Hawaiian astronomers have discovered an entirely new type of cosmic catastrophe – super-powerful explosions that are ten times more energetic than even the brightest supernovae. This phenomenon is called Extreme Nuclear Transients, or ENTs for short.
A study published in the journal Science Advances reveals the nature of ENTs. These are moments when supermassive black holes in the center of galaxies tear apart stars with masses at least three times the size of our Sun. This process, known as tidal collapse, generates an incredible release of energy.
“We have been observing tidal star collapse for over a decade. But ENTs are something completely different. They are nearly 10 times brighter than normal events and can shine for years, far outshining even the brightest supernovae,” explains Jason Hinkle, lead author of the study from the University of Hawaii.
The discovery happened almost by accident. Hinkle was analyzing data from the ESA’s Gaia space telescope, looking for long-lasting flares in the nuclei of galaxies. His attention was drawn to two strange signals from 2016 and 2018. Independently, two other groups used the ZTF (Zwicky Transient Facility) survey to detect a similar outburst in 2020. Subsequent observations from the Keck Observatory in Hawaii confirmed that all three events belonged to the same new class, ENTs.
Enormous energy
The key difference between ENTs is their enormous energy. The most powerful documented explosion, Gaia18cdj, released 25 times more energy than the most energetic supernovae. Each ENT emits as much energy as 100 Sun-like stars would produce over their entire 10-billion-year life cycle. For comparison, a normal supernova gives off the energy equivalent of one Sun.
“ENTs are not just the end of a massive star. They illuminate the processes that form the largest black holes in the Universe,” Hinkle notes. Although ENTs are at least 10 million times less common than supernovae, their extreme brightness makes them an invaluable tool for astronomers.
“Because of its incredible brightness, we can see ENTs at great distances. And in astronomy, looking far away means looking into the past. By observing these long-lasting flares, we get a glimpse of how black holes grew during the key era of ‘cosmic noon’ when the Universe was half the age it is today,” says study co-author Benjamin Shappee.
This discovery reveals a new, extremely energetic scenario for the interaction of stars and black holes, offering new opportunities to study the evolution of the Universe at great distances. ENTs have become new beacons in the darkness of space.
Earlier, we reported on how elusive cosmic events will help measure the rate of expansion of the Universe.
Provided by keckobservatory.org
