Spectroscopy of z~ 5 Lyman break galaxies in the ESO Remote Galaxy Survey Spectroscopy of z ~ 5 Galaxies
Spectroscopy of z~ 5 Lyman break galaxies in the ESO Remote Galaxy Survey Spectroscopy of z ~ 5 Galaxies
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ESO 远程星系巡天中 z~ 5 莱曼断裂星系的光谱 z ~ 5 星系光谱
DOI：
10.1111/j.1365-2966.2010.17375.x
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发表时间：
2010
影响因子：
4.8
通讯作者：
Douglas L
中科院分区：
文献类型：
--
作者：
Douglas L
我们提出了一个大型分光巡天的全球结果，以确定10个相距甚远的10个45弧分2视场中的2个莱曼破裂星系（LBG），其深度为IAB = 26.3。70个4.6 <z< 5.6的LBG的红移是通过它们的Lyα发射和/或一个强的连续谱断裂而被确认的，其中38个源显示出可探测的线发射在2.6 × 10− 18和7 × 10− 17 erg cm−2s−1之间。在光谱学证实的z 105星系中，超过一半的静止坐标系Lyα等效宽度大于20 μ m，是类似z 103 LBG样本中类似强线发射体频率的两倍。然而，当合理的校正光谱未经证实的来源，但在这些红移在两个样本中，我们发现没有显着差异的频率之间的样本的高等效宽度线发射器。一个典型的z/z 5线发射星系的静止坐标系紫外线连续斜率（主要通过测光测量，但在光谱学中也很明显）比一个典型的纯断裂星系更蓝，这种差异很难纯粹用恒星种群的年龄差异来解释。金属丰度和/或尘埃消光的变化可以更直接地解释这种差异。如果在低红移处确定的紫外连续斜率与金属丰度之间的相关性适用于z> 3，则典型的z ≥ 5 LBG的金属丰度比z ≥ 3的LBG低3倍。哈勃空间望远镜对LBG子集的成像表明，我们样品中绝大多数光谱证实的LBG是多个系统的成员（在0.2arcsec尺度上）和/或显示出扰动的形态。使用当地的LBG类似物作为模型，这种多样性可以解释为一个更大的看不见的结构内的超级星爆区域或合并事件在这个时代的高发生率。目前的数据无法区分这两种可能性。在10个场中的两个场中，z ≥ 5个LBG的面密度明显高于其余场。两者都显示出明显的尖峰在其红移分布表明在这些领域的强大的三维集群。相对于在4.8 <z< 5.6之间每0.1个红移中大约有一个源的预期，一个场在5.11 <z< 5.21之间有7个已识别的物体，另一个场在4.95 <z< 5.15之间有17个。这两种结构都不能被束缚，因为它们的红移深度可能会超出观测到的场。结构中的LBG之间的三维距离太大，它们无法通过相互引力相互作用触发恒星爆发，因此，寿命短的LBG可能只代表结构中重子的一小部分。
We present the global results of a large spectroscopic survey carried out in order to identifyz∼ 5 Lyman break galaxies (LBGs) across 10 widely separated ∼45 arcmin2fields to a depth ofIAB= 26.3. The redshifts of seventy 4.6 <z< 5.6 LBGs were identified through their Lyα emission and/or a strong continuum break, with 38 sources showing detectable line emission of between 2.6 × 10−18and 7 × 10−17erg cm−2s−1. Just over half of the spectroscopically confirmedz∼ 5 galaxies have rest-frame Lyα equivalent widths above 20 Å, double the frequency of similarly strong line emitters in similarz∼ 3 LBG samples. However, when reasonable corrections are made for the spectroscopically unconfirmed sources that are nevertheless at these redshifts in both samples, we find no significant difference in the frequency of high equivalent width line emitters between the samples. The rest-frame UV continuum slope of a typicalz∼ 5 line-emitting galaxy (as measured primarily from photometry, but also apparent in spectroscopy) is bluer than that of a typical break-only galaxy, a difference that is difficult to explain purely by differences in the ages of their stellar populations. Variation in metallicity and/or dust extinction can more straightforwardly account for this difference. If the correlation between metallicity and UV continuum slope identified at low redshift is applicable atz> 3, the typicalz∼ 5 LBGs have metallicities a factor of 3 lower than those of LBGs atz∼ 3.Hubble Space Telescopeimaging of a subset of the LBGs indicates that a large majority of the spectroscopically confirmed LBGs in our sample are members of multiple systems (on ∼ arcsec scales) and/or show disturbed morphology. Using local LBG analogues as a model, this multiplicity could be explained either by super-starburst regions within a larger unseen structure or by a high incidence of merging events at this epoch. The current data cannot distinguish between these two possibilities. The surface density ofz∼ 5 LBGs in two of the 10 fields is considerably higher than in the rest. Both show clear spikes in their redshift distributions indicating strong three-dimensional clustering in these fields. Against an expectation of about one source per 0.1 in redshift between 4.8 <z< 5.6, one field has seven identified objects between 5.11 <z< 5.21 and the other has 17 between 4.95 <z< 5.15. Neither structure can be bound given their depth in redshift and probably extend beyond the observed fields. The three-dimensional distances between LBGs in the structures are too large for them to have triggered their starbursts through mutual gravitational interaction, and so it is likely that the short-lived LBGs represent only a small fraction of the baryons in the structures.