Cosmology and Nongalactic Astrophysics2025-10-10v2High Energy Astrophysical PhenomenaInstrumentation and Methods for AstrophysicsSolar and Stellar AstrophysicsHigh Energy Physics - ExperimentHigh Energy Physics - Phenomenology
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 gaγ≲7.3×10−12~GeV−1 at 95\% CL for axion masses ma≲4×10−7\,eV. This constraint surpasses current ground-based experimental limits, studying previously unexplored regions of the axion-photon coupling parameter space up to masses of ma≲3.4×10−4\,eV. These findings mark a significant advancement in our ability to probe axion properties and strengthen indirect searches for dark matter candidates.
@article{arxiv.2407.03828,
title = {NuSTAR as an Axion Helioscope},
author = {J. Ruz and E. Todarello and J. K. Vogel and F. R. Candón and M. Giannotti and B. Grefenstette and H. S. Hudson and I. G. Hannah and I. G. Irastorza and C. S. Kim and M. Regis and D. M. Smith and M. Taoso and J. Trujillo Bueno},
journal= {arXiv preprint arXiv:2407.03828},
year = {2025}
}