Mapping dusty star formation in and around a cluster at z= 0.81 by wide-field imaging with AKARI
Mapping dusty star formation in and around a cluster at z= 0.81 by wide-field imaging with AKARI
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DOI：
10.1111/j.1365-2966.2008.13931.x
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发表时间：
2008-09
影响因子：
4.8
通讯作者：
Y. Koyama;T. Kodama;K. Shimasaku;S. Okamura;Masayuki Tanaka;Hyung-Mok Lee;M. Im;H. Matsuhara;T. Takagi;T. Wada;S. Oyabu
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文献类型：
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作者：
Y. Koyama;T. Kodama;K. Shimasaku;S. Okamura;Masayuki Tanaka;Hyung-Mok Lee;M. Im;H. Matsuhara;T. Takagi;T. Wada;S. Oyabu
基于斯巴鲁望远镜（Subaru Telescope）上的定焦相机（Prime - cam）和AKARI卫星上的红外相机的宽视场和多波长观测，我们研究了RXJ1716.4+6708星团及其周围尘埃恒星形成活动的环境依赖性。我们的光学数据表明，星系的光学颜色分布在星团外围、群和细丝等中密度环境中开始从蓝色到红色发生剧烈变化。结合AKARI红外数据，我们发现15 μm探测到的星系往往具有介于红色序列和蓝色云之间的光学颜色，并有一条尾巴进入红色序列，与尘埃恒星形成星系一致。星团周围~ 200 arcmin2范围内15 μm探测到的星系的空间分布表明，在星团中心区域探测到的15 μm星系很少。这可能是由于星团核心的恒星形成活动较低。然而，有趣的是，尽管光学颜色在中密度环境中开始改变，但在中密度环境中探测到的15 μm星系的比例与在低密度场中一样高。此外，我们发现15 μm探测到的具有光学红色的星系（尘埃红星系的候选者）和具有高比星形成率的星系也集中在中密度环境中。这些结果表明，由于某些特定于中密度环境的环境效应（如星系-星系相互作用），星团和细丝星系中的恒星形成活动被增强，这种现象可能与星系中恒星形成活动的截断直接相关，这种环境被视为光学颜色的急剧变化。
We present environmental dependence of dusty star-forming activity in and around the cluster RXJ1716.4+6708 at z= 0.81 based on wide-field and multiwavelength observations with the Prime Focus Camera on the Subaru Telescope (Suprime-Cam) and the Infrared Camera onboard the AKARI satellite. Our optical data show that the optical colour distribution of galaxies starts to dramatically change from blue to red at the medium-density environment such as cluster outskirts, groups and filaments. By combining with the AKARI infrared data, we find that 15-μm-detected galaxies tend to have optical colours between the red sequence and the blue cloud with a tail into the red sequence, consistent with being dusty star-forming galaxies. The spatial distribution of the 15-μm-detected galaxies over ∼200 arcmin2 around the cluster reveals that few 15-μm galaxies are detected in the cluster central region. This is probably due to the low star-forming activity in the cluster core. However, interestingly, the fraction of 15-μm-detected galaxies in the medium-density environments is as high as in the low-density field, despite the fact that the optical colours start to change in the medium-density environments. Furthermore, we find that 15-μm-detected galaxies which have optically red colours (candidates for dusty red galaxies) and galaxies with high specific star formation rates are also concentrated in the medium-density environment. These results imply that the star-forming activity in galaxies in groups and filaments is enhanced due to some environmental effects specific to the medium-density environment (e.g. galaxy–galaxy interaction), and such a phenomenon is probably directly connected to the truncation of star-forming activity in galaxies seen as the dramatic change in optical colours in such environment.