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arXiv 1412.7823astro-ph.CO
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大质量星系团(0.57 < z < 1.33)的重子含量

Baryon Content of Massive Galaxy Clusters (0.57 < z < 1.33)

I. Chiu, J. Mohr, M. Mcdonald, S. Bocquet, M. L. Ashby, M. Bayliss, B. A. Benson, L. E. Bleem, M. Brodwin, S. Desai, J. P. Dietrich, W. R. Forman, C. Gangkofner… 展开作者

I. Chiu, J. Mohr, M. Mcdonald, S. Bocquet, M. L. Ashby, M. Bayliss, B. A. Benson, L. E. Bleem, M. Brodwin, S. Desai, J. P. Dietrich, W. R. Forman, C. Gangkofner, A. H. Gonzalez, C. Hennig, J. Liu, C. L. Reichardt, A. Saro, B. Stalder, S. A. Stanford, J. Song, T. Schrabback, R. Suhada, V. Strazzullo, A. Zenteno

摘要:

我们用南极望远镜(SPT)选取了14个具有中位红移$z=0.9$和中位质量$M_{500}=6\times10^{14}M_{\odot}$的星系团,研究了它们的恒星质量、布里渊星系团质量(BCG)和团内中等质量(ICM)。我们估计恒星质量的每个集群和BCG使用六个测光带的范围从紫外线到近红外观察的VLT,HST和斯皮策。ICM的质量来自钱德拉和XMM-牛顿X射线观测,维里质量来自SPT Sunyaev-Zel'dovich效应签名。在$z=0.9$处,BCG质量$M_{\star}^{\textrm{BCG}}$构成$6\times10^{14}M_{\odot}$簇的晕质量的$0.12\pm0.01$ %,并且该分数落为$M_{500}^{-0.58\pm0.07}$。星系团的恒星质量函数具有特征质量$M_{0}=10^{11.0\pm0.1}M_{\odot}$,星系团中每单位质量的星系数比场中的大$1.65\pm0.2$倍。这两个结果是一致的测量组尺度和较低的红移。我们结合我们的SPT样品与以前发表的样品在低红移,我们纠正一个共同的初始质量函数和维里质量的系统差异。然后,我们探讨质量和红移的恒星分数(fstar),ICM分数(fICM),冷重子分数(fc)和重子分数(fb)的趋势。在枢轴质量为$6\times10^{14}M_{\odot}$和红移$z=0.9$时,特征值为fstar= $1.1\pm0.1$ %,fICM= $9.6\pm0.5$ %,fc= $10.4\pm1.2$ %和fb= $10.7\pm0.6$ %。这些分数都随团簇质量的显著性而变化,表明质量较高的团簇具有较低的fstar和fc以及较高的fICM和fb。当考虑15%的系统维里质量不确定性时,在这些重子分数中,在固定质量下没有统计上显著的红移趋势。(节略)

英文摘要:

We study the stellar, Brightest Cluster Galaxy (BCG) and intracluster medium (ICM) masses of 14 South Pole Telescope (SPT) selected galaxy clusters with median redshift $z=0.9$ and median mass $M_{500}=6\times10^{14}M_{\odot}$. We estimate stellar masses for each cluster and BCG using six photometric bands spanning the range from the ultraviolet to the near-infrared observed with the VLT, HST and Spitzer. The ICM masses are derived from Chandra and XMM-Newton X-ray observations, and the virial masses are derived from the SPT Sunyaev-Zel'dovich Effect signature. At $z=0.9$ the BCG mass $M_{\star}^{\textrm{BCG}}$ constitutes $0.12\pm0.01$% of the halo mass for a $6\times10^{14}M_{\odot}$ cluster, and this fraction falls as $M_{500}^{-0.58\pm0.07}$. The cluster stellar mass function has a characteristic mass $M_{0}=10^{11.0\pm0.1}M_{\odot}$, and the number of galaxies per unit mass in clusters is larger than in the field by a factor $1.65\pm0.2$. Both results are consistent with measurements on group scales and at lower redshift. We combine our SPT sample with previously published samples at low redshift that we correct to a common initial mass function and for systematic differences in virial masses. We then explore mass and redshift trends in the stellar fraction (fstar), the ICM fraction (fICM), the cold baryon fraction (fc) and the baryon fraction (fb). At a pivot mass of $6\times10^{14}M_{\odot}$ and redshift $z=0.9$, the characteristic values are fstar=$1.1\pm0.1$%, fICM=$9.6\pm0.5$%, fc=$10.4\pm1.2$% and fb=$10.7\pm0.6$%. These fractions all vary with cluster mass at high significance, indicating that higher mass clusters have lower fstar and fc and higher fICM and fb. When accounting for a 15% systematic virial mass uncertainty, there is no statistically significant redshift trend at fixed mass in these baryon fractions. (abridged)

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