Constraints on the chemical enrichment history of the Perseus Cluster of galaxies from high-resolution X-ray spectroscopy

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 χ 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 α-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 α-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.

How do atomic code uncertainties affect abundance measurements in the intracluster medium?

“…In particular, even using moderate‐resolution spectroscopy instruments, abundances can be measured more precisely in the ICM than in our own Solar System (de Plaa et al ; Mernier et al ). On paper, these ICM abundance ratios are invaluable because, as witnesses of billions of supernovae explosions, they can be directly compared to SNIa and SNcc yields expected from nucleosynthesis models and thus help to (dis)favor some of them (de Plaa et al ; Mernier et al ; Simionescu et al ). Whereas this exercise is, in practice, still difficult given the uncertainties related to the nucleosynthesis models themselves (De Grandi & Molendi ; Mernier et al ; Simionescu et al ), a clear picture that recently emerged—notably thanks to the exquisite spectral resolution provided by the Hitomi observatory on the Perseus cluster—is that the ICM chemical composition is surprisingly similar to that of our own Solar System (Hitomi Collaboration et al ; Mernier et al ; Simionescu et al ).…”

“…On paper, these ICM abundance ratios are invaluable because, as witnesses of billions of supernovae explosions, they can be directly compared to SNIa and SNcc yields expected from nucleosynthesis models and thus help to (dis)favor some of them (de Plaa et al ; Mernier et al ; Simionescu et al ). Whereas this exercise is, in practice, still difficult given the uncertainties related to the nucleosynthesis models themselves (De Grandi & Molendi ; Mernier et al ; Simionescu et al ), a clear picture that recently emerged—notably thanks to the exquisite spectral resolution provided by the Hitomi observatory on the Perseus cluster—is that the ICM chemical composition is surprisingly similar to that of our own Solar System (Hitomi Collaboration et al ; Mernier et al ; Simionescu et al ). One notable exception to this trend is the significantly super‐solar N/Fe abundance ratio measured in hot atmospheres of nearby clusters and groups, suggesting that AGB stars do contribute to the central ICM enrichment as well (Mao et al ; Sanders & Fabian ; Werner et al ).…”

Lessons learned from 19 years of high‐resolution X‐ray spectroscopy of galaxy clusters with the reflection grating spectrometer on board XMM‐Newton

“…RGS is even more efficient if used together with other high‐resolution spectrometers that cover the high‐energy (2–10 keV) X‐ray energy band, such X‐ray calorimeters. Simionescu et al () show a remarkable example of combining the XMM ‐ Newton /RGS soft X‐ray and Hitomi /SXS hard X‐ray spectra of the Perseus cluster with state‐of‐art atomic data, achieving an unprecedented accuracy on the relative α /Fe abundance ratios (Figure ). The abundance pattern agrees with that of the Solar nebula and challenges any linear combinations of supernova nucleosynthesis calculations.…”

“…Abundance ratios measured for the Perseus cluster with XMM ‐ Newton /reflection grating spectrometer (O, Ne, Mg to Fe) and Hitomi /SXS (Si through Ni to Fe, Simionescu et al ). The light blue strip is the systematic uncertainty on the Hitomi data.…”

“…However, the uniformity of the O/Fe and Ne/Fe abundance ratios over more than an order of magnitude in mass range (from giant ellipticals to groups and then clusters of galaxies) and the lack of spatial gradients and distribution with 1 "Solar" refers to the proto-Solar abundances of Lodders & Palme (2009). F I G U R E 4 Abundance ratios measured for the Perseus cluster with XMM-Newton/reflection grating spectrometer (O, Ne, Mg to Fe) and Hitomi/SXS (Si through Ni to Fe, Simionescu et al 2019). The light blue strip is the systematic uncertainty on the Hitomi data.…”