代表性XMM-牛顿星系团结构巡天中最亮星系团的恒星形成和UV颜色
Star formation and UV colors of the brightest Cluster Galaxies in the representative XMM-Newton Cluster Structure Survey
摘要：
我们提出了紫外宽带测光和光发射线测量的代表XMM-牛顿集团结构巡天（REXCESS）的集群中的32 Brilliant集团Galeries（BCGs）的样品z = 0.06-0.18。REXCESS星系团，选择研究星系团的标度关系，具有高质量的X射线测量。用该样品可以研究星形形成和BCG颜色与BCG和宿主性质的趋势。紫外光度法来自XMM光学监测器，并由现有的GALEX档案光度法进行补充。在7个（22%）BCGs中检测到Hα和禁带发射。所有的发射线BCGs占据归类为冷核心的集群，冷核心集群中的BCGs的发射线发生率为70%。Hα等效宽度、BCG中过量的紫外线产生和密集的X射线明亮的短冷却时间内的团内气体之间存在显著的相关性，包括所有Hα发射体都存在于具有短中心冷却时间和高中心ICM密度的系统中。在这7个星系中，基于Hα和UV过剩的恒星形成率估计是一致的，范围从每年0.1-8个太阳质量。REXCESS样品中发射线BCG的发生率是中等的，略低于其他X射线选择的样品（~ 35%），并且略高于但在统计学上与光学选择的略低红移BCG样品一致（~ 10 - 15%）。没有强光发射线的REXCESS BCGs的紫外光学色（UVW 1-R-4.7 \pm 0.3）与由模板和观测的以老恒星星族为主的椭圆星系的结果一致。我们没有看到UV光学颜色与光学亮度、R-K颜色、X射线温度、红移或X射线质心与X射线峰值之间的偏移的趋势（<w>）。
英文摘要：
We present UV broadband photometry and optical emission-line measurements for a sample of 32 Brightest Cluster Galaxies (BCGs) in clusters of the Representative XMM-Newton Cluster Structure Survey (REXCESS) with z = 0.06-0.18. The REXCESS clusters, chosen to study scaling relations in clusters of galaxies, have X-ray measurements of high quality. The trends of star formation and BCG colors with BCG and host properties can be investigated with this sample. The UV photometry comes from the XMM Optical Monitor, supplemented by existing archival GALEX photometry. We detected Hαand forbidden line emission in 7 (22%) of these BCGs, in optical spectra. All of the emission-line BCGs occupy clusters classified as cool cores, for an emission-line incidence rate of 70% for BCGs in cool core clusters. Significant correlations between the Hαequivalent widths, excess UV production in the BCG, and the presence of dense, X-ray bright intracluster gas with a short cooling time are seen, including the fact that all of the Hαemitters inhabit systems with short central cooling times and high central ICM densities. Estimates of the star formation rates based on Hαand UV excesses are consistent with each other in these 7 systems, ranging from 0.1-8 solar masses per year. The incidence of emission-line BCGs in the REXCESS sample is intermediate, somewhat lower than in other X-ray selected samples (-35%), and somewhat higher than but statistically consistent with optically selected, slightly lower redshift BCG samples (-10-15%). The UV-optical colors (UVW1-R-4.7\pm0.3) of REXCESS BCGs without strong optical emission lines are consistent with those predicted from templates and observations of ellipticals dominated by old stellar populations. We see no trend in UV-optical colors with optical luminosity, R-K color, X-ray temperature, redshift, or offset between X-ray centroid and X-ray peak (<w>).
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