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arXiv 1406.4528astro-ph.GAastro-ph.CO
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$0.8<z<1$星系群的GEEC2光谱巡天

The GEEC2 spectroscopic survey of Galaxy Groups at $0.8<z<1$

Michael L. Balogh, Sean L. McGee, Angus Mok, David J. Wilman, Alexis Finoguenov, Richard Bower, John S. Mulchaey, Laura C. Parker, Masayuki Tanaka

摘要:

我们目前的数据发布的双子座南GMOS光谱的领域中的11个星系群在$0.8<z<1$,在COSMOS领域。这构成了银河系环境演化协作2(GEEC 2)项目的基础,该项目旨在研究星系在整个宇宙时间内与$M\sim 10^{13}M_\odot$的晕演化。最后的样品包括$162$光谱-确认成员与$R<24.75$,是$>50$百分之完成的维里半径内的星系,并与恒星质量$M_{\rm star}>10^{10.3}M_\odot$。包括星系的光度红移,我们有一个有效的样本大小的$\sim 400$星系的维里半径内,这些团体。我们目前的群速度色散,动力学和恒星质量。结合GCLASS中相同红移的大质量星系团的样本,我们发现恒星的总质量与动力学质量有很强的相关性,具有$\log{M_{200}}=1.20\left(\log{M_{\rm star}}-12\right)+14.07$。这个恒星的比例为$~\sim 1$ %,低于一些晕占据分布模型的预测,但对晕质量的弱依赖性是一致的。大多数群体有一个容易识别的最大质量的星系(MMG)附近的星系分布的中心,我们提出的光谱特性和表面亮度适合这些星系。总的恒星质量分布的群体,不包括MMG,比较以及与浓度$4$的NFW配置文件,超过$\sim 0.2R_{200}$的星系。这比数量密度分布更集中,表明存在一些质量偏析。

英文摘要:

We present the data release of the Gemini-South GMOS spectroscopy in the fields of 11 galaxy groups at $0.8<z<1$, within the COSMOS field. This forms the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project to study galaxy evolution in haloes with $M\sim 10^{13}M_\odot$ across cosmic time. The final sample includes $162$ spectroscopically--confirmed members with $R<24.75$, and is $>50$ per cent complete for galaxies within the virial radius, and with stellar mass $M_{\rm star}>10^{10.3}M_\odot$. Including galaxies with photometric redshifts we have an effective sample size of $\sim 400$ galaxies within the virial radii of these groups. We present group velocity dispersions, dynamical and stellar masses. Combining with the GCLASS sample of more massive clusters at the same redshift we find the total stellar mass is strongly correlated with the dynamical mass, with $\log{M_{200}}=1.20\left(\log{M_{\rm star}}-12\right)+14.07$. This stellar fraction of $~\sim 1$ per cent is lower than predicted by some halo occupation distribution models, though the weak dependence on halo mass is in good agreement. Most groups have an easily identifiable most massive galaxy (MMG) near the centre of the galaxy distribution, and we present the spectroscopic properties and surface brightness fits to these galaxies. The total stellar mass distribution in the groups, excluding the MMG, compares well with an NFW profile with concentration $4$, for galaxies beyond $\sim 0.2R_{200}$. This is more concentrated than the number density distribution, demonstrating that there is some mass segregation.

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