Simulating the metal enrichment of the intracluster medium

We present results from Tree + SPH simulations of a galaxy cluster, aimed at studying the metal enrichment of the intracluster medium (ICM). The simulation code includes a fairly advanced treatment of star formation, as well as the release of energy feedback and detailed yields from both Type II and Type Ia supernovae, also accurately accounting for the lifetimes of different stellar populations. We perform simulations of a cluster with virial mass ~=3.9 × 1014 Msolar, to investigate the effect of varying the feedback strength and the stellar initial mass function (IMF). Although most of the models are able to produce acceptable amounts of Fe mass, we find that the profiles of the iron abundance are always steeper than observed. The [O/Fe] ratio is found to be subsolar for a Salpeter IMF, with [O/Fe]~=-0.2 at R > 0.1R200, whereas increasing to supersolar values in central regions, as a result of recent star formation. Using a top-heavier IMF gives a larger [O/Fe] over the whole cluster, at variance with observations. On the other hand, the adoption of a variable IMF, which becomes top-heavier at z > 2, provides a roughly solar [O/Fe] ratio. Our results indicate that our simulations still lack a feedback mechanism which should quench star formation at low redshift and transport metals away from the star-forming regions.