High-redshift QSOs provide important opportunities for advancing our understanding" of the astrophysics of galaxy formation and evolution. Although a growing number of these sources are now known to exist at redshifts beyond 4, systematic studies of the emission-line properties of these objects are quite limited. We present results of a program of high signal-to-noise spectroscopy for 44 QSOs using the Multiple Mirror Telescope Observatory and the W. M. Keck Observatory. The quasar spectra cover 1100-1700 A in the rest frame for sources spanning a luminosity range of ～2 orders of magnitude. Comparisons between these data and spectra of lower redshift quasars reveal a high degree of similarity, although differences are present in the profiles and the strengths of some emission features. An examination of the luminosity dependence of the emission lines reveals evidence for a weak or absent Baldwin effect among z approx> 4 QSOs. We compare measurements for objects in our sample with results from other high-redshift surveys characterized by different selection techniques. Distributions of equivalent widths for these different ensembles are consistent with a common parent population, suggesting that our sample is not strongly biased, or in any case, subject to selection effects that are not significantly different from other surveys, including the Sloan Digital Sky Survey. Based on this comparison, we tentatively conclude that the trends identified here are representative of high z QSOs. In particular, the data bolster indications of supersolar metallicities in these luminous, high-z sources, which support scenarios that assume substantial star formation at epochs preceding or concurrent with the QSO phenomena.
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机译：高红移QSO为增进我们对星系形成和演化的天体物理学的理解提供了重要的机会。尽管现在已知越来越多的红移4以上的源都存在着这些源，但对这些物体的发射线特性的系统研究仍在进行中。我们给出了使用多镜望远镜观测站和WM Keck观测站对44个QSO进行高信噪比光谱分析的程序的结果，在其余帧中，类星体光谱覆盖了1100-1700 A，适用于跨光度范围的源这些数据与较低的红移类星体的光谱比较显示出高度的相似性，尽管在轮廓和某些发射特征的强度上存在差异。 z大约4个QSO之间的鲍德温效应弱或不存在的证据我们将样品中的物体测量结果与resul比较来自其他以不同选择技术为特征的高红移调查。这些不同集合的等效宽度分布与普通父母群体一致，这表明我们的样本没有强烈的偏见，或者在任何情况下所受到的选择效应与包括Sloan Digital Sky Survey在内的其他调查没有显着差异。根据此比较，我们初步得出结论，此处确定的趋势代表了高z QSO。特别是，数据支持了这些高强度z发光源中超太阳能金属的指示，这支持了假设在QSO现象发生之前或与之同时发生的时期形成大量恒星的情况。
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