The formation history of massive cluster galaxies as revealed by CARLA
The formation history of massive cluster galaxies as revealed by CARLA
复制标题
DOI：
10.1093/mnras/stv1413
复制
发表时间：
2015-07
影响因子：
4.8
通讯作者：
E. Cooke;N. Hatch;A. Rettura;D. Wylezalek;A. Galametz;D. Stern;M. Brodwin;S. I. Muldrew;O. Almaini;C. Conselice;P. Eisenhardt;W. Hartley;M. Jarvis;M. Jarvis;N. Seymour;S. Stanford
中科院分区：
文献类型：
--
作者：
E. Cooke;N. Hatch;A. Rettura;D. Wylezalek;A. Galametz;D. Stern;M. Brodwin;S. I. Muldrew;O. Almaini;C. Conselice;P. Eisenhardt;W. Hartley;M. Jarvis;M. Jarvis;N. Seymour;S. Stanford
我们使用了来自射电活动星系核周围星团巡天（CARLA）的37个1.3 ≤ z ≤ 3.2的致密星团和原星团样本来研究大质量星系团的形成。我们使用光学i′波段和红外3.6和4.5 μm图像来统计选择这些原星系团中的源，并测量它们的中值观测颜色; i′ − [3.6]。我们发现原星系团中大质量星系的丰度随着红移的减小而增加，这表明这些天体可能形成一个演化序列，样本中的低红移星系团与高红移原星系团的后代具有相似的性质。我们发现原星系团星系在所研究的红移范围内具有近似不演化的双标架i′ − [3.6]色。我们比较了大质量星系团星系的i′ − [3.6]色的演化与简单的星系形成模型。考虑到整个星系团的人口，我们表明，在大多数大质量星系团中的恒星形成发生在至少2 Gyr，并在z = 2-3处达到峰值。从中值i′ − [3.6]色，我们不能确定单个星系的星星形成历史，但它们的星星形成必须迅速终止，以产生观察到的红色。最后，我们表明，z > 2的大质量星系必须在它们的0.5 Gyr范围内聚集，形成它们的恒星的重要组成部分。这意味着z > 2的原星系团中很少有大质量星系是通过干合并形成的。
We use a sample of 37 of the densest clusters and protoclusters across 1.3 ≤ z ≤ 3.2 from the Clusters Around Radio-Loud AGN (CARLA) survey to study the formation of massive cluster galaxies. We use optical i′-band and infrared 3.6 and 4.5 μm images to statistically select sources within these protoclusters and measure their median observed colours; 〈i′ − [3.6]〉. We find the abundance of massive galaxies within the protoclusters increases with decreasing redshift, suggesting these objects may form an evolutionary sequence, with the lower redshift clusters in the sample having similar properties to the descendants of the high-redshift protoclusters. We find that the protocluster galaxies have an approximately unevolving observed-frame i′ − [3.6] colour across the examined redshift range. We compare the evolution of the 〈i′ − [3.6]〉 colour of massive cluster galaxies with simplistic galaxy formation models. Taking the full cluster population into account, we show that the formation of stars within the majority of massive cluster galaxies occurs over at least 2 Gyr, and peaks at z ∼ 2–3. From the median i′ − [3.6] colours, we cannot determine the star formation histories of individual galaxies, but their star formation must have been rapidly terminated to produce the observed red colours. Finally, we show that massive galaxies at z > 2 must have assembled within 0.5 Gyr of them forming a significant fraction of their stars. This means that few massive galaxies in z > 2 protoclusters could have formed via dry mergers.