SIMBAD references

A detailed model of galactic evolution is proposed to explain both the iron content of the Intra-Cluster Medium (ICM) and of the ellipticals pertaining to the cluster. SNII are responsible for the production of Fe in the galaxies and of its partial ejection in the surrounding medium. A high formation rate of massive stars only (m>3M_☉) at the very early stage of evolution of ellipticals, reminiscent of starburst galaxies, is advocated. The high rate of SNII explosions induces a powerful galactic wind, followed by a more quiescent evolution where stars are formed, with a normal Initial Mass Function (IMF), from the enriched gas remaining after the wind phase and from the gas restored by the longest living stars produced during the early phase. Most of the iron is produced by the high-mass stars created in the early burst phase. The ICM iron mass per unit luminosity of member galaxies (2x10^–2M_☉/L_☉) is reproduced, together with a mean Mg/Fe ratio in the stellar component higher than solar, and other observed quantities on present elliptical galaxies (M/L ratio, stellar and ISM metallicities, remaining gas fraction). We discuss the influence of the parameters: astration rate in the burst phase and in the quiescent phase, mass loss rate during the wind phase. We found that the global iron production is very robust with respect to the parameters. On the other hand, a key factor is the total mass lost during the wind. It must be ≃50% in order to insure a correct share between present stars and the ICM. The evolution depends on the galaxy mass due to the deeper gravitational potential for larger galaxies. A possible weak point of the model is that, although metallicities increase with galaxy mass, other quantities (Mg/Fe and M/L) vary only slightly. It is concluded, as in previous works, that most of the cluster gas (80% for rich clusters) is of primordial origin, which explains the decrease of iron abundance with cluster temperature, itself related to the richness of the cluster. We also predict that the abundances of O and Si in the ICM, relative to Fe are higher than solar.