Investigating the Impact of Atomic Data Uncertainties on the Measured Physical Parameters of the Perseus Galaxy Cluster

Abstract

Accurate atomic data and plasma models are essential for interpreting the upcoming high-quality spectra from missions like XRISM and Athena. Estimating physical quantities, like temperature, abundance, turbulence, and the resonance scattering factor, is highly dependent on the underlying atomic data. We use the AtomDB tool variableapec to estimate the impact of atomic data uncertainties in Einstein A coefficients, collisional rate coefficients, and the ionization and recombination rates of H-, He-, and Li-like iron in modeling the spectrum of Perseus observed by Hitomi. The best-fit temperatures, abundances, resonance scattering factors, and turbulence parameters including atomic data uncertainties vary by approximately 17%, 35%, 30%, and 3%, respectively, from the best-fit temperatures, abundances, RS factors, and turbulence parameters estimated without atomic data uncertainties. These indicate that approximately 32%, 35%, and 25% of the best-fit temperatures, abundances, and resonance scattering factors when including uncertainties lie outside the 3 σ error regions of their corresponding best-fit values computed with zero atomic data errors. Expanding the energy range to 1.8–20.0 keV shows less variability, with 26% of the abundances and 22% of the resonance scattering factors lying outside the 3 σ errors of the best-fit values. We also studied correlations between physical parameters and atomic rate uncertainties to identify key atomic quantities requiring precise lab measurements. We report negative correlations between the best-fit temperatures and the z (1s2s ^3 S _1 → 1s ^2 ) collisional rate coefficients, abundances and y (1s2p ^3 P _1 → 1s ^2 ) collisional rate coefficients, and abundances and z collisional rate coefficients, and a positive correlation between the resonance scattering factors and the w (1s2p ^1 P _1 → 1s ^2 ) collisional rate coefficients.

Keywords

• X-ray astronomy
• Galaxy clusters
• Atomic spectroscopy