Passive galaxies in the early Universe: ALMA confirmation ofz∼ 3−5 candidates in the CANDELS GOODS-South field
Passive galaxies in the early Universe: ALMA confirmation ofz∼ 3−5 candidates in the CANDELS GOODS-South field
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早期宇宙中的被动星系：ALMA 确认 CANDELS GOODS-South 区域中的 z〜 3−5 个候选星系
DOI：
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发表时间：
2019
影响因子：
4.8
通讯作者：
M. Torelli
中科院分区：
文献类型：
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作者：
P. Santini;E. Merlin;A. Fontana;B. Magnelli;D. Paris;M. Castellano;A. Grazian;L. Pentericci;S. Pilo;M. Torelli
在早期宇宙中选择红色的被动星系是非常具有挑战性的，特别是在z~3之后，并且关键是要限制对它们快速组装和突然关闭星星形成过程负责的理论建模。本文分析了位于坎德尔南场深处的30个星系中的26个星系的阿尔马档案观测资料，这些星系是我们通过仔细和保守的SED拟合分析确定为z~3-5处的被动星系。阿尔马的数据被用来验证潜在的污染，从红色，尘埃，但星星-形成源，可能进入样品，由于类似的光学-近红外颜色。除了在<3sigma时的少数边缘检测外，我们只能推断出单个源和堆栈的上限。我们翻译的阿尔马连续测量到相应的SFR，使用各种远红外模型。这些SFR进行了比较，预测的次级恒星形成的解决方案的光学拟合和预期的位置的星星形成主序星。这一分析证实了9个候选人的被动性质，具有很高的信心，并表明，至少有一半的样本在统计意义上的分类是正确的。对于其余的源，分析仍然没有结论，因为现有的阿尔马数据不够深入，尽管叠加结果证实了它们的被动性质。尽管存在不确定性，这项工作提供了决定性的支持，在z~3以外的被动星系的存在。
The selection of red, passive galaxies in the early Universe is very challenging, especially beyond z~3, and it is crucial to constrain theoretical modelling of the processes responsible for their rapid assembly and abrupt shut-down of the star formation. We present here the analysis of ALMA archival observations of 26 out of the 30 galaxies in the deep CANDELS GOODS-South field that we identified as passive at z~3-5 by means of a careful and conservative SED fitting analysis. ALMA data are used to verify the potential contamination from red, dusty but star--forming sources that could enter the sample due to similar optical--nearIR colours. With the exception of a few marginal detections at <3sigma, we could only infer upper limits, both on individual sources and on the stacks. We translated the ALMA continuum measurements into corresponding SFRs, using a variety of far-IR models. These SFRs are compared with those predicted by secondary star-forming solutions of the optical fits and with the expected position of the star formation Main Sequence. This analysis confirms the passive nature of 9 candidates with high confidence and suggests that the classification is correct for at least half of the sample in a statistical sense. For the remaining sources the analysis remain inconclusive because available ALMA data is not deep enough, although the stacking results corroborate their passive nature. Despite the uncertainties, this work provides decisive support to the existence of passive galaxies beyond z~3.