Figure 6 in arXiv:0801.1193Caption: The authors create a composite UV spectrum from 75 (MIR selected) GMASS galaxies. Using this and the set of population synthesis models from Rix et al (2004; the 1978 index for the connoisseurs) they derive a stellar metal abundance of log (Z/Z_sun) = -0.574 +/- 0.159 [read this as an iron abundance]. This value is compared to models by Finlator & Davé (2007) in the figure above (red circles correspond to stellar abundance estimates at z~2 and black filled circles to gas-phase abundances at z~2). The triangles are gas-phase metallicities (oxygen) derived by Erb et al (2006) also at z~2.
The most immediate explanation for the difference between the stellar & gas-phase abundance is that we are seeing the effect of alpha-enhancement here.
Poster: Jarle Brinchmann
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