Astronomers have identified a new class of cosmic events, termed "extreme nuclear transients" (ENTs), far exceeding previous observations in energy output and duration.
These events occur when massive stars venture close to supermassive black holes at the centers of galaxies, leading to their disruption.
The discovery, published in Science Advances, promises to reshape our understanding of stellar death and black hole feeding.
ENTs are approximately ten times brighter than typical tidal disruption events (TDEs), lasting for years with smooth light curves.
The most extreme ENT radiated 25 times more energy than the most powerful supernovae, challenging existing models of black hole accretion.
These luminous events were found by searching for long-lived flares from distant galactic nuclei using data from the European Space Agency's Gaia mission.
Observations across the electromagnetic spectrum, including data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) and the W. M. Keck Observatory, were crucial in understanding ENTs.
The prolonged brightness of ENTs, coupled with their immense energy, suggests a slow accretion process of stellar debris onto supermassive black holes, differing from episodic accretion in active galactic nuclei.
The underlying process involves the tidal disruption of massive stars, forming an accretion disk that radiates prodigious energy.
ENTs offer a unique opportunity to study the behavior and growth of supermassive black holes across cosmic time.
Future surveys, such as those by the Vera C. Rubin Observatory and NASA's Roman Space Telescope, are expected to dramatically increase the discovery rate of these rare events.
The study of ENTs will provide unprecedented insights into the interplay between stellar life cycles and the extreme gravity environments of galactic nuclei.