Multi-wavelength study of X-ray luminous clusters at z ~ 0.3 - I. Star-formation activity of cluster galaxies
Multi-wavelength study of X-ray luminous clusters at z ~ 0.3 - I. Star-formation activity of cluster galaxies
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DOI：
10.1051/0004-6361/200811589
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发表时间：
2009-02
影响因子：
6.5
通讯作者：
F. Braglia;D. Pierini;A. Biviano;H. T. M. F. E. Physik;Garching;G. I. A. D. Trieste;Trieste;Italy University of British Columbia;Vancouver.;Bc;Canada.
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文献类型：
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作者：
F. Braglia;D. Pierini;A. Biviano;H. T. M. F. E. Physik;Garching;G. I. A. D. Trieste;Trieste;Italy University of British Columbia;Vancouver.;Bc;Canada.
上下文目前的宇宙形成和星系团演化的范式预见的增长主要是通过合并。在不同的环境应力作用下，星系团的中心和陷落区的星系团都发生了变化。目标。对于两个具有相反X射线形态的红移z = 0.3的X射线发光团簇（即，动力学状态），RXCJ 0014.33022和RXCJ 2308.3-0211，我们评估了星系群作为星系团地形函数的差异。这是一个试点研究的联合X射线和光学分析的REFLEX-DXL集群样品。方法.用B、V、a-ndR波段的联合测光法和低分辨多目标光谱法测定了团簇的大尺度结构和亚结构。测光红移和宽带光学颜色的确定。根据[O II]（λλ3726，3728 A）和Hδ（λ4102 A）特征以及D4000折点，对每个星系团100多个成员星系进行了光谱指数分析。从GALEX档案中检索其他远紫外（FUV）测光。光谱指数和FUV光学颜色的组合提供了星系中恒星形成历史的图像。结果尽管潜在的存在一小部分的星系与模糊的恒星形成活动，星系团成员的平均恒星形成历史被发现依赖于集群中心的距离，更有趣的是，在集群的子结构。这两个星团的核心区域主要是由古老的、被动演化的恒星群体所主导的星系，它们在（B −R）色−R星等图中定义了相同的红色序列。然而，在合并星系团RXCJ 0014.3-3022的两个明显的星系结构上，沿着发现恒星形成活动的急剧增加，直到它的维里半径和更远。它产生
Context. The current paradigm of cosmic formation and evolution of galaxy clusters foresees growth mostly through merging. Galaxies in the infall region or in the core of a cluster undergo transformations owing to different environmental stresses. Aims. For two X-ray luminous clusters at redshift z ∼ 0.3 with opposite X-ray morphologies (i.e., dynamical states), RXCJ 0014.33022 and RXCJ 2308.3-0211, we assess differences in galaxy populations as a function of cluster topography. This is a pilot study for the joint X-ray and optical analysis of the REFLEX-DXL cluster sample. Methods. Cluster large-scale structure and substructure are determined from the combined photometry in the B, V ,a ndR bands, and from multi-object optical spectroscopy at low resolution. Photometric redshifts and broad-band optical colours are determined. A spectral index analysis is performed, based on the [O II](λλ3726, 3728 A) and Hδ(λ4102 A) features, and the D4000 break, which are available for more than 100 member galaxies per cluster. Additional far-ultraviolet (FUV) photometry is retrieved from the GALEX archive. Combination of spectral indices and FUV-optical colours provides a picture of the star-formation history in galaxies. Results. In spite of the potential presence of a small fraction of galaxies with obscured star-formation activity, the average starformation history of cluster members is found to depend on clustercentric distance and, more interestingly, on cluster substructure. The core regions of both clusters mainly host galaxies dominated by old, passively evolving stellar populations, which define the same red sequence in a (B −R) colour−R magnitude diagram. However, a sharp increase in star-formation activity is found along two clearly evident filamentary structures of the merging cluster RXCJ 0014.3-3022, out to its virial radius and beyond. It is produced