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3.6. Metal Abundance in Intracluster Gas
The iron abundance in the intracluster gas is observed to be ~ 0.3 solar, with only small variations (± ~ 0.1) from cluster to cluster (e.g., Jones and Forman 1992). A strong correlation between the total iron mass in clusters and the total luminosity of the E + SO cluster galaxies is observed (Jones and Forman 1992). The metal enrichment of the intracluster gas is likely caused by gas stripped out of the elliptical galaxy members.
The iron abundance profile as a function of radius from the cluster center is generally flat, i.e., a constant abundance at all radii (except for some poor, low-mass clusters dominated by a single massive galaxy).
No evolution is observed in the overall iron abundance of clusters to z ~ 0.4 (Mushotzky 1996).
Recent results using ASCA observations (Mushotzky 1996) of different element abundances in nearby clusters (O, Ne, Mg, Si, S, Ar, Ca) suggest a SNII origin for the metals (resulting from early massive stars) rather than the expected SNIa. These new results will be expanded in the near future as additional accurate X-ray data become available and will provide further clues regarding the origin of the metallicity of the intracluster gas.