HomePhysicsAttempting to find Axions within the Galactic Middle

Attempting to find Axions within the Galactic Middle

• Physics 15, s163

A neutron star’s ultrastrong magnetic subject may create the circumstances for uncloaking a promising darkish matter candidate.

I. Heywood/College of Oxford; SARAO; J. C. Muñoz-Mateos/ESO

The axion—a hypothetical elementary particle—was initially conceived to resolve a puzzle regarding one of many 4 basic forces. Theorists then discovered one other use for this putative particle as a part of darkish matter, the mysterious substance that makes up 27% of the Universe’s mass. One place axions may present up is within the radio spectra of neutron stars. Now researchers searching for that signature have derived a brand new higher restrict on a key property of axions: how strongly they work together with photons [1].

One strategy to detecting axions is to use a powerful magnetic subject to a microwave cavity after which search for a predicted sign of axions changing into photons. In 2009 a pair of astronomers proposed that this conversion may additionally happen within the plasma threaded by a neutron star’s ultrastrong magnetic subject. The conversion is predicted to manifest as a slender, radio-frequency emission line whose actual frequency is determined by the axion mass and whose amplitude is determined by the axion density.

The anticipated sign is past the attain of present telescopes. Nevertheless, in 2020 the Massachusetts Institute of Expertise’s Joshua Foster and his collaborators demonstrated that it’s potential to derive helpful higher limits on the power of axion-photon conversion by searching for the sign the place it’s prone to be strongest: the Galactic Middle.

Now the identical group has seemed for that sign in information gathered throughout a seek for signatures of clever extraterrestrial life. They study the next and wider vary of axion mass than earlier than (15–35 𝜇eV versus 5–11 𝜇eV) and use a extra detailed mannequin of the neutron star inhabitants. Proof of axions stays elusive, however the brand new interaction-strength certain is extra stringent.

–Charles Day

Charles Day is a author and editor primarily based in Washington, DC, and the previous editor in chief of Physics In the present day.


  1. J. W. Foster et al., “Extraterrestrial axion search with the Breakthrough Pay attention Galactic Middle survey,” Phys. Rev. Lett. 129, 251102 (2022).

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