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The environment of a z=2 forming brightest cluster galaxy

Nina Hatch, Leiden Observatory

The high redshift, brightest protocluster galaxy MRC 1138-262 is likely to evolve into a massive cD galaxy. It is encompassed by a 200kpc Ly-alpha halo, has extended diffuse star formation and is surrounded by many satellite galaxies. Using multi-band high resolution imaging, I derive the properties of the central and satellite galaxies. There is a significant dispersion in the properties of these galaxies: half of the satellites are Ly-alpha emitters, while a third are massive and red, with no signs of current star formation. I discuss the differences and similarities between the line-emitting and red satellite galaxies, including morphology, mass and current star formation rate. The properties of the satellite galaxies are compared to other protocluster galaxies, and to simulations of massive galaxy formation. These results are discussed in the context of cosmological models of massive galaxy formation.