000163791 001__ 163791 000163791 005__ 20251107115328.0 000163791 0247_ $$2doi$$a10.1103/18sn-hxtb 000163791 0248_ $$2sideral$$a145851 000163791 037__ $$aART-2025-145851 000163791 041__ $$aeng 000163791 100__ $$0(orcid)0000-0002-3253-7027$$aRuz, J. 000163791 245__ $$aNuSTAR as an Axion Helioscope 000163791 260__ $$c2025 000163791 5060_ $$aAccess copy available to the general public$$fUnrestricted 000163791 5203_ $$aWe present a novel approach to investigating axions and axionlike particles by studying their potential conversion into x-rays within the Sun’s atmospheric magnetic field. Utilizing high-sensitivity data from the nuclear spectroscopic telescope array (NuSTAR) collected during the 2020 solar minimum, along with advanced solar atmospheric magnetic field models, we establish a new limit on the axion-photon coupling strength ≲7.3×10−12 GeV−1 at 95% CL for axion masses ≲4×10−7 eV. This constraint surpasses current ground-based experimental limits, studying previously unexplored regions of the axion-photon coupling parameter space up to masses of ≲3.4 ×10−4 eV. These findings mark a significant advancement in our ability to probe axion properties and strengthen indirect searches for dark matter candidates. 000163791 540__ $$9info:eu-repo/semantics/openAccess$$aby$$uhttps://creativecommons.org/licenses/by/4.0/deed.es 000163791 655_4 $$ainfo:eu-repo/semantics/article$$vinfo:eu-repo/semantics/publishedVersion 000163791 700__ $$aTodarello, E. 000163791 700__ $$0(orcid)0000-0002-5850-5517$$aVogel, J. K. 000163791 700__ $$aRodriguez Candón, F.$$uUniversidad de Zaragoza 000163791 700__ $$0(orcid)0000-0001-9823-6262$$aGiannotti, M.$$uUniversidad de Zaragoza 000163791 700__ $$aGrefenstette, B. 000163791 700__ $$aHudson, H.S. 000163791 700__ $$aHannah, I. G. 000163791 700__ $$0(orcid)0000-0003-1163-1687$$aGarcía Irastorza, I.$$uUniversidad de Zaragoza 000163791 700__ $$aKim, C. S. 000163791 700__ $$aRegis, M. 000163791 700__ $$aSmith, D. M. 000163791 700__ $$aTaoso, M. 000163791 700__ $$aTrujillo Bueno, J. 000163791 7102_ $$12004$$2038$$aUniversidad de Zaragoza$$bDpto. Física Teórica$$cÁrea Astronomía y Astrofísica 000163791 7102_ $$12004$$2390$$aUniversidad de Zaragoza$$bDpto. Física Teórica$$cÁrea Física Atóm.Molec.y Nucl. 000163791 773__ $$g135, 141001 (2025), 7$$pPhys. rev. lett.$$tPhysical Review Letters$$x0031-9007 000163791 8564_ $$s576841$$uhttps://zaguan.unizar.es/record/163791/files/texto_completo.pdf$$yVersión publicada 000163791 8564_ $$s2966699$$uhttps://zaguan.unizar.es/record/163791/files/texto_completo.jpg?subformat=icon$$xicon$$yVersión publicada 000163791 909CO $$ooai:zaguan.unizar.es:163791$$particulos$$pdriver 000163791 951__ $$a2025-11-07-10:24:44 000163791 980__ $$aARTICLE