Astronomers have observed the largest cosmic explosion ever detected!
A cosmic explosion of unimaginable power
The cosmic explosion, named AT2021lwx, is ten times brighter than any supernova known to date.
The Zwicky Transient Facility (ZTF) is a system designed to detect and process the presence of objects in space whose luminosity changes rapidly, such as supernovae, gamma-ray bursts, neutron stars, or collisions between comets and asteroids. It was made by a state-of-the-art camera installed at the Samuel-Ossin Telescope at the Palomar Observatory in California.
It all starts with spotting a simple lightning bolt in the sky and recording it in 2020 ZTF system It was then analyzed by astronomers a year later. Unable to calculate its luminosity at the time because they had no indication of its distance, astronomers believe this AT2021lwx event was not exceptional.
If a team of astronomers from the University of Southampton had not decided last year to resume the observation and analyze the light, it would have ended there and the event would have been completely forgotten.
These additional observations left astronomers speechless. They revealed an explosion 8 billion light-years from Earth that produced a fireball estimated to be 100 times the size of our solar system and twice as luminous as our sun.
In three years, this explosion, an almost unimaginable amount, released into space 100 times more energy than the Sun will produce at the end of these 10 billion years. billion years.
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A supermassive black hole engulfs a giant gas cloud
Astronomers believe that this massive explosion is the result of a huge cloud of gas that inevitably rushes into the gaping hole of a supermassive black hole. Researchers estimate that this gas cloud must be thousands of times larger than our Sun and a torus-shaped cloud of dust and gas (shaped like a circular donut with a hole in the middle) surrounding the black hole. However, astronomers cannot say what caused the gas cloud to drift away from its orbit and sink into the black hole.
Stellar black holes are black holes with masses 10 to 20 times that of our Sun. They are born from the gravitational collapse of a star that has consumed all of its hydrogen at the end of its lifetime. This is the inevitable end that awaits our Sun.
On the contrary Stellar black holes, supermassive black holes do not arise from the gravitational collapse of a star. The size of these cosmic monsters varies between a million and several billion solar masses. They are found in the heart of practically every galaxy, such as Sagittarius A*, which has a mass of only 4.152 million solar masses and is located at the center of the Milky Way, or the supermassive black hole lurking at the heart of the 21-mass elliptical galaxy NGC4889. A billion solar masses!
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A starburst is still going on
Named AT2021lwx, this cosmic explosion is not the brightest event observed so far. Last year the Gamma-ray burst GRB221009A It was very bright, but it only lasted a few minutes. On the other hand, this cosmic explosion is located 8 billion light-years away from Earth and was detected 3 years ago and is still going on today.
To explain this phenomenon of such force, astronomers originally thought it was an explosion caused by a fragmented star that was coming too close to a black hole, with one part of the star rushing into the black hole and another part forming a disk of material orbiting around it. .
Thanks to computer simulations, astronomers realized that this hypothesis was implausible. In fact, to obtain such a result, the mass of the star must be 15 times that of the Sun. However, such a large star is rare.
So researchers stick with their hypothesis of a vast cloud of gas and dust. They believe that it may have been dislodged due to a collision with a galaxy, or that part of this cloud may have been sent towards the event horizon of the black hole following the collision.
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Source: B Wiseman et al., “Multi-wavelength observations of the AT2021lwx unusual accretion event”, Monthly Notices of the Royal Astronomical SocietyVolume 522, Issue 3, July 2023, Pages 3992–4002, https://doi.org/10.1093/mnras/stad1000