Axion-like Particle Conversion in the Solar Magnetic Field

Abstract: Axion-like particles (ALPs), hypothetical extensions of the Standard Model, can convert into photons in an external magnetic field. Two recent studies~\cite{Todarello:2023ptf, Ruz:2024gkl} explored the phenomenology of ALP-photon conversion in the magnetic field of the solar atmosphere. Dark matter ALPs convert into radio photons and may be detected with next-generation radio interferometers, while ALPs produced in the solar core convert into X-rays. Thanks to solar observation acquired with the NuSTAR X-ray telescope, Ref.~\cite{Ruz:2024gkl} establishes stringent robust bounds on the ALP-photon coupling over a large portion of parameter space.