Exploring the progenitors of brightest cluster galaxies at z ∼ 2
Exploring the progenitors of brightest cluster galaxies at z ∼ 2
复制标题
DOI：
10.1093/mnras/stw2406
复制
发表时间：
2016-09
影响因子：
4.8
通讯作者：
Dongyao Zhao;C. Conselice;A. Arag'on-Salamanca;O. Almaini;W. Hartley;C. Lani;A. Mortlock;L. Old
中科院分区：
文献类型：
--
作者：
Dongyao Zhao;C. Conselice;A. Arag'on-Salamanca;O. Almaini;W. Hartley;C. Lani;A. Mortlock;L. Old
提出了一种追踪最亮星系团（BCGs）从z ≥ 2到z ≥ 0演化的新方法。我们得出结论的半分析模型的基础上，最好的方法来选择BCG祖在z 102是一个混合环境密度和恒星质量排名的方法。最终，我们能够回收45%的BCG祖细胞。我们将此方法应用于宇宙组装近红外深河外遗留巡天，超深巡天数据，以构建一个高红移的祖先样本。此外，我们还使用斯隆数字巡天数据与统计上可能的污染，以确保高和低红移之间的公平比较，在本地宇宙填充的比较。使用这些样本，我们表明，BCG的大小已经增长了一个因素的10.3.2，因为z 10.2，和BCG的祖先主要是晚型星系，表现出较低的集中配置文件比他们的早期类型的本地同行。我们发现BCG祖细胞具有更多的紊乱形态。相比之下，本地BCG具有更平滑的轮廓。此外，我们还发现BCGs的恒星质量自z 102以来已经增长了2.5倍，并且BCG祖先的星星形成率的中值为13.5百万光年，远高于它们静止的本地后代。我们证明，在z = 1-2星星的形成和合并的贡献相等BCG质量增长。然而，合并在BCG组装中起主导作用。我们还发现，BCG祖细胞在高Z是没有显着不同的其他星系类似的质量在同一时期。这意味着区分BCGs和正常的大质量椭圆星系的过程必须发生在z = 2处。
We present a new method for tracing the evolution of brightest cluster galaxies (BCGs) from z ∼ 2 to z ∼ 0. We conclude on the basis of semi-analytical models that the best method to select BCG progenitors at z ∼ 2 is a hybrid environmental density and stellar mass ranking approach. Ultimately, we are able to retrieve 45 per cent of BCG progenitors. We apply this method on the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey, Ultra Deep Survey data to construct a progenitor sample at high redshift. We furthermore populate the comparisons in local Universe by using Sloan Digital Sky Survey data with statistically likely contamination to ensure a fair comparison between high and low redshifts. Using these samples we demonstrate that the BCG sizes have grown by a factor of ∼3.2 since z ∼ 2, and BCG progenitors are mainly late-type galaxies, exhibiting less concentrated profiles than their early type local counterparts. We find that BCG progenitors have more disturbed morphologies. In contrast, local BCGs have much smoother profiles. Moreover, we find that the stellar masses of BCGs have grown by a factor of ∼2.5 since z ∼ 2, and the star formation rate of BCG progenitors has a median value of 13.5 Mʘ yr‾¹, much higher than their quiescent local descendants. We demonstrate that over z = 1–2 star formation and merging contribute equally to BCG mass growth. However, merging plays a dominant role in BCG assembly at z ≲ 1. We also find that BCG progenitors at high z are not significantly different from other galaxies of similar mass at the same epoch. This suggests that the processes which differentiate BCGs from normal massive elliptical galaxies must occur at z ≲ 2.