Astronomers were dazzled by the largest cosmic explosion ever recorded

Astronomers announced Friday the discovery of the “largest” cosmic explosion ever recorded, a ball of energy a hundred times the size of our solar system that suddenly ignited three years ago.

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Scientists have a new explanation to explain the cause of the phenomenon, but they insist that further research is needed to clarify the matter.

The event, indexed AT2021lwx, isn’t the brightest of all. That distinction goes to a gamma-ray burst (a massive burst of energy in a star’s collapse) GRB221009A, which was discovered in October 2022 and believed to be the “brightest ever seen.”

But the explosion described in the Monthly Notices of Britain’s Royal Astronomical Society could be described as “the largest” because it released infinitely more energy in three years than a gamma-ray burst, according to the study’s lead author, Philip Wiseman, an astrophysicist at Britain’s University of Southampton.

He told AFP that the AT2021lwx is the result of an “accidental discovery”.

The explosion was definitely detected in 2020, automatically, by the US Zwicky Transient Facility Observatory in California. But that detection was “sent unused in the observatory’s database,” Weizmann said. before scientists noticed it the following year.

Direct observation of the phenomenon changed the game. Analysis of the light proved that it took eight billion years to reach the telescope.

“a real mystery”

Astronomers are still wondering about the reason for this phenomenon. It could be a supernova, the explosion of a massive star at the end of its life, but the luminosity here is 10 times greater than expected.

Another possibility is a tidal rupture event, in which a star is torn apart by the gravitational forces of an approaching black hole. But then again, the AT2021lwx is three times too bright to validate such a scenario.

There is no known equivalent of the measured brightness except for quasars. These galaxies harbor at their cores a supermassive black hole that sucks matter in by emitting a massive amount of light.

But the light from quasars shimmers, while in this case, it suddenly increased three years ago. “We have never seen such a thing (…). It seemed to come out of nowhere, ”the scientist notes.

His team has an idea, which is contained in the study. His theory is that a huge cloud of gas, the size of 5,000 suns, is being devoured by a supermassive black hole.

Since the principle of science is that “there is no absolute certainty,” the team is working on new simulations — using data — to test the “unquestionable plausibility” of their theory.

The problem is that supermassive black holes are supposed to be at the center of galaxies. And this event, AT2021lwx, should be about the size of our Milky Way galaxy.

However, no one has yet detected a galaxy near the observed event. “It’s a real mystery,” says Philip Wiseman.

The search remains in the skies, and in the celestial databases, similar events will likely help lift the veil over the eruption.