A large scale structure traced by [OII] emitters hosting a distant cluster at z=1.62
A large scale structure traced by [OII] emitters hosting a distant cluster at z=1.62
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由 [OII] 发射器追踪的大规模结构，该发射器在 z=1.62 处托管着一个遥远的星团
DOI：
10.1111/j.1365-2966.2012.21063.x
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发表时间：
2012
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et al.
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作者：
K. Tadaki;et al.
利用斯巴鲁望远镜上的suprim - cam对ClG J0218.3−0510星团atz= 1.62内及其周围的[Oii]发射体进行了全景窄带成像调查，根据窄带过量和光度红移确定了352个[Oii]发射体。我们发现了一个巨大的丝状结构，其中有一些团块被[ii]发射器追踪到，并且发现ClG J0218.3−0510团块嵌入在一个比之前报道的更大的上层结构中。通过光纤多目标光谱仪观测到的Hα和/或[Oiii]发射谱线，对31个[Oii]发射体进行了光谱确认。在高密度区域，如星团核心和团块，恒星形成[ii]发射体显示出高过密度，比场区高10倍以上。有趣的是，在光选择样品中[ii]发射体的相对比例并不显著依赖于局部密度。虽然星团核心的恒星形成活动非常活跃，但同时也存在一些大质量的静止星系。此外，单个[ii]发射体的特性，如恒星形成速率（SFRs）、恒星质量和特定SFRs，也没有显示出对局部密度的显著依赖。这种缺乏对环境的依赖与我们之前Hayashi等人关于az= 1.5集群及其周围区域的结果是一致的。星团核心星系的恒星形成活动与atz ~ 1.6区域一样高，这一事实可能表明，恒星形成星系可能正处于从星暴模式到静止模式的过渡阶段，因此显示出与低密度环境中的恒星形成率相当的水平。由于高红移高密度区域的“偏倚”星系形成和演化，我们可能正在见证局部sr -密度关系逆转的开始，在此之外，大质量星系将以更偏倚的方式在原星团核心中大力形成。
We present a panoramic narrow-band imaging survey of [Oii] emitters in and around the ClG J0218.3−0510 cluster atz= 1.62 with Suprime-Cam on Subaru Telescope. 352 [Oii] emitters were identified on the basis of narrow-band excesses and photometric redshifts. We discovered a huge filamentary structure with some clumps traced by [Oii] emitters and found that the ClG J0218.3−0510 cluster is embedded in an even larger superstructure than the one reported previously. 31 [Oii] emitters were spectroscopically confirmed with the detection of Hα and/or [Oiii] emission lines by Fibre Multi Object Spectrograph observations. In the high-density regions such as cluster core and clumps, star-forming [Oii] emitters show a high overdensity by a factor of more than 10 compared to the field region. Interestingly, the relative fraction of [Oii] emitters in photo-zselected sample does not depend significantly on the local density. Although the star formation activity is very high even in the cluster core, some massive quiescent galaxies also exist at the same time. Furthermore, the properties of the individual [Oii] emitters, such as star formation rates (SFRs), stellar masses and specific SFRs, do not show a significant dependence on the local density, either. Such a lack of environmental dependence is consistent with our earlier result by Hayashi et al. on az= 1.5 cluster and its surrounding region. The fact that the star-forming activity of galaxies in the cluster core is as high as that in the field atz∼ 1.6 may suggest that the star-forming galaxies are probably just in a transition phase from a starburst mode to a quiescent mode, and are thus showing comparable level of star formation rates to those in lower density environments. We may be witnessing the start of the reversal of the local SFR–density relation due to the ‘biased’ galaxy formation and evolution in high-density regions at this high redshift, beyond which massive galaxies would be forming vigorously in a more biased way in protocluster cores.