Monday, June 5

Astronomers discover the largest cosmic explosion ever seen | Digital Trends Spanish

A group of astronomers from the University of Southampton have just revealed the largest cosmic explosion ever seen, ten times brighter than any known supernova and three times brighter than the brightest tidal disruption event, where a star falls into a supermassive black hole.

The research findings have been published this Friday, May 12 in Monthly Notices of the Royal Astronomical Society.

The explosion, known as AT2021lwx, has currently lasted for more than three years, compared to most supernovae which are only visibly bright for a few months. It took place nearly 8 billion light-years away, when the universe was about 6 billion years old, and is still being detected by a network of telescopes.

Researchers believe the explosion is the result of a vast cloud of gas, possibly thousands of times larger than our sun, that has been violently disrupted by a supermassive black hole. Fragments of the cloud would be swallowed, sending shock waves through its remnants, as well as into a large dusty “doughnut” surrounding the black hole. Such events are very rare and nothing on this scale has been witnessed before.

AT2021lwx was first detected in 2020 by the Zwicky Transient Facility in California, and subsequently picked up by the Hawaii-based Asteroid Terrestrial-impact Last Alert System (ATLAS).

“We came across this by chance, as it was flagged by our search algorithm when we were looking for a type of supernova,” says University of Southampton researcher Dr Philip Wiseman, who led the research. “Most supernovae and tidal disruption events only last a couple of months before fading away. For something to be brilliant for more than two years was immediately very unusual.”

By analyzing the spectrum of the light, dividing it into different wavelengths, and measuring the different absorption and emission characteristics of the spectrum, the team was able to measure the distance to the object.

“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 origin. Once we ran those calculations, we realized that this is extremely bright,” says Professor Sebastian Hönig from the University of Southampton, a co-author of the research.

The only things in the universe that are as bright as AT2021lwx are quasars: supermassive black holes with a constant stream of gas falling on them at high speed.

Professor Mark Sullivan, also from the University of Southampton and another co-author on the paper, explains: “With a quasar, we see the brightness flicker up and down over time. But looking back over a decade there was no detection of AT2021lwx, and suddenly it appears as bright as the brightest things in the universe, which is unprecedented.”

The team is now preparing to collect more data on the explosion, measuring different wavelengths, including X-rays that could reveal the object’s surface and temperature, and what underlying processes are taking place. They will also carry out enhanced computer simulations to test whether they match up with their theory of what caused the explosion.

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