In a groundbreaking discovery, astronomers have identified a new class of cosmic explosions, termed Extreme Nuclear Transients (ENTs), which are the most energetic events observed since the Big Bang. These rare phenomena occur when massive stars, at least three times the mass of our Sun, are torn apart by supermassive black holes, releasing energy that outshines entire galaxies.
The discovery was led by Jason Hinkle, a researcher at the University of Hawaiʻi’s Institute for Astronomy (IfA), who analyzed data from the European Space Agency’s Gaia space telescope. Hinkle identified unusual, long-lasting flares originating from the centers of distant galaxies, which did not match any known cosmic events. Further observations using ground-based telescopes, including the W. M. Keck Observatory, confirmed these as a distinct class of explosions.
ENTs are characterized by their exceptional brightness and longevity. Unlike typical tidal disruption events (TDEs), where a star is torn apart by a black hole and the resulting flare fades within weeks or months, ENTs remain luminous for years. One such event, named Gaia18cdj, emitted 25 times more energy than the most powerful supernova ever recorded, equivalent to the energy output of 100 Suns over their entire lifespans.
The immense luminosity of ENTs allows astronomers to observe them across vast cosmic distances, providing a unique opportunity to study the growth of supermassive black holes and the dynamics of galaxies in the early universe. Benjamin Shappee, a co-author of the study, noted that observing these prolonged flares offers insights into black hole growth during a period when galaxies were forming stars and feeding their central black holes more vigorously than they do today.
ENTs are estimated to be 10 million times rarer than supernovae, making their detection a significant achievement in astrophysics. Their discovery opens new avenues for understanding the most extreme processes in the universe and the role of supermassive black holes in galactic evolution.
The identification of ENTs underscores the importance of continuous monitoring of the sky for transient events. Future observations aim to uncover more of these rare explosions, which will help refine models of black hole behavior and the life cycles of massive stars. The findings were published in the journal Science Advances on June 4, 2025.
