The abundance of a-process elements such as magnesium and carbon relative to iron, measured fiom the broad emission lines of QSOs, can serve as a diagnostic of the star formation and chemical enrichment histories of their host galaxies We investigate the relationship between Fe/Mg and Fe/C abundance ratios and the resulting Fe II / Mg II A2800 and Fe II / 1900A-blend flux ratios, both of which have been measured in QSOs out to z " 6. Using a galactic chemical evolution model based on a starburst in a giant elliptical galaxy, we find that these flux ratios are good tracers of the chemical enrichment of the nuclei. However, the values of these ratios measured in objects at z " 6 suggest that iron enrichment has occurred more rapidly in these objects than predicted by the assumed elliptical starburst model, assuming currently favored cosmologies. This in turn suggests that refinements to the galactic chemical evolution models are needed.
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机译：镁和碳相对于铁的诸如镁和碳的碳的丰度，测量了QSOS的广泛排放线，可以作为其宿主星系的明星形成和化学浓缩历史的诊断，我们研究了Fe / Mg之间的关系和Fe / C丰度比和所得Fe II / Mg II A2800和Fe II / 1900A - 混合通量比，两者都在QSOS OUT中测量到Z“6.使用基于Starburst的银河化学进化模型一个巨大的椭圆星系，我们发现这些助焊剂比是核的化学富集的良好示踪剂。然而，在Z“6的物体中测量的这些比率的值表明在这些物体中发生了比预期的更快地发生了铁富集。假设的椭圆爆炸式模型，假设当前有利的宇宙。这反过来表明需要改进到银河系化学进化模型。
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