Abstract
We present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts. We use combined N-body/hydrodynamic simulations with a semi-numerical galaxy formation model. The mass loss by galactic winds is obtained by calculating transonic solutions of steady state outflows, driven by thermal, cosmic ray and MHD wave pressure. The inhomogeneities in the metal distribution caused by these processes are an ideal tool to reveal the dynamical state of a galaxy cluster. We present surface brightness, X-ray emission weighted temperature and metal maps of our model clusters as they would be observed by X-ray telescopes like XMM-Newton. We show that X-ray weighted metal maps distinguish between pre- or post-merger galaxy clusters by comparing the metallicity distribution with the galaxy-density distribution: pre-mergers have a metallicity gap between the subclusters, post-mergers a high metallicity between subclusters. We apply our approach to two observed galaxy clusters, Abell 3528 and Abell 3921, to show whether they are pre- or post-merging systems. The survival time of the inhomogeneities in the metallicity distribution found in our simulations is up to several Gyr. We show that galactic winds and merger-driven starbursts enrich the ICM very efficiently after in the central (~3 Mpc radius) region of a galaxy cluster.
Highlights
Modern X-ray observations of galaxy clusters show clearly a non-uniform, non-spherical distribution of metals in the intra-cluster medium (ICM) (e.g. Schmidt et al 2002; Furusho et al 2003; Sanders et al 2004; Fukazawa et al 2004; Hayakawa et al 2004)
We present an investigation of the metal enrichment of the intra-cluster medium (ICM) by galactic winds and merger-driven starbursts
As we focus in this paper on the enrichment of the ICM by galactic winds and starbursts, the metal maps give a direct measure of their efficiency
Summary
Modern X-ray observations of galaxy clusters show clearly a non-uniform, non-spherical distribution of metals in the ICM (e.g. Schmidt et al 2002; Furusho et al 2003; Sanders et al 2004; Fukazawa et al 2004; Hayakawa et al 2004). The first suggested transfer-processes were galactic winds (De Young 1978) and ram-pressure stripping (Gunn & Gott 1972). Other processes like kinetic mass redistribution due to galaxy-galaxy interactions (Kapferer et al 2005; Gnedin 1998), intra-cluster supernovae (Domainko et al 2004) or jets of AGNs are the latest suggestions for enriching the ICM. De Lucia et al (2004) used combined N-body and semi-analytical techniques to model the intergalactic and intracluster chemical enrichment due to galactic winds. Another approach are Tree+SPH simulations of galaxy clusters (Tornatore et al 2004) including galactic winds. A comparison of the efficiency between rampressure stripping and quiet galactic winds was recently done by Schindler et al (2005)
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