arXiv 1802.016092018-02-05astro-ph.GA

KMOS星系团巡天（KCS）II -环境对红移大质量星系团半导体结构性质的影响$1.39 < z <1.61$

The KMOS Cluster Survey (KCS) II - The Effect of Environment on the Structural Properties of Massive Cluster Galaxies at Redshift $1.39 < z <1.61$

Jeffrey C. C. Chan, Alessandra Beifiori, Roberto P. Saglia, J. Trevor Mendel, John P. Stott, Ralf Bender, Audrey Galametz, David J. Wilman, Michele Cappellari, … 展开作者

Jeffrey C. C. Chan, Alessandra Beifiori, Roberto P. Saglia, J. Trevor Mendel, John P. Stott, Ralf Bender, Audrey Galametz, David J. Wilman, Michele Cappellari, Roger L. Davies, Ryan C. W. Houghton, Laura J. Prichard, Ian J. Lewis, Ray Sharples, Michael Wegner

备注：: Accepted for publication in ApJ. 37 pages, 5 figures
DOI：: 10.3847/1538-4357/aaadb4

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摘要：

本文介绍了KMOS星系团巡天在$1.39<z<1.61$观测的三个星系团中大质量被动星系的结构特性。我们从光学和近红外哈勃太空望远镜成像和空间分辨的恒星质量图测量光加权和质量加权的大小。这些星系的静止坐标系$R$ -带的大小是一个因素的$\sim2-3$小于当地的同行。恒星质量和轻质量大小之间的关系的斜率是一致的，在集群和领域的最新研究。它们的质量加权尺寸小于其余帧$R$ -带尺寸，其中平均质量加权与轻加权尺寸比在簇之间在$\sim0.45$和$0.8$之间变化。我们发现，在两个更进化的集群被动星系的中值轻重量的大小是$\sim24\%$大于场星系，独立的使用圆形的有效半径或半长轴。这两个集群也显示出一个较小的尺寸比进化较少的集群，我们调查使用颜色梯度探测底层的$M_{*}/L_{H_{160}}$梯度。中值颜色梯度为$\nabla{z-H} \sim-0.4$ mag dex $^{-1}$，是局部值的两倍。使用恒星种群模型，这些梯度最好由年龄和金属丰度梯度的组合来再现。我们的研究结果有利于小合并的情况下，占主导地位的过程负责观察到的星系的属性和环境的差异，在这个红移。环境的差异支持集群经历加速的结构演化相比，该领域，可能通过一个时代的增强小合并活动在集群组装。

英文摘要：

We present results on the structural properties of massive passive galaxies in three clusters at $1.39<z<1.61$ from the KMOS Cluster Survey. We measure light-weighted and mass-weighted sizes from optical and near-infrared Hubble Space Telescope imaging and spatially resolved stellar mass maps. The rest-frame $R$-band sizes of these galaxies are a factor of $\sim2-3$ smaller than their local counterparts. The slopes of the relation between the stellar mass and the light-weighted size are consistent with recent studies in clusters and the field. Their mass-weighted sizes are smaller than the rest frame $R$-band sizes, with an average mass-weighted to light-weighted size ratio that varies between $\sim0.45$ and $0.8$ among the clusters. We find that the median light-weighted size of the passive galaxies in the two more evolved clusters is $\sim24\%$ larger than for field galaxies, independent of the use of circularized effective radii or semi-major axes. These two clusters also show a smaller size ratio than the less evolved cluster, which we investigate using color gradients to probe the underlying $M_{*}/L_{H_{160}}$ gradients. The median color gradients are $\nabla{z-H} \sim-0.4$ mag dex$^{-1}$, twice the local value. Using stellar populations models, these gradients are best reproduced by a combination of age and metallicity gradients. Our results favor the minor merger scenario as the dominant process responsible for the observed galaxy properties and the environmental differences at this redshift. The environmental differences support that clusters experience accelerated structural evolution compared to the field, likely via an epoch of enhanced minor merger activity during cluster assembly.

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