"Biggest explosions since the Big Bang": New form of cosmic eruption discovered
A previously unknown type of cosmic explosion is once again significantly brighter and more energetic than anything we know. They were discovered thanks to Gaia.
Artistic representation of an ENT
(Image: University of Hawaiʻi)
A research team has discovered a previously unknown form of cosmic explosion that is significantly more energetic than the previous record holders. This was announced by the University of Hawaii, where Jason Hinkle, head of the study, is conducting research. The explosions, known as ENT (for “extreme nuclear transients”), occur when a massive star is disintegrated by a supermassive black hole. They are almost ten times brighter than the so-called tidal disruption events and radiate for much longer. The extremely energetic explosions can be seen for years and outshine even the brightest known stellar explosions. The university speaks of the “largest explosions since the Big Bang”.
Process takes years
As the university explains, the process responsible for the ENT appears to be much “gentler and more protracted” than the tidal disruption events. An ENT therefore requires a star that is at least three times as massive as our sun. This is then “shredded” by a supermassive black hole, which takes some time. A recently discovered ENT is called Gaia18cdj and has released 25 times as much energy as the most powerful known supernova. In one year, it emitted as much energy as 100 suns would otherwise manage over their entire lifetime. At the same time, they are millions of times rarer than supernovae.
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Hinkle first noticed the gigantic explosions in data from ESA's Gaia space telescope because they remained visible for such a long time: “When I discovered these long-lived eruptions from the centers of distant galaxies, I knew I was looking at something unusual,” he recalls. He and his team then used archive images from other telescopes to characterize the events. Because they are so bright, they can be observed from enormous cosmic distances and offer a further glimpse into the history of the universe, he explains. This allows us to explore how black holes grew back then. That is why the search is now on for many more. The discovery is presented in the journal Science Advances.
(mho)
