A comparison of LBGs, DRGs, and BzK galaxies: their contribution to the stellar mass density in the GOODS-MUSIC sample
A comparison of LBGs, DRGs, and BzK galaxies: their contribution to the stellar mass density in the GOODS-MUSIC sample
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DOI：
10.1051/0004-6361:20065989
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发表时间：
2007-04
影响因子：
6.5
通讯作者：
A. Grazian;S. Salimbeni;L. Pentericci;A. Fontana;M. Nonino;E. Vanzella;S. Cristiani;C. Santis;S. Gallozzi;E. Giallongo;P. Santini
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作者：
A. Grazian;S. Salimbeni;L. Pentericci;A. Fontana;M. Nonino;E. Vanzella;S. Cristiani;C. Santis;S. Gallozzi;E. Giallongo;P. Santini
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不明确。目标。这项工作的目标是研究不同类别的高z星系的特性，特别关注LBG、DRG和BzK的恒星质量，以推导出它们对遥远宇宙总质量预算的贡献。方法.我们使用的GOODS-MUSIC目录，包含~3000 K s-选择（~10 000 z -选择）的星系，多波长覆盖范围从U波段延伸到斯皮策$8~\mu$m波段，光谱或准确的光度红移。我们选择了BM/BX/LBG，DRG和BzK星系的样本来讨论这些标准的重叠和局限性，这些标准可以被基于物理参数的选择标准所覆盖。然后，我们测量了这些星系的恒星质量，并计算了不同样本的恒星质量密度（SMD），最高红移为$\simeq$4。结果我们表明，BzK-PE标准是不是最佳的选择在暗端的早型星系。另一方面，BzK-SF是高度污染的被动演变的星系在红色$z-K$s的颜色。我们发现，LBG和DRG的贡献几乎相等的全球SMD在$z\ge 2$，并在一般情况下，恒星形成的星系形成了相当大的一部分的普遍SMD。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，我们有迹象表明，通过将选择推到更深的量级，较小规模的DRG的贡献可能超过LBG。需要进行更深入的调查，如HUDF，以证实这一建议。
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 for the stellar mass and star formation rate of 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 used the GOODS-MUSIC catalog, containing ~3000 K s-selected (~10 000 z -selected) galaxies with multi-wavelength coverage extending from the U band to the Spitzer $8~\mu$m band, with spectroscopic or accurate photometric redshifts. We selected samples of BM/BX/LBGs, DRGs, and BzK galaxies to discuss the overlap and the limitations of these criteria, which can be overridden by a selection criterion based on physical parameters. We then measured the stellar masses of these galaxies and computed the stellar mass density (SMD) for the different samples up to redshift $\simeq$4. Results. We show that the BzK-PE criterion is not optimal for selecting early type galaxies at the faint end. On the other hand, BzK-SF is highly contaminated by passively evolving galaxies at red $z-K$s colours. We find that LBGs and DRGs contribute almost equally to the global SMD at $z\ge 2$ 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 have indications that by pushing the selection to deeper magnitudes, the contribution of less massive DRGs could overtake that of LBGs. Deeper surveys, like the HUDF, are required to confirm this suggestion.