The biggest recorded cosmic explosion intrigues astronomers

The ‘biggest’ recorded cosmic explosion intrigues astronomers

While scientists have an unprecedented explanation to determine the cause of the phenomenon, they insist on the need to continue research to clarify the matter.

The event, catalog number AT2021lwx, is not the brightest on record. This distinction dates back to the gamma-ray burst (a colossal burst of energy associated with a star’s collapse) GRB221009A, discovered in October 2022 and thought to be the brightest on record.

Bright dots forming a circle on a dark background.

The burst, designated GRB221009A, was observed by many telescopes, including several from NASA.

Photo: NASA/Swift/A. beardmore

But the blast, described in the Monthly Notices of the Royal Astronomical Society (New Window) (in English), can be called the largest because, according to the study, it released infinitely more energy than the gamma-ray burst lead author Philip Wiseman in three years , Astrophysicist at the University of Southampton in the UK.

AT2021lwx is the result of an accidental discovery, he told AFP.

The explosion was automatically detected in 2020 by the American observatory Zwicky Transient Facility in California. According to Wiseman, however, this discovery remained unused in the observatory’s database. Before scientists noticed it the following year.

Direct observation of the phenomenon changed the game. Analysis of the light showed that it took 8 billion years to reach the telescope.

Astronomers are still puzzling over the cause of the 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 break, where a star is torn apart by the gravitational pull of a black hole it has come too close to. But again, AT2021lwx is three times too bright to confirm such a scenario.

The measured brightness has no known equivalent other than that of quasars. These galaxies harbor a supermassive black hole at their heart that gorges on matter by emitting a phenomenal amount of light.

But the light from the quasars is sparkling, while in this case it suddenly increased three years ago.

“We have never observed anything like this […]. She kind of appeared out of nowhere. »

– A quote from Philip Wiseman, astrophysicist at the University of Southampton

His team has an idea, which is set out in the study. His theory states that a gigantic cloud of gas the size of 5,000 suns is being swallowed up by a supermassive black hole.

Since the tenet of science is that there are never certainties, the team is working on new simulations – using the data – to test the inescapable plausibility of their theory.

The problem is that supermassive black holes are said to be at the center of galaxies. And that event AT2021lwx should be of a magnitude similar to that of our Milky Way.

However, no one has yet discovered a galaxy near the observed event. It’s a real mystery, notes Philip Wiseman.

It remains to search the sky and sky observation databases for similar events that will likely help lift the veil on the blast.