The Hubble Space Telescope GOODS NICMOS Survey: overview and the evolution of massive galaxies at 1.5< z< 3

We present the details and early results from a deep near-infrared survey utilizing the NICMOS instrument on the Hubble Space Telescope centred around massive M_* > 10¹¹ M_⊙ galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields North and South. The GOODS NICMOS Survey (GNS) was designed to obtain deep F160W (H-band) imaging of 80 of these massive galaxies and other colour-selected objects such as Lyman-break dropouts, BzK objects, distant red galaxies (DRGs), extremely red objects (EROs), Spitzer-selected EROs, BX/BM galaxies, as well as flux-selected submillimetre galaxies. We present in this paper details of the observations, our sample selection, as well as a description of the properties of the massive galaxies found within our survey fields. This includes photometric redshifts, rest-frame colours and stellar masses. We furthermore provide an analysis of the selection methods for finding massive galaxies at high redshifts, including colour-selection methods and how galaxy populations selected through these colour methods overlap. We find that a single colour selection method cannot locate all of the massive galaxies, with no one method finding more than 70 per cent. We however find that the combination of these colour methods finds nearly all of the massive galaxies that would have been identified in a photometric redshift sample, with the exception of apparently rare blue massive galaxies. By investigating the rest-frame (U-B) versus M_B diagram for these galaxies, we furthermore show that there exists a bimodality in colour-magnitude space at z < 2, driven by stellar mass, such that the most massive galaxies are systematically red up to z∼ 2.5, while lower mass galaxies tend to be blue. We also discuss the number densities for galaxies with stellar masses M_* > 10¹¹ M_⊙, whereby we find an increase of a factor of 8 between z= 3 and 1.5, demonstrating that this is an epoch when massive galaxies establish most of their stellar mass. We also provide an overview of the evolutionary properties of these galaxies, such as their merger histories, and size evolution.