Open AccessAbundance ratios in hierarchical galaxy formation
Author(s) -
Thomas Daniel
Publication year - 1999
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.1999.02552.x
Subject(s) - physics , astrophysics , galaxy , metallicity , star formation , initial mass function , galaxy formation and evolution , abundance (ecology) , cluster (spacecraft) , population , stellar mass , astronomy , demography , fishery , sociology , computer science , biology , programming language
The chemical enrichment and stellar abundance ratios of galaxies that form in a hierarchical clustering scheme are calculated. For this purpose, I adopt the star formation histories (SFH) as they are delivered by semi‐analytic models by Kauffmann. It turns out that the average SFH of cluster ellipticals does not yield globally α‐enhanced stellar populations. The starburst that occurs when the elliptical forms in the major merger therefore plays a crucial role in producing α‐enhancement. Only under the assumption that the initial mass function is significantly flattened with respect to the Salpeter value during the burst, can a Mg/Fe overabundant population be obtained. In particular, for the interpretations of radial gradients in metallicity and α‐enhancement, the mixing of global and burst populations are of great importance. The model predicts bright field galaxies to be less α‐enhanced than their counterparts in clusters.