For nearly 90 years, scientists have been searching for answers about dark matter—the invisible substance that makes up 85% of the universe’s matter.
Now, researchers from the University of California, Berkeley, believe a single cosmic event could hold the key: a nearby supernova.
When a massive star collapses into a neutron star, it triggers a powerful explosion called a supernova.
According to the researchers, this process could also produce huge numbers of a particle called the axion, a leading candidate for dark matter. Axions are extremely light and difficult to detect, but they could reveal themselves during the first 10 seconds of a supernova.
If axions exist, they would escape the collapsing star and interact with its intense magnetic field, transforming into gamma rays—high-energy light waves.
These gamma rays could be detected by instruments on Earth, offering clues about the axion’s mass and properties.
However, there’s a catch. To detect these gamma rays, the explosion would need to happen in our Milky Way galaxy or one of its satellite galaxies, and a gamma-ray telescope must be pointed in the right direction at the exact moment.
With current technology, this alignment is rare, giving scientists only a 1-in-10 chance of catching such an event.
Finding axions would solve one of physics’ greatest mysteries. Axions are a strong candidate for dark matter because they fit within the standard model of physics and could help unify theories of quantum mechanics and gravity.
Unlike other particles, such as neutrinos, axions are predicted to interact weakly with all four fundamental forces: gravity, electromagnetism, the strong force, and the weak force.
“This discovery would let us pinpoint the mass of the axion and its interaction strength,” said Benjamin Safdi, senior author of the study. “It would be a game-changer for dark matter research.”
The gamma-ray burst would also confirm decades of theoretical work on axions and shift the focus of current experiments, which are still searching for these particles in Earth-based laboratories.
The researchers warn that we may not be prepared when the next supernova occurs. On average, nearby supernovae happen once every few decades, but the last one, Supernova 1987A, occurred in the Large Magellanic Cloud nearly 40 years ago. At that time, gamma-ray telescopes weren’t sensitive enough to detect the predicted gamma rays from axions.
To avoid missing the next opportunity, the team has proposed building a fleet of gamma-ray telescopes capable of monitoring the entire sky 24/7. They’ve even named the project GALAXIS (GALactic AXion Instrument for Supernova).
“We’re worried the next supernova might happen before we have the right instruments in place,” Safdi explained. “If we miss it, we might not get another chance for decades.”
For now, the Fermi Gamma-ray Space Telescope offers the best chance of detecting gamma rays from a nearby supernova. Though its field of view is limited, a lucky break could still lead to groundbreaking discoveries.
“The best-case scenario is that Fermi catches a supernova,” Safdi said. “If it does, we could measure the axion’s mass, its interaction strength, and confirm its existence. There’s no ordinary matter that could mimic such an event, so the signal would be undeniable.”
The UC Berkeley team continues to explore new ways to detect axions. Their work has already put strict limits on the possible mass of the QCD axion—a specific type of axion tied to the strong force—and could refine these estimates further with additional data.
Safdi and his colleagues believe neutron stars, which are extremely hot and have the universe’s strongest magnetic fields, could be the perfect “laboratories” for studying axions. By understanding how these particles interact with extreme environments, scientists hope to unlock more secrets about dark matter and the universe itself.
While the next nearby supernova remains unpredictable, researchers are racing against time to ensure they’re ready.
A single detection could end decades of speculation and provide a definitive answer to one of science’s biggest questions: What is dark matter?
