A comparison among LBGs, DRGs and BzK galaxies: their contribution to the stellar mass density in the GOODS-MUSIC sample
A comparison among LBGs, DRGs and BzK galaxies: their contribution to the stellar mass density in the GOODS-MUSIC sample
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LBG、DRG 和 BzK 星系之间的比较：它们对 GOODS-MUSIC 样本中恒星质量密度的贡献
DOI：
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发表时间：
2007
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影响因子：
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通讯作者：
Italy.
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作者：
A. Roma;Monteporzio;I. O. A. D. Trieste;Trieste;Italy.
上下文目前高红移星系的分类方案很复杂，颜色选择标准很简单（即ERO、IERO、LBG、DRG、BzK），导致这些遥远星系的恒星质量和星星形成率的性质定义不清。目标。这项工作的目标是研究不同类别的高z星系的性质，特别是对恒星质量的LBG，DRG和BzKs，以获得他们的贡献，遥远的宇宙的总质量预算。方法.我们使用的是GOODS-MUSIC星表，其中包含了10000个K选择的星系（10000个z选择的星系），这些星系具有从U波段延伸到斯皮策8 µ m波段的多波长覆盖范围，具有光谱或精确的光度红移。我们选取了BM/BX/LBG、DRG和BzK星系的样本，讨论了这些标准的重叠和局限性，这些可以通过基于物理参数的选择标准来克服。然后，我们测量了这些星系的恒星质量，并计算了恒星质量密度（SMD）的不同样品的红移高达1.4。结果我们发现，BzK-PE标准是不是最佳的选择早型星系的暗端。另一方面，BzK-SF被处于红色z-Ks颜色的被动演化星系高度污染。我们发现，在z ≥ 2时，LBG和DRG对SMD的贡献几乎相等，一般来说，形成星星的星系构成了宇宙SMD的一个重要部分。被动演化的星系显示出从红移2到3的强烈的负密度演化，这表明我们正在见证这类天体的大规模组装时代。最后，我们发现有迹象表明，将选择推向更深的量级，较小规模的DRG的贡献可以克服LBG的贡献。需要更深入的调查，如HUDF，以证实这一建议。结论.
Context. The classification scheme for high redshift galaxies is complex at the present time, with simple colour selection criteria (i.e. EROs, IEROs, LBGs, DRGs, BzKs), resulting in ill-defined properties regarding stellar mass and star formation rate for these distant galaxies. Aims. The goal of this work is to investigate the properties of different classes of high-z galaxies, focusing in particular on the Stellar Masses of LBGs, DRGs and BzKs, in order to derive their contribution to the total mass budget of the distant Universe. Methods. We have used the GOODS-MUSIC catalog, containing ∼ 3000 Ks–selected ( ∼ 10000 z–selected) galaxies with multi-wavelength coverage extending from the U band to the Spitzer 8 µ m band, with spectroscopic or accurate photometric redshifts. We have selected samples of BM/BX/LBGs, DRGs and BzK galaxies, discussed the overlap and the limitations of these criteria, which can be overcome with a selection criterion based on physical parameters. We have then measured the stellar masses of these galaxies and computed the Stellar Mass Density (SMD) for the different samples up to redshift ≃ 4. Results. We show that the BzK-PE criterion is not optimal to select early type galaxies at the faint end. BzK-SF, on the other hand, is highly contaminated by passively evolving galaxies at red z − Ks colours. We find that LBGs and DRGs contribute almost equally to the global SMD at z ≥ 2 and in general that star forming galaxies form a substantial fraction of the universal SMD. Passively evolving galaxies show a strong negative density evolution from redshift 2 to 3, indicating that we are witnessing the epoch of mass assembly of such objects. Finally we find indications that pushing the selection to deeper magnitudes, the contribution of less massive DRGs could overcome that of LBGs. Deeper surveys, like the HUDF, are required to confirm this suggestion. Conclusions.