Researchers at the University of York suggest that dark matter could subtly tint light red or blue as it passes through, challenging the idea that it is completely invisible. This indirect interaction might allow detection using next-generation telescopes. The finding could simplify the search for the mysterious substance that dominates the universe.
Dark matter, which constitutes most of the universe and is known only through its gravitational effects on galaxies, might not be entirely undetectable by light-based methods. A study from the University of York proposes that light traveling through regions dense with dark matter could acquire a faint red or blue tint, depending on the type of dark matter encountered.
The research draws an analogy to the 'six handshake rule,' suggesting that even if dark matter does not directly interact with light, it could influence it indirectly via a chain of subatomic particles. For instance, Weakly Interacting Massive Particles (WIMPs) might connect through intermediaries like the Higgs boson and the top quark.
Dr. Mikhail Bashkanov, from the University of York's School of Physics, Engineering and Technology, explained: "It's a fairly unusual question to ask in the scientific world, because most researchers would agree that dark matter is dark, but we have shown that even dark matter that is the darkest kind imaginable -- it could still have a kind of color signature."
He added: "It's a fascinating idea, and what is even more exciting is that, under certain conditions, this 'color' might actually be detectable. With the right kind of next-generation telescopes, we could measure it. That means astronomy could tell us something completely new about the nature of dark matter, making the search for it much simpler."
The study, authored by A. Acar, C. Isaacson, M. Bashkanov, and D.P. Watts, outlines how these effects could be tested in future experiments to refine dark matter models. Dr. Bashkanov noted: "Right now, scientists are spending billions building different experiments -- some to find WIMPs, others to look for axions or dark photons. Our results show we can narrow down where and how we should look in the sky, potentially saving time and helping to focus those efforts."
Published in Physics Letters B (2025; 870: 139920), the work emphasizes integrating these insights into telescope designs to probe the unseen 85% of the cosmos.