Dark matter, an invisible substance that makes up a significant portion of the universe, continues to perplex scientists. Although it cannot be observed directly, its gravitational effects shape galaxies
and the cosmic web. Now, researchers may have discovered a promising method to study this elusive matter, bringing humanity closer to understanding the universe’s hidden mass.
The journey begins with a hypothetical particle known as the ‘Axion’. Proposed in the 1970s, axions are extremely light and difficult to detect. Scientists believe these particles could make up a large fraction of dark matter. To date, numerous experiments on Earth, including CERN’s ADMX and CAST projects, have tried to detect axions by looking into space, but none have produced definitive evidence.
Galaxy clusters have now emerged as a promising avenue. These enormous structures, each potentially a quadrillion times more massive than the Sun, contain strong magnetic fields. Gamma rays emitted from supermassive black holes in distant galaxies can interact with these fields, potentially converting into axions.
Professor Oleg Rukhaysky of the University of Copenhagen, Denmark, explains: “Galaxy clusters act like a prism. As gamma rays pass through them, some may turn into axions, creating subtle patterns in the data.”
When researchers combined observations from multiple clusters, a faint ‘step-like pattern’ appeared, which they have termed a ‘cosmic whisper’, a subtle signal that could indicate the presence of axions.
While this is not yet definitive proof, it narrows down where axions might exist and guides future searches. Scientists emphasise that this method can be repeated to gradually unravel the mystery of dark matter.
This approach opens a new frontier in understanding the universe’s hidden mass, bringing researchers one step closer to solving one of modern physics’ most perplexing puzzles.
