the Zwicky Transient Facility in California, followed by the Asteroid Earth Impact Last Alert System in Hawaii a few months later. They both keep an eye out for objects in the night sky that change rapidly in brightness, such as exploding stars, asteroids, and comets.

“We came across this by chance, as our search algorithm flagged it when we were looking for a type of supernova,” the study’s lead author, Dr. Philip Wiseman, a researcher at the University of Southampton in England, said in a statement. “Most supernovae and tidal disruption events only last a couple of months before fading away. For something to be shiny for more than two years was immediately very unusual.”

Follow-up observations were made using the space-based Neil Gehrels Swift Observatory, the New Technology Telescope in Chile, and the Gran Telescopio Canarias on La Palma, Spain.

The researchers were able to determine the distance between Earth and the event by analyzing the different wavelengths of light used to observe the explosion.

“Once you know the distance to the object and how bright it appears to us, you can calculate the brightness of the object at its source,” study co-author Sebastian Hönig, a professor at the University of Southampton, said in a statement.

The Asteroid Terrestrial Impact Last Alert System has observed the explosion every few nights for the past two and a half years.

The research team determined that the incredibly luminous event was nearly 100 times brighter than all 100 billion stars in the Milky Way combined.

The only celestial objects that rival the brightness of AT2021lwx are quasars, or supermassive black holes that constantly feed on high-speed gas.

“With a quasar, we see the brightness flicker up and down over time,” study co-author Mark Sullivan, a professor at the University of Southampton, said in a statement. “But looking back for over a decade, there was no detection of AT2021lwx, then all of a sudden it appears as bright as the brightest things in the universe, which is unprecedented.”

The team had initial theories by studying the luminosity of the explosion. Now the researchers want to collect more data through different wavelengths of light to learn the details of the event, including its temperature.

“At first, we thought that this flare could be the result of a black hole consuming a passing star. But our models showed that the black hole would have to have swallowed 15 times the mass of our Sun to stay this bright for so long,” said study co-author Dr Matt Nicholl, associate professor at Queen’s University Belfast in Ireland. del Norte, in a statement.

“It is very rare to find such a large star, so we think a much larger gas cloud is more likely. Many massive black holes are surrounded by gas and dust and we are still trying to figure out why this particular black hole started feeding so vigorously and so suddenly.”