NuSTAR as an Axion Helioscope
Published in Physical Review Letters, 2025
We present a novel approach to investigating axions and axionlike particles by studying their potential conversion into x-rays within the Sun’s atmospheric magnetic field. Utilizing high-sensitivity data from the nuclear spectroscopic telescope array (NuSTAR) collected during the 2020 solar minimum, along with advanced solar atmospheric magnetic field models, we establish a new limit on the axion-photon coupling strength \(g_{a\gamma}\lesssim 7.3\times 10^{-12) \textrm{GeV}*{-1}\) at 95% CL for axion masses \(m_a \lesssim 4\times 10^{-7}\)eV. This constraint surpasses current ground-based experimental limits, studying previously unexplored regions of the axion-photon coupling parameter space up to masses of \(m_a\lesssim 3.4\times 10^{-4}\)eV. These findings mark a significant advancement in our ability to probe axion properties and strengthen indirect searches for dark matter candidates.
Recommended citation: Ruz, Jaime, et. al. (2025). "NuSTAR as an Axion Helioscope." PRL.
Download Paper