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观测到的强透镜星系团的标度关系:宇宙学和星系团组装的结果

Observed Scaling Relations for Strong Lensing Clusters: Consequences for Cosmology and Cluster Assembly

Julia M. Comerford, Leonidas A. Moustakas, Priyamvada Natarajan

摘要:

观测到的星系团性质的标度关系是约束宇宙学参数以及团簇形成历史的有用工具。一个关键的宇宙学参数,sigma 8,约束使用观察到的星系团,虽然目前的估计sigma 8的动态放松的星系团的标度关系是有限的,在观察到的星系团质量-温度(M-T)关系的大的分散。在0.3 < z <0.8的八个强透镜团的样本中,我们发现观察到的团浓度-质量关系可以用于将M-T散射降低6倍。通常,仅松弛的簇被用于估计σ 8,但是将簇浓度-质量关系与M-T关系相结合也使得能够包括非松弛的簇。因此,从集群的sigma 8测量的准确性的所得收益是双重的:sigma 8上的错误减少,集群样本量增加。因此,通过包含非松弛簇,大大改善了关于来自簇的sigma 8确定的统计。进一步探索星系团的标度关系,我们发现最亮星系团(BCG)光度和星系团质量之间的相关性提供了深入了解星系团的组装历史。我们发现了一个陡峭的BCG亮度集群质量关系的强透镜集群比一般集群人口的初步证据,暗示强透镜集群可能有更活跃的合并历史。

英文摘要:

Scaling relations of observed galaxy cluster properties are useful tools for constraining cosmological parameters as well as cluster formation histories. One of the key cosmological parameters, sigma8, is constrained using observed clusters of galaxies, although current estimates of sigma8 from the scaling relations of dynamically relaxed galaxy clusters are limited by the large scatter in the observed cluster mass-temperature (M-T) relation. With a sample of eight strong lensing clusters at 0.3 < z <0.8, we find that the observed cluster concentration-mass relation can be used to reduce the M-T scatter by a factor of 6. Typically only relaxed clusters are used to estimate sigma8, but combining the cluster concentration-mass relation with the M-T relation enables the inclusion of unrelaxed clusters as well. Thus, the resultant gains in the accuracy of sigma8 measurements from clusters are twofold: the errors on sigma8 are reduced and the cluster sample size is increased. Therefore, the statistics on sigma8 determination from clusters are greatly improved by the inclusion of unrelaxed clusters. Exploring cluster scaling relations further, we find that the correlation between brightest cluster galaxy (BCG) luminosity and cluster mass offers insight into the assembly histories of clusters. We find preliminary evidence for a steeper BCG luminosity - cluster mass relation for strong lensing clusters than the general cluster population, hinting that strong lensing clusters may have had more active merging histories.

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