AKARI NEP深场中0.9<z<1.7的星系团
Galaxy Clusters at 0.9<z<1.7 in the AKARI NEP deep field
摘要：
在z 3的红序选择大质量星系团的性质之间存在着巨大的差距<1 and Lyman-break selected proto-clusters at z>。理解z>3的原星系团何时以及如何演化成z<1的被动星系团是很重要的。我们的目标是通过使用AKARI的天基N4（4um）成像来填充这个集群沙漠。z '-N4色是z>1时星系团的一个强大分离器，利用了4000 A的破裂和1.6 um的隆起。我们仔细地选择了16个在0.9<z<1.7的有希望的星系团候选者，它们都显示出明显的超密度星系和突出的红色序列。在此红移范围内，中红外S15 μ m/S9 μ m通量比是一个无干扰的指示星系恒星形成活动的指标，因为PAH发射线（6.2，7.7和8.6 μ m）发生了红移。统计结果表明，团星系的S15 μ m/S9 μ m通量比场星系低，在0.9<z<1.7时，星系团星系已经有较低的恒星形成活动，将这些星系团的形成时代推向了更高的红移。
英文摘要：
There is a huge gap between properties of red-sequence selected massive galaxy clusters at z<1 and Lyman-break selected proto-clusters at z>3. It is important to understand when and how the z>3 proto-clusters evolve into passive clusters at z<1. We aim to fill this cluster desert by using the space-based N4(4um) imaging with the AKARI. The z'-N4 color is a powerful separator of cluster galaxies at z>1, taking advantage of the 4000A break and the 1.6um bump. We carefully selected 16 promising cluster candidates at 0.9<z<1.7, which all show obvious over-density of galaxies and a prominent red-sequence. At this redshift range, the mid-infrared S15um/S9um flux ratio is an extinction-free indicator of galaxy star formation activity due to the redshifted PAH emission lines (6.2,7.7 and 8.6um). We show statistically that the cluster galaxies have a lower S15um/S9um flux ratio than field galaxies, i.e., cluster galaxies already have lower star-formation activity at 0.9<z<1.7, pushing the formation epoch of these galaxy clusters to a higher redshift.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
