Accurate Determination of Chemical Abundances near a Supermassive Black Hole

The metal abundances in galactic nuclei carry key information on the history of star formation and mass transfer in central regions of galaxies. X-ray fluorescence analysis is a unique tool to reliably measure the abundances of various elements via simple physics. Here we present a new observation of the active nucleus in the Circinus Galaxy with the XRISM satellite at unprecedented X-ray energy resolution. The fluorescent iron-K$?$ line profile modified by Compton scattering indicates that the material responsible for its emission is cold, metal-rich, and is located $\gtrsim$0.024 parsecs (pc) from the supermassive black hole, consistent with the dusty torus region. The abundance pattern derived from comparing fluorescent line intensities of different metals shows sub-solar ratios of argon- and calcium-to-iron, and a super-solar ratio of nickel-to-iron. This abundance pattern is best produced by a combination in number fraction of 92⁺²₋₄% core-collapse supernovae from progenitor stars less massive than 20⁺³₋₂ M⊙ and 8⁺⁴₋₂ % type-Ia SNe. This suggests that gas feeding the super-massive black hole was enriched by recent core-collapse supernovae. Our findings imply that in metal-rich environments stars more massive than about 20 M⊙ directly collapse into black holes or make faint SNe without ejecting heavy metals into the space.