Comparison of g_ae × g_aγ across different instruments and different astrophysical objects. The bounds for CAST are obtained from Barth et al. (2013), NuSTAR’s Betelgeuse bounds from Xiao et al. (2022), Suzaku bounds from Dessert et al. (2019), projected sensitivity of IAXO from Abeln et al. (2021a), Chandra’s MWD study from Dessert et al. (2022), and NuSTAR’s M82 bounds from Ning & Safdi (2025). This study improves on the previous limits by over an order of magnitude for the most optimistic case. The study of M82 with NuSTAR might still provide the tightest constraints in the literature; however, the limitation of their analysis is discussed in the conclusion.