“Astronomers Discover Largest Cosmic Explosion Ever Recorded: AT2021lwx”

An explosion that has lasted for three years and is ten times brighter than a supernova: astronomers have a cosmic phenomenon discovered which they believe is the largest thud ever recorded in the universe.

The object, 8 billion light-years away, was first spotted in 2020, but it’s only three years later that observers fully understand the scale of the explosion dubbed AT2021lwx.

The research team, led by the British University of Southampton, encountered the phenomenon with a telescope that scanned the sky for objects whose brightness changes rapidly. That could indicate a supernova, an exploding star.

But AT2021lwx is not a supernova, they only last a few months. This massive, years-long explosion is more like one tidal disruption event (TDE), where a black hole eats a star. The monster was nicknamed “Scary Barbie” because of its size (and its second designation ZTF20abrbeie).

Now the cosmic bang appears to be even more gigantic than previously thought. It’s not an ordinary TDE, where only a star goes into a black hole. There are several explanations, but the most likely is that not a star but a giant cloud of gas, a thousand times the size of our sun, falling into a supermassive black hole.

Due to its size, the phenomenon is three times as bright as a normal TDE, but that brightness does go up and down. That probably has to do with shooting shock waves that are created when pieces of gas cloud devour. They encounter incoming gas and the huge disk of dust surrounding the black hole, which resembles a rotating donut. This releases electromagnetic radiation.

AT2021lwx is not the brightest explosion ever seen. This is in the name of a ten-hour long gamma-ray flash that was detected in 2022.

The explosion is now being examined by a whole battery of telescopes, on Earth and in space. The team, led by the University of Southampton, will be looking at the explosion in different wavelengths in the near future. For example, more must become clear about the temperature of exploding gas clouds and which processes lie behind it. In addition, the astronomers will use computer simulations to check whether their theory is correct.

“With new research facilities becoming available in the coming years, we hope to learn more,” the team writes. “It could be that these phenomena, even though they are extremely rare, are so powerful that they play a key role in the gradual changes at the heart of galaxies.”