arXiv 0901.13182009-01astro-ph.CO

早型布里渊星系团星系团小回视时间结构性质的演化及其对环境的依赖性

Evolution in the structural properties of early-type Brightest Cluster Galaxies at small lookback time and dependence on the environment

M. Bernardi

备注：: 18 pages, 22 figures. Accepted for publication in MNRAS
DOI：: 10.1111/j.1365-2966.2009.14601.x

阅读 PDF

arXiv 页面 ↗HTML 原文 ↗

摘要：

目前，SDSS早型BCGs比类似L的早型星系具有更大的Re，无论这些其他物体是否在现场，或者是星团中的卫星（BCGs的Re ~ L）。在固定的M* 和形成时间，BCGs在较低的z是较大的，并具有较小的速度分散，即Re的增加和sigma随着年龄的下降。结果，在z~0.25处，对应于3阶Gyrs的回望时间，对于最亮的BCGs，BCGs比它们的较低z对应物小多达70%：Re演化为（1+z）^{0.85（Mr+21）}。在大部分早期型粒子群中也可以看到类似但较弱的演化：在Mr<-22时，Re演化为（1+z）^{0.7（Mr+21）}，而在Mr>-22时，演化约为（1+z）^{-0.7}，与Mr无关。σ-L相关性也演化为：（1+z）^{-0.2（Mr+21）}在Mr < -22（对于BCGs）和（1+z）^{0.2}对于暗星系。Re和sigma-M* 相关性产生一致的结果。如果早期类型的BCGs是从许多枯燥的小合并而不是几个大合并中成长起来的，那么这些趋势就很容易理解。只有在这样的情况下，BCGs才可能是z~2处超致密星系的后代;主要的干合并（它会使星系的大小与质量成比例地增加）不能使这些星系在z~0处符合BCGRe-M * 关系。我们还比较了我们的早期型BCGs的年龄和大小与卫星。在相同的红移下，BCGs比类似L或M* 的卫星大。虽然两颗卫星和BCGs都有相同的弱年龄-L或年龄-M * 关系，但这可以通过注意到BCGs通常比它们组中的卫星年长约1 Gyr来理解，并且它们的亮度约为0.5 mags。最后，我们发现，平均卫星L是近似独立的BCG L，在最近的预测的基础上的L-依赖的聚类协议。

英文摘要：

At the present time, SDSS early-type BCGs have larger Re than early-type galaxies of similar L, whether these other objects are in the field, or are satellites in clusters (Re ~ L for BCGs). At fixed M* and formation time, BCGs at lower z are larger and have smaller velocity dispersions, i.e. Re increases and sigma decreases with age. As a result, at z~0.25, corresponding to a lookback time of order 3 Gyrs, BCGs are smaller than their lower z counterparts by as much as 70% for the brightest BCGs: Re evolves as (1+z)^{0.85(Mr+21)}. Qualitatively similar but weaker evolution in the sizes is also seen in the bulk of the early-type population: at Mr<-22 Re evolves as (1+z)^{0.7(Mr+21)}, while at Mr>-22 the evolution is approximately (1+z)^{-0.7}, independent of Mr. The sigma-L correlation also evolves: (1+z)^{-0.2(Mr+21)} at Mr < -22 (as for the BCGs) and (1+z)^{0.2} for fainter galaxies. The Re- and sigma-M* correlations yield consistent results. These trends are most easily understood if early-type BCGs grew from many dry minor mergers rather than a few major mergers. Only in such a scenario can BCGs be the descendents of the superdense galaxies seen at z~2; major dry mergers, which increase the size in proportion to the mass, cannot bring these galaxies onto the BCG Re-M* relation at z~0. We also compared the ages and sizes of our early-type BCGs with satellites. BCGs are larger than satellites of similar L or M* at the same redshift. Although both satellites and BCGs trace the same weak age-L or age-M* relation, this can be understood by noting that BCGs are typically about 1 Gyr older than the satellites in their group, and they are about 0.5 mags more luminous. Finally, we find that the mean satellite L is approximately independent of BCG L, in agreement with recent predictions based on the L-dependence of clustering.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

相关论文