Scientists from the University of Hawaii’s Institute for Astronomy (IfA) have discovered the most energetic cosmic explosions since the Big Bang.
Extreme nuclear transients (ENTs) occur when massive stars several times larger than our Sun are torn apart by supermassive black holes.
ENTs shine with intense luminosity, much brighter than supernovae, which originate from the violent death of massive stars.
Biggest explosions ever seen
One ENT observed by the team at IfA emitted over 25 times more energy than the most energetic supernovae known, radiating the energy of around 100 Suns in a single year.
"We’ve observed stars getting ripped apart as tidal disruption events for over a decade, but these ENTs are different beasts, reaching brightnesses nearly 10 times more than what we typically see," says Jason Hinkle, the researcher at IfA who led the study.
The vast amount of energy released by these explosions can be visible over huge distances.
Hinkle first uncovered ENTs when searching for long-lived flares coming from galactic centres.
The intense outbursts are examples of transients: astrophysical events that change brightness over a relatively short time.
In his search of data from ESA’s Gaia mission, he discovered two particularly unusual events that brightened over a timescale longer than typical transients, and without their other characteristics.
The researchers determined that ENTs could not be simple supernovae because they release far more energy.
Instead, their unique characteristics suggest the involvement of a supermassive black hole.
Insights into black hole secrets
"ENTs provide a valuable new tool for studying massive black holes in distant galaxies," adds Benjamin Shappee, associate professor at IfA and the study’s co-author.
"By observing these prolonged flares, we gain insights into black hole growth when the Universe was half its current age, when galaxies were happening places – forming stars and feeding their supermassive black holes 10 times more vigorously than they do today."
ENTs remain rare, occurring 10 million times less frequently than supernovae. As such, their detection is challenging.
Future observatories like the Vera C Rubin Observatory and NASA’s Roman Space Telescope will aid in the search for these cosmic flashbangs.
Future study of ENTs
Words: Chris Lintott
To follow up on discoveries like these, you need a telescope capable of monitoring the whole sky, one that can ferret out unusual events.
We’re about to get such an instrument, with the Vera C Rubin Observatory now starting operations as of summer 2025.
With a mirror as large as some of the largest telescopes on Earth, the world’s largest camera and an ability to scan the whole sky every three nights, Rubin will help spot the ‘weird’ in the Universe.
Producing 30 terabytes of data a night and issuing roughly 10 million alerts, it will revolutionise how astronomical research is conducted.
We’re about to be surprised by more ENTs – and plenty of other novelties besides.
This article appeared in the August 2025 issue of BBC Sky at Night Magazine
