Scientists have discovered the most powerful blasts of energy in the known universe.
Dubbed extreme nuclear transients, or ENTs, the cosmic explosions are unprecedented in their intensity.
They happen when massive stars – much bigger than our Sun – go too close to a supermassive black hole and are torn to pieces.
The resulting collision throws out vast amounts of energy that travel right across the cosmos.
“We’ve observed stars getting ripped apart as tidal disruption events for over a decade, but these ENTs are different beasts, reaching brightnesses nearly ten times more than what we typically see,” said Jason Hinkle, who led the study.
“Not only are ENTs far brighter than normal tidal disruption events, but they remain luminous for years, far surpassing the energy output of even the brightest known supernova explosions.”
The most energetic ENT, for instance, throws out 25 times more energy than the most powerful known supernova. A supernova can emit as much energy a year as the Sun does over its 10-billion-year lifetime, but ENTs can emit 100 times that over a single year.
The discovery came from work looking for flares that were being emitted from the centre of galaxies. In data from the European Space Agency’s Gaia telescope, Jason Hinkle spotted two strange flares that appeared to last longer than normal transients, and had other unexpected characteristics.
“Gaia doesn’t tell you what a transient is, just that something changed in brightness,” said Hinkle. “But when I saw these smooth, long-lived flares from the centers of distant galaxies, I knew we were looking at something unusual.”
That began a years-long project to find out what the flares were coming from. Eventually, a third was found and further research showed that the ENTs were a new kind of unseen astrophysical event.
The ENTs are notable not only for their intensity and unprecedented nature. Researchers also hope they can be used to better understand black holes – and the universe that holds them.
“ENTs provide a valuable new tool for studying massive black holes in distant galaxies. Because they’re so bright, we can see them across vast cosmic distances – and in astronomy, looking far away means looking back in time,” said Benjamin Shappee, a co-author on the study.
“By observing these prolonged flares, we gain insights into black hole growth when the universe was half its current age when galaxies were happening places—forming stars and feeding their supermassive black holes 10 times more vigorously than they do today.”
But such ENTs are hard to find, happening at least 10 million times left often than supernovae. Researchers hope that upcoming new equipment such as the Vera C Rubin Observatory and Nasa’s Roman Space Telescope will allow for more of them to be discovered.
The work is reported in the journal Science Advances.
