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VLT and NTT Observations of Two EIS Cluster Candidates. Detection of the Early-Type Galaxies Sequence at z~1

L. da Costa·M. Scodeggio·L. F. Olsen·M. Nonino·R. Rengelink·R. Bender·M. Franx·H. E. Jorgensen·A. Renzini·P. Rosati
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Abstract

Optical data from the ESO VLT-UT1 Science Verification observations are combined with near-infrared data from SOFI at the NTT to obtain optical-infrared color-magnitude diagrams for the objects in the fields of two EIS cluster candidates. In both cases, evidence is found for a well-defined sequence of red galaxies that appear to be significantly more clustered than the background population. These results suggest that the two systems are real physical associations. The (R-Ks), (I-Ks) and (J-Ks) colors of the red sequences are used, in conjunction with similar data for spectroscopically confirmed clusters, to obtain redshift estimates of z ~ 0.9 and z ~ 1.0 for these two systems. These results make these EIS cluster candidates prime targets for follow-up spectroscopic observations to confirm their reality and to measure more accurately their redshift.

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L. da Costa, M. Scodeggio, L. F. Olsen, M. Nonino, R. Rengelink, R. Bender, M. Franx, H. E. Jorgensen, A. Renzini, P. Rosati. 1999-01-19. VLT and NTT Observations of Two EIS Cluster Candidates. Detection of the Early-Type Galaxies Sequence at z~1. https://arxiv.org/abs/astro-ph/9901248

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