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24 February 2022

Axions shedding light on dark matter

Review conducted by King’s physicists delves into the theory of axions, and their context within the wider fields of particle physics and cosmology.

universe galaxy

Research developments in the fields of particle physics and cosmology has led to a growing interest in the axion particle – a hypothetical particle which explains why neutrons behave in a certain way in the presence of electromagnetic fields. If detected, the axion particle would play a key role in explaining the origin of dark matter in the Universe.

Published in Science Advances, the review conducted by Professor John Ellis (Clerk Maxwell Professor of Theoretical Physics) and Dr David Marsh (Lecturer and Ernest Rutherford Fellow) from King’s Department of Physics, and Durham University’s Dr Francesca Chadha-Day, focuses on the theory of axions, how axions are produced in the early Universe, and how astrophysics and particle physics work together to tell us how to search for axions in the laboratory.

The axion behaves like a field covering the Universe, and this field can also explain where dark matter comes from. Dark matter is known to make up around 85% of our Milky Way galaxy, but experts are not yet sure what it is made of. The axion particle is a good explanation, because it interacts very weakly with light (axions are ‘dark’), and there are processes in the early Universe that can cause the axion field to oscillate back and forth and become excited. Research hypothesises that the energy stored in these oscillations is axion dark matter, which if detected could provide the solution to one of the greatest mysteries of the Universe.

Furthering the understanding of axions also contributes towards developing the technology that could detect them. Interest in detecting axions has underpinned dozens of ongoing experiments around the world, which seek to find the axion in the next ten to twenty years. The Science Advances review from the King’s team complements a companion article by Professor Yannis Semertzidis and Dr SungWoo Youn, which explains how the technology being developed works.

On developments in the field, David commented;

The next few decades will be an incredibly exciting time to work in the search for axions. Just like in the 2000s as physicists awaited the switch on of the LHC to find the Higgs, we are now waiting for these numerous axion experiments to switch on and tell us whether the axion exists. Nothing is a sure bet in theoretical physics, but now for the first time there will be vast amounts of data coming in to help axion researchers like me. Finding the axion would solve some of the deepest mysteries in the Universe. I can't wait to see what happens!

Dr David Marsh

In this story

David Marsh

Proleptic Lecturer

Professor John Ellis FRS

Clerk Maxwell Professor of Theoretical Physics