Constraining the axion–photon coupling using radio data of the Bullet cluster

Abstract

Axion is one of the most popular candidates of the cosmological dark matter. Recent studies considering the misalignment production of axions suggest some benchmark axion mass ranges near $$m_a \sim 20$$ m a ∼ 20 μeV. For such axion mass, the spontaneous decay of axions can give photons in radio band frequency $$\nu \sim 1{-}3$$ ν ∼ 1 - 3 GHz, which can be detected by radio telescopes. In this article, we show that using radio data of galaxy clusters would be excellent to constrain axion dark matter. Specifically, by using radio data of the Bullet cluster (1E 0657-55.8), we find that the upper limit of the axion–photon coupling constant can be constrained to $$g_{a \gamma \gamma } \sim 10^{-12}{-}10^{-11}$$ g a γ γ ∼ 10 - 12 - 10 - 11 GeV$$^{-1}$$ - 1 for $$m_a \sim 20$$ m a ∼ 20 μeV, which is tighter than the limit obtained by the CERN Axion Solar Telescope (CAST).

Cosmology of axion dark matter

“…20, moving from the infrared to the hard X-ray. Several other searches for spontaneous axion decay lines at longer wavelengths can be found in the literature-in the microwave [534] and radio [535,536] bands, for example-but unsurprisingly, these fall short of the stellar bounds on axions and so do not probe any self-consistent parts of parameter space.…”

Feebly-interacting particles: FIPs 2020 workshop report

“…In [599] it is pointed out for the first time that the echo signal relies on the historical luminosity of the photon source, unlike that the forward-going signals studied in Ref. [641,642,643] require the brightest radio sources today. This opens up the possibility to probe axion DM with time-varying radio sources that may be dim today but were once very bright, such as supernova remnants (SNRs).…”