We report evidence of a fully established galaxy cluster at z = 2.07, consisting of a ~20σ 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 7.2×1043 erg s-1 and the stellar mass content of the red galaxy population, we estimate a halo mass of 5.3-8×1013 M_⊙, 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.
A mature cluster with X-ray emission at z = 2.07 / Gobat R.; Daddi E.; Onodera M.; Finoguenov A.; Renzini A.; Arimoto N.; Bouwens R.; Brusa M.; Chary R.-R.; Cimatti A.; Dickinson M.; Kong X.; Mignoli M.. - In: ASTRONOMY & ASTROPHYSICS. - ISSN 0004-6361. - STAMPA. - 526:(2011), pp. 126-133. [10.1051/0004-6361/201016084]
A mature cluster with X-ray emission at z = 2.07
BRUSA, MARCELLA;CIMATTI, ANDREA;
2011
Abstract
We report evidence of a fully established galaxy cluster at z = 2.07, consisting of a ~20σ 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 7.2×1043 erg s-1 and the stellar mass content of the red galaxy population, we estimate a halo mass of 5.3-8×1013 M_⊙, 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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
