‘Cosmic radio’ could find dark matter in 15 years

Scientists have designed a ‘cosmic radio’ detector which could discover dark matter in 15 years. 

Published today in Nature, scientists at King’s College London, Harvard University, UC Berkley and others have shared the foundation of what they believe will be the most accurate dark matter detector to date. 

Dark matter is the unobservable form of matter could make up as much as 85% of mass in the Universe, but scientists are not sure exactly what it is. 

Axions are one of the leading candidates for dark matter. These are tiny, weakly interacting particles that could exist in the universe – responsible for gravitational effects in space which cannot yet be explained. 

Axions are thought to have a frequency like a wave, but scientists do not know where they exist on the electromagnetic spectrum – though they are thought to range from kilohertz, a frequency that can be heard by humans, to the very high terahertz frequency. 

In the latest study, researchers explain how a detector which they dub a cosmic car radio, could alert scientists when it finds the frequency of the axion. Known as a Axion quasiparticle (AQ), the team believe it could help discover dark matter in fifteen years. 

The AQ is designed so its frequency can be transmitted into space, a frequency that would match with the axion. When it identifies and ‘tunes in’ to that frequency, it will emit very small amounts of light. AQ operates at the highest terahertz frequencies, which many researchers believe to be the most promising place to look for axions. 

Co-author Dr David Marsh, Ernest Rutherford Fellow at King’s College London, said: “We can now build a dark matter detector that is essentially a cosmic car radio, tuning into the frequencies of the wider galaxy until we find the axion. We already have the technology, now it’s just a matter of scale and time.” 

The team believe by creating a much larger piece of AQ material, they can create a functioning detector in five years. After that, they estimate it will take another decade of scanning the spectrum of high frequencies where dark matter is thought to be hiding before they find it. 

To create the quasiparticles, the researchers used manganese bismuth telluride (MnBi₂Te₄), a material known for its unique electronic and magnetic properties. This was shaved down to just a few two-dimensional layers of material layered on top of one another.  

Having developed the material over the past six years in the lab, Jian-Xiang Qiu, lead author from Harvard University said “Because MnBi₂Te₄ is so sensitive to air we needed to exfoliate it down to a few atomic layers to tune its properties accurately. This means we get to see this kind of interesting physics, and see how it interacts with other quantum entities like the axion.” 

Dr Marsh added: “This is a really exciting time to be a dark matter researcher. There are as many papers being published now about axions as there were about the Higgs-Boson a year before it was found. Theorists proposed that axions acted like a radio frequency in 1983 and we now know we can tune in to it – we’re closing in on the axion and fast.” 

Read the paper here