用新的测光红移方法研究星系团Abell 2199

Study of Galaxies Cluster Abell 2199 Using New Photometric Redshifts Technique

Sloan数字巡天第4批数据的释放（SDSSDR4）提供了新的星系团观测数据。采用最新研究的测光红移技术对Abell 2199没有光谱红移的星系进行了测光红移估计，挑选出了一批暗的成员星系候选体，使得样本的数量比单独用NED的样本增加了近1／4。通过对样本中470个成员星系运用k-test所得到的结果分析得出，原来确定的各子团星系的数目有所增加，但biweight位置和尺度与原来研究的各子团biweight位置和尺度值相比没有太大的变化。通过对团星系的空间分布和方位角的估算，可看出从核区到～5．5。的特大尺度，由于引力作用而显示出线性排列方式，揭示了一个延展到8．0h^-1Mpc由星系或暗物质组成的纤维状结构，进一步支持了星系形成的等级结构模型。

With the fourth data of Sloan Digital Sky Survey （ SDSS DR4） being released, more and more data of galaxies clusters become available. The photometric redshifts （PRs） estimation of galaxies cluster Abell 2199 which have no spectroscopic observation are performed using the recent PR technique. A number of faint member galaxy candidates are selected. There is one fourth increase in the number of member galaxies compared with those only from NED. 470 newly selected galaxies are analyzed using k-test. There is no remarkable change between this analysis and early results for biweight location and scale of this cluster. From the spatial distribution and the shape of Abell 2199, the ellipticity and position angle coincides remarkably with those in previous studies from a very small core region to a very large area （～5. 5°）. Some neighboring groups and dusters beyond the virial region of A2199 are roughly colinear, suggesting the presence of an extended （8.0 h^-1 Mpc） filament of galaxies and/or dark matter. The identification of this filament provides a direct support for hierarchical model of structure formation.