An example of an entirely new type of cosmic explosion that vastly outnumbers most supernovae could be the result of a small or medium-sized black hole destroying a star.
Astronomers watched the explosion, dubbed AT2022aedm, erupt from a red galaxy located about 2 billion light-years from Earth using ATLAS’ network of robotic telescopes located in Hawaii, Chile and South Africa. It was quickly recognized as something it had never seen before.
“We’re always looking for things that are a little weird and different from the standard types of supernovae, of which we find hundreds or even thousands a year,” says Matt Nichol, leader of the team behind the discovery and an astrophysicist at Queens. The University of Belfast told Space.com. “AT2022aedm stood out because it was one of the brightest explosions we’ve ever seen, and it was also one of the fastest to fade after its peak.”
The explosion observed by Nichol and his team released up to 100 times more energy than the average supernova. In addition, as the supernovae faded over the course of months, Nicol noted that AT2022aedm faded to 1% of its original brightness in just 14 days, after which it disappeared completely. This means that in just two weeks, AT2022aedm has released as much energy as the Sun in its 10-billion-year lifetime.
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It’s no surprise why AT2022aedm sent shockwaves through the team and earned a class of its own, with the scientists behind the discovery calling it the first “Luminous Fast Cooler” or “LFC”. This name is a reference to his explosive qualities as well as to the love of Nicole and his teammates for the English football team Liverpool Football Club, which is also known by the acronym ‘LFC’.
“I think the most promising explanation for LFCs like AT2022aedm is models involving the destruction of stars by Black holeNicole explained.
This was the conclusion he and his colleagues reached by first eliminating a few other prime suspects.
Extraordinary Suspects: How the Finger Was Pointed at Destructive Black Holes
One of the first steps that Nicoll and the Queen’s University Belfast scientists took was to eliminate some of the usual culprits of cosmic cataclysms.
Not only did the explosion look like a supernova, because it was so powerful and so fast, but the location in which it originated also helped characterize the LFC as something entirely new.
One of the most common types of supernovae is the primary collapsed supernova, which forms when massive stars more than 8 times the mass of the Sun run out of fuel for nuclear fusion. Star cores become unable to resist gravity any longer and eventually collapse. This leaves behind a black hole, or neutron star, in the core of stellar debris from the star’s outer layers.
“AT2022aedm cannot be a normal supernova collapsing at its center, because the galaxy in which it is seen contains only old, low-mass stars; it does not contain anything more than eight times the mass of the Sun, and that is what you need to have to get it,” Nicol explained. on a supernova.”
Instead, another common space explosion, a Type Ia supernova, occurs when stellar remnants called white dwarfs strip matter from a companion star. This stripping of matter causes the white dwarf to exceed the mass limit needed to trigger a supernova and create a neutron star or black hole, but these events create a uniform radiation output. This is why astronomers call them “standard candles” and use them to accurately measure cosmic distances.
However, the AT2022aedm looks nothing like that.
This led the team to point the finger at black holes. But even then, they managed to clear the usual suspects.
Supermassive black holes are being purged
Events that see black holes rip stars apart and then feed on the stellar remnants are rare, but not unknown. Astronomers have spotted many examples of so-called “tidal disturbance events,” or “TDEs,” as well as the light emitted during violent actions.
TDEs usually occur when a star comes close to a supermassive black hole at the heart of a galaxy. The mass of such a black hole can be millions, or even billions, of times that of our sun. The gravitational effects of these supermassive black holes generate enormous tidal forces in their stellar subjects that stretch and compress the stellar bodies, tearing them apart in a process called “spaghetti”.
However, Nicol and his colleagues immediately saw that this LFC could not be the result of any TDA being driven by a supermassive black hole. Again, this is partly due to where Liverpool F.C. emerged from. Supermassive black holes lie at the heart of galaxies, and Nicol said AT2022aedm was seen far from the center of its home galaxy. This means that a smaller black hole (not at the galactic core) could have caused this event.
“If you have a lower mass black hole in a dense environment with lots of stars, and one of those stars gets very close to the black hole, even if it is a stellar black hole 10 to 100 times more massive than the Sun.” “The Sun will still be able to tear apart and consume a star,” he continued.
Nichol added that he and the team have yet to rule out a more interesting suspect.
There is still a chance that the LFC could be the creation of an “intermediate-mass” or intermediate-mass black hole that lies between stellar-mass black holes and supermassive black holes, which have masses from 100 to a few thousand times greater. from the sun.
This is a tantalizing prospect, not only because intermediate-mass black holes have remained elusive, but also because studying them could help explain how supermassive black holes grew to such frightening sizes early in cosmic history.
“Intermediate-mass black holes are expected to consume stars, and they do not have to be the center of galaxies because they could be expelled from the center by a larger black hole,” Nicol said. “LFCs are likely to be associated with intermediate-mass black holes, and if so, it would give us a new way to try to find and calculate intermediate-mass black holes.
“This is probably the most important thing you can do in terms of trying to understand how supermassive black holes got so big.”
The team has already made significant progress in its investigations at the LFC, rummaging through archival data to find two “cold states” that match AT2022aedm, suggesting that this class of powerful cosmic explosions had been seen before but was buried in the data and could have been Lost.
Nicholl’s next step is to study globular clusters, which are incredibly dense collections of stars that can provide the conditions needed for small or medium black holes to destroy a star and launch the LFC.
Even if this research is successful, the astrophysicist is unlikely to be disappointed in discovering something completely new.
“We’ve looked up at the sky for a very long time, and sometimes people think we’ve seen all there is to see,” Nicol concluded. “I think things like this are really exciting because they remind us that the universe still has a lot of surprises in store, and when we build a new telescope, we’ll find new things, and that will help us understand our universe better.”
The team’s research is published Sept. 1 in The Astrophysical Journal Letters.
