How do scientists hunt for elusive particles? One approach is to see how they might affect white dwarfs, the remnants of dead stars.
Lately, astronomers have been curious about a theoretical particle called the axion. This concept emerged decades ago to tackle a tricky problem with the strong nuclear force. Initially, attempts to find it in particle colliders were unsuccessful, leading to the idea’s decline in popularity.
However, recent research has revived interest. The axion could help explain dark matter, a mystery that still puzzles astrophysicists. Although these particles might be flooding the universe, they’ve managed to evade direct detection.
Even though axions are nearly invisible, they can still leave traces. A paper published in November 2025 explored how to study axions using existing data from the Hubble Space Telescope. While they didn’t find any axions, they did clarify what we understand about these particles and our universe.
The researchers focused on white dwarfs. These dense star remnants contain about the mass of our Sun but are smaller than Earth. They resist collapse due to electron degeneracy pressure, a fascinating quantum effect where electrons refuse to occupy the same state.
Some theories suggest that axions might form when fast-moving electrons collide. Since the electrons in white dwarfs move at almost the speed of light, they could produce many axions. If these axions escape, they would drain energy from the white dwarf, causing it to cool faster than usual.
To test this idea, scientists used simulations that model star evolution. They predicted white dwarf temperatures over time, considering both scenarios with and without axion cooling. They then compared their findings to data from globular cluster 47 Tucanae. This cluster is essential because all its white dwarfs formed around the same time, providing a consistent sample for analysis.
Ultimately, the study found no evidence of axion cooling among the white dwarfs. However, it established important limits on how efficiently electrons can produce axions, suggesting a direct interaction is unlikely.
So, while the search for axions continues, astronomers may need to find new and innovative ways to uncover these mysterious particles.
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