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arXiv 1111.6693astro-ph.CO
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北极极(NEP)超星系团z = 0.087的AKARI观测:过渡星系的中红外视图

AKARI Observation of the North Ecliptic Pole (NEP) Supercluster at z = 0.087: mid-infrared view of transition galaxies

Jongwan Ko, Myungshin Im, Hyung Mok Lee, Myung Gyoon Lee, Seong Jin Kim, Hyunjin Shim, Yiseul Jeon, Ho Seong Hwang, Christopher N. A. Willmer, Matthew A. Malkan… 展开作者

Jongwan Ko, Myungshin Im, Hyung Mok Lee, Myung Gyoon Lee, Seong Jin Kim, Hyunjin Shim, Yiseul Jeon, Ho Seong Hwang, Christopher N. A. Willmer, Matthew A. Malkan, Casey Papovich, Benjamin J. Weiner, Hideo Matsuhara, Shinki Oyabu, Toshinobu Takagi

摘要:

我们提出的中红外(MIR)的性质的星系内的超星系团在北极地区在z?0.087 AKARI卫星观测到的。我们使用的数据从AKARI NEP宽(5.4 deg 2)IR调查和星系演化研究(CLEVL)任务计划的集群。我们发现,近红外(3 μm)-中红外(11 μm)颜色可以作为一个指标,具体的恒星形成率和存在的中间年龄恒星星族。从MIR观测中发现,红序星系不仅由被动演化的红色早型星系组成,而且还包括1)“弱SFG”(盘控星系,其恒星形成速率比蓝云星系低\sim 4)和2)“中等MXG”(膨胀星系,其MIR尘埃辐射比正常的红色早型星系强)。这两个群体可能是一组过渡星系,从蓝色的、恒星形成的、晚型星系演变成红色的、静止的、早型星系。我们发现弱SFG在中等质量(1010 M \odot < M \star <1010.5 M \odot)时占优势,并且通常在类似于星系团外围的局部密度中发现。在这个质量范围内,有40%的超星系团成员星系可以被归类为弱SFG,但在任何星系密度下,它们的比例在更大的质量(M \star > 1010.5 M \odot)时会下降到< 10%。在1010 M \odot < M \star <1011 M \odot的红序星系中,中间MXG的比例也随着密度和质量的增加而减少。特别是,\sim 42%的红序列星系的早期型形态被归类为中等密度的中间MXG。这些结果表明,恒星的形成活动强烈依赖于恒星的质量,但形态转变主要是由环境控制。

英文摘要:

We present the mid-infrared (MIR) properties of galaxies within a supercluster in the North Ecliptic Pole region at z?0.087 observed with the AKARI satellite. We use data from the AKARI NEP-Wide (5.4 deg2) IR survey and the CLusters of galaxies EVoLution studies (CLEVL) mission program. We show that near-IR (3 μm)-mid- IR (11 μm) color can be used as an indicator of the specific star formation rate and the presence of intermediate age stellar populations. From the MIR observations, we find that red-sequence galaxies consist not only of passively evolving red early-type galaxies, but also of 1) "weak-SFG" (disk-dominated star-forming galaxies which have star formation rates lower by \sim 4 \times than blue-cloud galaxies), and 2) "intermediate- MXG" (bulge-dominated galaxies showing stronger MIR dust emission than normal red early-type galaxies). Those two populations can be a set of transition galaxies from blue, star-forming, late-type galaxies evolving into red, quiescent, early-type ones. We find that the weak-SFG are predominant at intermediate masses (1010M\odot < M\star < 1010.5M\odot) and are typically found in local densities similar to the outskirts of galaxy clusters. As much as 40% of the supercluster member galaxies in this mass range can be classified as weak-SFGs, but their proportion decreases to < 10% at larger masses (M\star > 1010.5 M\odot) at any galaxy density. The fraction of the intermediate-MXG among red- sequence galaxies at 1010M\odot < M\star < 1011M\odot also decreases as the density and mass increase. In particular, \sim42% of the red-sequence galaxies with early-type morphologies are classified as intermediate-MXG at intermediate densities. These results suggest that the star formation activity is strongly dependent on the stellar mass, but that the morphological transformation is mainly controlled by the environment.

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