亚毫米星系真的能追踪到最大质量的暗物质晕吗？发现处于高度活跃演化阶段的高Z星系团
Do submillimeter galaxies really trace the most massive dark matter halos? Discovery of a high-z cluster in a highly active phase of evolution
摘要：
我们提出了一个z~1.99的亚毫米星系团（SMG）的详细观测结果，发现在我们整个调查的~100个SMG跨越800平方弧分的最强红移尖峰。这是目前已知的最大空白场SMG浓度，并且从SMG的潜在选择函数中抽取的机会<0.01%。我们比较了在这个红移的星系的紫外线观测，我们发现了一个不那么引人注目的过密度，有11%的机会从它的选择函数中被提取出来。我们使用这个z~1.99的过密度来比较UV和submm选择的星系的偏置，并测试SMG是否可以居住在不太过密度的环境中，其明显的聚类信号主要由高度活跃的合并时期在适度的质量结构。这种令人印象深刻的活跃的形成阶段，在低质量的集群是不是在模拟中看到的东西，虽然我们提出了一个玩具模型，使用合并的偏见，可以占SMG中看到的偏见。虽然增强的恒星质量积累似乎是其他高z星系团的特征，但这种结构中的UV星系和亚毫米星系都没有表现出比场星系更大的恒星质量（尽管结构中多余的SMG代表了比场星系更大的体积平均恒星质量）。我们的研究结果对未来在长波长下对高z星系（如SCUBA 2和Herschel）进行调查具有重要意义。我们认为，由于这些调查将选择在其高峰期的恒星爆发的星系，他们可以探测更广泛的环境，而不仅仅是丰富的集群的祖先，更完整地揭示了星系形成和组装的关键事件和阶段。
英文摘要：
We present detailed observations of a z~1.99 cluster of submillimeter galaxies (SMGs), discovered as the strongest redshift spike in our entire survey of ~100 SMGs across 800 square arcmin. It is the largest blank-field SMG concentration currently known and has <0.01% chance of being drawn from the underlying selection function for SMGs. We have compared UV observations of galaxies at this redshift, where we find a much less dramatic overdensity, having an 11% chance of being drawn from its selection function. We use this z~1.99 overdensity to compare the biasing of UV- and submm-selected galaxies, and test whether SMGs could reside in less overdense environments, with their apparent clustering signal being dominated by highly active merger periods in modest mass structures. This impressively active formation phase in a low mass cluster is not something seen in simulations, although we propose a toy model using merger bias which could account for the bias seen in the SMGs. While enhanced buildup of stellar mass appears characteristic of other high-z galaxy clusters, neither the UV- nor submm-galaxies in this structure exhibit larger stellar masses than their field galaxy counterparts (although the excess of SMGs in the structure represents a larger volume-averaged stellar mass than the field). Our findings have strong implications for future surveys for high-z galaxies at long wavelengths such as SCUBA2 and Herschel. We suggest that since these surveys will select galaxies during their episodes of peak starbursts, they could probe a much wider range of environments than just the progenitors of rich clusters, revealing more completely the key events and stages in galaxy formation and assembly.
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