Astronomers capture largest cosmic explosion ever: Know what caused it
Researchers have captured the largest-ever explosion in space and it is unlike anything witnessed before. What's astonishing is that the blast has raged on for over three years now and is 10 times brighter than any known supernova, an explosion that occurs when stars die. The explosive event, named AT2021lwx, was caused due to a supermassive black hole devouring a huge gas cloud.
Why does this story matter?
Cosmic events are mysterious but quite interesting, nonetheless. The duration and intensity of the AT2021lwx event make it the most energetic explosion ever recorded. To put things into perspective, supernovas, which are considered the "biggest explosions humans have ever seen," per NASA, typically last only a few months, whereas AT2021lwx has been flaring up for three years straight.
Black holes are usually surrounded by a large dusty "doughnut"
The AT2021lwx event was triggered due to a massive cloud of gas—possibly thousand times larger than our Sun—being sucked into a supermassive black hole. Black holes are typically surrounded by a large dusty "doughnut" which is where the enormous gas cloud might have originated. But it's unclear what caused the gas blob to fall off its orbit into the black hole.
Black holes are typically surrounded by gas and dust
Astronomers think that some of the large amounts of dust and gas surrounding the supermassive black hole might have been disrupted probably due to a galactic collision, hurtling the material toward the black hole. As the material made reached the boundary of the black hole, it would have expelled great amounts of heat and light, illuminating some parts of the black hole's dusty "doughnut."
The event was first spotted in 2020
The event was first spotted in 2020 by the Zwicky Transient Facility in California, which probes the night sky for cosmic events including supernovae, asteroids, and passing comets. Initially, the AT2021lwx event did not stand out to astronomers. Follow-up observations allowed researchers to estimate the distance of the event, roughly eight billion light-years, which led them to conclude that it was a rare event.
"It's a fireball 100 times the size of solar system"
Referring to AT2021lwx, Philip Wiseman, an astronomer at Southampton University, said, "We've estimated it's a fireball 100 times the size of the solar system with a brightness about 2tn times the Sun's." What's even more fascinating is that in three years, the explosive event has released about 100 times as much energy as the Sun will in its 10 billion-year lifetime.
Astronomers thought AT2021lwx could be a tidal disruption event
Initially, scientists also thought the explosion could be a tidal disruption event (TDE), a common cosmic occurrence that causes bright flashes in the sky. TDEs usually occur when a star wanders too close to a black hole and ends up being ripped apart. The black hole engulfs some portion of the star and the rest is stretched into a disc.
A large gas cloud appeared to be more plausible cause
However, simulations revealed that a star up to 15 times the mass of the Sun would have been required to cause a TDE which would be able to account for an event with the magnitude of AT2021lwx. "Encountering such a huge star is very rare, so we think a much larger cloud of gas is more likely," Wiseman said.
We are hoping to discover more events like this: Wiseman
"With new facilities, like the Vera Rubin Observatory's Legacy Survey of Space and Time, coming online in the next few years, we are hoping to discover more events like this and learn more about them," Wiseman said. "It could be that these events, although extremely rare, are so energetic that they are key processes to how the centers of galaxies change over time."
