DISCOVERY OF NINE EXTENDED IONIZED GAS CLOUDS IN A z = 0.4 CLUSTER
DISCOVERY OF NINE EXTENDED IONIZED GAS CLOUDS IN A z = 0.4 CLUSTER
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DOI：
10.1088/0004-6256/149/2/36
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发表时间：
2013-09
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影响因子：
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通讯作者：
M. Yagi;L. Gu;Y. Koyama;F. Nakata;T. Kodama;T. Hattori;Michitoshi Yoshida
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作者：
M. Yagi;L. Gu;Y. Koyama;F. Nakata;T. Kodama;T. Hattori;Michitoshi Yoshida
根据 Suprime-Cam/Subaru 的深 Hα 成像数据，我们在阿贝尔 851 星团 (A851) z = 0.4 的星系周围发现了九个扩展的电离气体云 (EIG)。我们调查了 30 × 25 arcmin 区域，并且仅在簇中心附近发现了 EIG（arcmin ∼ 750 kpc）。 EIG 的母星系是恒星形成或星暴后星系，所有这些星系都是经光谱证实的星团成员。九个母星系中的四个显示出盘中恒星分布的扭曲，这可能是最近相互作用的迹象，并且相互作用可能形成了 EIG。另一方面，六个母星系（其中一个与那些表现出扭曲的星系重叠）显示出没有恒星的 Hα 发射，这意味着冲压压力剥离。最亮母星系的光谱显示出星暴后的特征，类似于后发星团中发现的 Hα 剥离星系。与此同时，A851 中两个最亮的母星系比后发星团中的 EIG 母星系质量更大。这与恒星形成星系的“缩小”是一致的，尽管它仍在统计方差之内。我们还分析了另一个 z = 0.39 ?> 簇 CL0024+17 的 Suprime-Cam 数据，但没有发现 EIG。 A851和CL0024+17之间的主要区别是存在与A851主体碰撞的子星系团，其中A851的9个母星系中有6个或7个存在，并且子星系团中EIG的比例明显高于A851和CL0024+17的主子星系团。
From deep Hα imaging data of Suprime-Cam/Subaru, we discovered nine extended ionized gas clouds (EIG) around galaxies in the Abell 851 cluster (A851) at z = 0.4. We surveyed a 30 × 25 arcmin region, and the EIGs were found only near the cluster center ( arcmin ∼ 750 kpc). The parent galaxies of the EIGs are star-forming or post-starburst galaxies, all of which are spectroscopically confirmed members of the cluster. Four out of the nine parent galaxies show distortion of stellar distribution in the disk, which can be a sign of recent interaction, and the interaction may have made the EIGs. On the other hand, six parent galaxies (one overlaps those exhibiting distortion) show Hα emission without stars, which implies ram pressure stripping. The spectrum of the brightest parent galaxy shows a post-starburst signature and resembles the Hα stripped galaxies found in the Coma cluster. Meanwhile, two brightest parent galaxies in A851 are more massive than the EIG parent galaxies in the Coma cluster. This is consistent with a “downsizing” of star-forming galaxies, though it is still within the statistical variance. We also analyzed Suprime-Cam data of another z = 0.39 ?> cluster, CL0024+17, but found no EIGs. The key difference between A851 and CL0024+17 would be the existence of a subcluster colliding with the main body of A851, in which six or seven out of the nine parent galaxies in A851 exist, and the fraction of EIGs in the subcluster is significantly higher than the main subcluster of A851 and CL0024+17.