HOW to search for hypothetical invisible particles? Astronomers found a unique way. They observed how quickly the particles were able to “kill” white dwarfs, the dense cores left over from the death of a star.
In recent years, the astronomical community has become increasingly interested in a theoretical particle called Axion. This particle was conceived decades ago to solve complex problems in the strong nuclear force. Even though it had faded because it failed to be discovered in particle collider experiments, Axion has emerged again as a strong candidate to explain the mystery of dark matter.
The Secret Behind Star Cooling
Even though Axion is considered nearly invisible, its existence still leaves its mark on the universe. In a paper released November 2025 on the arXiv server, the researchers outlined how to test the Axion model using archival data from the Hubble Space Telescope.
The main target of this study is white dwarfs. This object is very exotic because it has a mass equivalent to the Sun but is smaller in size than Earth. Inside it, there is a “sea” of electrons that move very fast, approaching the speed of light.
According to several theoretical models, these very fast moving electrons can trigger the formation of Axions. Because Axion can shoot out of a white dwarf without a hitch, this process automatically “robs” the star of its energy. As a result, the white dwarf will cool much faster than would be expected naturally.
Testing Hubble Data on Cluster 47 Tucanae
The researchers incorporated this “Axion cooling” model into sophisticated software that simulates stellar evolution. They then compared these temperature predictions with real data from globular cluster 47 Tucanae collected by Hubble. This cluster was chosen because all the white dwarfs within it were born at about the same time, providing a stable sample for study.
The result? The researchers found no evidence of extra cooling due to Axion in the white dwarf population. However, this finding provides a very clear new limitation for science: electrons cannot possibly produce Axions more often than a one in a trillion chance.
The results of this study do not completely invalidate the Axion theory, but show that the possibility of direct interaction between electrons and Axions is very small. This finding forces scientists to look for smarter and more innovative ways to hunt for mysterious particles that hold the key to the secrets of the universe’s dark matter. (Space/Z-2)
