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arXiv · 1011.1837

A mature cluster with X-ray emission at z=2.07

R. Gobat·E. Daddi·M. Onodera·A. Finoguenov·A. Renzini·N. Arimoto·R. Bouwens·M. Brusa·R. -R. Chary·A. Cimatti·M. Dickinson·X. Kong·M. Mignoli
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Abstract

We report evidence of a fully established galaxy cluster at z=2.07, consisting of a ~20sigma overdensity of red, compact spheroidal galaxies spatially coinciding with extended X-ray emission detected with XMM-Newton. We use VLT VIMOS and FORS2 spectra and deep Subaru, VLT and Spitzer imaging to estimate the redshift of the structure from a prominent z=2.07 spectroscopic redshift spike of emission-line galaxies, concordant with the accurate 12-band photometric redshifts of the red galaxies. Using NICMOS and Keck AO observations, we find that the red galaxies have elliptical morphologies and compact cores. While they do not form a tight red sequence, their colours are consistent with that of a >1.3$~Gyr population observed at z~2.1. From an X-ray luminosity of .2*10^43 erg s^-1 and the stellar mass content of the red galaxy population, we estimate a halo mass of 5.3-8*10^13 Msun, comparable to the nearby Virgo cluster. These properties imply that this structure could be the most distant, mature cluster known to date and that X-ray luminous, elliptical-dominated clusters are already forming at substantially earlier epochs than previously known.

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R. Gobat, E. Daddi, M. Onodera, A. Finoguenov, A. Renzini, N. Arimoto, R. Bouwens, M. Brusa, R. -R. Chary, A. Cimatti, M. Dickinson, X. Kong, M. Mignoli. 2010-11-08. A mature cluster with X-ray emission at z=2.07. https://doi.org/10.1051/0004-6361/201016084

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