We have studied the spatial clustering of high redshift ( z > 1 ) extremely red objects ( EROs ) as a function of photometric redshift in the GOODS Southern Field using public data .
A remarkable overdensity of extremely red galaxies ( I - K _ { s } > 4 ) is found at an average photometric redshift z _ { phot } = 1.10 .
Nine objects ( six are EROs ) within 50 arcsec of the brightest infrared galaxy in this overdensity present spectroscopic redshifts in the range 1.094 < z _ { spec } < 1.101 with a line-of-sight velocity dispersion of \sigma _ { v } = 433 ^ { +152 } _ { -74 } km s ^ { -1 } typical of an Abell richness class R = 0 cluster .
Other potential members of this cluster , designated as GCL J0332.2-2752 , have been identified using photometric redshifts and the galaxy density profile studied as a function of radius .
The mass of the cluster is preliminary estimated at M _ { cl } \sim 5 - 7 \times 10 ^ { 13 } M _ { \sun } .
Using available Chandra data , we limit the rest-frame X-ray luminosity of the cluster to less than L _ { X } = 7.3 \times 10 ^ { 42 } erg s ^ { -1 } ( 0.5-2.0 keV ) .
This low-mass , low L _ { X } cluster at z > 1 shows the potential of EROs to trace clusters of galaxies at high redshift .