Coevolution of brightest cluster galaxies and intracluster light using CLASH
Coevolution of brightest cluster galaxies and intracluster light using CLASH
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DOI：
10.1093/mnras/stv450
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发表时间：
2015-03
影响因子：
4.8
通讯作者：
Claire Burke;M. Hilton;C. Collins
中科院分区：
文献类型：
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作者：
Claire Burke;M. Hilton;C. Collins
利用哈勃望远镜星团透镜和超新星巡天（CLASH）的数据，我们研究了星系团核心的恒星质量集合。我们测量了最亮星系团（BCG）恒星质量的增长，总的集群光中的集群内光（ICL）的比例和在样本的红移范围内，0.18 < z < 0.90的BCG中发生的合并的数量。我们发现，BCGs增长的恒星质量的平均1.4倍，从他们的同伴吸积，这种增长减少到1.2倍，假设50%的吸积恒星质量成为ICL，符合模拟的预测。我们发现，ICL显示出显着的增长在同一红移范围内，增长的4-5倍，其贡献的总集群光。这一结果与我们先前在较高红移下对ICL的研究结果一致，然而，我们测量的增长比ICL组装模拟预测的要陡一些。我们发现高质量的伴星，因此主要的合并（与质量≥ BCG的1/2的物体合并）对我们的样本来说非常罕见。我们的结论是，次要合并（与质量小于BCG的1/2的物体合并）是低红移下恒星质量组装的主要过程，大部分来自相互作用的恒星质量最终贡献给ICL，而不是建立BCG。从一个粗略的估计的恒星质量增长的ICL，我们还得出结论，大多数的ICL恒星必须来自星系的核心以外的集群下降，模拟预测。ICL的增长似乎是宇宙后半期星系团核心的主要演化事件。
We examine the stellar mass assembly in galaxy cluster cores using data from the Cluster Lensing And Supernova survey with Hubble (CLASH). We measure the growth of brightest cluster galaxy (BCG) stellar mass, the fraction of the total cluster light which is in the intracluster light (ICL) and the numbers of mergers that occur in the BCG over the redshift range of the sample, 0.18 < z < 0.90. We find that BCGs grow in stellar mass by a factor of 1.4 on average from accretion of their companions, and this growth is reduced to a factor of 1.2 assuming 50 per cent of the accreted stellar mass becomes ICL, in line with the predictions of simulations. We find that the ICL shows significant growth over this same redshift range, growing by a factor of 4–5 in its contribution to the total cluster light. This result is in line with our previous findings for ICL at higher redshifts, however, our measured growth is somewhat steeper than is predicted by simulations of ICL assembly. We find high-mass companions and hence major merging (mergers with objects of masses ≥1/2 of the BCG) to be very rare for our sample. We conclude that minor mergers (mergers with objects with masses <1/2 of the BCG) are the dominant process for stellar mass assembly at low redshifts, with the majority of the stellar mass from interactions ending up contributing to the ICL rather than building up the BCG. From a rough estimate of the stellar mass growth of the ICL we also conclude that the majority of the ICL stars must come from galaxies which fall from outside of the core of the cluster, as predicted by simulations. It appears that the growth of the ICL is the major evolution event in galaxy cluster cores during the second half of the lifetime of the Universe.