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arXiv 0708.3671astro-ph
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强透镜星系团RCS 022434-0002.5(z=0.778)的多波长分析

A Multiwavelength Analysis of the Strong Lensing Cluster RCS 022434-0002.5 at z=0.778

Amalia K. Hicks, Erica Ellingson, Henk Hoekstra, Mike Gladders, Howard Yee, Mark Bautz, David Gilbank, Tracy Webb, Rob Ivison

摘要:

我们提出了两个(共101 ks)钱德拉观测z=0.778光学选择透镜集群RCS 022434 -0002.5的结果,随着弱透镜和动力学分析这个对象。在R(2500)(362 h(70)^(-1)kpc)范围内提取的X射线谱导致5.1(+0.9,-0.5)keV的积分簇温度。RCS 022434 -0002.5的表面亮度曲线表明堆芯中存在轻微过量的发射。这个物体的硬度比图像显示,这个中心发射主要是由软X射线产生的。进一步的研究得出星系团的冷却时间为3.3 × 10^9年,这还不到当前LCDM宇宙学中宇宙年龄的一半。一个弱透镜分析使用HST图像,我们的弱透镜质量估计被发现是在很好的协议与X射线确定的质量的集群。光谱分析显示,RCS 022434 -0002.5的速度色散为900 +/- 180 km/s,与其X射线温度一致。然而,发现RCS 022434 -0002.5的核心气体质量分数比预期的普遍值低三倍。X射线点源的径向分布在这个星团的R(200)范围内,峰值约为0.7 R(200),这可能表明星团势影响了该半径处的活动星系核活动。X射线和无线电(VLA)点源位置之间的相关性也进行了检查。

英文摘要:

We present the results of two (101 ks total) Chandra observations of the z=0.778 optically selected lensing cluster RCS022434-0002.5, along with weak lensing and dynamical analyses of this object. An X-ray spectrum extracted within R(2500) (362 h(70)^(-1) kpc) results in an integrated cluster temperature of 5.1 (+0.9,-0.5) keV. The surface brightness profile of RCS022434-0002.5 indicates the presence of a slight excess of emission in the core. A hardness ratio image of this object reveals that this central emission is primarily produced by soft X-rays. Further investigation yields a cluster cooling time of 3.3 times 10^9 years, which is less than half of the age of the universe at this redshift given the current LCDM cosmology. A weak lensing analysis is performed using HST images, and our weak lensing mass estimate is found to be in good agreement with the X-ray determined mass of the cluster. Spectroscopic analysis reveals that RCS022434-0002.5 has a velocity dispersion of 900 +/- 180 km/s, consistent with its X-ray temperature. The core gas mass fraction of RCS022434-0002.5 is, however, found to be three times lower than expected universal values. The radial distribution of X-ray point sources within R(200) of this cluster peaks at ~0.7 R(200), possibly indicating that the cluster potential is influencing AGN activity at that radius. Correlations between X-ray and radio (VLA) point source positions are also examined.

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