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arXiv 0904.0220astro-ph.CO
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后发座星系团的弱透镜研究

A weak lensing study of the Coma cluster

Raphael Gavazzi, Christophe Adami, Florence Durret, Jean-Charles Cuillandre, Olivier Ilbert, Alain Mazure, Roser Pello, Melville P. Ulmer

摘要:

由于观测的限制,基于弱透镜效应的附近星系团中的暗物质测定仍然非常罕见,尽管它们对于独立于其他方法的星系团性质的测定非常重要。我们提出了一个弱透镜的后发座星系团(红移0.024)的基础上在CFHT获得的深层图像的研究。在获得我们领域中星系的光度红移后,基于u(1x 1 deg 2),以及B,V,R和I波段(42'x52')的深度图像,使我们能够消除前景星系,我们对u图像中进行的形状测量应用弱透镜计算。我们推导出一个地图的质量分布在昏迷,以及径向剪切剖面,在不同半径的质量和浓度参数。我们得到M_200c = 5.1+4.3-2.1 × 10^14 Msun和c_200c=5.0+3.2-2.5,与以前的测量结果很好地吻合。有了深宽视场图像,现在可以用弱透镜技术分析附近的星系团,从而开辟了一个广阔的新研究领域。

英文摘要:

Due to observational constraints, dark matter determinations in nearby clusters based on weak lensing are still extremely rare, in spite of their importance for the determination of cluster properties independent of other methods. We present a weak lensing study of the Coma cluster (redshift 0.024) based on deep images obtained at the CFHT. After obtaining photometric redshifts for the galaxies in our field based on deep images in the u (1x1 deg2), and in the B, V, R and I bands (42'x52'), allowing us to eliminate foreground galaxies, we apply weak lensing calculations on shape measurements performed in the u image. We derive a map of the mass distribution in Coma, as well as the radial shear profile, and the mass and concentration parameter at various radii. We obtain M_200c = 5.1+4.3-2.1 x10^14 Msun and c_200c=5.0+3.2-2.5, in good agreement with previous measurements. With deep wide field images it is now possible to analyze nearby clusters with weak lensing techniques, thus opening a broad new field of investigation.

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