NuSTAR as an Axion Helioscope
astro-ph.CO
/ Authors
J. Ruz, E. Todarello, J. K. Vogel, F. R. Candón, M. Giannotti, B. Grefenstette, H. S. Hudson, I. G. Hannah, I. G. Irastorza, C. S. Kim
and 4 more authors
/ Abstract
We present a novel approach to investigating axions and axion-like particles (ALPs) 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 $g_{aγ}\lesssim 7.3\times 10^{-12}$~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.