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Discovery of an overdensity of faint red galaxies in the vicinity of the z=1.786 radio galaxy 3C 294

S. Toft, K. Pedersen, H. Ebeling, J. Hjorth

astro-pharXiv:astro-ph/0303663

Abstract

We report the discovery of an overdensity of faint red galaxies in the vicinity of the z=1.786 radio galaxy 3C 294. The overdensity, discovered in a 84 min Ks-band ISAAC/VLT image is significant at the 2.4 sigma level (compared to the local field density), and overlaps with the extended X-ray emission around 3C 294 detected with the Chandra X-ray Observatory. The near-infrared colours of the galaxies making up the overdensity show a large scatter and the galaxies do not follow a red sequence in the colour magnitude diagram. If the galaxies are in a cluster at z=1.786 they must be dominated by young stellar populations with different star-formation histories.

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