Perspectives on Intracluster Enrichment and the Stellar Initial Mass Function in Elliptical Galaxies. (arXiv:1301.3200v1 [astro-ph.CO])

Perspectives on Intracluster Enrichment and the Stellar Initial Mass Function in Elliptical Galaxies. (arXiv:1301.3200v1 [astro-ph.CO]):
The amount of metals in the Intracluster Medium (ICM) in rich galaxy clusters
exceeds that expected based on the observed stellar population by a large
factor. We quantify this discrepancy -- which we term the "cluster elemental
abundance paradox" -- and investigate the required properties of the
ICM-enriching population. The necessary enhancement in metal enrichment may, in
principle, originate in the observed stellar population if a larger fraction of
stars in the supernova-progenitor mass range form from an initial mass function
(IMF) that is either bottom-light or top-heavy, with the latter in some
conflict with observed ICM abundance ratios. Other alternatives that imply more
modest revisions to the IMF, mass return and remnant fractions, and primordial
fraction, posit an increase in the fraction of 3-8 solar mass stars that
explode as SNIa or assume that there are more stars than conventionally thought
-- although the latter implies a high star formation efficiency. We discuss the
feasibility of these various solutions and the implications for the diversity
of star formation, the process of elliptical galaxy formation, and the nature
of this "hidden" source of ICM metal enrichment in light of recent evidence of
an elliptical galaxy IMF that, because it is skewed to low masses, deepens the
paradox.