Dark matter is one of the biggest mysteries in physics. It is thought to make up 85% of the matter in the universe, but it has never been directly detected. One possible candidate for dark matter is the axion, a hypothetical particle that was first proposed in the 1970s.
A team of astrophysicists, led by researchers from the universities of Amsterdam and Princeton, has now shown that if dark matter consists of axions, it may reveal itself in the form of a subtle additional glow coming from pulsars, which are rotating neutron stars. Their work is published in the journal Physical Review Letters.
Pulsars are some of the most powerful electromagnetic fields in the universe. If axions exist, they could convert into light in the presence of these strong fields. The researchers simulated the production of axions around pulsars and found that they would emit a low-energy radio signal.
The researchers then compared their simulations to observations of 27 nearby pulsars. They found no evidence for an excess radio signal, but their results did place the strongest limits to date on the interaction that axions can have with light.
The researchers say that their work is just a first step in the search for axions. They are hopeful that future observations with more sensitive telescopes will be able to detect the subtle glow of axions from pulsars, and finally confirm whether or not they are a constituent of dark matter.
The research by the team of astrophysicists is significant because it provides a new way to search for axions, which are a possible candidate for dark matter. If dark matter consists of axions, then detecting the subtle glow of axions from pulsars would be a direct confirmation of the existence of dark matter.
The research also has implications for our understanding of pulsars themselves. The simulations performed by the researchers showed that the production of axions around pulsars could affect the way that pulsars emit radio waves. This could help scientists to better understand the physics of pulsars and how they work.
Journal Information: Dion Noordhuis et al, Novel Constraints on Axions Produced in Pulsar Polar-Cap Cascades, Physical Review Letters (2023). DOI: 10.1103/PhysRevLett.131.111004
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