[GSP2013] 4280 , the SIMBAD biblio

We present the spectroscopic confirmation of a structure of galaxies surrounding the radio galaxy MRC 0156-252 at z=2.02. The structure was initially discovered as an overdensity of both near-infrared selected z>1.6 and mid-infrared selected z>1.2 galaxy candidates. We used the VLT/FORS2 multi-object spectrograph to target ∼80 high-redshift galaxy candidates, and obtain robust spectroscopic redshifts for more than half the targets. The majority of the confirmed sources are star-forming galaxies at z>1.5. In addition to the radio galaxy, two of its close-by companions (<6") also show AGN signatures. Ten sources, including the radio galaxy, lie within |z-2.020|<0.015 (i.e., velocity offsets <1500km/s) and within projected 2Mpc comoving of the radio galaxy. Additional evidence suggests not only that the galaxy structure associated with MRC 0156-252 is a forming galaxy cluster but also that this structure is most probably embedded in a larger-scale structure.