A team of astronomers at the University of Hawai’i’s Institute for Astronomers (IfA) have discovered a new type of cosmic explosion that exceeds anything observed previously
These events, known as extreme nuclear transients (ENTs), are the most energetic explosions seen since the Big Bang, creating a new lens through which scientists can explore black holes and galaxy evolution.
A new class of cosmic explosions
ENTs differ from typical supernovae or previously known black hole activity due to their brightness and longevity. These explosions happen when enormous stars are slowly pulled apart and consumed by the supermassive black holes at the centre of galaxies.
Although supernovae usually fade within a few weeks, extreme nuclear transients can stay luminous for years. Their brightness is even more intense than that of the most intense supernovae, nearly ten times the amount.
A particular event, Gaia18cdj, released 25 times more energy than any supernova ever recorded. In just one year, it emitted as much energy as 100 Suns would over their entire lifetimes.
Discovery through data
The discovery started when astronomer Jason Hinkle noticed unusual flares In the publicly available data from the Gaia space telescope. These flares did not bear resemblance to traditional cosmic events.
Instead, they were smooth, long-lasting light curves originating from the centres of distant galaxies, which is strong evidence of an entirely different phenomenon.
To investigate this further, the IfA team utilised data from multiple powerful telescopes, including those operated by the Asteroid Terrestrial-impact Last Alert System (ATLAS) on Haleakalā and Mauna Loa, the W. M. Keck Observatory on Maunakea, as well as other Earth-based and space-based observatories. Years of observations helped researchers confirm that these were not ordinary tidal disruption events or supernovae but something far more extreme.
The distant universe
ENTs are extremely rare, millions of times less common than a supernova, but their brightness makes them more detectable across vast cosmic distances.
This makes them an important new tool for studying the early universe. Because light from these events can travel billions of years to reach Earth, astronomers can effectively look into the distant past when galaxies were younger and black holes were rapidly growing.
These events present a new opportunity to study how supermassive black holes grew during a period when star formation and black hole feeding were significantly more active than they are today.
More discoveries in the future
By identifying extreme nuclear transients , astronomers may be able to make discoveries that could reshape our understanding of black holes and galaxy evolution. Upcoming observatories, such as the Vera C. Rubin Observatory and NASA’s Roman Space Telescope, are expected to detect many more of these rare explosions, allowing astronomers to create a clearer picture of the cosmic process driving the growth of galaxies and the black holes at their centres
By studying the evolution of massive stars, scientists gain new insights into how these stars meet their end and how their destruction contributes to the formation and evolution of the largest structures in the universe.
