We study the origin of iron and alpha-elements (O, Mg, Si) in clusters of
galaxies. In particular, we discuss the [O/Fe] ratio and the iron
mass-to-luminosity ratio in the intracluster medium (ICM) and their link to the
chemical and dynamical evolution of elliptical and lenticular galaxies. We
adopt a detailed model of galactic evolution incorporating the development of
supernovae- driven galactic winds which pollute the ICM with enriched ejecta.
We demonstrate \it quantitatively \rm the crucial dependence upon the assumed
stellar initial mass function in determining the evolution of the mass and
abundances ratios of heavy elements in typical model ICMs. We show that
completely opposite behaviours of [alpha/Fe] ratios (\ie positive versus
negative ratios) can be obtained by varying the initial mass function without
altering the classic assumptions regarding type Ia supernovae progenitors or
their nucleosynthesis. Our results indicate that models incorporating somewhat
flatter-than-Salpeter initial mass functions (ie x approx 1, as opposed to
x=1.35) are preferred, provided the intracluster medium iron mass-to-luminosity
ratio, preliminary [alpha/Fe]>0 ASCA results, and present-day type Ia
supernovae rates, are to be matched. A simple Virgo cluster simulation which
adheres to these constraints shows that approx 70% of the measured ICM iron
mass has its origin in type II supernovae, with the remainder being synthesized
in type Ia systems.Comment: 25 pages of uuencoded compressed PostScript. 4 PostScript figures and
4 PostScript tables available from
http://www-astro.physics.ox.ac.uk/~bkg/gibson.html Accepted for publication
in Astronomy & Astrophysics
