Physicists at the Lawrence Berkeley National Laboratory in the United States have found that the mysterious high-energy radiation emitted from the vicinity of a group of neutron stars may indicate the existence of axions – not yet discovered particles within the framework of New Physics, the search for which has been going on since 1977. It is assumed that special types of axions form dark matter. This is reported in an article published in the journal Physical Review Letters. The research is summarized in a press release on Phys.org.
It is believed that axions can form in the core of neutron stars and transform into photons in the presence of a powerful magnetic field. To detect the electromagnetic radiation associated with axions, you need to find stars that do not emit radiation at different wavelengths that can mask the desired signal.
These objects include the Magnificent Seven neutron stars that emit only X-ray and ultraviolet radiation. They are located at a distance of 200-500 parsecs from the Earth.
The researchers ruled out the scenario that the excess X-rays produced by the Magnificent Seven are actually emitted by other, more distant objects. These sources would be found in datasets from the XMM-Newton and Chandra X-ray space telescopes.
The extra X-rays likely originate from axions hitting an extremely strong electromagnetic field billions of times stronger than the magnetic fields that could be created on Earth, the scientists concluded. The axions themselves resemble neutrinos in their properties, since both have insignificant masses and rarely and weakly interact with matter.
The axion is currently viewed as the most promising candidate for dark matter particles, since another hypothetical candidate, the massive WIMP particle, has gone unnoticed in experiments aimed at detecting it.
In addition, there may be a whole family of axion-like particles that form dark matter, as suggested by string theory. If axions are found, it will prove that there is a whole new area of physics outside the Standard Model describing the properties of all known particles.
To find out, the next step will be to study white dwarfs, which are not expected to emit X-rays.
“If we see an abundance of X-rays there too, our arguments will be pretty compelling,” said lead author Benjamin Safdie.