Constraints on the Chemical Enrichment History of the Perseus Cluster of Galaxies from High-Resolution X-ray Spectroscopy

TL;DR

High-resolution X-ray spectroscopy of the Perseus Cluster core reveals precise elemental abundances, challenging existing supernova models and suggesting neutrino physics may be key to understanding chemical enrichment.

Contribution

This study provides the most precise measurements of elemental abundances in the Perseus Cluster core using high-resolution spectroscopy, highlighting discrepancies with current supernova nucleosynthesis models.

Findings

Ar/Fe, Ca/Fe, Ni/Fe ratios determined with <10% uncertainty

Simple enrichment model matches high-resolution data well

Existing supernova models struggle to reproduce observed element patterns

Abstract

High-resolution spectroscopy of the core of the Perseus Cluster of galaxies, using the $Hitomi$ satellite above 2 keV and the $XMM$-$Newton$ Reflection Grating Spectrometer at lower energies, provides reliable constraints on the abundances of O, Ne, Mg, Si, S, Ar, Ca, Cr, Mn, Fe, and Ni. Accounting for all known systematic uncertainties, the Ar/Fe, Ca/Fe, and Ni/Fe ratios are determined with a remarkable precision of less than 10%, while the constraints on Si/Fe, S/Fe, and Cr/Fe are at the 15% level, and Mn/Fe is measured with a 20% uncertainty. The average biases in determining the chemical composition using archival CCD spectra from $XMM$-$Newton$ and $Suzaku$ range typically from 15-40%. A simple model in which the enrichment pattern in the Perseus Cluster core and the proto-solar nebula are identical gives a surprisingly good description of the high-resolution X-ray spectroscopy results, with $\chi^2=10.7$ for 10 d.o.f. However, this pattern is challenging to reproduce with linear combinations of existing supernova nucleosynthesis calculations, particularly given the precise measurements of intermediate $\alpha$-elements enabled by $Hitomi$. We discuss in detail the degeneracies between various supernova progenitor models and explosion mechanisms, and the remaining uncertainties in these theoretical models. We suggest that including neutrino physics in the core-collapse supernova yield calculations may improve the agreement with the observed pattern of $\alpha$-elements in the Perseus Cluster core. Our results provide a complementary benchmark for testing future nucleosynthesis calculations required to understand the origin of chemical elements.