Red sequence determination of the redshift of the cluster of galaxies JKCS 041: z ~ 2.2
Résumé
This paper aims at robustly determining the redshift of the cluster of galaxies JKCS 041 and at putting constraints on the formation epoch of the color-magnitude sequence in two very high redshift clusters. New deep z' - J data show a clear narrow red sequence that is co-centered with, and similary concentrated on, the extended X-ray emission of the cluster of galaxies JKCS 041. The JKCS 041 red sequence is 0.32 ± 0.06 mag redder in z' - J than the red sequence of the zspec = 1.62 IRC0218A cluster, putting JKCS 041 at z ≫ 1.62 and ruling out z