Spatial distribution of metals in the ICM. Evolution of the iron excess in relaxed galaxy clusters

We investigate the spatial distribution of iron in the intracluster medium (ICM) in a selected sample of 41 relaxed clusters in the redshift range 0.05 < z < 1.03 using Chandra archival data. We compute the azimuthally averaged, deprojected ZFe profile of each cluster out to ~0.4r500, and identify a peak in the distribution of iron followed by a flatter distribution at larger radii. Due to the steep gradient both in gas density and abundance, we find that the emission-weighted iron abundance within 0.2r500, which entirely includes the iron peak in most of the cases, is on average ~25 per cent higher than the mass-weighted value, showing that spatially resolved analysis and accurate deprojection are key to study the evolution of iron enrichment in the very central regions of cool-core clusters.We quantify the extent of the iron distribution in each cluster with a normalized scale parameter rFe, defined as the radius where the iron abundance excess is half of its peak value. We find that rFe increases by a factor of ~3 from z ~ 1 to z ~ 0.1, suggesting that the spatial distribution of iron in the ICM extends with time, possibly due to the mixing with the mechanical-mode feedback from the central galaxy. We also find that the iron mass excess within 0.3r500, when normalized to the total baryonic mass within the same region, does not evolve significantly, showing that this iron mass component is already established at z ~ 1.