Honolulu, Hawaii — Astronomers have captured an extraordinary celestial event as a massive star, significantly larger than our sun, strayed perilously close to a supermassive black hole, resulting in a rare and incredibly energetic explosion. This unprecedented event has led to the identification of a new cosmic phenomenon termed “extreme nuclear transients,” or ENTs.
According to research detailed in Science Advances, these ENTs exhibit brightness levels nearly ten times greater than those recorded in typical tidal disruption events. Jason Hinkle, a researcher with the University of Hawaii’s Institute for Astronomy, noted that while the phenomenon of stellar disintegration has been documented for over a decade, these new events signal a starkly different and more powerful occurrence.
The most remarkable of these ENTs, designated as Gaia18cdj, released 25 times the energy of the most powerful supernova ever documented. Remarkably, ENTs generate as much energy in just one year as our Sun will output over its entire 10-billion-year lifespan, dramatically shifting the understanding of cosmic phenomena.
Hinkle and his team observed two unusual light flares in data collected from the European Space Agency’s Gaia space observatory. The distinct characteristics of these flares—smooth and sustained—prompted them to investigate further. “When I noticed these long-lived, consistent signals from remote galaxies, it was clear we were observing something extraordinary,” Hinkle remarked.
As they analyzed data from telescopes across the globe, the researchers concluded that the energy produced significantly exceeded that of a typical supernova, indicating that the flares were likely the result of a massive star being consumed by a supermassive black hole.
In a fascinating twist, the steady brightness of the ENTs diverges from the usually chaotic nature of black hole accretion, suggesting a much more gradual process tied to the assimilation of a massive star. Co-author Benjamin Shappee added that these ENTs can serve as powerful tools for understanding the dynamics of massive black holes in distant galaxies, as they allow astronomers to witness events across vast distances in the universe.
"Observing these extended flares enables us to glean insights into the evolution of black holes at a time when the universe was significantly younger, a period marked by vigorous star formation and exceptionally active black holes,” Shappee explained.
Hinkle emphasized the importance of these findings, noting that ENTs not only signify the dramatic conclusion of a massive star’s life but also shine a light on the underlying mechanisms that facilitate the growth of the universe’s largest black holes. As research continues, these discoveries promise to enhance our comprehension of cosmic evolution and the fundamental processes shaping our universe.